INTRODUCTION

The benefits of combining enhanced recovery after surgery (ERAS) interventions with an outpatient THA/TKA program are uncertain. The primary objective was to compare adverse event rate and secondly to compare pain management, functional recovery, PROMs and patients' satisfaction.

Mechanical alignment (MA) techniques for total knee arthroplasty (TKA) may introduce significant anatomic modifications, as it is known that few patients have neutral femoral, tibial or overall lower limb mechanical axes.

A total of 1000 knee CT-Scans were analyzed from a database of patients undergoing TKA. MA tibial and femoral bone resections were simulated. Femoral rotation was aligned with either the trans-epicondylar axis (TEA) or with 3° of external rotation to the posterior condyles (PC). Medial-lateral (DML) and flexion-extension (DFE) gap differences were calculated.

Extension space ML imbalances (3mm) occurred in 25% of varus and 54% of valgus knees and significant imbalances (5mm) were present in up to 8% of varus and 19% of valgus knees. For the flexion space DML, higher imbalance rates were created by the TEA technique (p < 0 .001). In valgus knees, TEA resulted in a DML in flexion of 5 mm in 42%, compared to 7% for PC. In varus knees both techniques performed better. When all the differences between DML and DFE are considered together, using TEA there were 18% of valgus knees and 49% of varus knees with < 3 mm imbalances throughout, and using PC 32% of valgus knees and 64% of varus knees.

Significant anatomic modifications with related ML or FE gap imbalances are created using MA for TKA. Using MA techniques, PC creates less imbalances than TEA. Some of these imbalances may not be correctable by the surgeon and may explain post-operative TKA instability. Current imaging technology could predict preoperatively these intrinsic imitations of MA. Other alignment techniques that better reproduce knee anatomies should be explored.

Assessing patients' functional outcomes following total hip arthroplasty with traditional scoring systems is limited by their ceiling effects. The Forgotten Joint Score (FJS) has been suggested as a more discriminating option. The actual score in the FJS which constitutes a “forgotten joint”, however, has not been defined. The emerging concept of joint perception led to the development of the Patient's Joint Perception question (PJP) to assess the patient's opinion of their prosthetic joint.

Two hundred fifty-seven THAs were assessed at a mean of 68 months follow-up (range 57–79). Outcomes included the WOMAC, FJS and the PJP. Correlation of the scores as well as the ceiling effects were analysed

The mean FJS was 88.5 (range 27.1–100). PJP was correlated with the FJS and WOMAC (Spearman's rho: −0.510 and 0.465 respectively). Fifty-two percent of the patients felt their hip as a natural joint (FJS CI 95% 93.3–96), 24.1% as an artificial joint with no restriction (FJS CI 95% 83.1–90.5), and 23.3% as an artificial joint with minor restrictions (FJS CI 95% 73.8–82.2). Only 0.8% had major restrictions and none reported a non-functional joint. The ceiling effect was high with both the WOMAC and FJS, with 27.2% and 31.9%. In addition, 28.6% of the patients had a WOMAC >10 and 23.4% a FJS of < 9 0 while reporting having a natural hip. Furthermore, 21.5% with a perfect WOMAC or 21.9% with a perfect FJS, reported having an artificial joint with or without limitation.

A forgotten hip perception corresponds to a FJS >93. In 20–30% of the cases, the WOMAC and FJS failed to identify the forgotten joint, or reached the maximum score when the patients did not feel their hip was natural. The PJP is a simple and reliable tool that enables identification of patients that feel their hip is natural.

For many years, achieving a neutral coronal Hip-Knee-Ankle angle (HKA) measured on radiographs has been considered a factor of success for total knee arthroplasty (TKA). Lower limb HKA is influenced by the acquisition conditions, and static HKA (sHKA) may not be representative of the dynamic loading that occurs during gait. The primary aim of the study was to see if the sHKA is predictive of the dynamic HKA (dHKA). A secondary aim was to document to what degree the dHKA changes throughout gait.

We analysed the 3-D knee kinematics during gait of a cohort of 90 healthy individuals (165 knees) with the KneeKG™ system. dHKA was calculated and compared with sHKA values. Knees were considered “Stable” if the dHKA remained positive or negative – i.e. in valgus or varus – for greater than 95% of the corresponding phase and “Changer” otherwise. Patient characteristics of the Stable and Changer knees were compared to find contributing factors.

The dHKA absolute variation during gait was 10.9±5.3° [2 .4° – 28.3°] for the whole cohort. The variation was greater for the varus knees (10.3±4.8° [2.4° – 26.3°]), than for the valgus knees (12.8±6.1° [2.9° – 28.3°], p=0.008). We found a low to moderate correlation (r = 0.266 to 0.553, p < 0 .001) between sHKA and the dHKA values for varus knees and no correlation valgus knees. Twenty two percent (36/165) of the knees demonstrated a switch in the dHKA (Changer). Proportion of Changer knees was 15% for varus sHKA versus 39% for valgus sHKA (p < 0.001).

Lower limb radiographic measures of coronal alignment have limited value for predicting dynamic measures of alignment during gait.

Mechanical alignment (MA) techniques for total knee arthroplasty (TKA) introduces significant anatomic modifications and secondary ligament imbalances. A restricted kinematic alignment (rKA) protocol was proposed to minimise these issues and improve TKA clinical results.

A total of 1000 knee CT-Scans were analyzed from a database of patients undergoing TKA. rKA tibial and femoral bone resections were simulated. rKA is defined by the following criteria: Independent tibial and femoral cuts within ± 5° of the bone neutral mechanical axis and, a resulting HKA within ± 3° of neutral. Medial-lateral (ΔML) and flexion-extension (ΔFE) gap differences were calculated and compared with MA results. With the MA technique, femoral rotation was aligned with either the trans-epicondylar axis (TEA) or with 3° of external rotation to the posterior condyles (PC).

Extension space ML imbalances (>/=3mm) occurred in 33% of TKA with MA technique versus 8% of the knees with rKA (p /=5mm) were present in up to 11% of MA knees versus 1% rKA (p < 0 .001). Using the MA technique, for the flexion space ΔML, higher imbalance rates were created by the TEA technique (p < 0 .001). rKA again performed better than both MA techniques using TEA of 3 degrees PC techniques (p < 0 .001). When all the differences between ΔML and ΔFE are considered together: using TEA there were 40.8% of the knees with < 3 mm imbalances throughout, using PC this was 55.3% and using rKA it was 91.5% of the knees (p < 0 .001).

Significantly less anatomic modifications with related ML or FE gap imbalances are created using rKA versus MA for TKA. Using rKA may help the surgeon to balance a TKA, whilst keeping the alignment within a safe range.

Background

Achieving a neutral static Hip-Knee-Ankle angle (sHKA) measured on radiographs has been considered a factor of success for total knee arthroplasty (TKA). However, recent studies have shown that sHKA seems to have no effect on TKA survivorship. sHKA is not representative of the dynamic loading occurring during gait, unlike the dynamic HKA (dHKA).

INTRODUCTION

In recent years, there has been a shift toward outpatient and short-stay protocols for patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). We developed a peri-operative THA and TKA short stay protocol following the Enhance Recovery After Surgery principles (ERAS), aiming at both optimizing patients’ outcomes and reducing the hospital length of stay. The objective of this study was to evaluate the implementation of our ERAS short-stay protocol. We hypothesized that our ERAS THA and TKA short-stay protocol would result in a lower complication rate, shorter hospital length of stay and reduced direct health care costs compared to our standard procedure.

Background

Mechanical alignment (MA) techniques for total knee arthroplasty (TKA) introduce significant anatomic modifications and secondary ligament imbalances. A restricted kinematic alignment (rKA) protocol was proposed to minimize these issues and improve TKA clinical results.

Background

Assessing patients’ functional outcomes following total knee arthroplasty (TKA) with traditional scoring systems is limited by their ceiling effects. The Forgotten Joint Score (FJS) has been suggested as a more discriminating option. The actual score in the FJS which constitutes a “forgotten joint,” however, has not been defined. The emerging concept of joint perception led to the development of the Patient's Joint Perception question (PJP) to assess the patient's opinion of their prosthetic joint.

INTRODUCTION

Mechanical alignment in TKA introduces significant anatomic modifications for many individuals, which may result in unequal medial-lateral or flexion-extension bone resections. The objective of this study was to calculate bone resection thicknesses and resulting gap sizes, simulating a measured resection mechanical alignment technique for TKA.

Aims

This study reports the mid-term results of total hip arthroplasty (THA) performed using a monoblock acetabular component with a large-diameter head (LDH) ceramic-on-ceramic (CoC) bearing.

The mechanical alignment (MA) for Total Knee Arthroplasty (TKA) with neutral alignment goal has had good overall long-term outcomes. In spite of improvements in implant designs and surgical tools aiming for better accuracy and reproducibility of surgical technique, functional outcomes of MA TKA have remained insufficient. Therefore, alternative, more anatomicaloptions restoring part (adjusted MA (aMA) and adjusted kinematic alignment (aKA) techniques) or the entire constitutional frontal deformity (unicompartment knee arthroplasty (UKA) and kinematic alignment (KA) techniques) have been developed, with promising results. The kinematic alignment for TKA is a new and attractive surgical technique enabling a patient specific treatment. The growing evidence of the kinematic alignment mid-term effectiveness, safety and potential short falls are discussed in this paper. The current review describes the rationale and the evidence behind different surgical options for knee replacement, including current concepts in alignment in TKA. We also introduce two new classification systems for “implant alignments options” (Figure 1) and “osteoarthritic knees” (Figure 2) that would help surgeons to select the best surgical option for each patient. This would also be valuable for comparison between techniques in future research.

For figures/tables, please contact authors directly.

The mechanical alignment (MA) for Total Knee Arthroplasty (TKA) with neutral alignment goal has had good overall long-term outcomes. In spite of improvements in implant designs and surgical tools aiming for better accuracy and reproducibility of surgical technique, functional outcomes of MA TKA have remained insufficient. Therefore, alternative, more anatomical options restoring part (adjusted MA (aMA) and adjusted kinematic alignment (aKA) techniques) or the entire constitutional frontal deformity (unicompartment knee arthroplasty (UKA) and kinematic alignment (KA) techniques) have been developed, with promising results. The kinematic alignment for TKA is a new and attractive surgical technique enabling a patient specific treatment. The growing evidence of the kinematic alignment mid-term effectiveness, safety and potential short falls are discussed in this paper. The current review describes the rationale and the evidence behind different surgical options for knee replacement, including current concepts in alignment in TKA. We also introduce two new classification systems for “implant alignments options” and “osteoarthritic knees” that would help surgeons to select the best surgical option for each patient. This would also be valuable for comparison between techniques in future research.

Management of pseudotumours associated with MoM THA can be difficult and complications are frequent. The functional outcome of patients after revision surgery may be suboptimal. The objective of this study was to assess our experience with revisions of failed MoM THA due to pseudotumours.

78 hips were diagnosed with pseudotumours in 70 patients following metal-on-metal hip replacements. Of these, 68 MoM THA were revised in 62 patients. Pre operative symptoms, radiographic analysis, metal ion levels, MRI results, intra-operative findings, WOMAC scores, the satisfaction level and the complication rate were recorded.

Five patients had a resurfacing arthroplasty as their primary implants while the remaining 63 hips in 57 patients had MoM THA of different brands. The average time between the primary and revision surgery was 69 months (range 15–120). The average age at revision was 59 years (43–87). The mean follow-up was 24 months (range 2–73). 36 patients had minimal one year follow-up. Most lesions consisted of cystic changes and solid lesions were observed in 19 patients. In 57 hips, the pseudotumours were located posteriorly or postero-laterally around the greater trochanter. Intra operatively, muscle necrosis was observed in 15(22%) patients. Most THA cases demonstrated wear and corrosion at the head neck junction of the femoral implants. Thirty-five patients (44.9%) had greater than 50 degrees of cup abduction, including 10 patients (12.8%) with an abduction angle greater than 60 degrees. The average pre operative and postoperative Co ion levels were 27.46 ug/L (range 0.36–145.6) and 2.46 (range 0.4–12.48), respectively. Post revision, a total of 10 hips (14.7%) sustained a dislocation, with seven (10.3%) of them experiencing recurrent dislocations. In 8/10 hips, the femoral head size was 36mm or greater. Revision for dislocation occurred in seven(10.3%) patients. Three(4.4%) deep and one(1.47%) superficial infections occurred and deep infections were re-operated. One(1.47%) fracture of the greater trochanter and one (1.47%) psoas tendinitis did not need revision. Therefore, a total of 10 patients (14.7%) were reoperated. 6 revisions for instability were performed in the first 34 patients, while 1 were done in the last 34 patients. At one year post revision surgery, the mean WOMAC score was 19.68 (range 0–48). In comparison, the mean WOMAC score of the same patients one year after their primary surgery was 8.1 (0–63). Patient satisfaction level of patients one year post revision surgery was 7.61 (range 5–10) compared to 4.15 (range 0–7) pre-revision one.

The complication rate after revision of pseudotumours is high. Most re revisions occurred secondary to instability despite the use of larger femoral heads. The functional outcome at one year post revision seems to be lower than that seen after primary THA but similar to other revisions in the literature. Experience in the management of these patients may reduce the complication rate.

Modifying Knee anatomy during mechanical Total Knee Arthroplasty (TKA) may impact ligament balance, patellar tracking and quadriceps function. Although well fixed, patients may report high levels (20%) of dissatisfaction. One theory is that putting the knee in neutral mechanical alignment may be responsible for these unsatisfactory results. Kinematic TKA has gained interest in recent years; it aims to resurface the knee joint and preservation of natural femoral flexion axis about which the tibia and patella articulate, recreating the native knee without the need for soft tissue relaease. That's being said, it remains the question of whether all patients are suitable for kinematic alignment. Some patients' anatomy may be inherently biomechanically inferior and recreating native anatomy in these patients may result in early implant failure. The senior author (PAV) has been performing Kinematic TKA since 2011, and has developed an algorithm in order to better predict which patient may benefit from this technique.

Lower limb CT scans from 4884 consecutive patients scheduled for TKA arthroplasty were analysed. These exams were performed for patient-specific instrumentation production (My Knee®, Medacta, Switzerland). Multiple anatomical landmarks used to create accurate CT-based preoperative planning and determine the mechanical axis of bone for the femur and tibia and overall Hip-knee-Ankle (HKA). We wanted to test the safe range for kinematic TKA for the planned distal resection of the femur and tibia. Safe range algorithm was defined as the combination of the following criteria: – Independent tibial and femoral cuts within ± 5° of the bone neutral mechanical axis and HKA within ± 3°. The purpose of this study is to verify the applicability of the proposed safe range algorithm on a large sample of individual scheduled for TKA.

The preoperative tibial mechanical angle average 2.9 degrees in varus, femoral mechanical angle averaged 2.7 degrees in valgus and overall HKA averaged of 0.1 in varus. There were 2475 (51%) knees out of 4884, with femur and tibia mechanical axis within ±5° and HKA within ±3° without need for bony corrections. After applying the algorithm, a total of 4062 cases (83%) were successfully been evaluated using the proposed protocol to reach a safe range of HKA ±3° with minimal correction. The remaining 822 cases (17%) could not be managed by the proposed algorithm because of their unusual anatomies and were dealt with individually.

In this study, we tested a proposed algorithm to perform kinematic alignment TKA avoiding preservation/restoration of some extreme anatomies that might not be suitable for TKA long-term survivorship. A total of 4062 cases (83%) were successfully eligible for our proposed safe range algorithm for kinematic TKA. In conclusion, kinematically aligned TKA may be a promising option to improve normal knee function restoration and patient satisfaction. Until we have valuable data confirming the compatibility of all patients' pre arthritic anatomies with TKA long-term survivorship, we believe that kinematically alignment should be performed within some limits. Further studies with Radiostereometry or longer follow up might help determine if all patients' anatomies are suitable for Kinematic TKA.

Large bearing surfaces are appealing in total hip arthroplasty (THA) as they may help create a greater range of impingement free motion and reduce the risk of dislocation. However, attempts to achieve this with a metal bearing surface have been blighted by adverse reactions to metal debris. Ceramic bearings have a good long-term track record in more conventional head sizes, and manufacturing techniques now permit the use of larger ceramic bearing surfaces using monoblock uncemented acetabular components. In this study, we are reviewing the early results of the Maxera® acetabular component (Zimmer, Indiana) at our institution.

All data was collected prospectively. Maxera® acetabular component is a Titanium (Ti) shell with plasma sprayed Ti for the osteointegrative surface. Delta ceramic liner is inserted & locked into the cup shell by the manufacturer (non-modular). With the Maxera cup system, the bearing diameter is dictated by the acetabular component size. Acetabular components (AC) of 46 and 48 mm have a bearing diameter (BD) of 36 mm, AC of 50 and 52 mm: have a 40 mm BD, AC of 54 and 56 mm: have a BD of 44 mm and AC of 58–64: have a 48mm BD. Delta ceramic femoral head size of 44 and 48 mm have a modular Ti sleeve between the head and femoral stem trunnion. Femoral head sizes of 36 and 40 mm have no Ti sleeve. All THA had an uncemented femoral stem. Implants were inserted with a posterior approach. Patients were reviewed at 6 weeks, 6 months and then annually with radiographs. Clinical function was evaluated using WOMAC and UCLA scores along with joint perception questionnaires.

Five hundred components have been implanted in 442 patients (250 women, 192 men) with a mean age of 55, (min 17, max 80) and a mean BMI of 26.9 (min 17.8, max 51). The mean acetabular size was 54 (min 46, max 64), leading to a mean femoral head size of 44. At a minimum of two years follow-up (mean 3.8 years): 5 patients have been revised, 4 secondary to undetected intraoperative fracture of the femur and only one due to early displacement of a Maxera® cup (0.2%). Five patients reported a mild squeaking; two reported clicking and one patient presented with a symptomatic heterotopic ossification. The WOMAC score improved significantly post-operatively, (57.4 compared to 4.4 post-operatively, p<0.001). The mean post-operative UCLA score was 6.9. Sixty percent (60.6%) of patients rated their joint perception as either “natural” or “artificial without limitation”. two patients (0.4%) suffered a dislocation after high velocity trauma without recurrence after closed reduction. No ceramic component fracture was recorded.

This prospective study shows that this monoblock acetabular component provides an easy implantation with minimal complications. The ceramic bearing surface provides good clinical function and joint perception. Bearing surfaces of this design may provide an alternative to large head metal on metal (MoM) implants without the side effects of metal debris/ions.

This randomised trial evaluated the outcome of a single design of unicompartmental arthroplasty of the knee (UKA) with either a cemented all-polyethylene or a metal-backed modular tibial component. A total of 63 knees in 45 patients (17 male, 28 female) were included, 27 in the all-polyethylene group and 36 in the metal-backed group. The mean age was 57.9 years (39.6 to 76.9). At a mean follow-up of 6.4 years (5 to 9.9), 11 all-polyethylene components (41%) were revised (at a mean of 5.8 years; 1.4 to 8.0) post-operatively and two metal-backed components were revised (at one and five years). One revision in both groups was for unexplained pain, one in the metal-backed group was for progression of osteoarthritis. The others in the all-polyethylene group were for aseptic loosening. The survivorship at seven years calculated by the Kaplan–Meier method for the all-polyethylene group was 56.5% (95% CI 31.9 to 75.2, number at risk 7) and for the metal-backed group was 93.8% (95% CI 77.3 to 98.4, number at risk 16) This difference was statistically significant (p <  0.001). At the most recent follow-up, significantly better mean Western Ontario and McMaster Universities Arthritis Index Scores were found in the all-polyethylene group (13.4 vs 23.0, p = 0.03) but there was no difference in the mean Knee injury and Osteoarthritis Outcome scores (68.8; 41.4 to 99.0 vs 62.6; 24.0 to 100.0), p = 0.36). There were no significant differences for range of movement (p = 0.36) or satisfaction (p = 0.23).

This randomised study demonstrates that all-polyethylene components in this design of fixed bearing UKA had unsatisfactory results with significantly higher rates of failure before ten years compared with the metal-back components.

Cite this article: Bone Joint J 2015;97-B:786–92.

A total of 219 hips in 192 patients aged between 18 and 65 years were randomised to 28-mm metal-on-metal uncemented total hip replacements (THRs, 107 hips) or hybrid hip resurfacing (HR, 112 hips). At a mean follow-up of eight years (6.6 to 9.3) there was no significant difference between the THR and HR groups regarding rate of revision (4.0% (4 of 99) vs 5.8% (6 of 104), p = 0.569) or re-operation rates without revision (5.1% (5 of 99) vs 2.9% (3 of 104), p = 0.428). In the THR group one recurrent dislocation, two late deep infections and one peri-prosthetic fracture required revision, whereas in the HR group five patients underwent revision for femoral head loosening and one for adverse reaction to metal debris. The mean University of California, Los Angeles activity scores were significantly higher in HR (7.5 (sd 1.7) vs 6.9 (sd 1.7), p = 0.035), but similar mean Western Ontario and McMaster Universities Osteoarthritis Index scores were obtained (5.8 (sd 9.5) in HR vs 5.1 (sd 8.9) in THR, p = 0.615) at the last follow-up. Osteolysis was found in 30 of 81 THR patients (37.4%), mostly in the proximal femur, compared with two of 83 HR patients (2.4%) (p < 0.001). At five years the mean metal ion levels were < 2.5 μg/l for cobalt and chromium in both groups; only titanium was significantly higher in the HR group (p = 0.001). Although revision rates and functional scores were similar in both groups at mid-term, long-term survival analysis is necessary to determine whether one procedure is more advantageous than the other.

Cite this article: Bone Joint J 2013;95-B:1464–73.

Purpose

The purpose of the study was to determine the rate of conversion from RSA to THR in a number of Canadian centers performing resurfacings

Purpose of the study: The purpose of this work was to compare the subjective and functional outcomes of patients with a large diameter total hip arthroplasty (LD-THA) or hip resurfacing (HR).

Material and methods: Forty-eight persons were assessed and double blind randomised to receive either LD-THA (n=24) or HR (n=24). The clinical and radiographic assessment and gait analysis were performed preoperatively and at three, six and 12 months postoperatively. Gait analysis was performed once in a third group of healthy adults (n=14) who served as controls.

Results: The two groups were comparable preoperatively regarding demongraphic and functional characteristics. Postoperatively, the two groups with prostheses exhibited very rapid recovery with normalization of test results compared with controls within three to six months. The clinical assessment, the analysis of postural balance, gait analysis and most of the specific tests were not different between the two groups with prostheses.

Conclusion: There was no remarkable difference in subjective or objective assessments between subjects with a LD-THA or HR. This suggests that the only potential advantage of HR is the preservation of femoral bone stock. Long-term HR implant survival will determine the reality of this benefit.

Purpose: Even with modern ancillary and good surgical experience, rotational implant positioning is sometimes sub-optimal, leading to poor results. Except for obvious cases with patellar instability, the symptoms are often vague and non-contributive to the diagnosis of failure. This is why implant malpositioning and particularly malrotational postioning remain an underestimated cause of failure after primary total knee arthroplasty (TKA). We report our experience with TKA revision for rotational malpositioning.

Method: We retrospectively assessed the results of TKA revisions in 22 knees for malrotational positioning. In all cases, malrotational implant positioning was confirmed by CT-scan according to Berger’s protocol.

Results: Mean age was 66 years (47–74) at the time of the primary TKA. After the index procedure, all patients presented early anterior knee pain with patellar instability (tilt and subluxation in ten cases, and permanent patellar dislocation in two cases). Malrotational positioning predominated on the tibial component with mean 23° internal rotation. Mean cumulative malrotation (tibial plus femur) was 22° internal rotation. All but four patients underwent femoral and tibial component revision. In two cases, only the tibial component was revised, and in two other cases, isolated transposition of the anterior tibial tuberosity was carried out. One was a failure, and finally underwent a successful full revision. At a mean follow-up of 30 months (12–60), we noted significant functional outcome improvement. One patient, who underwent a patellectomy previously at the index TKA procedure, had persistant anterior knee pain. No patient presented patellar instability.

Conclusion: The diagnosis of implant malrotational positioning is sometimes difficult. The most common errors are tibial component positioning. In case of suspicion of malrotational positioning, protocolized CT-scan allows quick and simple diagnosis. If the malrotation is confirmed, TKA revision should be performed upon patient disability and severity of the symptoms. It is important not to delay the surgery, particularly in cases of patellofemoral dislocation because of the risks of developing soft tissue contractures resulting in a more difficult revision procedure.

Purpose: Massive cavitary and segmental bone defects of the medial wall in revision arthroplasty are usually managed with large auto and/or allograft in association with a cemented or a cementless cup. To obtain a satisfactory hip center reconstruction with such a procedure can be sometimes challenging and the complications rate can be high. One other option is the use of a cup with a medial expansion (“protrusio cup”) to treat the medial bone defect.

Method: We carried out a retrospective study including 21 consecutive acetabular revisions arthroplasties using a cementless Converge Protrusio™ cup (Zimmer, Warsaw, IN, USA). Clinical outcomes were assessed by Harris Hip Score (HHS), WOMAC index and SF-12. Hip centre was assessed on anteroposterior (AP) view and the reconstruction was considered as satisfying when its location was located from − 10 to + 10 mm proximally (y axis) and/or medially (x axis) in comparison with ideal theoretical hip center location. Cup migration and modification of abduction angle were considered as significant when there were respectively > 4mm and to > 4° in comparison with the immediate postoperative AP view.

Results: At the last follow up [radiological data: 71.6 months (24–128.3) and clinical data: 72.1 months (24–129.5)], two patients were died and there were no lost of follow up. The mean HHS was 79.4% (52–100), WOMAC 82% (46–100), SF-12 52 (23–71) and 44 (18–65). Bone defect were filled with cancellous bone chips allograft in 16 cases and bulk bone allograft was used in only two cases to manage a large segmental defect of the roof. Bone graft integration was completed in all cases. The mean abduction cup angle was 43.6° (32–60). A satisfying hip centre positioning was obtained in 19 cases on x axis and in 10 cases on y axis, in all the remaining cases, we noted an improved implant positioning. The complications were: recurrent dislocation in one case (successfully revised with a constrained liner), infection in two cases (1 treated conservatively and the other one revised in two times procedure) and Brooker’s type III and IV ectopic ossifications in three cases. A significant cup migration occurred in only one case at nine years but was not revised because of painless. No case required revision for aseptic loosening.

Conclusion: Protusio cups appear as a reliable procedure to manage bone loss in acetabular revision. The revision procedure is widely simplified by reducing the use of the massive allograft and by promoting a satisfying hip center reconstruction to allow an optimal biomechanical joint functioning. Moreover, the cementless fixation in contact with patient acetabular bone makes more easy bone integration.

Purpose of the study: A medial incision for implantation of a total knee arthroplasty (TKA) offers an excellent surgical exposure while minimising the length of the skin opening. This incision however implies section of the proximal portion of the infrapatellar branch of the medial saphenous nerve, potentially associated with lateral hypoesthesia and formation of a neuroma (painful scar). We hypothesised that an anterolateral skin incision would produce less hypoesthesia and postoperative discomfort.

Material and methods: We conducted a prospective randomised study to compare the degree of hypoesthesia after a medial or lateral skin incision for the implantation of a TKA. Fifty-knees in 43 patients, mean age 65.9±8.4 years were included; 26 knees for the lateral incision and 24 for the medial. All patients had the same type of implant. Clinical results were assessed with WOMAC, KOOS and SF36. Semme-Weinstein monofilaments were applied to measure sensitivity at 13 characteristic points. Patients were assessed at six weeks and six months. The zone of hypoesthesia was delimited and photographed for measurement with Mesurim Pro9^®. Satisfaction with the surgery and the scar was noted. Data were processed with Statview^®; p< 0.05 was considered significant.

Results: The two groups were comparable preoperatively regarding age, gender, body weight, height, body mass index, body surface area, aetiology, and clinical score. Operative time, blood loss, and number of complications were comparable. The functional outcomes (WOMAC, KOOS, SF36) were comparable at six weeks and six months. Active flexion was significantly greater at six months in the lateral incision group (p=0.03). The zone of hypoesthesia was significantly smaller in the lateral incision group at six weeks (p< 0.01) and at six months (p< 0.01), as were the number of points not perceived on the filament test (p< 0.01 in both cases) while the length of the incision was comparable (p> 0.05). This was associated subjectively, with less loss of sensitivity and less anterior pain reported by the patient at six months.

Discussion: Lateral and medial incisions enable comparable functional outcomes. The lateral incision produces less hypoesthesia and less anterior pain. This improves the immediate postoperative period and facilitates rehabilitation as is shown by the gain in flexion at six months.

Purpose: Bone stress transmission by an implant has been demonstrated to be inversely proportional to its rigidity. Since trabecular metal has a high elasticity modulus, it is hypothesised that it should have a preservative impact on bone mineral density (BMD) loss. No current studies prospectively compare BMD variations using such implants.

Method: A randomized study recruiting 65 patients with osteoarthritis of the knee, were assigned to a cemented titanium or a non-cemented trabecular metal tibial base plate. Each patient had a DXA scan of the proximal tibia on the TKA side at two weeks, six months, one and two years follow-up. Analytic methods for DXA scans were standardized (Variation coefficient=0,59–0,84%), and BMD variation compared between groups using the Student t-Test.

Results: Versus early post operative evaluation, BMD loss was found in the two groups. Fixed effects on BMD, such as patient’s height (p< 0.001) and tibial implant size (p=0.04) were demonstrated. Patella resurfacing and polyethylene thickness had no effect on BMD. BMD loss was more important under titanium implants (−30.9%) than trabecular metal implants (−6.3%). The most affected area was the metaphysis (p=0.002) compared to the diaphysis (p=0.054).

Conclusion: Trabecular metal tibial base plate seems to diminish BMD loss under tibial implant compared to traditional titanium base plate. A long-term study will be necessary to determine the tibial trabecular metal component survival rate.

Purpose of the study: Tribology studies of total hip arthroplasty (THA) have demonstrated that large diameter head in metal-on-metal bearings produce fewer wear particles than small diameter heads. The other advantages of this option are better stability, less dislocation, and optimal joint range of motion. The purpose of this work was to compare blood levels of chromium, cobalt and titanium six months and one year after implantation of different models of large diameter metal-on-metal THA.

Material and methods: We conducted a retrospective comparative and randomised study including 110 patients who had been implanted with a larger diameter head THA/Zimmer? Smith and Nephez, Biomet or Depuy. The metal ion concentrations (Cr, Co, Ti) were measured in whole blood by an independent laboratory using high-resolution mass spectrometry (HR-ICP-MS). Blood samples were drawn preoperatively and postoperatively at six months and one year.

Results: At six months, the concentrations of metal ions in whole blood expressed as mean (range) for Cr (μg/L) Co (μg/L) and Ti (μg/L) were, respectively: Zimmer 1.3 (0.4/2.8) 1.7 (0.9/6.8) 2.5 (0.6/6.7); Smith and Nephew 2.0 (0.7/4.2) 2.1 (0.5/6.6) 1.1 (0.5/4.1); Biomet 1.2 (0.4/2.2) 0.9 (0.3/3.4) 1.4 (0.8/2.4); Depuy 1.7 (0.5/3.2) 1.9 (0.3/4.2) 1.3 (0.5/3.9). There was a significant difference between groups for Cr (p=0.006), Co (p=0.047) and Ti (p< 0.001). The Biomet implants presented the lowest concentrations for Cr and Co; the Zimmer implants gave the highest levels of Ti.

Discussion and Conclusion: Several implant-related factors affect blood concentrations of metal ions: contact surfaces leading to “active” abrasion but also wear in other parts of the implant giving rise to “passive” corrosion. Bearing wear is related to the diameter of the head, its roughness, its spherical shape, joint clearance, the manufacturing technique (forging, casting) and its carbon content. The Biomet head corresponds to a better compromise for these different factors. Passive corrosion can result from an exposed metal surface or from metal to metal contact. This explains the high level of Ti ions found for all implants tested since titanium is not present in the bearings.

Purpose: Femoral neck narrowing (FNN) has been reported after metal-on-metal hip resurfacing (HR). It is significant (> 10%) in a number of cases (from 0 up to 27.6%). Its origin remains unclear, but bone remodelling, impingement, head necrosis and osteolysis have been incriminated. The aims of this study were to assess these issues and describe their consequences in a prospective series with a minimum follow-up of five years.

Method: Fifty-seven HRs in 53 patients (30 men, 23 women, average age 49.2±8.4 years) were included prospectively with clinical (WOMAC, UCLA activity score) and radiological evaluation at one, two and five years. All patients received the Durom™ resurfacing system (Zimmer, Warsaw, IN, USA), with cementless acetabular cup and cemented femoral implant. All cases were undertaken via a posterior approach. Femoral and acetabular implant positioning was assessed. The neck-to-head prosthesis (N/H) ratio was calculated at the junction of the neck with the femoral component and at mid-distance between the neck junction and the inter-trochanteric line (N1/2/H) on anterior-posterior view. Ion concentrations (chromium, cobalt and titanium) were measured at 12 months. We considered p< 0.05 as the significance level.

Results: The N/H ratio decreased significantly at one, two and five years in comparison to the postoperative data (p< 0.01 for all parameters) and N1/2/H declined significantly only at one and two years (p=0.003 and p=0.03, respectively). There was no difference in the N/H ratio or N1/2/H between two and five years. We encountered no deleterious consequences of FNN on clinical outcome, and no significant relationship with cup positioning, gender, body mass index or level of activity. Femoral positioning in valgus was associated with a decrease in N1/2/H at one and two years (p=0.02), whereas the N/ H ratio tended to be lower when cobalt concentration was elevated (p=0.08). Significant FNN was observed in two cases at two years (−12.9% and – 11.1%) with a localized and progressive femoral anterior-superior notch absent on immediate postoperative X-rays. At five years, we noted three other cases with circumferential FNN, limited at the junction neck-cup area (average narrowing around – 20% between two and five years). One of these cases presented a femoral stem fracture. Osteonecrosis was confirmed during surgical revision.

Conclusion: In the current group, FNN was seen infrequently up to five years after surgery (9%). Mechanically-induced remodelling should be differentiated from overall FNN which may be due to femoral head necrosis. In this case, revision could be proposed before implant failure or femoral loosening. Impingement causes very early and localized FNN at the upper part of the neck; for these patients, simple observation should be the rule, all the more since they are usually pain-free and rarely disabled.

Purpose: Tribological studies of hip arthroplasty suggest that larger diameter metal-on-metal (MOM) articulations would produce less wear than smaller diameter articulations. Other advantages of these large femoral head implants include better stability with lower dislocation rates and improved range of motion. The aim of the present study was to compare chromium (Cr), cobalt (Co) and titanium (Ti) ion concentrations up to one year after different large diameter MOM total hip arthroplasties (THAs).

Method: One hundred and twelve patients were randomized to receive large (femoral head > 36 mm diameter) metal-on-metal articulation THA (LDH) from one of the following companies: Zimmer, Smith & Nephew, Biomet or Depuy. Samples of whole blood were collected pre-operatively and post-operatively at six months and one year. Cr, Co and Ti concentrations were measured by high-resolution mass spectrometry in an independent laboratory. All LDH implants have a modular Cr-Co tapered sleeve for leg length adjustment, except for Biomet with its sleeve made of Ti. All groups had Ti stems, and Zimmer and Biomet had, in addition, a Ti acetabular porous surface for secondary fixation. We undertook statistical analysis (SPSS 14.0) with p< 0.05 as significant.

Results: The groups were comparable in respect to pre-operative parameters (age, gender ratio, body mass index, etc.) as well as post-operative functional scores at six months and one year. We found that Biomet, Depuy and Smith & Nephew LDH had similar Co ion levels at 12 months post-op with 1.5, 1.4 and 1.6 ug/L, respectively. Durom LDH had the highest Co level with 2.3 ug/L (p< 0.01 versus the three other groups). The highest Ti ion levels were observed in the Zimmer group with 3.2 ug/L (p< 0.01 versus the three other groups) and the Biomet group with 2.0 ug/L (p=0.01 versus Zimmer and NS versus the other 2). Ti levels tripled versus pre-op for BHR and ASR (0.5 versus 1.5 and 0.5 versus 1.4 ug/L).

Conclusion: Different implant factors may influence metal ion levels measured in whole blood: articular surface wear and implant passive corrosion. Zimmer’s Durom LDH presents higher Co levels than the other groups. Since previously-published Durom hip resurfacing (same bearing characteristics as Durom LDH) showed much lower Co ion results, the modular sleeve may be incriminated. The plasma-sprayed acetabular surface of Zimmer’s and Biomet’s components seems to be responsible for the significant difference in Ti versus the other implants. Biomet’s plasma-sprayed Ti appears to be less prone to corrosion than Durom’s plasma spray coating. When evaluating metal ion release from MOM THA, total metal load from the implants should be considered, and newer implant designs should be evaluated scientifically before their widespread clinical use. LDH-THA should be seen as an improvement and should not be blamed as the source of metal ion release when a specific implant produces unsatisfactory results.

Purpose: Antero-medial parapatellar skin incision in total knee arthroplasty (TKA) provides excellent surgical exposure with minimal skin incision length. However, it is associated with the infrapatellar branch of the saphenous nerve section, leading to antero-lateral knee hypoesthesia and sometimes painful nevroma. We hypothesized that

antero-lateral skin incision in TKA produces a lower rate of hypoesthesia compared to the medial parapatellar cutaneous approach, and

Method: A total of 69 knees in 64 patients who underwent TKA were randomized for antero-medial (n=35) or antero-lateral (n=34) skin incision. Mean age was 66.4±8.2 years. Functional outcome was assessed by WOMAC, KOOS and SF-36 scores pre-operatively and at six weeks, six months and one year follow-up. Range of motion (active and passive flexion and extension) was measured. The area of hypoesthesia was analyzed in a standardized manner by an independent observer using a calibrated Semme-Weinstein monofilament applied on 13 reference points. A digital photograph was taken, and the area of hypoesthesia was then measured informatically (Mesurim Pro^® software). Patient satisfaction with their scar and their surgery was evaluated. Statistical analysis was carried out with p< 0.05 considered as significant.

Results: The two groups were comparable pre-operatively. There was no significant difference in functional outcome (WOMAC, KOOS, SF-36 scores) at six weeks, six months and one year between the two groups. Active and passive ranges of motion were comparable. The area of hypoesthesia and the number of non-perceived points in the monofilament test were significantly lower after antero-lateral incision at six weeks (p=0.007 and p=0.02, respectively) and 6 months (p=0.02 and p=0.005, respectively). At one year, the area of hypoesthesia was lower in the antero-lateral group, but was not significant (p=0.08). Antero-lateral incision patients reported a lower rate of subjective sensitivity loss and anterior knee pain at six weeks, six months and one year.

Conclusion: Antero-medial and antero-lateral parapatellar skin incisions in TKA have a similar functional outcome. However, antero-lateral cutaneous incision produces a lower rate of hypoaesthesia and less anterior knee pain in the early recovery period.

Purpose of the study: Despite a survival rate to the order of 90–95% at ten years, implant malposition and particularly malrotation can cause an underestimation of failure after total knee arthroplasty (TKA). We report our experience with revision TKA for isolated malrotation.

Material and methods: Twelve patients underwent revision for isolated maltrotation of an implant. This series of three men and nine women, mean age 66 years, range 47–74 years at primary surgery, were reviewed retrospectively. During the follow-up, all patients complained of early onset anterior knee pain, which was generally noted severe, associated with moderate patellar instability in four cases, noted severe in 7 others and extreme in one (permanent patellar dislocation). Half of the patients also exhibited hyperlaxity was invalidating instability. Range of motion was generally preserved (2/5/100). In all cases, the rotational problems were confirmed on the computed tomography which revealed predominant tibial malrotation, measured at 23 mean internal rotation and a cumulative malrotation (femur+tibia) of 22 internal rotation.

Results: All patients except two required revision of both femoral and tibial implants. In one case, the tibial piece was alone changed and in another, isolated translation of the anterior tibial tuberosity was performed. For eight of eleven cases, the revision implants had a stem and femoral inserts were used to control the bone stock loss induced by the corrective cuts in six cases and requiring more or less extensive ligament balance procedures in six. At mean follow-up (30 months, range 12–60), there was a very significant improvement in the functional results; only one patients with a history of patellectomy complained of persistent anterior pain. None of the patients complained of patellar instability.

Discussion: Excessive cumulative internal rotation of the implants induces increased stress on the patella, causing early anterior pain, then subluxation and finally dislocation beyond −15 to −20° internal rotation. These position errors are concentrated on the tibia were care must be taken to respect the anatomic landmarks (bicondylar axis, anterior tibial tuberosity) to avoid early failure. In the event of major rotational disorders, revision may be required with procedures to correct the ligament balance.

Purpose: The long term exposure to metal ions released from metal-metal articulations is worrying. Studies have shown comparable ion level between metal-metal HR and 28mmTHA. No study has analyzed the amount of ion released from LDH-THA. We compared the amount of ion released from HR and LDH-THA from the same manufacturer.

Method: Whole-blood concentrations of Cobalt was measured prospectively (pre op, 3, 6, 12, 24 months) with HR-ICPMS in 74 HR and 54 LDH-THA with the same metal bearing characteristics and acetabular component (monoblock Cobalt-Chrome with titanium plasma-spray coating). The femoral head of LDH-THA was inserted on a titanium stem with a Cobalt-Chrome adapter sleeve to adjust offset and leg length.

Results: Demographic data was similar. The pre op Cobalt level (ug/L) were 0.10 vs. 0.11, 3 months 0.90 vs. 0.84, 6 months 0.90 vs. 1.28, 12 months 0.68 vs.1.75, and 24 months 0.56 (5.6X preop level) vs. 1.82 (16.5X preop level) in the HR and LDH-THA groups, respectively. The cobalt level decreased after 6 months in HR, whereas it was still increasing at 2y with LDH-THA.

Conclusion: In order to reduce wear and ion release from metal-metal bearing, most manufacturers focus research on improvements at the bearing surfaces. This study has shown that the simple addition of a sleeve with 2 modular junctions can results in a dramatic increase in ion release, diminishing the value of improvements made at the bearing surface. The total amount of ion released from a metal-metal implant should be considered globally and as such, better modular taper designs should be developed.

Purpose: Clinical studies still show significant variability in offset and leg length reconstruction after 28mmTHA. Precise restoration of hip biomechanics is important since it reduces wear and improves stability, abductor function and patient satisfaction. There is a tendency to increase offset and leg length to ensure stability of 28mmTHA. This may not be needed with the more stable LDHTHA and hip resurfacing implants, therefore potentially improving the precision of the hip reconstruction. The aim of this study was to verify this assumption.

Method: Leg length and femoral offset were measured on standardized digital radiographs with a computer software in 254 patients (49 HR, 74 LDHTHA, 132 28mmTHA) with unilateral hip involvement and compared to the normal contralateral side.

Results: Femoral offset was increased in 72% of 28mmTHA (mean +3.3mm), 56% of LDHTHA (mean +1.0mm) and 8% of HR (mean −3.2mm) (intergroup differences p< 0.05). The mean LLI was greater after 28mmTHA (+2,29mm) vs. (−0.45mm for LDHTHA and −1.8mm for HR). The percentage of patients with increased leg length > 4mm was greater for 28mmTHA (11%) compared to LDHTHA (2.7%) and HR (2%).

Conclusion: The stability afforded by the larger head of LDHTHA reduces the surgeon’s tendency to increased leg length and femoral offset to avoid instability as during 28mmTHA. In addition, compared to HR, LDHTHA allows more precise restoration of equal leg length and femoral offset in patient with greater pre operative deformities (low femoral offset and LLI > 1cm). LDHTHA may represent the most precise method of hip joint reconstruction.

Purpose: Better clinical outcome is generally reported after hip resurfacing when compared to conventional 28mmTHA. This may simply be the consequences of biased patient selection, patient perception or the advantageous use of larger diameter femoral heads in HR. The true clinical benefits of HR can only be assessed by comparison with LDH-THA in a blinded randomized study to eliminate/reduce those biases. This was the aim of the study.

Method: Charnley class A patients were randomized between HR or LDH-THA and kept blinded for one year. Clinical data, gait analysis, postural balance evaluations and functional tests were performed pre-operatively at 3, 6, 12 and 24 months postoperatively. Fourteen normal patients served as controls.

Results: Twenty-four patients were assigned to each group. There was no significant difference in WOMAC, SF-36, activity scores, and patient satisfaction. A slight advantage was observed for HR during the functional reach test (postural balance) and for LDH-THA during the step test (speed, strength and balance), all other tests showing no differences. Both groups quickly reached controls value for all tests by 3 months.

Conclusion: We have failed to demonstrate a clear difference in outcome between HR and LDH-THA. Both groups fully recovered quickly. The postulated clinical advantages of HR over 28mmTHA most likely result from using a larger head in highly motivated patients. The only clear advantage of HR over LDH-THA remains proximal femoral bone conservation, although with the excellent durability of currently used femoral stems, HR has to demonstrate comparable survivorship before bone conservation is considered a true benefit.

Purpose: The goal of this study is to compare patients’ perception of their hip or knee joint following joint replacement surgery.

Method: A total of 357 patients who underwent hip or knee joint surgery were included in the study. Of the patients who had knee replacement surgery, 46 had unicompartmental knee replacement (UKR) and 119 had total knee replacement (TKR). In the group of patients who had hip replacement surgery, 98 underwent hip resurfacing (SRA) and 97 had total hip replacements (THR). The perception patients had of their replaced articulation as well as functional outcome scores such as the WOMAC and SF-36 were measured at one year post-surgery and compared between the four groups.

Results: Although global satisfaction and clinical outcome scores were excellent in all four groups, WOMAC scores at 1–2 year follow-up were significantly different between hip or knee replacement surgery (p< 0.0001). Also, the perception that patients had of their reconstructed joint was significantly different between the hip and knee groups (p< 0.001). Half of patients from the hip group considered their replaced hip “as a natural joint” and 76% considered their joint as having no functional limitations compared to only 19% and 39% respectively for the knee group. Of patients with knee joint surgery, 14% (20/165) considered their joint as “artificial with important limitations” as opposed to only 1% (2/195) of those who had hip joint surgery. There were no significant differences in Womac scores or perception when comparing TKR and UKR or THR and SRA patients. Perception was strongly correlated to Womac scores for all four groups (R²=0.951).

Conclusion: Hip and knee joint replacement surgery are recognized as highly effective medical interventions in terms of cost/benefit ratio in current medical practice. It is remarkable to see that replacement of each of these articulations can yield vastly different results in terms of patient function, perception and satisfaction. From this study, it is clear that research in prosthetic development and surgical techniques should be focused on the interventions such as knee joint replacement, which are not yet capable of offering both a high level of function and satisfaction to patients.

Background: Acetabular implant revision with large bone defects, can be challenging. One of the reconstruction options is a “jumbo cup” (outer diameter ≥62mm in women and ≥66mm in men). We hypothesized that cementless jumbo cups is a reliable technique to reconstruct hip joint with satisfying radiological and clinical outcomes.

Material and Methods: Fifty-two consecutive acetabular revisions arthroplasty where a cementless jumbo cup was used were assessed. Clinical outcomes were assessed by Harris Hip Score (HHS), WOMAC index and SF-12. Hip centre was assessed on anteroposterior (AP) view according to Pierchon’s criteria. The reconstructed hip center was considered as satisfying when its location was located from −10 to + 10 mm proximally (y axis) and/or medially (x axis) in comparison with ideal theoretical hip center location. Cup migration and modification of abduction angle were considered as significant when there were respectively ≥5mm and to ≥5° in comparison with the immediate postoperative AP view.

Results: Mean component size was 67.6 mm (min 62, max 81). According to Paprosky classification, there were 5 cases of type 1, 11 type 2A, 12 type 2B, 11 type 2C, 11 type 3A and 2 type 3B. Cancelous bone chips allograft were used in 34 cases and bulk bone allograft in 14. Immediate postoperative AP view showed a mean abduction cup angle of 41.3° (26–53), a satisfying hip centre positioning in 78% on x axis and in 70 % on y axis. In the remaining cases, we noted an improved implant positioning. For the patients with intact contra-lateral hip (n=29), we noted, in comparison with normal side, a mean lateralisation of the hip center of 3 mm (−10 – +16) and a mean ascension of 7 mm (−10 – +33) associated with an average limb length discrepancy of – 4 mm (−19 – +9). At the last follow up [radiological data: 79 months (24–236) and clinical data: 88 months (27–241)], 6 patients were died and 3 were lost of follow up. The mean HHS was 82% (15–100), WOMAC 86% (27–100), SF-12 46 (14–61) and 53 (15–63). Bone graft integration was completed in all but 3 cases. Significant cup migration (≥5mm) occurred in only one case. The complications were: dislocation in 5 cases (4 revisions with constrained liner), infection in 4 cases (2 treated conservatively and 2 revised in 2 times procedure) and Brooker’s type III or IV ectopic ossifications in 11 cases. No case required revision for aseptic loosening.

Discussion: Jumbo cups appear as a reliable procedure to manage bone loss in acetabular revision. The complication rate is comparable with other reconstruction procedures (massive allograft, reinforcement rings, high hip center…). Cementless fixation and satisfying hip center restoration promote respectively the bone integration and allow an optimal biomechanical joint functioning. These are the main conditions for high long term survival rate.

Introduction: Better clinical outcome is generally reported after hip resurfacing when compared to conventional 28mmTHA. This may simply be the consequences of biased patient selection, patient perception or the advantageous use of larger diameter femoral heads in HR. The true clinical benefits of HR can only be assessed by comparison with LDH-THA in a blinded randomized study to eliminate/reduce those biases. This was the aim of the study.

Materials and Methods: Charnley class A patients were randomized between HR or LDH-THA and kept blinded for one year. Clinical data, gait analysis, postural balance evaluations and functional tests were performed preoperatively, at 3, 6, 12 and 24 months postoperatively. 14 normal patients served as controls.

Results: 24 patients were assigned to each group. There was no significant difference in WOMAC, SF-36, activity scores, and patient satisfaction. A slight advantage was observed for HR during the functional reach test (postural balance) and for LDH-THA during the step test (speed, strength and balance), all other tests showing no differences. Both groups quickly reached controls value for all tests by 3 months.

Discussion: We have failed to demonstrate a clear difference in outcome between HR and LDH-THA. Both groups fully recovered quickly. The postulated clinical advantages of HR over 28mmTHA most likely result from using a larger head in highly motivated patients. The only clear advantage of HR over LDH-THA remains proximal femoral bone conservation, although with the excellent durability of currently used femoral stems, HR has to demonstrate comparable survivorship before bone conservation is considered a true benefit.

Background: Moore et al. recently described five radiological signs (absence of radiolucent line, zone 2 osteo-penia, superolateral buttress, inferomedial buttress and radial trabeculae) for predicting osseointegration of porous coated uncemented acetabular components in the long term. The positive predictive value for a stable fixation was 96.9% when three or more signs were present. 83% of the cups with one or no signs were unstable.

Aim: To evaluate the prevalence of these signs in clinically well functioning uncemented acetabular components in the short term and to evaluate whether there is a difference acetabular components with different modulus of elasticity.

Materials and methods: The preoperative, immediate postoperative and the latest (minimum 2 years) radiographs of 196 hip replacements with 2 different acetabular components: a 2.9 mm, thin, flexible, macro textured titanium component (Allofit, Zimmer) and a 4 mm thick, stiff, titanium plasma sprayed chrome-cobalt component (Durom, Zimmer) were reviewed by two independent observers searching for the five osseointegration signs. The observers also looked for conventional signs of loosening including: continuous radiolucency of more than 2 mm, component migration of more than 3 mm, component rotation, or the presence of broken screws.

Results: 95 Allofit components and 101 Durom components were available for evaluation. None of the hips were considered loose according to conventional criteria and were well functioning. Out of the new osseointegration signs, at least one sign was present in 100 % of the cases, two signs or more in 30%, three signs or more in 5% and four signs in 1%. There was no difference between the two types of cups. In addition, superolateral buttress and zone 2 osteopenia were also present in preoperative/immediate postoperative radiographs in 8% and 4% of respectively.

Conclusion: Apart from absence of radiolucency, very few of the five osseointegration signs were present at short term follow-up of two very different well functioning uncemented acetabular components designs. We conclude they are not useful in evaluation of unce-mented acetabular components at a follow up of 2–5 years. Further study at mid-term follow-up might reveal whether the bony adaptive changes occur with time.

Purpose: The aim of our study was to compare the precision and effectiveness of a CT-free computer navigation system against conventional technique (using a standard mechanical jig) in a cohort of unselected consecutive series of hip resurfacings.

Method: 139 consecutive Durom hip resurfacing procedures (51 navigated and 88 non-navigated) performed in 125 patients were analysed. All the procedures were done through a posterior approach by two surgeons and the study cohort include the hip resurfacings done during the transition phase of the surgeons’ adoption of navigation.

Results: There were no significant differences in the patients caracteristics, native neck-shaft angles, component sizes and blood loss between the two groups. There was a significant difference in the operative time between the two groups (111 minutes for the navigated group versus 105 minutes for the non-navigated group; p=0.048). There were 4 cases of notching in the non-navigated group. There was no other intra-operative technical problem in either of the groups nor were there any femoral neck fractures. No significant difference was found between the mean post-operative stem-shaft angles (138.5° for the navigated group versus 139.0° for the non navigated group, p=0.740). However there was a significant difference in the difference between the planned stem-shaft angle versus the post-operative stem-shaft angle (0.4° for the navigated group versus 2.1° for the non-navigated group; p=0.005). While, none of the cases in the navigated group had a post-operative stem-shaft angle with more than 5° deviation from the planned neck-shaft angle when compared to 33 cases (38%) in the non-navigated group (p≤0.001). For a given patient with a target angle set, it is estimated that positioning precision using the navigation is 1.3° +/− 0.9°, compared to 4.4° +/− 3.6° without navigation (p< 0.0001).

Conclusion: Hip resurfacing is a technically demanding procedure with a steep learning curve. Varus placement of the femoral component and notching have been recognised as important factors associated with early failures following hip resurfacing. While conventional instruments allowed reasonable alignment of the femoral component, our study has shown that use of computer navigation allows more accurate placement of the femoral component even when the surgeons had a significant experience with conventional technique.

Purpose: Surface replacement arthroplasty is being increasingly offered as the treatment of choice to young and active patients with hip arthritis with proposed advantages including bone conservation and better functional outcome. Excellent outcome has been reported in the few recent short-term clinical series of surface replacement arthroplasty. However they have an inbuilt patient selection bias. There are no direct prospective randomized studies comparing the newer generation of surface replacement arthroplasty with conventional total hip arthroplasty. Our study addresses this issue.

Method: 210 hips in 194 patients were randomized to receive either an uncemented total hip arthroplasty or a hybrid metal-on-metal surface replacement arthroplasty. Complications, functional outcomes, along with patient satisfaction and radiographic evaluation were compared at a minimum of two years follow up.

Results: Patients in both groups demonstrated a very high satisfaction rate and achieved similar functional scores. Four dislocations occurred in the THA group (one needing acetabular cup revision) and none in the SRA group. There were no femoral neck fractures in the surface replacement arthroplasty group. However, two surface replacement arthroplasty cases underwent revision for late head collapse and one needed a femoral neck osteoplasty for persisting femoro-acetabular impingement. Better biomechanical restoration was attained with surface replacement arthroplasty. All the components were considered to be stable after an average follow up of 45 months.

Conclusion: Although surface replacement arthroplasty of the hip offer similar patient satisfaction, functional outcome and complication rate as an uncemented total hip arthroplasty in a young and active group of patients, different complications were associated to each procedure. Better patient selection could avoid some of the complications in the surface replacement arthroplasty group. One main advantage that remains for the surface arthroplasty technique it is the proximal femoral bone stock preservation. However, long term survival analysis is necessary to determine the true advantage of these implants over total hip arthroplasty.

We have updated our previous randomised controlled trial comparing release of chromium (Cr) and cobalt (Co) ions and included levels of titanium (Ti) ions. We have compared the findings from 28 mm metal-on-metal total hip replacement, performed using titanium CLS/Spotorno femoral components and titanium AlloFit acetabular components with Metasul bearings, with Durom hip resurfacing using a Metasul articulation or bearing and a titanium plasma-sprayed coating for fixation of the acetabular component.

Although significantly higher blood ion levels of Cr and Co were observed at three months in the resurfaced group than in total hip replacement, no significant difference was found at two years post-operatively for Cr, 1.58 μg/L and 1.62 μg/L respectively (p = 0.819) and for Co, 0.67 μg/L and 0.94 μg/L respectively (p = 0.207). A steady state was reached at one year in the resurfaced group and after three months in the total hip replacement group. Interestingly, Ti, which is not part of the bearing surfaces with its release resulting from metal corrosion, had significantly elevated ion levels after implantation in both groups. The hip resurfacing group had significantly higher Ti levels than the total hip replacement group for all periods of follow-up. At two years the mean blood levels of Ti ions were 1.87 μg/L in hip resurfacing and and 1.30 μg/L in total hip replacement (p = 0.001).

The study confirms even with different bearing diameters and clearances, hip replacement and 28 mm metal-on-metal total hip replacement produced similar Cr and Co metal ion levels in this randomised controlled trial study design, but apart from wear on bearing surfaces, passive corrosion of exposed metallic surfaces is a factor which influences ion concentrations. Ti plasma spray coating the acetabular components for hip resurfacing produces significantly higher release of Ti than Ti grit-blasted surfaces in total hip replacement.

Background: Leg length equality and femoral offset restoration are important parameters related to success of total hip arthroplasty (THA). However, it is not uncommon for errors to occur during surgery which can lead to less optimal functional result and potential source for litigation. Several techniques that are commonly used to assess leg length and femoral offset during THA include pre-operative templating, intra-operative measurements with a ruler using bony landmarks, assessing soft tissue tension and using measurement device with a reference pin in the iliac crest. We have previously reported on our precision to reconstruct the diseased hip with THA done without navigation. Post-operative radiographic analysis demonstrated that leg length was restored to within +/− 4mm of the contralateral side in only 60% of the patients with 4 patients needing a shoe lift. With regards to femoral offset reconstruction, it was increased by a mean of 5.1 mm and restored to within +/− 4mm of the normal contralateral side in only 25% of patients.

Computer navigation has proven to be a more precise tool to achieve optimal positioning of THA implants and precise biomechanical reconstruction of the hip joint. However, performing complete THA using navigation is complex including the requirement to change the position of the patient during registration. A recent stand-alone CT-free hip navigation software from Orthosoft Inc allows navigation to be used for limb length and offset measurements during THA. We report our results from a preliminary study using this technique in 14 hips undergoing THA.

In this technique, a tracker is placed over the iliac crest. There is no need to fix a tracker on the femur. Registration of the following are done: greater trochanter (using a screw), patella (using an ECG lead) and the plane of the operating table (using three points on the surface of the operating table in a triangular configuration). The centre of rotation of the hip is determined by either mapping the acetabulum or by using the appropriate sized calibrated reamer. With the definitive acetabular component in place, the new center of rotation is registered and the hip is reduced with trial femoral component. Re-registration of the new position of the greater trochanter and patella allows the computer to calculate the relative change in the limb length and offset compared to the pre-operative status. The differences in the pre-operative and post-operative limb length and offset were calculated using Imagika software and compared with the navigated values recorded by the computer.

The mean absolute error for the relative change in the limb length as measured by the computer when compared to the radiographic measurement was 1.25 mm with a standard deviation of 1.77 mm. The mean absolute error for the relative change in the offset as measured by the computer when compared with the radiographic measurement was 2.96 mm with a standard deviation of 2.56 mm. The process of navigation was quick and on average adds 10 minutes to the operative time.

Our preliminary study shows that the accuracy of the navigation software is very good in estimating the change in the limb length intra-operatively with a maximum error of 3 mm. The accuracy was also good in estimating the offset (3 mm or less except in one case where the error was 5 mm and this may be due to technical error in registration). This compares favorably with our own data on THA done without navigation. This easy to use navigation technique has the potential to decrease the magnitude of error in restoration of limb length and offset during THA.

We thank Francois Paradois and Michael Lanigan from Orthosoft Inc. for their technical advice.

Hip Resurfacing (HR) is nowadays widely used as an alternative to Total Hip Replacement (THR), especially for the young and active patients. Because of the more physiological distribution of the load in the femur, this technique is particularly known to reduce bone loss due to stress shielding behaviour, a major problem encountered with THA. Different computational studies have analysed the performance of HR prostheses. Therefore, the purpose of this study is to apply a computational approach, in fact a bone remodelling analysis, in order to investigate its application to evaluate the bone structure changes postoperatively.

A Finite Element model was developed of a femur with HR prosthesis. The model was reconstructed starting with the femur medical images, and then the prosthesis was positioned in the clinical implantation angle (5° valgus). A cement mantle thickness of 1mm was included. Then a Finite Element Analysis in combination with a bone remodelling model (bone material properties) was performed. The results obtained predict as there is a certain bone loss in the superolateral and inferior medial zone. Additional bone material apposition is locally found with the aim of fixing the implant stem on the medial side, but also a remarkable distal ingrowth around the stem tip. All these findings are in good qualitative agreement with clinical observations.

We conclude that the numerical simulation used in this study is a useful tool in predicting bone remodelling inside a cemented HR prosthesis. This kind of methodologies will help on the design of devices, surgical techniques, etc.

The aim of our study was to compare the precision and effectiveness of a CT-free computer navigation system against conventional technique (using a standard mechanical jig) in a cohort of unselected consecutive series of hip resurfacings.

One hundred and thirty nine consecutive Durom hip resurfacing procedures (51 navigated and 88 non-navigated) performed in 125 patients were analysed. All the procedures were done through a posterior approach by two surgeons and the study cohort include the hip resurfacings done during the transition phase of the surgeons’ adoption of navigation.

There were no significant differences in the gender, age, height, weight, BMI, native neck-shaft angles, component sizes and blood loss between the two groups. There was a significant difference in the operative time between the two groups (111 minutes for the navigated group versus 105 minutes for the non-navigated group; p=0.048). There were 4 cases of notching in the non-navigated group and none in the navigated group. There were no other intra-operative technical problems in either of the groups nor were there any femoral neck fractures.

No significant difference was found between the mean post-operative stem-shaft angles (138.5° for the navigated group versus 139.0° for the non navigated group, p=0.740). However there was a significant difference in the difference between the planned stem-shaft angle versus the post-operative stem-shaft angle (0.4° for the navigated group versus 2.1° for the non-navigated group; p=0.005). There was significantly more scatter in the difference between the post-operative stem-shaft angle and the planned stem-shaft angle in the non-navigated group (standard deviation = 3.6°) when compared with the navigated group (standard deviation = 0.9°; Levene’s test for equality of variances = p≤0.01). No case in the navigated group showed a post-operative stem-shaft angle of more than 5° deviation from the planned neck-shaft angle when compared to 33 cases (38%) in the non-navigated group (p≤0.001). While only 4 cases (8%) in the navigated group had a postoperative stem-shaft angle deviating more than 3° from the planned stem-shaft angle, this occurred in 50 cases (57%) in the non-navigated group (p≤0.001).

Hip resurfacing is a technically demanding procedure with a steep learning curve. Varus placement of the femoral component and notching have been recognised as important factors associated with early failures following hip resurfacing. While conventional instruments allowed reasonable alignment of the femoral component, our study has shown that use of computer navigation allows more accurate placement of the femoral component even when the surgeons had a significant experience with conventional technique.

Heterotopic ossification (HO) occurs commonly after total hip arthroplasty (THA). Its severe form can result in impaired range of motion with reduced functional outcome. The rate and severity of HO after hip surface replacement arthroplasty (SRA) have never been well studied.

Two hundred and ten hips were randomised to receive uncemented metal-on-metal THA or metal-on-metal SRA. Standard radiographs of the pelvis were assessed for HO by two reviewers at the latest follow-up (minimum of six months), using Brooker severity grading and Kjaersgaard-Andersen regional classification.

The incidence of HO was 38.5% in the SRA group compared to 32.6% in the THA group (p=0.5). However, there was a significant difference in severity grades for the two groups (chi square, p=0.02). According to Brooker’s classification, nearly half of HO was of grade two in SRA and of grade one in THA. SRA was associated with significantly higher rates of severe HO (grades three and four) than THA (12.5% vs. 2.2%; p=0.009). Inter-rater agreement for Brooker grading was excellent (Cohen’s kappa, 0.88; p< 0.01).

The incidence of HO after hip arthroplasty seems to be determined by patient-related factors. However, HO severity appears to be associated with local surgical factors and thereby SRA may result in more severe HO than THA. An extensive surgical approach, additional soft tissue release and the blunt damage occurring in gluteal muscles with SRA may signal the induction of more severe HO. Peri-operative deposition of bone debris derived from femoral head preparation may also play a role by transplanting osteoprogenitor cells. Surgeons must be aware of this risk of severe HO when offering SRA as an alternative treatment to younger patients. Routine prophylaxis with NSAIDs needs to be considered in these patients. A meticulous surgical technique to reduce muscle damage, pulsed lavage to clear bone debris, and debridement of necrotic tissue, may help to decrease the risk of severe HO in SRA.

INTRODUCTION: Improved factors influencing component wear with regards to bearing surfaces, metallurgy, tribology, and manufacturing technology allowed reintroduction of metal-on-metal (MOM) articulation in total hip arthroplasty (THA) and surface replacement arthroplasty (SRA).

MATERIALS AND METHODS: Sixty three patients were implanted with a forged, high carbon content, chrome-cobalt, MOM SRA component (Durom, Zimmer, USA). Samples of whole blood and serum were collected pre-operatively and, post-operatively at three months, six months one year and two years. Chromium and cobalt concentrations were measured using a a high-resolution, sector-field, inductively-coupled plasma mass spectrophotometer (HR-SF-ICP-MS).

RESULTS: At two years, whole blood levels were Cr 1.25 umol/L (SD 0.55), Co 0.62 umol/L (SD 0.26). In comparison to the pre-operative levels, the levels increased significantly for both elements Cr 1.3X, Co 5.0 X. Component size was inversely proportional to the chromium and cobalt ion levels at one year post operatively (ANOVA regression analysis, p = 0.0404, for Co and p = 0.0156 for Cr). Other factors such as age and activity level did not correlate with the metal ions levels.

DISCUSSION AND CONCLUSION: Chromium and cobalt metal ions measured in patients following implantation of the high carbon content, forged, metal on metal SRA implants used in this study are very low in comparison to other published results with different SRA implants. We believe that these encouraging results found with the SRA components used are resultant of favourable manufacturing and tribologic factors such as low surface roughness, high carbon content, forged chromium and cobalt material, component clearance, and optimum component sphericity. The results of this study are also in accordance with the concepts of reduced wear with larger diameter MOM articulations.

PURPOSE: The purpose of this study was to compare the level of post operative sport activity in a randomized study of SRA and THA.

INTRODUCTION: Return to high activity level has been proposed has an advantage of hip resurfacing (SRA) compared to THA. However, patient selection for SRA favours higher demand individuals, thus leading to a biased comparison of both techniques.

MATERIALS AND METHODS: Patients were randomized to THA or SRA. At minimum one year follow-up, the patients were asked about the activities they have resumed, the level of satisfaction regarding return to sports and the factors limiting full return to intense activities. 80 THA and 85 SRA with a mean follow-up of 16 months were analyzed.

RESULTS: The postoperative UCLA activity score was significantly higher in the SRA group (6.3 versus 7.1, p< 0.05). 77% of the SRA patients returned to high or moderate activity level vs 39% in the THA group (p=0.007). In the THA group, the activity level was mostly restricted due to concern about instability. However, some THA patients were still able to perform high demand activities.

DISCUSSION AND CONCLUSION: This study suggests that SRA allows return to higher activity level when compared to THA. This may be due in part to the larger diameter head of SRA which improves stability and suction-fit (reducing micro separation of the bearing during activities). Enhanced proprioception due to the retained femoral neck may also be involved in the bias towards SRA. Further follow-up is will determine if higher activity level is detrimental to implant survivorship

Introduction: Heterotopic ossification (HO) occurs commonly after total hip arthroplasty (THA). Its severe form can result in impaired range of motion with reduced functional outcome. The rate and severity of HO after hip surface replacement arthroplasty (SRA) have never been well studied.

Methods: Two hundred and ten hips (194 patients) were randomized to receive uncemented metal-on-metal THA (103) or metal-on-metal SRA (107). Standard antero-posterior radiographs of the pelvis were assessed for HO by 2 reviewers at the latest follow-up (minimum of 6 months), using Brooker severity grading and Kjaersgaard-Andersen regional classification.

Results: Pre-operative and post-operative data were similar for both groups. The incidence of HO was 38.5% in the SRA group compared to 32.6% in the THA group (p=0.5). However, there was a significant difference in severity grades for the 2 groups (chi square, p=0.02). According to Brooker_s classification, nearly half of HO was of grade 2 in SRA and of grade 1 in THA. SRA was associated with significantly higher rates of severe HO (grades 3 and 4) than THA (12.5% vs. 2.2%; p=0.009). Inter-rater agreement for Brooker grading was excellent (Cohen_s kappa, 0.88; p< 0.01). HO in SRA involved both the central and lateral regions in 26% of cases, whereas only 3% of HO in THA showed such a pattern (p=0.025). Risk factors, such as male gender, osteoarthritis, bilateral predilection, and previous history of HO, were observed in both groups. Patients with HO had reduced internal hip rotation (16.4° vs. 22.2°; p=0.02) and a higher incidence of postoperative hip pain (52% vs. 30%; p=0.04), but comparable functional outcome scores.

Discussion: The incidence of HO after hip arthroplasty seems to be determined by patient-related factors. However, HO severity appears to be associated with local surgical factors and thereby SRA may result in more severe HO than THA. An extensive surgical approach, additional soft tissue release and the blunt damage occurring in gluteal muscles with SRA may signal the induction of more severe HO. Peri-operative deposition of bone debris derived from femoral head preparation may also play a role by transplanting osteoprogenitor cells. Surgeons must be aware of this risk of severe HO when offering SRA as an alternative treatment to younger patients. Routine prophylaxis with NSAIDs needs to be considered in these patients. A meticulous surgical technique to reduce muscle damage, pulsed lavage to clear bone debris, and debridement of necrotic tissue, may help to decrease the risk of severe HO in SRA.

Purpose: Tribological studies suggest that larger metal-on-metal articulations would produce less wear than smaller diameter components. The aim of the present study is to describe whole blood Chrome and Cobalt ions concentration after metal-metal total hip arthroplasty (THA) and surface replacement arthroplasty (SRA).

Methods: 180 patients eligible for the study were randomized to receive uncemented 28 mm metal-metal THA or a hybrid metal-metal SRA. Whole blood samples were collected pre-operatively, at three, six months and one year post operatively. Chrome and Cobalt concentration were measured by mass spectrophotometry.

Results: At one year post op, whole blood levels of the were Cr 1.8 umol/L and Co 0.6 umol/L for the SRA and Cr 1.7 umol/L and Co 0.8 umol/L for the THA group (Cr, p=0.676 and Co, p=0.08). In comparison to pre-operative levels, the post operative levels significantly incresed for all elements Cr 1.9x and Co 3.8x for the SRA; Cr 1.3x and Co 3.4x. for the SRA group, Anova regression tests showed a significant relation between component size and Cr and Co metal ions levels; the larger the component, the lower the ions levels (Cr p=0.0285 and Co p=0.0442)

Conclusions: Using these specific implants, the increases whole blood metal ions were similar to the best results found in the literature for 28 mm metal-metal THA. Results of this study confirm the good tribologic performances of the Metasul large diameter metal-metal articulations. Funding: Commerical funding Funding Parties: Zimmer

A descriptive study of osteoporotic fractures and the evaluation of the relative risk of hip fracture following a minor fracture were done on 2.5 million individuals from 1980 to 1997. People aged forty-five years old and older have a risk for hip fracture after a minor fracture of 2.3–17.3 time the risk of people without previous fracture. Given the availability of pharmaceuticals that decrease the fracture risk dramatically within the first 18 months of therapy, the average four to six years time between minor and hip fracture represents a perfect window of opportunity for preventive treatment.

Osteoporotic fractures, especially hip fractures, represent a major health problem in terms of morbidity, mortality and cost. Since the availability of new treatments for osteoporosis, a better understanding of the disease is needed to define the indications for treatment.

A descriptive study of osteoporotic fractures and the evaluation of the relative risk of hip fracture following a minor fracture were done on a population aged fortyfive years old and older from 1980 to 1997 (2.5 million individuals).

During the follow-up period, 220,120 fractures (hip, wrist, proximal humerus and ankle) were recorded. Wrist fractures were the most frequent (42.2%) followed by hip fractures (32.5%). Although the proportions of fracture sites were similar for both sexes, 75% of the fractures occurred in females. The mortality rate 1 year after a hip fracture is increased by 14–27% for men and 9–13% for women. Men and women aged fortyfive years old and older have a risk for hip fracture after a humerus or a wrist fracture of 2.3–17.3 time the risk of people without previous fracture. The average time between a wrist or humerus fracture and a hip fracture was four to six years.

Wrist and humerus fractures represent a major risk for future hip fracture. Given the availability of pharmaceuticals that decrease the risk of hip fracture dramatically within the first eighteen months of therapy, the interval between minor and hip fracture represents a perfect window of opportunity for preventive treatment to decrease the risk of future hip fracture.

The dramatic improvement in clinical function after total hip arthroplasty (THA) has been well-documented. Gait studies, however, demonstrate abnormal gait pattern after THA. THA patients may complain of thigh pain, leg length inequality, instability and reduced range of motion. Surface replacement arthroplasty (SRA) has the benefit of restoring a more normal hip anatomy and biomechanics, which could improve clinical function and patient satisfaction after surgery. We compared the clinical function and patient satisfaction in a group of young patients randomized to receive SRA or THA. The results are presented and discussed.

The dramatic improvement in clinical function after total hip arthroplasty (THA) has been well-documented. However gait studies demonstrate abnormal gait patterns after THA, and patients may complain of thigh pain, leg length inequality, instability and reduced range of motion. Surface replacement arthroplasty (SRA) has the benefit of restoring a more normal hip anatomy and biomechanics, which could improve clinical function and patient satisfaction after surgery.

All patients eligible for the study were randomised to receive uncemented metal-metal THA or a hybrid metal-metal SRA. Clinical data were prospectively collected pre-operatively and at three, six and twelve months post-operatively. WOMAC score, SF-36, Merle D’Aubigné, and other clinical data, along with patient satisfaction, were compared.

One hundred and fifty patients were randomized. Both groups demonstrated a very high satisfaction rate. Although there was a tendency for the SRA group to participate in more demanding activities at six months post-operatively, no difference was found in clinical function scores. Two isolated dislocations occurred in the THA group and none in the SRA group. There were no other significant complications in either group.

The few short-term clinical data reported in the literature for new generation SRA implants demonstrate an excellent outcome comparable to THA. Despite enthusiasm about total hip resurfacing, no direct prospective comparative study with THA has been published in the literature. This study confirms the safety and benefits of metal-metal SRA of the hip in the early post-operative period.

Funding: This research project was funded by Zimmer, Warsaw

One hundred and forty eight hybrid total hip arthroplasties in patients less than seventy years old were randomised to metal on polyethylene or alumina on alumina bearing surfaces. At two to seven years of follow-up, no significant difference was found on hip scores or survivorship of the implants. No specific complication associated to alumina components like fracture or malpositionning of the acetabular insert were observed. Alumina on alumina bearing surfaces give early clinical and radiological results similar to metal on polyethylene, suggesting that they have a potential to become good bearing surfaces in hip arthroplasty for young patients.

The excellent results obtained with metal-polyethylene (M-P) bearing surfaces in total hip arthroplasty (THA) are still limited by the production of polyethylene wear debris, osteolysis and aseptic loosening. Because of it superior tribologic properties and bioinert composition, alumina-alumina (AL-AL) bearing surfaces are proposed to improve survival of THA but previously reported early complications prevented widespread use of alumina ceramic. This study compares early results and complication with Ceraver M-P and AL-AL THA.

One hundred forty-eight Ceraver hybrid THA in patients less than seventy years old were randomised to M-P or AL-AL bearing surfaces. We present the clinical and radiological results for patients two to seven years after their surgery.

No significant difference was found on W.O.M.A.C. and Merle D’Aubigné Postel scores. No specific complication associated with alumina components like fracture or malpositionning of the acetabular insert were observed in this study. Documented complications were: infection 4 AL-AL/2 M-P; dislocation 1 AL-AL/4 M-P; and heterotopic ossification 47% AL-AL/24% M-P. No aseptic loosening was observed.

Ceraver AL-AL bearing surfaces give early clinical and radiological results similar to M-P. Our results are in accordance with studies suggesting that AL-AL have a potential to become good bearing surfaces in THA in the young patients.

Funding: funding was obtained from Ceraver, Paris to perform this study.