Aims

Dual-mobility acetabular components (DMCs) have improved total hip arthroplasty (THA) stability in femoral neck fractures (FNFs). In osteoarthritis, the direct anterior approach (DAA) has been promoted for improving early functional results compared with the posterolateral approach (PLA). The aim of this study was to compare these two approaches in FNF using DMC-THA.

Dual mobility cups (DMC) reduce the risk of dislocation in femoral neck fractures (FNF). Direct anterior approach (DAA), historically promoted for better stability, has been developed in recent years for better functional results. The aim of this study was to compare the early functional results of DMC in FNF by DAA versus posterolateral approach (PLA).

A prospective study was conducted on a continuous series of patients who received DMC for FNF by DAA or PLA. The primary endpoint was Harris Hip Score and Parker score assessed at the first follow-up visit. Intraoperative complications were collected during hospitalization. One year clinical results and all cause revision rate were also collected. Radiographic data of cup positioning and limb length were evaluated.

Fifty-two patients were included in the DAA group and 54 in the PLA group. Two patients were lost to follow-up. The mean age was 72.8 years. There was no significant difference in HHS or Parker score at 3 and 12 months follow up (p=0.6, p= 0.75). DAA was associated with more intraoperative complications with 4 fractures and 1 femoral nerve deficit (p=0.018). There were 3 revisions in the DAA group (1 infection, 1 dislocation, 1 peri prosthetic fracture) and 1 in the PLA group (infection), which was not statistically significant (p=0.34). Cup anteversion was 6° greater and inclination 9° lesser in DAA group (p=0.028, p<0.01).

Results suggest that DAA does not provide any early functional benefit in THA-DMC for FNF compared to PLA. It could lead to more intraoperative complications and a higher revision rate. DAA requires an experienced surgeon and careful patient selection.

Aims

Two-stage exchange revision total hip arthroplasty (THA) performed in case of periprosthetic joint infection (PJI) has been considered for many years as being the gold standard for the treatment of chronic infection. However, over the past decade, there have been concerns about its safety and its effectiveness. The purposes of our study were to investigate our practice, collecting the overall spacer complications, and then to analyze their risk factors.

Two-stage exchange revision total hip arthroplasty performed in case of infection has been considered during many years the gold standard for treatment of chronic infection. Nevertheless, during the last decade, concerns have risen regarding its safety and its efficiency. The purpose of our study was to, first investigate the spacer complications, then to analyze their risks factors.

We retrospectively included 125 patients with chronic hip periprosthetic joint infection who underwent a two stage exchange revision arthroplasty performed between January 2013 and December 2019. All spacer complications were systematically collected and risk factors were analyzed. Statistical evaluation were performed using the Student and Mann-Whitney tests.

Our study confirms the hypothesis of a high-risk strategy with 42% of patients who had a mechanical spacer failure and a 20% recurrence of infection during the average two years period of follow-up. We found a high rate of spacer migration (23%) and a low rate of spacer fracture (8%) compared to literature.

The most important finding was that the majority of spacer complications and failures were found in a population with high medical comorbidities as highlighted by the ASA, Charlson and Lee score associations, as well as with the cardiac, pulmonary, kidney or hepatic chronic conditions.

This study showed that a two-stage hip exchange revision is a high-risk procedure regarding complications and mechanical failures of PMMA spacers.

In patients with high medical comorbidities, other strategies may be considered and interdisciplinary cooperation with other facilities are needed to identify and control each risk factor.

Aims

The aim of this study was to compare the ability of tantalum, 3D porous titanium, antibiotic-loaded bone cement, and smooth titanium alloy to inhibit staphylococci in an in vitro environment, based on the evaluation of the zone of inhibition (ZOI). The hypothesis was that there would be no significant difference in the inhibition of methicillin-sensitive or methicillin-resistant Staphylococcus aureus (MSSA/MRSA) between the two groups.

Introduction

Numerous fluoroscopic studies have been conducted to investigate kinematic variabilities of total knee arthroplasty (TKA). In those studies, subjects having a posterior stabilized (PS) TKA experience greater weightbearing knee flexion and posterior femoral rollback of the lateral condyle. In those same studies, subjects did experience a high incidence of variable medial condyle motion and reverse axial rotation, especially occurring when the cam engaged the post. More recently, a PS TKA was designed to accommodate both gender and ethnicity. Therefore, the objective of this study was to assess in vivo kinematics for subjects having this TKA type to determine if subjects having this PS TKA experienced more optimal knee kinematics.

Introduction

Periprosthetic joint infection (PJI) remains the main cause of failure in primary and revision total knee arthroplasties (TKAs). Local delivery of antibiotics, mainly antibiotic-loaded bone cement (ALBC), is commonly employed to prevent PJI. Over the past decade, tantalum and porous titanium have been successfully utilized as metaphyseal fixation devices to address bone loss and improve biologic fixation during revision TKA. However, no study has examined the antimicrobial properties compared to bone cement. The purpose of this study was to compare the ability of tantalum, 3D porous titanium, antibiotic-loaded bone cement (ALBC) and smooth titanium alloy (STA) to inhibit Staphylococci bacterial agents in an in vitro medium environment, based on the evaluation of the zone of inhibition (ZOI) and the antibacterial activity duration. Our study hypothesis was that we will found no significant difference between groups to inhibit Methicillin-Sensitive or Methicillin-Resistant Staphylococcus aureus (MSSA/MRSA) agents.

Aims

The aims of this study were to compare the mean duration of antibiotic release and the mean zone of inhibition between vancomycin-loaded porous tantalum cylinders and antibiotic-loaded bone cement at intervals, and to evaluate potential intrinsic antimicrobial properties of tantalum in an in vitro medium environment against methicillin-sensitive Staphylococcus aureus (MSSA).

Aims

In patients where the proximal femur shows gross deformity due to degenerative changes or fracture, the contralateral femur is often used to perform preoperative templating for hip arthroplasty. However, femurs may not be symmetrical: the aim of this study was to determine the degree of variation between hips in healthy individuals and to determine whether it is affected by demographic parameters.

The contralateral femur is frequently used for preoperative templating of total hip arthroplasty assuming femoral symmetry. We aimed to define the degree of asymmetry between left and right proximal femurs and whether if affected by demographics parameters.

A CT-scan based modeling and analytics system of 346 CT-scans was used for this study, including pelvis and bilateral femora from 211 men and 135 women (mean age 61 ±16 years, mean BMI 26± 5 kg/m²⁾. The femoral neck shaft angle (NSA), femoral offset (FO), femoral neck version (FNV), femoral length (FL), canal flare index (CFI) and femoral head diameter (FHD) were calculated for each patient. We then, analyzed symmetry based on absolute differences(AD) and percentage of asymmetry(%AS).

An asymmetry >2% was found for NSA (mean AD=2.9°; mean %AS=2.3; p=0.03), FO (AD=3.8mm; %AS=9.1; p=0.01), FNV (AD=5.1°; %AS=46.7; p=0.001) and CFI (AD=0.2mm; %AS=5.4; p=0.7). Percentage of asymmetry was <2% for FL (AD=3.6mm; %AS=0.8; p=0.7) and FHD (AD=0.3mm; %AS=1.2; p=0.8). No correlation and predictive value was found between either AD or %AS and age, ethnicity, gender, height, weight or BMI.

Our data support assumptions of substantial asymmetry of the proximal femur which is not affected by demographics or proximal femoral size.

Clinical relevance: Upper femurs are not symmetric. Preoperative planning on contralateral femur might be affected this geometrical bias.

Background

A principle of Total Knee Arthroplasty (TKA) is to achieve a neutral standing coronal alignment of the limb (Hip Knee Ankle (HKA) angle) to reduce risks of implant loosening, reduce polyethylene wear, and optimise patella tracking. Several long-term studies have questioned this because the relationship between alignment and implant survivorship is weaker than previously reported. We hypothesize standing HKA poorly predicts implant failure because it does not predict dynamic HKA, dynamic adduction moment, and loading of the knee during gait. Therefore, the aim of our study is to assess the relationship between the standing (or static) and the dynamic (gait activity) HKAs.

A principle of Total Knee Arthroplasty (TKA) is to achieve a neutral standing coronal alignment of the limb (Hip Knee Ankle (HKA) angle) to reduce risks of implant loosening, reduce polyethylene wear, and optimise patella tracking. Several long-term studies have questioned this because the relationship between alignment and implant survivorship is weaker than previously reported. We hypothesize standing HKA poorly predicts implant failure because it does not predict dynamic HKA, dynamic adduction moment, and loading of the knee during gait. Therefore, the aim of our study is to assess the relationship between the standing (or static) and the dynamic (gait activity) HKAs.

We performed a prospective study on a cohort of 35 patients (35 knees) who were treated with a posterior-stabilized TKA for primary osteoarthritis between November 2012 and January 2013. Three months after surgery each patient had a standardized digital full-leg coronal radiographs and was classified as neutrally aligned TKA (17 patients), varus aligned (9 patients), and valgus aligned (4 patients). Patients then performed a gait analysis for level walking and dynamic HKA and adduction moment during the stance phase of gait were measured.

We found standing HKA having a moderate correlation with the peak dynamic varus (r=0.318, p=0.001) and the mean and peak adduction moments (r=0.31 and r=-0.352 respectively). In contrast we did not find a significant correlation between standing HKA and the mean dynamic coronal alignment (r=0.14, p=0.449). No significant differences were found for dynamic frontal parameters (dynamic HKA and adduction moment) between patients defined as neutrally aligned or varus aligned.

In our practice, the standing HKA after TKA was of little value to predict dynamic behaviour of the limb during gait. These results may explain why standing coronal alignment after TKA may have limited influence on long term implant fixation and wear.

Treatment of osteoarthritis of the knee remains a challenging problem since the evolution of the disease may be different in each compartment of the knee, as well as the state of the ligaments. Total knee arthroplasty may provide a reliable long-lasting option but do not preserve the bone stock. In another hand, compartmental arthroplasty is a bone and ligament sparing solution to manage limited osteoarthritis of the knee affecting the medial, lateral or the patello-femoral compartment.1, 2, 3

Patient's selection and surgical indication are based on the physical examination and on the radiological analysis including full-length x-rays and stress x-rays. Clinical experience has shown the need for high flexion in patients who have both high flexibility and a desire to perform deep flexion.

Additionally the shape differences related to anatomy or the patient expectations after the surgery may also affect the surgeon decision. 4

The limited incision into the extensor mechanism allows a quicker recovery which represents a functional improvement for the patient additionally to the cosmetic result. A dedicated physiotherapy starting on the following day allowing weight bearing exercises protected by crutches and focusing on early mobilization and range of motion combined to a multimodal pain management approach is critical despite the type of individualized solution chosen for the patient knee. 5

Since bony landmarks may be different form a patient to another one as well as anatomical shapes, several tools have been developed in order to provide the surgeons an assisted tool during the surgery adapted to each knee, this include navigation, patient specific instrumentation and robotic surgery.

Improving the adaptation between the implant and the patient bone during total hip arthroplasty (THA) may improve the survival of the implant. This requires a perfect understanding of the tridimensional characteristics of the patient hip. The perfect evaluation of the tridimensional anatomy of the patient hip can be done pre-operatively using X-rays and CT-scan. All patients underwent a standard x-rays evaluation in the same center according to the same protocol. Pre-operatively, the frontal analysis of the hip geometry was performed and the optimal center of rotation, CCD angle, neck length and lever arm was analyzed to choose the optimal solution for proper balance of the hip in order to obtain adequate range of motion, appropriate leg length, and correct tension of the abductors muscles. Standard or lateralized monoblock stems can be valid or modular neck shape can be choosen among 9 available shape. These 9 frontal shapes are available in standard, anteverted or retroverted shapes, leading to 27 potential neck combinations. In case of important hip deformation, a custom implant can be used in order to balance the extra-medullar geometry without compromising the intra-medullary adaptation of the stem.

We prospectively included 209 hips treated in our institution with total hip arthroplasty performed using a supine Watson-Jones approach and the same anatomic stem. The mean patient age was 68 years and the mean BMI 26 Kg/m². Intra-operatively the sagittal anatomy of the hip was analyzed and standard, ante or retro modular necks were tested for the frontal shape defined pre-operatively.

According to the pre-operative frontal planning, non-standard necks were required in 24 % of the cases to restore the anatomy of the hip. Intra-operatively, a sagittal correction using anteverted neck was required in 5% of the cases and retroverted necks in 18% of the cases. Harris hip score improved from 56 to 95 points at min. 5 year follow-up. No leg length discrepancy greater than 1 cm was observed. Restoration of the lever arm (mean 39.3 mm, range 30 to 49 mm) and of the neck length (55.2, range 43 to 68 mm) was adapted for 95% compared to the non operate opposite side. Disturbed anatomy like in DDH or post-traumatic cases may require additional solutions to balance the hip such combined osteotomy or customized stem and neck.

Partial knee arthroplasty (PKA), either medial or lateral unicompartmental knee artroplasty (UKA) or patellofemoral arthroplasty (PFA) are a good option in suitable patients and have the advantages of reduced operative trauma, preservation of both cruciate ligaments and bone stock, and restoration of normal kinematics within the knee joint. However, questions remain concerning long-term survival. The goal of this review article was to present the long-term results of medial and lateral UKA, PFA and combined compartmental arthroplasty for multicompartmental disease. Medium- and long-term studies suggest reasonable outcomes at ten years with survival greater than 95% in UKA performed for medial osteoarthritis or osteonecrosis, and similarly for lateral UKA, particularly when fixed-bearing implants are used. Disappointing long-term outcomes have been observed with the first generation of patellofemoral implants, as well as early Bi-Uni (ie, combined medial and lateral UKA) or Bicompartmental (combined UKA and PFA) implants due to design and fixation issues. Promising short- and med-term results with the newer generations of PFAs and bicompartmental arthroplasties will require long-term confirmation.

Cite this article: Bone Joint J 2015;97-B(10 Suppl A):9–15.

Introduction:

Recent studies have concluded that gender influences hip morphology at the time of surgery as well as dysplastic development of the hip. This may lead to a particular choice of implant including stem design and/or neck modularity. In this study we hypothesized that not only gender but also morphotype and etiology (primary osteoarthritis versus aseptic osteonecrosis) may be a significant factor to predict the anatomy of the hip at the time of total hip arthroplasty (THA).

Introduction

Previous fluoroscopic studies compared total knee arthroplasty (TKA) kinematics to normal knees. It was our hypothesis that comparing TKA directly to its non-replaced controlateral knee may provide more realistic kinematics information. Using fluoroscopic analysis, we aimed to compare knee flexion angles, femoral roll-back, patellar tracking and internal and external rotation of the tibia.

Anterior knee pain is one of the most frequently reported musculoskeletal complaints in all age groups. However, patient's complaints are often nonspecific, leading to difficulty in properly diagnosing the condition. One of the causes of pain is the degeneration of the articular cartilage. As the cartilage deteriorates, its ability to distribute the joint reaction forces decreases and the stresses may exceed the pain threshold. Unfortunately, the assessment of the cartilage condition is often limited to a detailed interview with the patient, careful physical examination and x-ray imaging. The X-ray screening may reveal bone degeneration, but does not carry sufficient information of the soft tissues' conditions. More advanced imaging tools such as MRI or CT are available, but these are expensive, time consuming and are only suitable for detection of advanced arthritis. Arthroscopic surgery is often the only reliable option, however due to its semi-invasive nature, it cannot be considered as a practical diagnostic tool. However, as the articular cartilage degenerates, the surfaces become rougher, they produce higher vibrations than smooth surfaces due to higher friction during the interaction. Therefore, it was proposed to detect vibrations non-invasively using accelerometers, and evaluate the signals for their potential diagnostic applications.

Vibration data was collected for 75 subjects; 23 healthy and 52 subjects suffering from knee arthritis. The study was approved by the IRB and an Informed Consent was obtained prior to data collection. Five accelerometers were attached to skin around the knee joint (at the patella, medial and lateral femoral condyles, tibial tuberosity and medial tibial plateau). Each subject performed 5 activities; (1) flexion-extension, (2) deep knee bend, (3) chair rising, (4) stair climbing and (5) stair descent. The vibration and motion components of the signals were separated by a high pass filter. Next, 33 parameters of the signals were calculated and evaluated for their discrimination effectiveness (Figure 1). Finally the pattern recognition method based on Baysian classification theorem was used for classify each signal to either healthy or arthritic group, assuming equal prior probabilities.

The variance and mean of the vibration signals were significantly higher in the arthritic group (p=2.8e-7 and p=3.7e-14, respectively), which confirms the general hypothesis that the vibration magnitudes increase as the cartilage degenerates. Other signal features providing good discrimination included the 99^th quantile, the integral of the vibration signal envelope, and the product of the signal envelope and the activity duration. The pattern classification yielded excellent results with the success rate of up to 92.2% using only 2 features, up to 94.8% using 3 (Figure 2), and 96.1% using 4 features.

The current study proved that the vibrations can be studied non-invasively using a low-cost technology. The results confirmed the hypothesis that the degeneration of the cartilage increases the vibration of the articulating bones. The classification rate obtained in the study is very encouraging, providing over 96% accuracy. The presented technology has certainly a potential of being used as an additional screening methodology enhancing the assessment of the articular cartilage condition.

Background

Acetabular component malpositioning during hip arthroplasty increases the risk of dislocation, reduces range of motion and can be responsible for early wear and loosening. There have been numerous reports on the optimal orientation of the acetabular component in total hip arthroplasty (THA). Lewinnek et al recommended an abduction angle of 40°±10° and an anteversion of 15°±10° for cup alignment in THA. The purpose of the in vivo study was to compare computer assisted acetabular component insertion versus free-hand placement. The goal of the cadaveric study was to compare in vitro a new tool using ultrasound with the standard percutaneous manual methods for the anterior pelvic plane registration during computer-assisted total hip arthroplasty.

Introduction

It is documented in the literature the very good results of lateral unicompartmental knee arthroplasty (UKA) when the standard accepted indications are followed. In our experience these indications can be extended to include post-traumatic osteoarthritis (OA) with malunion secondary to tibial plateau fracture. We report our results concerning 15 UKAs in these particular situations.

We describe the results of 81 consecutive revision total hip replacements with impaction grafting in 79 patients using a collared polished chrome–cobalt stem, customised in length according to the extent of distal bone loss. Our hypothesis was that the features of this stem would reduce the rate of femoral fracture and subsidence of the stem.

The mean follow-up was 12 years (8 to 15). No intra-operative fracture or significant subsidence occurred. Only one patient suffered a post-operative diaphyseal fracture, which was associated with a fall. All but one femur showed incorporation of the graft. No revision for aseptic loosening was recorded.

The rate of survival of the femoral component at 12 years, using further femoral revision as the endpoint, was 100% (95% confidence interval (CI) 95.9 to 100), and at nine years using re-operation for any reason as the endpoint, was 94.6% (95% CI 92.0 to 97.2).

These results suggest that a customised cemented polished stem individually adapted to the extent of bone loss and with a collar may reduce subsidence and the rate of fracture while maintaining the durability of the fixation.

Purpose of the study: Three-screw fixation is the classical treatment for true Garden I in the elderly patient. Complication rates have been high in the literature. Furthermore, in this context outcome for arthroplasty after failed osteosynthesis is less satisfactory than first-intention arthroplasty. This is why functional treatment of Garden I fractures of the neck of the femur has been proposed, including rapid return to the upright position and strict radiographic and clinical control. The purpose of this work was to first evaluate the results of this management option for true Garden I fractures in patients aged over 65 years and second to search for factors predictive of secondary displacement.

Material and methods: All patients aged over 65 years and admitted to the unit for true Garden I fractures from January 2005 to December 2006 were included in this prospective study. A functional treatment including early return to the upright position and walking test on day 1 was instituted, followed by radiographic controls on days 2, 7, 14, 21, and 45 then at 3 months and one year. Referral to a rehabilitation centre at discharge on day 5 was scheduled if there was no displacement. In the event of a displacement, arthroplasty was performed. Fifty-seven patients, mean age 82.8±8.5 years (range 65–99) were included. The radiographic and clinical follow-ups were made by an independent observer.

Results: The displacement rate was 29.8%. These patients were treated by arthroplasty. In the group of patients without displacement, at minimum one year follow-up, there has been no need for surgical revision excepting one case of osteonecrosis at one year requiring implantation of a total prosthesis. The mean Parker score in this group was 6.4 and the mean Harris score 83, it was 85 in the arthroplasty group. Among the predictive factors identified at multivariate analysis were: age, gender, side, type of fracture, fracture orientation, degree of valgus or sagittal displacement, general status. Displacement was not statistically predictive.

Discussion: The results of our prospective study show that 70% of patients included were treated successfully without surgery, confirming reports in the literature and justifying utilisation of this management strategy.

Purpose of the study: It has been demonstrated that the anatomy of the distal femur differs by gender. The ratio of the mediolateral/anteroposterior distance, the shape of the distal femur, and the orientation of the trochlea differ between males and females. To adapt to these differences, prostheses specifically designed for female patients (TKAgender) were developed. The purpose of our study was to compare the first objective and subjective outcomes with these prostheses.

Material and methods: Thirty women who underwent bilateral surgery within a six month interval for degenerative joint disease of the knee between March 2006 and March 2008 were included in a comparative prospective study. The side receiving the gender implant was determined at random. Operative and postoperative protocols were the same excepting the femoral implant. Patients were not informed of which knee had received the gender prosthesis. Mean age in this series was 67 years and mean BMI 26. All implants were cemented. At minimum one year follow-up, objective and subjective analysis included specific questions concerning preference and quality of life presented by an independent observer.

Results: The Knee Society clinical scores were comparable in the two groups, as were the results for the different items of the KOOS score. For preferences: the patients preferred the gender knee in 75% of the cases (p< 0.01), they reported less noise or cracking sounds in the anterior part of the knee for 68% (p=0.03) and had the impression that the knee recovered faster in 64% (p=0.04).

Discussion: To our knowledge, this is the first report of results concerning implants specifically designed for female patients. At short-term, the only difference in the patients’ preference was a subjective feeling of less impairment for the patellar track. It will be interesting to follow these patients to assess the long-term impact on the patellofemoral articulation.

Most of computer-assisted computer assisted system rely on the peri-operative acquisition of the anterior pelvic plane defined as the plane crossing the two anterior iliac spine and the symphysis. The goal of this study was to evaluate in vivo and in vitro the accuracy of the anterior pelvic plane acquisition, considered as the reference for computer-assisted total hip arthroplasty (THA).

Cup placement was performed using an imageless computer-assisted system in thirty patients during THA. Post-operatively the position of the cup was evaluated on computed tomography using a validated tridimensional software. The differences between the perioperative and postoperative angles for abduction and anteversion were compared using a two-group pair test.

On two cadavers four clinicians performed ten times the anterior pelvic plane acquisition using three Methods: percutaneously, with ultrasound and by direct bony acquisition defined as the reference. The mean error for each anterior pelvic plane acquisition method was compared using a univariate variance model for repeated measurements.

In vivo, the mean difference between the perioperative and postoperative abduction angles was 4° and not statistically significant. For anteversion, the difference was 4° and not significant in patients with BMI < 27. The difference was 11° and significant in patients with BMI > 27 (p< 0.001). In vitro, the mean errors for rotation and tilt were respectively 3.8 ° and 19.25 ° for cutaneous acquisition, 2.8° and 6.2° for ultrasound acquisition method. The errors were statistically higher with the percutaneous method (p< 0.001).

According to our results, the accuracy of the standard percutaneous acquisition method of the anterior pelvic plane in computer-assisted THA is limited. The ultrasound acquisition method may represent a reliable alternative.

Purpose of the study: Because of the growing number of aseptic loosening of total hip arthroplasty (THA), a reliable biological marker would be useful to diagnosis osteolysis early and non-invasively while avoiding the risk of false positives. The purpose of this study was to analyse the value of the interleukin-10(IL10)-alphaTNF ratio in serum and synovial fluid as a marker of THA aseptic loosening.

Material and methods: Blood synovial fluid samples were collected in 27 volunteers with a cemented THA (group THA) and 30 healthy subjects comparable for age and gender who were programmed for total hip arthroplasty because of primary osteoarthritis (group OA). We analysed: locally by the level of alphaTNF and IL10 in the supernate of differentiated THP-1 with and without adjunction of synovial fluid (SF); in the bloodstream the production of alphaTNA and IL10 by monocytes; the correlation between serum and SF levels and the presence or not of loosening.

Results: In the THA group, SF induced a relative decrease in IL10 strangly not associated with an increase in alphaTNF. However, the IL10/alphaTNF ratio was significantly lower in the OA group. Circulating monocytes produced more alphaTNF in the THA group while there was no significant difference in the production of IL10 by the two groups. However, the IL10/alphaTNF ratio was significantly higher (2-fold) in the THA group. Regarding serum cytokine levels, there was a local accumulation of alphaTNF in the THA group and IL10 in the OA group.

Discussion: The IL10/alphaTNF ratio alone was significantly correlated with aseptic loosening, locally and in the general bloodstream. IL10 or alphaTNF did not alone correlate in all conditions. These results show that use of this ratio appears to be more effective than assay of a single proinflammatory cytokine for the early diagnosis of aseptic loosening. The validity of this ratio is supported by its local and general correlation. A comparative prospective study in healthy subjects using a non-invasive method (except for the blood samples) should be conducted to confirm the clinical pertinence of this marker.

Purpose of the study: Besides enabling a precise calculation of the needs for blood (in ml) for each type of orthopaedic surgery, an adequate estimation of average total blood loss (TBL) as a function of total blood volume (TBV) enables initiation of blood sparing techniques. Thus, when the balance is negative, erythropoietin could be advisable. The purpose of this work was to analyse the impact of prescribing erythropoietin as a function of the expected blood balance on the rate of homologous blood transfusions. We also wanted to determine the financial impact of this prescription strategy.

Material and methods: This prospective study included 229 patients (153 THA and 76 TKA) who underwent surgery from January 2005 to December 2008 with a standard anaesthesia, analgesia and surgical protocol. TBL was considered to be 10% of TBV for THA and TKA. Mean gain in serum haemoglobin (Hb) per injection of erythropoietin (1 ampoule Eprex) was 0.8 g/dl. Using the patient’s Hb level at the preop exam (Hbpreop), the anaesthetist determined the volume available (VA) for each patient and for each type of operation. When VA was negative, the Hb needed to reach the desired level (HbA) so that VA=0 (zero risk of transfusion) was calculated. The number of Eprex ampoules prescribed (amp) was determined from the formula: (HbA-Hbpreop)/0.8. Hb levels on day 0, day 1, day 3(discharge) and day 28 were noted, as were the number of homologous transfusions and the total number of ampoules of Eprex delivered.

Results: Sixty-six patient received one amp (33.2%), 96 had two amp (42%), 40 three amp (17.5%) and 17 four amp (7.4%). For 220 patients (92%), Eprex delivered was within the approved dose (92%). The mean Hb levels were: Hbpreop=12.4, HbA=13.5, Hbd0=13.9, Hbdischarge=11.2, and Hbd28=11.9. Total consumption was 456 amp instead of 916 (229x4), i.e. a savings of 460 amp corresponding to 173 880 euros (460 x 378 euros). There were six homologous transfusions (2.6%).

Discussion: In orthopaedic surgery, adapted prescription of erythropoietin as a function of the TBL enabled, in this series, a simplification of the prescription procedure and avoided the risks related to high Hb levels > 15g with a financial savings of 760 euros per operation (173880 euros for 229 patients) without increasing the rate of homologous transfusion. This strategy is currently being evaluated for prosthesis revision surgery.

Previosuly, Komistek et al. have shown that the kinematics of the patellofemoral joint is altered after a TKA surgery. Specifically the implanted patella experiences significantly less rotation than the natural patella. Also, in early flexion, the patellofemoral contact positions differed significantly between implanted and non-implanted patellae. It was also found that some of TKA subjects experience patellofemoral separation. These kinematical differences may lead to adverse mechanical conditions and increase fatigue or cause loosening of the implant components. This study’s objective was to determine the three-dimensional patellofemoral kinematics and correlate it with the in vivo sound (vibrations) detected using accelerometers for subjects having a TKA and a non-implanted knee under in vivo, weight bearing conditions. The correlation of the knee mechanical conditions with the vibration data may indicate new parameters that may be used to diagnose the condition of the articular cartilage or implant components.

Fifteen subjects (average age 71.8 ±7.4years) having one implanted knee (mobile bearing Hi-Flex PS) and the healthy contralateral knee, performed

deep knee bend to maximum flexion,

Three miniature, piezoelectric, three-axial accelerometers were attached to the patella and femoral epicondyle. The study was approved by the Institutional Review Board and informed consent was obtained from all subjects. The sensors detected the vibration magnitudes and frequencies of the articulating patellofemoral joint surfaces. The signals were amplified and low-pass filtered at 5 kHz by a signal conditioner. The 3D tibiofemoral and patellofemoral kinematics were derived for both knees using a previously published 3D-to-2D registration technique. The 3D bone models were recovered from CT scans, while implant models were obtained from the manufacturer. The patellofemoral rotations were described using the Grood and Suntay convention. The kinematics and sound data were synchronized and recorded under fluoroscopic surveillance, for 10 patients. Then a subset of seven subjects having a TKA was re-analyzed for their contralateral (non-implanted) knee. The vibration signal was then converted to audible sound and correlated with the 3D kinematics.

On average, the subjects achieved more flexion with their TKA (103.4°±15.9°) than with their contralateral knee (96.3°±18.3°). The patellofemoral kinematics varied between the TKA and nonimplanted patella groups; the resurfaced patella experienced less flexion, less medial rotation and less tilt than the contralateral patella. The patellar flexion results were consistent with previously reported literature for both TKA and non-implanted patellae. Also, the resurfaced patellae contacted the femur more proximally than healthy patellae. Audible signals were found for both groups of subjects. The frequency analysis demonstrated that specific frequencies were in similar range for both groups, but the magnitudes and variations were different for the TKA and contralateral knees.

This study correlated 3D patellofemoral kinematics with sound under in vivo conditions for three different activities. Variable audible signals were detected for TKA and non-implanted knees. Vibration magnitude and frequency identification, under in vivo conditions, for TKA may lead to a better understanding of wear and failure modes with respect to the patellofemoral mechanics, more specifically, the patellar insert. Currently this initial study is being expanded to degenerated knee joints and failed TKAs for possible applications of the vibration analysis to the early diagnosis of knee arthritis, detection of implant loosening or wear and monitoring of implant osteointegration progress.

Unicompartmental knee arthroplasty (UKA) is a logic procedure when osteoarthritis or avascular necrosis is limitad to one femorotibial compartment. The indications for the procedure includes osteoarthrosis or osteonecrosis with full-thickness loss of articular cartilage limited to one of the tibiofemoral knee compartments. Physical examination should ensure full range of knee motion. Frontal and sagittal knee stability has to be tested. A particular attention should be given to the state of the anterior cruciate ligament. The status of the patellofemoral joint should be analysed by physical examination and patellofemoral view at 30, 60 and 90° of flexion. Preoperative anteroposterior varus and valgus stress radiographs should be done to confirm the complete loss of articular cartilage in the involved compartment, the full thickness cartilage in the opposite compartment and the possibility of full correction of the deformity to neutral.

The so-called minimally invasive surgery (MIS) procedure using a specific instrumentation is able to provide quicker recovery since the extensor mechanism disruption is eliminated. More importantly the radiological evaluation has shown that precise implantation of the components is possible with an MIS approach which is important for the long term results of the arthroplasty. The clinical results at ten years of follow-up of cemented metal-backed UKA performed through a conventional approach have shown results comparable to those obtained with total knee arthroplasty. The in vivo kinematic evaluation of patients implanted with UKA has shown that kinematics similar to the normal knee can be obtained, enhancing the importance of a functional anterior cruciate ligament.

Recent design improvements have increased the femorotibial area of contact to accommodate high flexion angles. Additionally our experience has demonstrated that modern UKA is a valid alternative for young and active patients with unicompartmental tibiofemoral noninflammatory disease, including both osteoarthritis and avascular necrosis. Compared to medial UKA lateral UKA represents in our experience only 5% of all UKA implantations.

However the long term results of lateral UKA compares at least equally with those reported for medial UKA.

Introduction: The incidence of contralateral, second hip fractures after a first hip fracture is as high as 20% in the elderly. Femoroplasty using an injectable and resorbable bi-phosphonate loaded bone substitute to prevent controlateral hip fracture may represent a promising preventive therapy. We aimed to evaluate the biomechanical consequences of the femoroplasty using this bone substitute.

Materials and Methods: Twelve paired human cadaveric femora from donors with a mean age of 86 years (7 women and 6 men) were randomly assigned for femoroplasty and biomechanically tested for fracture load against their native contralateral control. Anterior–posterior and lateral radiographs and DXAscan’s were made before injection. Femoroplasty were performed under fluoroscopic guidance with an injectable and resorbable bi-phosphonate loaded bone substitute. All femurs were fractured by simulating a fall on the greater trochanter by an independent observer.

Results: Mean T-score of the tested femur were −3. Bone density was comparable for each pair of femur. All the observed fractures were Kyle II throchanteric fractures. Mean fracture load was 2786 Newton in the femoroplasty group (group F) versus 2116 Newton in the control group (group C) (p< 0.001). Fracture loads were always higher in the group F: mean 41.6% (mini: 1.2%/maxi:102.1%). Effect of femoroplasty was significantly superior for women and also correlated to initial bone density (p< 0.0001).

Discussion:According to our results, femoroplasty with an injectable and resorbable bi-phosphonate loaded bone substitute can provide significant biomechanical reinforcement of the proximal femur to prevent controlateral fracture.

Introduction: Women have gender specific shape of the distal femur. To fit these gender characteristics, gender specific femoral implants were developed for total knee arthroplasty (TKA). We aimed to compare

objective and subjective functional improvement;

Materials and Methods: 30 women (60 knees) operated on successively (6 months in between) for a bilateral TKA between March 2006 and March 2008 by the same surgeon were included in this prospective study. The same surgical protocol and the same post-operative management protocol were applied for both sides. Mean age was 67±3 and mean BMI 26±4 Kg/m². At a minimum follow-up of one year, evaluation objective and subjective functional improvement, patient satisfaction and preference and cost-utility analysis were performed double blind.

Results: Knee Society knee score and Knee Osteoarthritis Outcome Score (KOOS) improvements were comparable in both groups. However, 75% of the women preferred their gender TKA (p< 0.001). 68% of the women described less crepitus or anterior knee bothering after gender TKA (p=0.003) and 64% had faster recovery with the gender implant (p< 0.001). The cost-utility analysis was favorable for the gender knee.

Discussion: No objective or subjective superiority in terms of functional improvement was shown with gender specific implants at this short-term follow-up. However significant differences in terms of patient satisfaction and preference and a favorable cost-utility analysis were observed. These results should now be confirmed at longer-follow-up. Despite comparative functional improvement, patient satisfaction and preference were higher for the side implanted with a gender specific TKA in this prospective comparative study.

Introduction and Method: For 16 years, now, we have been using custom made femoral stems (titanium stem, HA coated) based on preoperative patient CT scans in young patients presenting with symptomatic osteoarthritis of the hip. The aim was to provide optimum initial fit-and-fill of the stem in the femoral medullary canal, conferring the best chance of secondary osteoin-tegration. This, with a goal of long term survivorship. The custom stem also enables dialling-in correction of the (often abnormal) femoral neck version (in young patients presenting with arthritis) to a more normalised 15 degrees of anteversion.

Results: We present the long term results (5–16 year, mean of 10 years), clinical, survivorship and radiological, of 312 primary total hip arthroplasties in 280 patients, all of whom were under the age of 50 years of age (mean age 40).

At 10 years we have a survivorship, if femoral aseptic loosening is used as an end point, of 97.6%. There was a deep infection rate of 1.2%, and a dislocation rate of 1.9%. There were no cases of thigh pain, and no intra-operative femoral neck/shaft fractures.

Discussion: The under 50’s with hip arthritis requiring total hip arthroplasty are a highly challenging group, they are young, active and tend to have distorted anatomy. Our results are superior to those previously published using either cemented or standard uncemented stems. Thus, justifying the increased initial financial outlay on the custom-made stem.

Introduction: Due to the diversity of the prosthetic implants for hip arthroplasty, a better matching between the implant and the intra and extra-medullary characteristic of the patient anatomy is now possible. This adaptation however requires a perfect understanding of the tridimensional characteristics of the patient hip anatomy. Little data are available in the literature. We aimed to analyze the muscular and bony anatomy of the hip at the time of arthroplasty.

Material and Methods: data acquisition was performed according a standardized CT-scan in the same center for all patients within the standard workup before arthroplasty. Standardized measurements were obtained after automatic tridimensional bone reconstructions using dedicated software. 549 femurs in 469 patients including primitive coxarthrosis (COX), dysplasic development of the hip (DDH) and aseptic osteonecrosis (ONA) were analyzed. Mean age was 58 and 70% of the patients were women. Tridimensional reconstruction of the muscular anatomy of the hip was performed for 30 patients using manual contouring on dedicated software. Characteristics of the bony and muscular anatomy were then analyzed according to the etiology and correlations between bony and muscular anatomy were evaluated.

Results: Concerning the bone analysis, mean offset was 23.2 ±1.5mm in the DDH group, 40.5±1.2 mm in the COX group and 29.6± 0.9mm in the ONA group(p< 0.001). Neck-shaft angle was 132±25º in the DDH group, 130±0.5º in the COX group and 134±1º in the ONA group (p< 0.001). Mean anteversion was 33±3.5º in the DDH group, 25±3.8º in the COX group and 16±3.2º in the ONA group (p< 0.001). Concerning the muscular analysis, gluteus medius and minimus volumes were correlated with the body mass index and with the gender, but not with patient age (p: NS). Location of the muscular insertion of the gluteus medius and minimus on the greater trochanter were correlated with the femoral anteversion.

Discussion: The results of our study demonstrated that bony and muscular anatomical characteristics were correlated with the etiology of the degenerative joint disease, with the patient body mass index and gender. Surgeons should be aware of these characteristics to improve the patient anatomy reconstruction during the arthroplasty.

Introduction: morphological analysis of the general shape of the bones and of their particular variations according to the patient age, gender and pathology is an important step to improve the orthopedic management. We aimed to performed a gender specific analysis of the bi and tridimensional anatomy of the distal femur in vitro and in vivo.

Materials and Methods: in vitro data were obtained from CT-scan performed on 92 dry men femurs and 52 dry women femurs. Using a manual contouring method and a segmentation method, tridimensional reconstructions were obtained and according to two different algorithms, the regions of discrepancies between men and women were determined. An automatic calculation of 59 defined measurements was then performed. In vivo data providing from 59 CT-scans of men femur and 73 CT-scan of women femurs were acquired. Standardized bidimensional measurements at the level of the trochlear cut were performed.

Results: in vivo, statistically significant differences were observed for the: medio-lateral distance (M-Ld women=7.4±0.4cm vs M-Ld men=8.4±0.5cm; p< 0.0001), anteroposterior distance (A-Pd women=5.9±0,4cm vs A-Pd men= 6.4±0.4cm; p< 0.0001) and for the ratio anterior-posterior distance/medio-lateral distance (p< 0.0001). The trochlear groove angle was comparable in the two groups. In vitro, the tridimensional shape of the distal femur was more trapezoidal in women than in men. Medio-lateral distances were also statistically greater in men than in women (p< 0.01), the ratio anterior-posterior distance/medio-lateral distance was also statistically greater in men than in women (p< 0.01) and the Q angle more open in women than in men (p< 0.01).

Discussion: Three types of differences between men and women were observed in this gender specific evaluation of the distal femur anatomy. First, for a same anteroposterior distance, the medio-lateral distance was smaller in women. Second, the global shape of the distal femur was more trapezoidal in women and third the Q angle was more open in women. This gender specific anatomy should be clinically considered when performing total knee arthroplasty in women and gender specific implants may be required.

A clinical and radiographic study was conducted on 97 total hip arthroplasties (79 patients) performed for congenital hip dislocation using three-dimensional custom cementless stem. The mean age was 48 years (17 to 72). The mean follow up was 123 months (83 to 182).

According to Crowe, there were 37 class 1, 28 class 2, 13 class 3 and 19 class 4. The average lengthening was 25 mm (5 to 58 mm), the mean femoral anteversion 38.6° (2° to 86°) and the correction in the prosthetic neck −23.6° (71° to 13°). The average Harris hip score improved from 58 to 93 points. Six hips (6.2%) required a revision. The survival rate was 97.7% ± 0.3% at 13 years.

Custom cementless stem allows anatomical reconstruction and good functional results in a young and active population with disturbed anatomy, while avoiding a femoral osteotomy.

Purpose of the study: Malposition of the acetabular implant of a total hip arthroplasty can provoke dislocation, limited joint movement, and early wear. The purpose of this prospective randomized study was to assess the efficacy of a image-free navigation system to achieve correct acetabular position for total hip arthroplasty.

Material and methods: The navigation software for the acetabular component used intraoperative anatomic acquisition. The prospective randomized study included two groups of 20 patients. In the first group, the acetabular implant was inserted using the computer-assisted system and in the second using the conventional method. The same operator performed all procedures via an anterolateral approach and using the same non-cemented hemispheric cup. The postoperative assessment was performed by an independent investigator who noted the cup inclination on the standard ap view and cup anteversion on the computed tomography; then using a dedicated system for 3D reconstruction, the same values were determined one month after surgery.

Results: Each group included ten men and ten women, mean age 63 years and mean body mass index 24. For the computed-assisted group, mean additional operative time for navigation was 13 minutes (range 8–20 min). The intraopeartive concordance with the surgeons subjective impression was excellent for 12 patients and good for 8. Mean intraoperative values were for the computer-assisted group were: for operative mode: inclination 30° (25–46°), anteversion 14° (0–25°), radiographic mode: inclination 35° (25–47°), anteversion 13° (0–26°), anatomic mode: inclination 36°, anteversion 19° (0–27°). There was no significant difference between the intraoperative and postoperative values for the computer-assisted group. There was no significant difference between the average values between the computer-assisted and conventional groups but the standard deviation was smaller in the computer-assisted group.

Discussion and conclusion: The image-free navigation system enables reliable positioning of the prosthetic cup for total hip arthroplasty and increases the precision of acetabular implantation without increasing significantly operative time. This first step must be integrated into the computerized preoperative planning for total hip arthroplasty. The next step will be to use the navigation system for implanting the femoral component.

Purpose of the study: Acetabular dysplasia is a recognized cause of premature hip degeneration. With increasing use of arthroplasty, the role of conservative treatment can be debated. The purpose of this work was to describe technical advances achieved with Ganz triple periacetabular osteotomy and evaluate long-term results.

Material and methods: This study included 32 dysplastic hips in 28 patients treated by Ganz triple osteotomy and assessed a mean 12 years follow-up (range 2 – 20 years). Mean age was 32 years (range 18–47). There were 24 women and four men. Hip joint measurements were made on preoperaive standard x-rays with complementary recentered views if needed as well as computed tomography (CT) to better distinguish progressive degeneration. For early patients, the iniail osteotomy involved three cuts (ilioischial, iliopubic, ilial) starting close to the acetabulum and performed via three approaches: sub coxofemoral, intrapelvic, extrapelvic. The first technical change involved osteotomy of the anterosuperior iliac spine and an oblique iliac cut farther from the acetabulum.

Results: Mean preoperative angles were: 135° (121 to 150°) for CC’D, 23.2° (3 to 40°) for HTE, 8.4° (−14 to 22°) VCE, 11.3° (−26 to 32°) for VCA. The postoperative values were: 134.5° (121 to 150°) for CC’D, 9.5° (−9 to 20°) for HTE, 31.7° (14 to 60°) for VCE, 31.7° (10 to 48°) for VCA. Six patients required total hip arthroplasty on average four years later (range 2 – 9 years), including one patient with aseptic necrosis of the acetabulum.

Discussion and Conclusion: This study confirms the usefulness of triple periacetabular osteotomy for conservative treatment of acetabular dysplasia. In light of our results, the following changes have been instituted:

all three cuts are performed via a single intra-pelvic approach;

Purpose of the study: Compter-assisted surgery enables improved precision of prosthetic implantations, but the basis of data acquisition remains variable. The purpose of this study was to assess the radiological quality of a total knee arthroplasty (TKA) implanted with a computer-assisted surgical technique with or without pre-operative imaging.

Material and methods: This was a case-control study of a group of 40 patients who underwent TKA implanted with a navigation systm (N+) which was compared with a control group of patients who underwent the same procedure with a conventional technique (N-). The two groups were comparable for: age, gender, BMI, preoperative HKA. The same surgeon operated all patients using the same cemented posterior stabilized TKA. Outcome was analyzed by an independent operator. The same navigation system was used for all knees, with, for the first 20 knees, acquisition based on preoperative computed tomography and for the next 20 knee, intra-operative acquisition. Postoperatively, six radiographic parameters were studied for each knee on the ap and lateral views. An optimal interval was determined for each parameter and the number of optimal criteria was noted for each knee.

Results: The mean HKA was 177.5° in the N- group and 179.2° in the N+ group. The angle of implantation of the femoral piece was 90.3° in the N- group and 90° in the n+ group. The mean posterior tibial slope was 3.5° in the N+ group and 3.1° in the N- group. There was a significant difference for the tibial prosthetic angle in favor of the N+ group, i.e. 89° compared with 87.3° for the N- group. The overall quality of the implantation was considered optimal for 54.5% of knees in the N+ group and for 29.8% in the N- group. There was no significant difference between computed tomographic acquisition and intraoperative acquisition.

Discussion and conclusion: This study demonstrates that the results exhibit a distribution closer to the ideal values for the navigation group but that the difference is solely significant for the tibial implantation. This improvement requires a longer operative time of 18 minutes. The lack of any difference between the computed tomographic acquisition and the intraoperative acquisition suggests that intraoperative acquisition should be favored for reasons of cost and simplicity. Computed tomography imaging can still be useful for a precision of the biepicondylar line in certain complex situations such as revision arthroplasty.

Purpose of the study: Changes in prosthetic design to adapt to knee flexion greater than 120 degrees can modify the bone-prosthesis fixation and also displace the femorotibial contact. The purpose of this study was to analyze mid-term results in a consecutive series of 186 arthroplasties and to examine the femorotibial kinematics in vivo.

Material and methods: A posterior stabilized cemented prosthesis with a plateau with motion limited to rotation was used. Design changes concerned: lengthening of the posterior femoral condyle, scooping out the poly-ethylene anteriorly with reorientation and change in the height of the posterior stabilization stem. The same technique was used for all patients who followed the same rehabilitation protocol. Mean age was 69 years (range 22–87). All patients were evaluated clinically with the IKS score and radiologically on the anterioposterior and lateral images. An in vivo analysis of the femorotibial kinematics in the weight bearing condition was also performed in 20 patients under fluoroscopic control with automatic 3D modelization.

Results: Mean follow-up was 40 months (range 2–5 years). Mean IKS function score improved from 34 preoperatively to 96 at last follow-up. The knee score improved from 53 on average to 91 at last follow-up. The mean flexion was 115° (range 45–135°) preop-eratively and 120° (115–145°) at last follow-up. One implant was removed for infection and arthrolysis was performed for one case of stiff joint. Radiographically: the mean postoperative femorotibial alignment was 179° (178–181°), the mean tibial slope 3.8° (0–10°°, the mean patellar height (0.8° (0.56–1°), and the mean elevation of the joint space (4.5 mm. There were two cases of progressive lucent lines in the tibial zone which were stable at last follow-up. All patients analyzed showed a mean posterior displacement of the femorotibial point of contact of 9.7 mm at flexion.

Discussion and conclusion: Changes in prosthesis design to adapt to greater range of flexion do not appear to have a negative effect at mid-term on implant fixation. The clinical flexion ranges obtained were encourageing and the correlation with kinematic results show that the degree of preoperative flexion remains a determining factor for the postoperative outcome. Posterior displacement of the femoro-tibial point of contact, observed in all patients examined fluoroscopically, certainly contributed to the good postoperative flexion.

A clinical and radiological study was conducted on 97 total hip replacements performed for congenital hip dislocation in 79 patients between 1989 and 1998 using a three-dimensional custom-made cementless stem. The mean age at operation was 48 years (17 to 72) and the mean follow-up was for 123 months (83 to 182).

According to the Crowe classification, there were 37 class I, 28 class II, 13 class III and 19 class IV hips. The mean leg lengthening was 25 mm (5 to 58), the mean pre-operative femoral anteversion was 38.6° (2° to 86°) and the mean correction in the prosthetic neck was −23.6° (−71° to 13°). The mean Harris hip score improved from 58 (15 to 84) to 93 (40 to 100) points. A revision was required in six hips (6.2%). The overall survival rate was 89.5% (95% confidence interval 89.2 to 89.8) at 13 years when two hips were at risk.

This custom-made cementless femoral component, which can be accommodated in the abnormal proximal femur and will correct the anteversion and frontal offset, provided good results without recourse to proximal femoral corrective osteotomy.

Introduction: Deep flexion may affect both femorotibial contact pattern and patellofemoral interface. The objective of this study was to conduct the first in vivo kinematic analysis that determines the 3D motions of the femorotibial and patellofemoral joints, simultaneously from full extension into deep flexion.

Methods: Three-dimensional femorotibial and patello-femoral kinematics were evaluated during a deep knee bend using fluoroscopy for five subjects having a normal knee, five having an ACL-deficient knee and 20 subjects having a TKA designed for deep flexion.

Results: The average weight-bearing range-of-motion was 125 degrees, significantly higher than in previous studies. On average, subjects experienced 4.9o of normal axial rotation and only three subjects experienced an opposite rotation pattern. On average, subjects experienced −9.7 mm of posterior femoral rollback (PFR) and all subjects experienced at least −4.4 mm of PFR. These subjects experienced less patellofemoral translation than the normal knee, but the average motion was similar in pattern to the normal knee. On average, the subjects having a TKA experienced patella tilt angles that were similar to the normal knee.

Discussion: It is assumed that femorotibial kinematics can play a major role in patellofemoral kinematics. Altering the patella motion and/or the patellar ligament rotation could lead to much higher forces at the patel-lofemoral interface. In this study, these subjects experienced kinematic patterns that were very similar to the normal knee and it can be deducted that forces acting on the patella were not significantly increased for TKA subjects compared with the normal subjects.

Using radiography and computer tomography (CT) we studied the morphology of 83 hips in 69 Caucasian adults with osteoarthritis secondary to developmental dysplasia of the hip (DDH). A previously published series of 310 hips with primary osteoarthritis was used as a control group. According to the Crowe classification, 33 of the dysplastic hips were graded as class I, 27 as class II and 23 as class III or class IV.

The intramedullary femoral canal had reduced mediolateral and anteroposterior dimensions in all groups compared with the control group. Only in Crowe class II hips was the femoral neck-shaft angle increased. The proximal femur had more anteversion in all the developmental dysplasia of the hip groups, ranging from 2° to 80°. Templated measurement of acetabular dimensions for plain radiography closely matched measurements taken by CT.

The results of our study confirm the observations previously confined to the Japanese population.

Purpose: Wrist fractures are often seen in elderly subjects who cannot generally tolerate aggressive fixation of unstable fractures. Percutaneous intra-focal pinning (Kapandji) is usually employed. The purpose of this study was to compare the classical treatment of unstable extra-articular fractures of the lower quarter of the radius with posterior displacement with a modified pinning technique.

Material and methods: This prospective radiological study concerned two groups of randomised patients aged 30 – 70 years who were hospitalised for surgical treatment of Pouteau-Colles fractures. In the first group, all patients were treated by the classical intra-focal technique using one or two dorsal pins and one lateral pin (group K). In the second group, all patients were treated by fixation with one or two infrafocal dorsal pins and a third pin inserted transfocally (group KM). Preoperative care, anaesthesia, and postoperative care (21 days immobilisation, pin removal at 45 days) were the same in both groups. The following anatomic measurements were made on the radiographs at day 1, 21, 45, and last follow-up: radial inclination on the lateral and AP views, bistyloid line.

Results: Group K included 49 patients, mean age 45 years. Group KM included 46 patients, mean age 54 years. There was no statistical difference between groups for age, gender, side, type of fracture. Radial inclination on the AP view was 19.2 (10–27 in group KM and 23.2 (19-30) in group. On the lateral view, radial inclination was 0 (−11 to 20) in group KM and −5.7 (−25 to 2) in group K. The proportion of bistyloid lines considered satisfactory was not different between groups.

Discussion: Infra-focal pinning can have limitations for maintaining reduction to bone healing. The Kapandji technique modified by use of a third transstyloid pin appears to provide better stabilisation of unstable fractures of the lower extremity of the radius, particularly in older subjects who cannot tolerate aggressive surgery. This preliminary study should be completed by a radio-clinical analysis in a larger number of patients to confirm these results.

Purpose: Most revisions of total knee arthroplasty (TKA) occur before the fifth year. The leading cause is prosthesis malalignment. Computer-assisted surgery is presented as a technique which improves implantation precision. The purpose of this study was to evaluate the radiographic quality of computer-assisted TKA implantation in comparison with conventional implantation.

Material and methods: A prospective randomised study was conducted with a total of 82 patients assigned randomly to conventional instrumentation (group 1) or computer-assisted implantation (group 2). The two groups were comparable for age, gender, body mass index, side, and preoperative femorotibial angle (HKA). The same surgeon operated all patients using the same cemented posterostabilised prosthesis. Radiographically, the HKA, the theta angle between the mechanical and anatomic femoral axis, the angle of the femoral and tibial implantations, and the posterior tibial slope were noted. All measures were taken by an independent operator who was unaware of the operative technique.

Results: There was no statistical difference in the HKA 177.5° in group 1 and 179.2° in group 2 (p=0.13); the theta angle was 6° in group 1 and 5.9° in group 2 (p=0.78); the femoral implantation angle was 90.3° in group 1 and 90° in group 2 (p=0.74); the posterior tibial slope was 3.5° in group 1 and 3.15° in group 2 (p=0.65). There was a statistical difference in the tibial angle, 87.3° in group 1 and 89° in group 2 (p=0.012).

Discussion: This study demonstrates a significant improvement in the navigation group for the position of the tibial implant and no difference for the femoral implant. This might be related to the cut guide which allowed more intra-operative adjustment for the tibia. Blood loss was equivalent in the two groups (503 mg) and operative time was longer in the navigation group (18 minutes).

Conclusion: It appears important to have specifically adapted cut guides for computer-assisted surgery and to reduce operative time.

Purpose: Implantation of a unicompartmental knee pros-thesis (UKP) via a short incisiosn was proposed to improve rapid postoperative recovery. But it is known that long-term survival is highly dependent on implantation quality. The purpose of this study was to evaluate the influence of implantation quality assessed radiographically and that of rapid recovery after unicompartmental arthroplasty using the conventional or minimally invasive approach.

Material and methods: A continuous series of the first 25 cases of UKP implanted using the minimally invasive approach (group 1) was compared with a homogeneous group of matched knees in a series of 145 UKP implanted with the same approach as used for total knee arthroplasty (group 2). The groups were comparable for age, gender, weight, and height. The same medial cemented UKP with a metallic tibial base plate was implanted in both groups. Postoperative radiographic measures included the overall mechanical axis, the femoral and tibial implantation orientations, and the posterior tibial slope.

Results: There was no significantly different between groups 1 and 2 for mechanical axis (3.6° and 4.7° respectively), tibial implantation angle (87° and 88°), or posterior tibial slope (2.6° and 2°). The femoral implantation angle was also comparable (2.3° and 2.9°) with the exception of one knee (9°) in group 1. Hospital stay, use of crutches and resumed activity were significantly shorter in group 1. Blood loss (222 and 244 ml respectively), postoperative pain (visual analogue scale), and full flexion at one year were comparable between the groups.

Discussion: The basic difference between the two approaches is the absence of patellar eversion and rupture of the extensor system with the minimally invasive method. This probably explains the more rapid recovery of function and activity in this group. The one case of significant femoral deviation noted in this group points out the need for greater care in positioning the specific guides for the short incision approach. To evaluate the long-term results of UKP implanted with the minimally invasive approach, the same criteria for patient selection and prosthetic implantation should be used.

Purpose: Impacted piecemeal allografts for nonce-mented hemispheric cups raises a problem of primary stability in the case of extensive bone defects. The high centre of rotation of the oversized cup further increases bone loss, requiring an extralong neck. The purpose of this study was to describe the use of impacted piecemeal grafts associated with a pressfit supporting ring with reposition of the centre of rotation.

Material and methods: The piecemeal grafts were impacted into the acetabulum to fill the defect. The hydroxyapatite coated ring was pressfit for primary stability then stabilised with axial screws in the upper paste. A distal hook on the obturator foramen repositioned the centre of rotation. The study group included 103 cases of acetabular reconstruction, including 34 for aseptic loosening and type 2 and 3 acetabular substance loss. Clinical and radiographic assessment was performed at 5 and 12 years.

Results: Mean patient age was 58 years, mean weight was 64kg. The Harris score improved from 53 points preoperatively to 88 points at last follow-up. Radiographically, there were no cases of cup migration according to the Massin classification, and the centre of rotation (Pierchon) was anatomic in 66% horizontally and in 44% vertically. There were two lucent lines in zone 2 and mean polyethylene wear was 0.015 mm per year. Graft integration (Conn) was identical to the host in 84% with disappearance of the interface in 67%. There were three dislocations treated without changing the implant and two revisions for infection.

Discussion: Several theoretical and clinical studies have shown that the high centre of rotation increases stress on the implants and decreased abductor force. The results obtained in this study with a maximum 12 year follow-up show that indications for this pressfit technique associating reposition of the centre of rotation, fixation for stability, and restoration of bone stock can be widened. Limitations are bone destructions with rupture of the pelvic girdle.

Introduction: Recent studies showed that the position of the center of rotation and the prosthetic neck may infl uence implant fixation in hip arthroplasty. The purpose of this study is to evaluate the use of modular necks and their limits to restore hip geometry after the arthroplasty.

Methods: The study radiographically evaluates 117 cases of unilateral hip arthroplasty using a modular neck / head concept (Wright Medical). The analysis evaluated on a weight-bearing frontal pelvis view: center of rotation, horizontal abductor ratio, and vertical abductor index, comparatively to the controlateral hip using the student’t test. On the computerized templates of the association effectively used in each case was measured: neck length, lever arm and neck anteversion.

Results: In craniopodal the center of rotation averaged 0.19 in women and 0.23 in men. In mediolateral it averaged 0.26 in women and 0.32 in men. The mean horizontal abductor ratio was 0.65 in women and 0.70 in men. The mean vertical abductor index was 6:..4° in women and 6.5° in men. The mean neck length was 55.2 mm, the mean lever arm 39.3 mm, and the 15° ante or retroverted neck was noted in 10 %.

Discussion and conclusion: Restoration of the center of rotation was more accurate in mediolateral than in craniopodal, with a higher location as previously noted in the litterature. Abductor function was correctly restored excepted for the vertical index in women, probably due to the large variations of pelvis width. The limits of modular necks are large hip dysmorphy where neck length averages 60 mm, lever arm 45 mm and neck anteversion requires 30° of correction.

Introduction: Minimally invasive surgery (MIS) has recently been proposed for unicompartmental arthroplasty to allow quick function recovery. The purpose of this study is to evaluate retrospectively the indications in which this technique would have been possible and successful.

Methods: The requirements for the minimal invasive technique are: a pre-operative flexion of 100° and a lesion limited to one compartment of the knee. The preoperative status, operative findings and clinical outcome of 160 cases of unicompartmental knee arthroplasty (MG, Zimmer) were analyzed to determine whether the criteria for MIS would have been possible.

Results: Preoperatively 12 knees had a flexion less than 100°. Postoperatively four of them had a limited flexion ranging from 90° to 100°. In 53 knees (33 %), peripheral osteophytes were removed on the opposite tibiofemoral joint. None of them were revised for progression of osteoarthritis. In 33 knees (21 %) a patelloplasty was associated to the procedure for peripheral osteophytes. Two of them were revised at 12 and 20 months for osteoarthritis progression.

Discussion: Removal of peripheral osteophytes can be successfully associated to the unicompartmental procedure when using a conventional surgical approach. In 96 of the 160 knees (60 %) MIS was not recommended either for limited preoperative flexion or for peripheral osteophytes. In 2 knees unicompartmental arthroplasty itself was not the correct indication and total knee arthroplasty would have been the right solution. Finally, in 62 of the 160 knees (39 %) unicompartmental arthroplasty using MIS was indicated. In conclusion unicompartmental knee arthroplasty may be either performed by conventional or minimal approach based on the preoperative clinical and radiological evaluation.

Purpose: The current concern to achieve 120° postoperative flexion in certain patients raises the problems of polyethylene wear, prosthesis stability, and surgical technique. The purpose of this clinical and radiographic comparative study was to analyse pertinent factors

Material and methods: We studied two groups of posterior stabilised total knee prostheses with mobile plateaux. In group A (23 knees), the plateau had rotatory and translation mobility. In group B (36 knees) the plateaux only had rotatory mobility and the posterior condyle was long. We studied clinical flexion before surgery and postoperatively at one year. The radiographic analysis included: mechanical axis, height of the articular space, patellar height, anteroposterior prosthetic surface. In both groups the patients had undergone medial parapatellar arthrotomy and had participated in the same rehabilitation programme.

Results: There was no statistically significant difference between the two groups for age, gender, weight, height, pre-operative diagnosis, or preoperative flexion (mean 120.8°, range 90–130° in group A and mean 120.7°, range 90–140° in group B). Mean postoperative flexion was 114.8° (50–140°) in group A and 130.4° (90–150°) in group B. The difference was statistically significant. There were two episodes of instability in group A and none in group B. There was no difference concerning the pre- or postoperative axis or patellar height. There was a difference in articular space height and anteroposterior prosthetic surface.

Discussion: The gain in flexion achieved in group B is related to the smaller anteroposterior prosthetic surface and the more systematic use of distractors to clear the posterior part of the knee. The design of the posterior condyle could also be involved, allowing better congruence beyond 120°. The difference in stability between the two groups could be related to a difference in the distance between the apex of the tibial attachment and the posterior stabilisation cam. This study demonstrated that increased flexion is possible after total knee arthroplasty in certain patients. It is related to surgical technique but also has direct implications for prosthesis design.

Purpose: The Oxford unicompartmental prosthesis has congruent joint surfaces due to use of a mobile meniscus whose upper part matches the sphere constituted by the femoral component. The purpose of this work was to report results in a series of 75 prostheses studied with mean follow-up of 12.4 years (range 10–14 years).

Material and methods: Mean age of patients was 65 years (38–84), with 67% women and mean body mass index of 28.7 (21.2–40.6). Patients gave their subjective assessment of the arthroplasty and the IKS scores were determined. Radiographically, the mechanical alignment of the lower limb was evaluated pre- and postoperatively on the full stance images. The Kennedy classification (4 grades) was used to assess passage of the mechanical axis through the knee.

Results: At last follow-up, three patients were lost and eight had died. According to their subjective assessment, 84% of the patients were enthusiastic or satisfied. The overall IKS score showed that 52% of the patients were above 180 points, 25% above 150 points. Mean varus was 11° (2–24°) preoperatively and 5.7° (5° valgus to 14° varus) at last follow-up. The mechanical axis passed in the sufficient correction zone (c or 2) in 77% of the knees, undercorrection zone in 17% and in the overcorrection zone in 6%.Seven prostheses were revised for mechanical failure: four for loosening, two for extensive degeneration, and one for pain giving a survival curve of 90% at 12 years. It must be added that two meniscal dislocations occurred, one early due to wound dehiscence and infection and one late, both after a fall.

Discussion: Most loosenings occurred early and at the tibial level. Defective alignment could be incriminated in one case. The other knees exhibited a reactive line under the tibial plateau. The rate of dislocation should probably decline with the use of progressive reamers, not available at the time of this series. Finally none of the prostheses were revised for wear, confirming the proper prosthesis design.

The objective of this present study was to determine the in vivo kinematic patterns for subjects implanted with a patellofemoral arthroplasty (PFA).

Twenty subjects, all having a PFA, were studied (< 2 years post-op) under fluoroscopic surveillance to determine patellofemoral contact positions, sagittal plane, and medial/lateral translation using a skyline view.

The patellofemoral contact patterns for each subject having a PFA was highly variable, 11.9 mm of translation. The average amount of patella rotation during the full flexion cycle was 26.3 degrees, while one subject experienced 48.6 degrees. The average amount of medial/lateral translation was 3.8 mm (5 > 5 mm). Five subjects experienced grater than 5 mm of motion.

This was the first study to ever determine the in vivo kinematics for subjects having a PFA and the in vivo medial/lateral translation patterns of the patellofemoral joint. Subjects in this study experienced high variability and some abnormal rotational patterns. Most of the subjects who underwent PFA in this study had a previous history of subluxed or dislocated patella which affects the normal patella tracking, especially regarding tilting and translation. This tracking may also be directly affected by patellofemoral conformity, a consequence of femoral implant design. Finally, after PFA the patello-tibial tilt angle is influenced by the anteroposterior positioning of the femoral component.

The results of this very first in vivo kinematic study may play an important role, not only for design consideration of patellofemoral replacement but also for surgical technique in order to obtain optimal implant positioning.