Aims

Mechanical impingement of the iliopsoas (IP) tendon accounts for 2% to 6% of persistent postoperative pain after total hip arthroplasty (THA). The most common initiator is anterior acetabular component protrusion, where the anterior margin is not covered by anterior acetabular wall. A CT scan can be used to identify and measure this overhang; however, no threshold exists for determining symptomatic anterior IP impingement due to overhang. A case-control study was conducted in which CT scan measurements were used to define a threshold that differentiates patients with IP impingement from asymptomatic patients after THA.

Mechanical irritation or impingement of the iliopsoas tendon accounts for 2–6% of persistent postoperative pain cases after total hip arthroplasty (THA). The most common trigger is anterior cup overhang. CT-scan can be used to identify and measure this overhang; however, no threshold exists for symptomatic anterior iliopsoas impingement. We conducted a case–control study in which CT-scan was used to define a threshold that differentiates patients with iliopsoas impingement from asymptomatic patients after THA.

We analyzed the CT-scans of 622 patients (758 CT-scans) between 2011 and 2020. Out of this population we identified 136 patients with symptoms suggestive of iliopsoas impingement. Among them, 6 were subsequently excluded: three because the diagnosis was reestablished intra-operatively (one metallosis, two anterior instability related to posterior prosthetic impingement) and three because they had another obvious cause of impingement (one protruding screw, one protruding cement plug, one stem collar), leaving 130 patients in the study (impingement) group. They were matched to a control group of 138 patients who were asymptomatic after THA. The anterior cup overhang (anterior margin of cup not covered by anterior wall) was measured by an observer (without knowledge of the clinical status) on an axial CT slice based on anatomical landmarks (orthogonal to pelvic axis).

The impingement group had a median overhang of 8 mm [IQR: 5 to 11] versus 0 mm [IQR: 0 to 4] for the control group (p<.001). Using ROC curves, an overhang threshold of 4 mm was best correlated with a diagnosis of impingement (sensitivity 79%, specificity 85%, PPV = 75%, NPV = 85%).

Pain after THA related to iliopsoas impingement can be reasonably linked to acetabular overhang if it exceeds 4 mm on a CT scan. Below this threshold, it seems logical to look for another cause of iliopsoas irritation or another reason for the pain after THA before concluding impingement is present.

The management of prosthetic joint infection (PJI) has been widely performed for total hip arthroplasties (THA), but none has compared it with hip resurfacing arthroplasty (RSA). We also carried out a retrospective case-control study comparing the surgical treatment of PJI by surgical debridement and implant retention between RSA and THA in order to clarify whether there was a difference in terms of (1) successful healing of PJI (2) functional scores after recovery (3) risk factors for recurrence of PJI. Our hypothesis was that simple debridement with prosthesis retention regardless of the timeframe allowed to obtain a higher success rate for RSA compared to THA.

From 2010 to 2018, a single-center case-control study based on 3056 RSA found 13 PJI were age-matched (based on the 139 THA PJI treated) with 15 THA PJI (mean age of 53 years old (47–58) for THA and 59 (45–66) for RSA (p=0.34)). We compared their survival (absence of infectious recurrence) and the means differences between the 2 groups (demographical, clinical and biological data).

There was no difference between the 2 groups concerning: age (p=0.3), BMI (p=0.4), initial diagnosis (p=0.4), operating time for primary surgery (p=0.3), the presence of a postoperative hematoma (p=0.4), the type of bacteria (p=0.5), the total duration of antibiotic therapy (p=0.9) and the type of antibiotic therapy (p=0.6). Early postoperative infections (less than 6 weeks) occurred in 7/13 RSA cases (54%) compared to 11/15 THA cases (73%). At the mean follow-up of 5 years (2–7), the success rate without recurrence was significantly higher in the RSA group 100% versus 66.7% (10/15) for the THA group (p=0.044). At the last follow-up, the Oxford Hip Score was higher in the RSA versus THA group's (14 versus 22 p=0.004).

Simple surgical debridement an RSA without changing implants after PJI can be done regardless of the time to onset of infection. This is secondary to the absence of metaphyseal bone invasion and the low content of joint fluid.

The hip-shelf procedure is less often indicated since the introduction of peri-acetabular osteotomy (PAO). Although this procedure does not modify pelvic shape, its influence on subsequent total hip arthroplasty (THA) is not known. We performed a case-control study comparing THA after hip-shelf surgery and THA in dysplastic hips to determine: 1) its influence on THA survival, 2) technical issues and complications related to the former procedure.

We performed a retrospective case-control study comparing 61 THA cases done after hip-shelf versus 63 THA in case-matched dysplastic hips (control group). The control group was matched according to sex, age, BMI, ASA and Charnley score, and bearing type. We compared survival and function (Harris, Oxford-12), complications at surgery, rate of bone graft at cup insertion, and post-operative complications.

The 13-year survival rates for any reason did not differ: 89% ± 3.2% in THA after hip shelf versus 83% ± 4.5% in the controls (p = 0.56). Functional scores were better in the control group (Harris 90 ± 10, Oxford 41/48) than in the hip-shelf group (Harris 84.7 ± 14.7, Oxford 39/48) (p = 0.01 and p = 0.04). Operative time, bleeding and rate of acetabular bone grafting (1.6 hip-shelf versus 9.5 control) were not different (p > 0.05). Postoperative complication rates did not differ: one transient fibular nerve palsy and two dislocations (3.2%) in the hip-shelf group versus four dislocations in the control group (6.3%).

The hip-shelf procedure does not compromise the results of a subsequent THA in dysplastic hips. This procedure is simple and may keep its indications versus PAO in severely subluxed hips or in case of severe femoral head deformity.

Cementless distally locked stems were introduced in revision hip arthroplasty (RTHA) in the late 1980s to deal with severe femoral bone loss. These implants have not been assessed over the long-term, particularly the influence of the design and porous coating. Therefore we performed a retrospective case-control study at a minimum 10-years' follow-up comparing the straight Ultime™ stem with 1/3 porous coating versus the anatomical Linea™ stem with 2/3 proximal coating with hydroxyapatite.

We performed a single-center case-control study measuring survival, function based the Harris and Oxford-12 scores, and rate of thigh pain. X-rays were done at regular intervals and at follow-up. No femoral bone graft was used at insertion.

The two groups were comparable in terms of age, sex and follow-up (mean 12.2 years in Ultime and 10.8 years in Linea cohorts); however they differed in the severity of bone loss therefore the results were adjusted according to this variable. Ten-year survival considering revision for any reason was 63.5% ± 5.4 for Ultime and 91.6% ± 2.7 for Linea (p < 0.001). Merle d'Aubigné scores and Oxford-12 were higher in the Linea group 82.9 ± 12.4 and 26.3/48, respectively, versus 69.5 ± 16 and 21/48 in the Ultime group (p < 0.001). Thigh pain was observed in 30% of Ultime cases versus 3% of Linea cases. Bone reconstruction measured via cortical thickness was better in the Linea group and correlated to metaphyseal filling at insertion.

This study confirms the benefits of using of locked stems in RTHA with severe bone loss. Better metaphyseal filling and optimized porous coating help to minimize thigh pain and the revision rate.

Introduction

In valgus knees, ligament balance remain difficult when implanting a total knee arthroplasty (TKA), this leads some authors to systematically propose the use of constrained devices. Others prefer reserving higher constraints to cases where it is not possible to obtain final satisfactory balance: less than 5 of residual frontal laxity in extension in each compartment, and a tibiofemoral gap difference not in excess to 3mm between flexion and extension. The goal of the study was to assess if is possible to establish preoperative criteria that can predict a constrained design prosthetic implantation at surgery.

Introduction

The prosthetic impingement occurs if the range of motion of the hip exceeds implant mobility or in case of component malorientation. This retrieval study was designed to assess the frequency and the risk factors of this phenomenon.

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 of the study: The objectives of this work were to assess the stability of outcome achieved after Duquennoy procedure to tighten the lateral capsule-ligament structures of the ankle joint. To do this, we reviewed the same series of patients at 3 and 25 years follow-up to analyse the very long-term stability, laxity, and stiffness of the ankle joint and any osteoarthritic degradation.

Material and methods: From 1975 to 1986, we performed 75 Duquennoy procedures on the lateral capsule and ligament structures of the ankle joint. At mean 25 years follow-up (2007) we were able to review 28 ankles (27 patients) with the same method as applied in 1980 (3 years follow-up). The function outcome was assessed with the Good, Karlsson, Duquennoy and Tegner scores. Clinically, other than joint range of motion, were noted varus laxity or anterior drawer. Static x-rays were obtained to search for signs of osteoarthritis and stress images to measure talocrural laxity, in comparison with the preoperative figures and the 1980 data.

Results: There were two early technique failures (one persistent talocrural instability, one subtalar instability). Good and Karlsson scores were good or excellent in 92% of cases. Patients were very satisfied with the operation and the VAS was 8.9/10. Pain and occasional instability were reported by 27% of patients. There was no talocrural no subtalar stiffness at last follow-up. Radiographic laxity declined significantly between the preoperative value and the last review. Only one patient presented a narrow talocrural space (less than 50% narrowing). Eight patients had osteophytes whose presence was not correlated with poor functional outcome. These osteophytes were also present on the controlateral side. Importantly, there was no significant difference in the mean function scores between 3 and 25 years follow-up (Duquennoy score). Similarly joint range of motion and radiographic laxity remained stable over time.

Discussion: The Duquennoy procedure to tighten the lateral capsule and ligament structures is a simple technique with rare complications which provides excellent results both in terms of ligament stability and in terms of preservation from degenerative osteoarthritis. These results remain stable over time. Conversely, the technique has no action on the subtalar joint and should not be proposed as treatment for associated subtalar laxity, if diagnosed.

Purpose of the study: For young active patients, implantation of metal backed socket with a metal-on-metal bearing is an attractive tribological alternative when a standard prosthesis cannot be implanted. Metal ion assays have not been reported in this type of population. The purpose of this work was to present the clinical, radiographic and metal ion results.

Material and methods: Between 1998 and 2003 23 total hip arthroplasties (THA) (six primary and 17 revision) were implanted with a cemented Metasul™ bearing in a Muller inlay. Mean follow-up was 6.1 years (5–10). None of the patients was lost to follow-up. The Harris and PMA scores were noted as were signs of implant loosening or migration. Metal ions were assayed in total blood (Cr and Co) by mass spectrometry and atomic emission spectrometry (Ti).

Results: At follow-up, the mean Harris and PMA scores were significantly increased, from 62.2 to 95.2 (p = 0.01) and from 12.9 to 17.4 (p = 0.02) respectively. No revisions were required for aseptic loosening or failure of fixation. The radiographs did not reveal any signs of osteolysis or lucency. The mean levels of Cr, Co and Ti were 1.85μg/l (0.8–3.2). 1.24μg/l (0.5–1.86) and 9.62μg/l (5–18) respectively. Ti > 10μg/l was noted in six patients; Ti > 10 μg/l and Cr > 2μg/l in five patients. There was no correlation of metal ion levels with size of the implants, activity level, gender, clinical scores or cup inclination.

Discussion: The mean Co and Cr levels observed in this series were similar to those reported in the literature for standard THA (cementless press fit cups). Ti levels have only been reported in rare studies so that comparison with other series is hazardous. The Ti level observed here appeared to depend on the femoral stem resurfacing (in our series, the porous surface of the stem was coated with a Ti-6Al-7nB alloy).

Conclusion: Cementing the metal-on-metal bearing in the supporting inlay appears to be a reliable and attractive technique for this young and active population. Levels of Cr and Co in blood were the same as reported for standard implants. These levels of metal ions should be followed to confirm the long-term results.

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 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 of the study: Locked implants have yielded favourable results for femoral bone reconstruction for revision total hip arthroplasty, but defective integration has also been reported due to insufficient bioactive coating. The purpose of this work was to evaluate a locked pivot with a two-third proximal hydroxyapatite coating.

Material and methods: From 1996 to 2007, 158 femoral implants (Linea™) were implanted for hip arthroplasty revision. The 143 cases with more than one year follow-up were reviewed (14 deaths, 1 lost to follow-up); 83 revisions for aseptic loosening, 41 periprosthetic fractures, 19 revisions in an infected context. Patients were reviewed retrospectively by a non-operator observer. These were older patients (mean age 68 years, range 31–93) and 36 patients had complex situations requiring at least two prior prostheses; 25% had severe grade 3 or 4 (SOFCOT) bone lesions and 59% diaphyseal damage.

Results: Clinical improvement was significant, the Postel Merle d’Aubigné score improved from 7.7 + 4.3 (0–17) to 15.6 + 2.2 (8–18) at mean 50 months (14–131) (p< 0.001). At last follow-up, 14 patients (10%) reported thigh pain and only seven pivots (5%) had not achieved Engh osteointegration (five with thigh pain two without). There were no fractures. There was on non-union of the femorotomy. According to the Hoffman index, femoral bone regeneration was significant at the metaphyseal and diaphyseal levels. Eighteen of the 19 infections cured, all periprosthetic fractures healed. The implant survival was 88.9% at 91 months (65–96.7%). There were five pivot replacements for non integration and/or thigh pain which resolved in all cases; there were no other pivot replacements. The quality of the metaphyseal and diaphyseal filling was predictive of the quality of the bone fixation of the pivot (p< 0.01).

Discussion: Compared with older models of locked pivots, this implant reduced the rate of thigh pain while allowing constantly satisfactory bone reconstruction. The metaphyseal and diaphyseal filling index is the main factor predictive of clinical and radiological success by favouring osteointegration. Maximal filling, obtained with a full range of implant diameters and lengths, contributes to this good result.

Purpose of the study: Hip resurfacing (HR) is becoming popular again with the advent the the metal-on-metal bearing. This type of surgery is proposed for young, often very active, patients for whom restoration of optimal hip joint range of motion constitutes and important objective. The purpose of this work was to analyse anterior translation of the femoral component to optimise joint range of motion (particularly flexion).

Material and method: From September 2007 to May 2008, 68 hip resurfacing prostheses were implanted in 66 patients aged on average 45 years (range 19–61). All procedures were performed by the same operator using a posterorlateral approach and the same surgical technique. Anterior head-neck offset was a constant objective. The Postel-Merle-d’Aubigné and Harris scores as well as the Devane classification and the WOMAC and the SF-12 were noted. Joint range of motion was noted preoperatively and at last follow-up by and independent operator. Anterior head-neck offset was measured radiographically on the Dunn view using an original technique and calibrated by the Imagika software according to the known diameter of the implants.

Results: All clinical scores as well as the activity level and the subjective scores improved significantly. There were no revisions. The mean anterior head-neck offset was 4.5 mm (range 2–9). Significant correction was observed for gain in postoperative flexion and increased offset (p< 0.005). The group of patients who had an anterior offset considered to be significant (> 4 mm) exhibited significantly better flexion than the group of patients with a small anterior offset.

Discussion: Hip resurfacing has a poor head-neck ratio, depending on the patient’s anatomy, which compares unfavourable with conventional hip prostheses (THA). Nevertheless, the joint range of motion after resurfacing, as observed in our study and in the literature, does not show any decline compared with THA. The greater gain in flexion is an important factor to take into consideration, especially in a young active athletic subject. Each millimetre of gain in anterior offset produces a significant increase in flexion. This offset can be improved by the surgical technique (implanting the femoral component tangentially to the posterior cortical), but also by the design of the resurfacing prosthesis (thick femoral component, increased cement sheath). After hip resurfacing, anterior offset appears to be an essential biomechanical factor for restoration of joint motion.

Purpose of the study: Drilling along yields disappointing results for osteonecrosis of the femoral head due to the high failure rate despite prolonged rest and also because of the risk of fracture. To prevent these problems, we have developed a new drilling technique which was evaluated prospectively.

Material and methods: The procedure performed percutaneously uses a lateral cortical orifice measuring 5mm, non-concentrated autologous bone marrow was injected after drilling. Osteoinductive protein (BMP7) was associated in random fashion (groups BMP+ and BMP−). Ficat stage 1 and 2 necrosis was included. Outcome was the rate or revision for prosthesis.

Results: Forty hips (36 patients) were included and assessed at mean four years (range 2–6). The necrosis was related to: alcoholism (n=5), cortisone (n=25), barotraumas (n=2), metabolic disease (n=4), idiopathic condition (n=4). Group BMP- (drilling+bone marrow) included 24 hips and group BMP+ (drilling+bone marrow+BMP7) 16 hips. The groups were comparable regarding necrosis stage (15% stage 3, 65% stage 2, 20% stage 1) and mean Koo index (27 BMP+ vs 34 BMP-; NS). There were no infections and no fractures despite immediate and complete weight-bearing. The revision rate for prosthesis was higher in the BMP- group (67%) than in the BMP+ group (43%) but the difference did not reach significance (p=0.10). The failure rate was not affected by the severity of the necrosis in the BMP+ group: all stage 3 hips were revised in the BMP- group versus none in the BMP+ group. The only variable predictive of revision for prosthesis was the Koo index (p=0.02).

Discussion: Adjunction of BMP did not improve significantly the success rate of drilling with bone marrow adjunction but adding BMP appeared to limit the unfavourable impact of server necrosis observed in the BMP- group. To reach a statistical power of 80%, 40 cases would be needed in each arm. This threshold has not yet been reached. It can be noted however that the proposed method does ensures early weight bearing without the risk of complications. Similarly, since it is a percutaneous procedure, later arthroplasty is not compromised. The principle confounding factor, the richness of the bone marrow, was not assessed, motivating a new randomized trial with measurement of CFU-F.

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.

Introduction: Metal on metal hip replacement using large diameter bearings can be used as part of a hip resurfacing (HR) system or with a large diameter head total hip arthroplasty (LDH-THA). Both types of implant release metal ion, but the amount of ion released after LDH-THA has not been studied. The aim of the present study was to assess whole blood metal ion release at one year following LDH-THA.

Material and Method: Pre and post operative Cr, Co and Ti concentrations in whole blood were measured using a high resolution mass spectrometer (HR-ICP-MS) in 29 patients with LDH-THA (Durom LDH, Zimmer). The results were compared to published ion levels on a HR system (Durom, Zimmer) possessing the same tribological characteristics, the only differences being the presence of a modular sleeve and opened femoral head design in LDH-THA.

Summary of results: Post operative Cr, Co and Ti mean levels of LDH-THA were 1.3, 2.0 and 2.8 μg/L at 6 months and 1.3, 2.2 and 2.7 μg/L at 12 months. In the LDH-THA, the opened femoral head design showed significantly higher Co ion concentrations than the closed femoral head design (3.0 vs 1.8 ug/L, p=0.037). Compared to previously published results after HR, Co levels were significantly higher at one year in the LDH THA (2.2 ug/L vs. 0.7 ug/L, p< 0.001).

Discussion: 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 demonstrated that the addition of a sleeve with modular junctions and an open femoral head design of LDH-THA causes more Co release than bearing surface wear (157% and 67% respectively). Even if no pathological metal ion threshold level has been determined, efforts should be made to minimize their release. We recommend modification or abandonment of the modular junction and femoral head closed design for this specific LDH-THA system. The total amount of ion released from a metal-metal implant should be considered globally and newer implant design should be scientifically evaluated before their widespread clinical use.

Introduction: The prosthetic impingement occurs if the range of motion of the hip exceeds implant mobility or in case of component malorientation. This phenomenon is rarely studied in the literature and most data have come from sporadic cases. This study was designed to assess the frequency and the risk factors of this phenomenon.

Material: The frequency and the severity of the impingement were calculated from a continuous series of 413 cups retrievals. These cups were examined macroscopically twice by two independent observers. The cam effect was noted as: absent, grade 1 (visible at gross inspection but measuring < 1 mm), grade 2 (notch measuring 1–3 mm), grade 3 (notch measuring > 3 mm). The risk factors were analyzed for 298 retrievals that had complete clinical charts.

Results: Among the 413 cups explants, the frequency of impingement was 51.3 percent (grade 3 in 12% and grade 2 in 24%). The impingement was the reason for removal in only 1.7 percent (only for hard bearings), meaning that impingement was mainly an unexpected event (98.3 percent). The impingement was more frequent when revisions were performed because of instability (80 percent; odd-ratio 4.2 (1.1–16.2)) than for loosening (52%) osteolysis (59%) or infection (38%) (p =.002). Likewise, impingement was more frequent when the sum of hip motion exceeded 200 degrees (sum of motion in the 6 degrees of freedom of the hip) (66% versus 45% if the sum was below 200°). The other risk factors were: use of heads with skirts (78% versus 55%), liner with an elevated rim (73% versus 55%), and head-neck ratio below 2.

Discusssion and conclusion: This study underlines the impingement is common when assessing cup retrievals (over 50 percent). One should be aware of impingement when performing hip replacement in patients having a high range of motion. This situation may require prostheses with a high head-neck ratio, as well as use of computer-assisted surgery. One should avoid liners with elevated rim as well as heads with skirts to prevent dislocation, particularly when other risk factors are detected.

Introduction: Cementless revision hip arthroplasties require a stable initial fixation that does not compromise a subsequent bone reconstruction. In case of severe femoral bone loss, stems usually requires distal fixation that may induce stress shielding and finally reduce the spontaneous bone reconstruction. We introduced the use of distally locked revision stems in 1993 hoping strong fixation and bone reconstruction. The goal of the current study was to assess if these components fulfill these two objectives.

Materials and Methods: 101 cementless femoral revision stems with distal locking by screws (Ultime™ Wright-Cremascoli) were inserted from 1993 to 2001. These stems were smooth distally and porous coated with or without HA 1/3 proximally. The indication to use these components was severe bone loss (Paprosky grade IIC and III in 51%) when press fit distal fixation could not be obtained. The use of bone graft was limited to segmental defects or to treat trochanteric non-union. An extended trochanteric osteotomy was performed in 89%. The revision was performed because of aseptic loosening in 43,4%, periprosthetic fracture in 24,2% and infected loosening in 25,2%. The results were assessed after a mean follow-up of 6 years (5–12).

Results: 13 patients deceased and 2 were lost for follow-up. All the extended trochanteric osteotomies healed. Merle d’Aubigné hip score increased from 8.3 to 13.4, but thigh pain was observed in 44%. Bone reconstruction was significant according to Hoffman index at 3 levels of assessment. The 5-year survivorship was 87% considering aseptic revision for any reason. Seventeen repeated femoral procedures were performed: 9 related to thigh pain (because there was no proximal osteointegration) that were revised for short primary stems, 8 because of stem fractures (all occurred at the level of the proximal hole with the same stem size because there was no proximal fixation as long as the stems were smooth or without HA-coating.

Discussion: This serie has the longest follow-up using locked revision stems. Despite severe pre-operative bone loss, primary fixation and significant bone reconstruction were obtained for all the cases without extensive bone grafting. The major weakness, thigh pain and stem break, were related to unadequate femoral coating for these cementless stems that did not achieved osteointegration. Conversly, the reoperations were simple, allowing the use of short primary designs as bone reconstruction was achieved in all cases without extensive bone grafting. These locked stems allow a strong primary distal fixation that does not compromise bone regeneration. An improvement of femoral coating (extension to 2/3 and use of hydroxyapatite) may reduce the rate of thigh pain and reoperation.

Purpose of the study: The incidence of revision hip arthroplasty is increasing. In order to overcome certain problems related to loss of femoral bone stock, an original technique was developed combining fragmented allograft material and a metallic mesh with a non filling stem cemented distally in a healthy zone to ensure stability.

Materials and Methods: The clinical data (Postel-Merle-d’Aubigné, PMA score) and radiographic findings (implant migration, loss of bone stock using the SOFCOT and PAPROSKY classification, quality of cementing, filling, and graft aspect, graft lysis, periprosthetic lucency, final aspect of the graft) were collected retrospectively. The operation and the technical difficulties and intraoperative complications were noted.

Results: We report a series of 32 hips treated with this technique and having a mean follow-up of 12.5 years (range 8–20 years). The population studied had particularly significant bone loss (78.2% SOFCOT stage 3 and4). These hips underwent revision for aseptic loosening. The implantation technique required a femoral window in 39.1%. Preventive cerclage was often used (39.1%) but did not prevent fracture or missinsertion in 30.4%. The PMA score improved significantly from 10.6 (7–18) preoperatively to 17 (12–18) at last follow-up. Radiologically, femoral bone regeneration at last follow-up had an aspect of corticalisation in 63.6% of hips, and of cancellous trabeculation in 36.4%. Femoral implant survival was 100% at eight years, and 92.8±6.88% at mean follow-up of 12.5 years. There was only one revision at eleven years for secondary osteolysis related to polyethylene wear in a very active subject implanted before the age of 50 years.

Discussion: The clinical and radiographic results are very satisfactory for this series of femoral revisions using an impacted fragmented graft material and with the longest follow-up reported in the literature. Distal fixation limited migration observed when the stem is entirely cemented in the graft, but did not affect reconstruction which demonstrated long-term stability. This technique, initiated in 1986 without a specific instrument set, had now demonstrated its long-term reliability. The only problem is the length of the operation and the complications related to femoral preparation.

Implantation of a large-diameter femoral head prosthesis with a metal-on-metal bearing surface reduces the risk of dislocation, increases the range of movement, minimises the risk of impingement and, in theory, results in little wear.

Between February 2004 and March 2007 we implanted 100 consecutive total hip replacements with a metal-on-metal bearing and a large femoral head into 92 patients. There were 51 men and 41 women with a mean age of 50 years (18 to 70) at the time of surgery.

Outcome was assessed using the Western Ontario McMaster University osteoarthritis index and the Harris hip score as well as the Devane activity score. These all improved significantly (p < 0.0001). At the last follow-up there were no cases of dislocation, no impingement, a good range of movement and no osteolysis, but seven revisions, two for infection and five for aseptic loosening. The probability of groin pain increased if the other acetabular component inclination exceeded 50° (p = 0.0007). At 4.8 years of follow-up, the projected survival of the Durom acetabular component, with revision for any reason, was 92.4% (sd 2.8) (95% confidence interval 89.6 to 95.2).

The design of the component made it difficult both to orientate and seat, which when combined with a poor porous coating, produced unpredictable fixation and a low survival at five years.

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.

The purpose of this study was to compare the post operative ROM of patients randomised between SRA and 28mm THA.

Restoration of normal ROM has been proposed as an advantage of hip resurfacing (SRA) over THA and is due to the use of larger diameter femoral heads. However, the head-neck diameter ratio, which is an important factor governing ROM, would in theory allow more ROM with THA (28mm head/14mm neck = ratio 2:1) versus SRA (approximate ratio 1.3–2.0:1).

Patients were randomised between SRA and THA. Osseous landmarks were identified with a marker pen. Both ASIS served as the reference line for the pelvis position. Digital photographs of hip motion were taken and a blinded rater (with respect to the side and type of surgery) performed range of motion testing on the operated and normal side. Pre-study validation of ROM measurement method with a software program revealed high intra and inter observer reliability.

Sixty SRA and sixty-two THA were evaluated at minimum follow-up of twelve months. Preoperative ROM and demographic data were similar for both groups. No significant differences (p> 0.05) were found in the total arc of motion (SRA=204.2°, THA=196.5°), arc of rotation (SRA=47.7°, THA=44.3°), flexion-extension arc (SRA=118.1, THA=120.1), abduction-adduction arc (SRA=43.1°, THA=42.9°).

In theory, ROM should have been greater in THA. Fear of instability may have limited ROM recovery potential in THA. Since pre operative soft tissue contracture is an important factor influencing post operative ROM, the complete capsular release performed during SRA may have been an advantage of this technique.

Purpose of the study: Theoretically, long-term functional and radiographic degradation is predictable after ankle fusion, but sound evidence from consecutive analysis of the same cohort is lacking. The purpose of this study was to evaluate the same cohort of patients who underwent ankle fusion.

Material and Methods: The cohort included 52 ankle fusions which had been analyzed in 1984 at seven years (2–22 years) of follow-up then again in 2000 using the same evaluation criteria. Among the 52 patients, six were lost to follow-up, 20 had died and one had undergone leg amputation. The second analysis thus included 25 patients (18 men and 7 women), mean age 62±12.6 years (40–94) at the 2000 assessment performed 23±4.5 years (19–36 years) after the fusion. Functional outcome was assessed with the 100-point Duquennoy scale. Osteoarthritis of the subtalar and mediotarsal joints were assessed preoperatively and at follow-up using the same scale.

Results: The functional outcome did not deteriorate significantly between 1984 and 2000. The mean score was 65.8±22.6 (19–92) in 1984 and 64.7±18.3 (34–90) in 2000 (p=0.67). Fifteen patients (60%) had a good or very good outcome at seven years, and 14 (56%) at 23 years. Between 1984 and 2000, ten patients improved their score (on average 10.4 points, range 1–21 points), two had an unchanged score and thirteen a lower score (on average 10 points, range −1 to −24). Ten of these thirteen patients developed severe intercurrent conditions explaining the degradation. At last follow-up, sixteen ankles were pain free or nearly pain free. Twelve patients considered their ankle as a forgotten problem and had no regrets concerning the operation. The evolution of the subtalar joint in 16 cases (nine fusions including five at the same time as the ankle fusion and four performed within four years) showed that all developed early osteoarthrtic degradation with aggravation between 1984 and 2000, leading in the majority of cases to severe degenerative disease. This osteoarthritis was painful in less than one-third of the cases (including the four secondary subtalar fusions and the four sub-talar fusions which were painful at mobilization). The mediotarsal joints degradation was later and less severe than for the subtalar joint with a majority of moderate osteoarthritis. Ten ankles exhibited compensatory hypermobility of the forefoot measured at more than 15° without pain.

Discussion: This long-term follow-up with two successive assessments using the same evaluation criteria did not demonstrated late degradation of function expected after ankle fusion. It did show however the presence of radiographic degradation of the subtalar joint but with little clinical expression at a minimal follow-up of 19 years. There was no need for complementary fusion between 4 and 23 years follow-up.

Introduction: The anterior pelvic plane (APP), described by Lewinnek, is defined by the following points : anterior iliac spines, pubic symphysis. This plan is mostly considered as vertical in weight bearing and is currently used as the reference to guide cup insertion by means of imageless computer assistance (CAS). However, to our knowledge, there is no data that strongly confirm APP is vertical in weight bearing and how much his orientation is modified with regards operative position, or THA insertion. This study assessed these data by means of a radiological analysis.

Material and Methods: The orientation of the APP was measured with regards to the vertical plane on weight-bearing profile X-rays of the pelvis in 106 subjects including:

1) 82 patients with THA (40 who had at least one dislocation, and 42 matched patients without instability randomly selected, 19 of these 42 underwent a profile X-ray of the pelvis before and after THA insertion)

Results: Thirty-eight percent of the subjects in weight-bearing had an orientation of the APP different of more than ± 5° from vertical plane and 13% were out of the interval ±10°. The orientation of the APP was not significantly different between the groups (standard and THA) nor between the groups who had stable or unstable THA. The orientation of the APP was significantly modified between lying and weight-bearing posture, from a mean of 1,2° lying to −2,25° upright. Under these conditions, 12 subjects presented a variation of more than 7°. Insertion of a THA did not significantly modify the orientation of the APP in weight-bearing among the 19 subjects (variations were small (−1° ± 7° [from – 21° to 8°]), but were more than 5° for 7 of the 19 subjects).

Discussion and Conclusion: Most of the surgeons use the APP as a reference to guide navigation for cup insertion, considering it is vertical in weight-bearing. However, it is not true for 38% with a margin of 10°, which is equivalent to approximately half of the anatomical anteversion of the acetabulum. Standing up produced a significant variation of the orientation of the APP with regards to lying position. These errors that are not integrated by most of the CAS without preoperative CT scans, may produce cam effect or dislocation when the patient is moving to sited position. The variations of APP orientation with regards to vertical plane suggest it is not adequate to guide the CAS insertion of the cup. There is no reliable reference, easily identifiable during surgery that integrates the variations of position of the pelvis. This leads us to promote a new CAS for THA insertion free of reference plane, based on kinematics.

Delayed sciatic nerve palsy is uncommon after primary hip replacement. Two kinds of sciatic palsy have been reported with regard to the time of onset: early palsy related to wound haematoma or lumbosacral nerve elongation which occurs between surgery and 18 days, is more frequent than delayed palsy, occurring between 10 and 32 months, which is usually caused by cement extrusion or heat produced by cement polymerisation.

We present two cases of delayed, transient sciatic nerve palsy arising at three weeks and four months after primary cementless arthroplasty, respectively, without haematoma and with a normal lumbar spine. These palsies were possibly caused by excessive tension from minor limb lengthening of 2 cm to 4 cm required to achieve leg-length equality. As the initial symptoms were limited to calf pain and mild numbness in the foot, surgeons should be aware of this mode of onset, particularly when it is delayed after hip replacement. Both patients recovered fully by 12 months after surgery so we did not undertake surgical exploration of the nerve in either patient.

Purpose: Femoral offset restoration is recognised as an important part of THA procedure to reduce the joint reactive force and improve stability. In SRA, femoral offset is often reduced due to the femoral component valgus position. The main objective of this study was to correlate the clinical function of SRA and THA patients with their different biomechanical hip reconstruction (femoral offset).

Methods: 156 patients aged 23 to 65 years old and suffering from advanced hip joint degeneration were randomly assigned to two treatment groups: the THA or SRA group. All surgeries were performed through a posterior approach. Standardized pre and post operative antero-posterior radiographs of the pelvis were made and clinical scores were assessed.

Results: Compared to the normal contra lateral side, the femoral offset increased on average 4.85mm (range -2.77 to 11.59mm, SD 3.31) for THA and decreased an average of 3.42mm (range −7.78 to 1.96, SD 2.12) for SRA (p=0.0001). In addition, offset restoration was within lees than 4 mm in 60.0% of the SRA group and 21.8% in the THA group (p=0.0001). There were no differences between the both groups in terms of clinical and subjective scores: the PMA and SF-36 scores were, respectively, in average 17.1 (SD 0.4) and 101 (SD 1.25) for THA and 17.0 (SD 0.4) and 101 (SD 1.14) for SRA. No relation was found between offset restoration and clinical scores for both groups.

Conclusions: In this study, surgeons were less precise reconstructing the femoral offset in the THA group compared to the SRA group. However, femoral offset was lower (reduced) in the SRA in comparison to THA. This significant decreased femoral offset in SRA, seems inherent to the preferential valgus positioning of the femoral component in that technique. The excellent clinical outcome reported with SRA does not suggest that restoring normal offset is as crucial for the success of SRA because no correlation was found between femoral offset and the clinical scores used.

Thirty-nine cementless hip replacements using metal-on-metal articulation were consecutively implanted in thirty patients less than fifty years of age and compared with a matched control group of cementless replacements using ceramic-on-polyethylene articulation. The Harris hip score at follow-up (minimum five years) for the metal-on-metal was 94.9 (range, 74–100). After the same follow-up, the results of the ceramic-on-polyethylene were significantly worse: nine osteolyses and seven surgical revisions related to wear. Five-year survival rates were 97% +/− 2% for the ceramic-on-polyethylene and 100% for the metal-on-metal. The metal-on-metal may be recommended to prevent wear problems in younger and more active patients.

The aim of the current study was to assess the results of metal-on-metal articulating components inserted as a primary hip replacement in patients under the age of fifty, comparated with a matched control group using ceramic-on-polyethylene.

Patients and methods

The inclusion of patients was: under fifty years of age and a diagnosis of arthrosis or necrosis of the femoral head.

Femoral stem and cup migration was detected. A variation over five millimeters between the follow-up radiographs was considered as migration.

At the follow-up in 2003, the cobalt concentrations in the whole blood were assessed in the metal-on-metal cohort. The detection limit of cobalt in the whole blood was 0.06 μg/L.

None of the components had migration.

At a mean follow-up of sixty-nine months, the median concentration of cobalt in the whole blood was 0.62μg/L. Only eight patients had cobalt levels greater than 1 μg/L.

Considering a reoperation with the exchange of one of the components as end point, the five year survival rates were 100% for the metal-on-metal group and 97% + 2 for the ceramic-on-polyethylene group. Our study suggests that the metal-on-metal articulation gives a significant improvement in terms of resistance to wear when compared with these conventional bearing components. Our results suggest the metal-on-metal articulation with cementless components can be recommended in the young and active patient to prevent the occurrence of wear and osteolysis. A careful assessment of patients with high levels of whole-blood cobalt should be performed.

Funding: Aucun

We have undertaken a prospective, randomised study to compare conservation of acetabular bone after total hip replacement and resurfacing arthroplasty of the hip. We randomly assigned 210 hips to one of the two treatment groups. Uncemented, press-fit acetabular components were used for both.

No significant difference was found in the mean diameter of acetabular implant inserted in the groups (54.74 mm for total hip replacement and 54.90 mm for resurfacing arthroplasty). In seven resurfacing procedures (6.8%), the surgeon used a larger size of component in order to match the corresponding diameter of the femoral component.

With resurfacing arthroplasty, conservation of bone is clearly advantageous on the femoral side. Our study has shown that, with a specific design of acetabular implant and by following a careful surgical technique, removal of bone on the acetabular side is comparable with that of total hip replacement.

We have compared the biomechanical nature of the reconstruction of the hip in conventional total hip arthroplasty (THA) and surface replacement arthroplasty (SRA) in a randomised study involving 120 patients undergoing unilateral primary hip replacement. The contralateral hip was used as a control.

Post-operatively, the femoral offset was significantly increased with THA (mean 5.1 mm; −2.8 to 11.6) and decreased with SRA (mean −3.3 mm; −8.9 to 8.2). Femoral offset was restored within sd 4 mm in 14 (25%) of those with THA and in 28 (57%) of the patients receiving SRA (p < 0.001). In the THA group, the leg was lengthened by a mean of 2.6 mm (−6.04 to +12.9), whereas it was shortened by a mean of 1.9 mm (−7.1 to +2.05) in the SRA group, compared with the contralateral side. Leg-length inequality was restored within sd 4 mm in 42 (86%) of the SRA and 33 (60%) of the THA patients. The radiological parameters of acetabular reconstruction were similar in both groups.

Restoration of the normal proximal femoral anatomy was more precise with SRA. The enhanced stability afforded by the use of a large-diameter femoral head avoided over-lengthening of the limb or increased offset to improve soft-tissue tension as occurs sometimes in THA. In a subgroup of patients with significant pre-operative deformity, restoration of the normal hip anatomy with lower pre-operative femoral offset or significant shortening of the leg was still possible with SRA.

A 34-year-old woman with a benign form of osteopetrosis developed osteoarthritis of the hip. In order to avoid the difficulties associated with inserting the femoral component of a conventional total hip arthroplasty, a hybrid metal-on-metal resurfacing was performed. There were several technical challenges associated with the procedure, including the sizing of the component, press-fit fixation of the acetabular component and femoral head preparation, as well as trying to avoid a fracture. No surgical complication occurred. After more than a year following surgery, the patient showed excellent clinical function and remained satisfied with the outcome. We conclude that the hybrid metal-on-metal resurfacing arthroplasty represents a valuable option for the treatment of patients with osteopetrosis and secondary hip osteoarthritis.