[Survival of cementless dual mobility sockets: ten-year follow-up]. / Survie a dix ans d'une cupule double mobilité non cimentée.

PURPOSE OF THE STUDY: We report a retrospective series of 106 total hip prosthesis with ten years follow-up. The purpose of this study was to analyze survival of cementless dual mobility sockets. MATERIAL AND METHODS: The series included 90 consecutive patients with 106 first-intention total hip prosthesis, all with cementless dual mobility sockets. All prosthesis (Novae-1 socket and Profil-1 stem, Serf) were implanted within a 6-month period. The stainless steal socket was coated with alumina and had two short anchorage studs and a superior mooring screw and a polyethylene retentive liner. The stem had a 22.2 mm chromium cobalt head. The main indication for arthroplasty was degenerative joint disease. Mean age at implantation was 56 years (range 23-87). All patients were seen for physical examination and x-rays every two or three years. We noted cup survival at ten years (actuarial method), defining surgical revision for cup replacement due to an aseptic cause as the endpoint. RESULTS: Twelve patients died during the 10-year follow-up and one was lost to follow-up. The Postel-Merle d'Aubligné score improved from 7.1 preoperatively to 15.8 at ten years. There were two isolated acetabular loosenings, two intra-prosthetic dislocations due to advanced wear of the polyethylene insert. The overall survival rate of the socket was 94.6% at ten years. There were no episodes of prosthetic instability in this series. DISCUSSION: This study demonstrates the good ten-year survival of the dual mobility socket, comparable to that of conventional prostheses. The absence of any case of prosthetic instability in this series confirms the good short-term and long-term stability of the dual mobility socket. Intraprosthetic dislocation, due to loss of the polyethylene retaining ring is the main limitation of this method. The incidence was however low (2% at ten years) and treatment was not a problem. We recommend using the dual-mobility socket as the first-intention implant for patients with a high risk of post-operative instability, but also recommend it for all patients aged over 70 years since instability is the leading cause of surgical revision after this age.

[Dual articulation retentive acetabular liners and wear: surface analysis of 40 retrieved polyethylene implants]. / Analyse de surface après explantation de 40 cupules rétentives en polyéthylène à double mobilité

PURPOSE OF THE STUDY: The original concept of dual articulation retentive liners has been implemented in routine clinical practice for total hip arthroplasty since 1976. The retentive liner improves stability and the dual mobility favors preservation of joint motion. In this study, we analyzed wear of the two concave and convex surfaces in 40 retrieved polyethylene implants in order to search for factors favoring wear. MATERIAL AND METHODS: Forty polyethylene inserts were examined. These implants had been removed after mean implantation of eight years. Mean patient age at implantation was 48 years. The inserts were removed because of prosthesis infection or mechanical failure. Macroscopic examination was followed by a surface analysis with direct measurement of alterations of the curvature radii. Internal concavity was measured in the three dimensions using a 4-mm stylus (BNH 706). External convexity was measured by lateral projection. The estimated error was +/- 5 microm for both measurement methods. Manufacturers' tolerances for these implants were approximately 50 microm. Linear and volumetric wear was determined by comparing the measured dimensions with the theoretical dimensions of new inserts. RESULTS: Macroscopically, all of the pieces studied had lost their initial striation on the convex surface; 40% of the pieces displayed visible wear of the retentive collar. Mean annual wear was 9 microm (SD 9microm) for the convex surface and 73 microm (SD 69 microm) for the concave surface. Mean total wear, taken as the sum of the wears on the convex and concave surfaces was 82 microm (SD 72 microm). Volumetric wear was 28.9 mm3/yr for the convex surface (SD 27.6) and 25.5 for the concave surface (SD 23.2) giving a mean annual total volumetric wear of 54.3 mm3/yr (SD 39.6). DISCUSSION: Total wear observed for these 40 dual articulation liners which had functioned in vivo was to the same order as reported for the metal-polyethylene bearing with 22.2 mm femoral heads. Considering the wear on both the convex and concave surface, the dual articulation was not associated with increased wear compared with the conventional metal-polyethylene bearings, but with the advantages of retention and greater stability. CONCLUSION: Use of a dual articulation acetabular liner is an attractive solution when a metal-polyethylene bearing is considered. The benefit in terms of joint stability does not increase wear.

Dual mobility retentive acetabular liners and wear: surface analysis of 40 retrieved polyethylene implants.

PURPOSE OF THE STUDY: Dual mobility systems with retentive acetabular liners have been used in clinical practice for total hip arthroplasty since 1976. The dual mobility system preserves a wide range of motion while providing greater stability. This study measured wear on the concave and convex surfaces of 40 retrieved polyethylene liners, to evaluate the advantages of this system in relation to wear. MATERIAL AND METHODS: Forty polyethylene inserts that had been removed due to infection or mechanical failure after a mean 8 years were analyzed. The mean age of patients at arthroplasty was 46 years old. Macroscopic analysis was followed by surface analysis with direct measurement of changes in the curvature radii. The internal concave surface was measured in three dimensions using a 4-mm stylus (BNH 706). External convexity was measured by lateral projection. The estimated error was ± 5 µm for both measurement methods. Manufacturers' tolerance for these implants was approximately 50 µm. Linear wear and wear volume was determined by comparing the measured dimensions with the theoretical dimensions of new liners. RESULTS: Macroscopically, all of the pieces studied had lost the initial machined grooves on the convex surface; 40% of the pieces showed visible wear of the retentive collar. Mean annual convex surface wear was 9 µm (SD 9µm) and 73 µm (SD 69 µm) for the concave surface. Mean total wear, which was the sum of the wear on the convex and concave surfaces was 82 µm (SD 72 µm). Wear volume was 28.9 mm(3)/yr for the convex surface (SD 27.6) and 25.5 for the concave surface (SD 23.2) with a mean annual total wear volume of 54.3 mm(3)/yr (SD 39.6). DISCUSSION: Total wear in the 40 dual mobility liners that had functioned in vivo was similar to that reported in metal-polyethylene bearings with 22.2mm femoral heads. The results of wear in both the convex and concave surfaces show that wear with the dual mobility system was not increased compared to conventional metal-polyethylene bearings, while providing better retention and greater stability. CONCLUSION: The use of dual mobility acetabular liners is an attractive solution when a metal-polyethylene bearing is needed. The increased joint stability is not associated with increased wear.

Femoral deficiency reconstruction using a hydroxyapatite-coated locked modular stem. A series of 43 total hip revisions.

INTRODUCTION: We report a continuous prospective series of patients operated on for total hip prosthesis femoral component loosening involving a bone defect. Reconstruction was performed using a hydroxyapatite-coated locked modular stem. The study's objective was to assess medium term clinical and X-ray results obtained with this original concept. MATERIALS AND METHODS: The patients included received a REEF (DePuy) femoral implant for aseptic loosening or loosening associated with a periprosthetic fracture. Implantation was systematically accompanied by an extended trochanteric osteotomy (ETO). Patients were followed up prospectively by clinical and X-ray examination. Their loosening was graded at inclusion according to Vives' classification as revised by SOFCOT in 1999. Analysis focused on actuarial implant survivorship, dislocation and the bone/implant interface. RESULTS: Forty-three hips were included: mean follow-up was 58.2 months (12-92) and mean age at surgery was 72.4 years (37-94). The main indications were severe bone loss rated grade III (n=15) or IV (n=16) according to the SOFCOT classification. There was one long-term failure, involving implant fracture secondary to nonunion of the femoral shaft. Mean Postel and Merle d'Aubigné (PMA) clinical assessment score increased from six preoperatively to 14.5 at end of follow-up. X-ray analysis found no stem migration by end of follow-up. There was consistent consolidation of the ETO around the stem, except in one case of stem fracture which evolved into tight nonunion. In terms of metaphyseal integration, five patients showed radiolucency without evolution over follow-up, and eight had severe calcar cortical atrophy at end of follow-up. Mean 5-year actuarial survivorship was 97.7+/-2.3%, with a 2% incidence of dislocation. DISCUSSION: The complications rate was low, and results were comparable with those reported in the literature. The study confirmed the interest of the extended trochanteric osteotomy exposure and the effectiveness of the hydroxyapatite-coated interlocked modular stem concept in the treatment of hip prosthesis loosening with femoral bone loss (involving or not the cortex). On analysis, the one case of failure does not prescribe the surgical technique employed. Implant osseointegration was difficult to analyze. The extent of the surgical approach and of its corresponding sequels, combined with the complexity of adjusting the implant, however, restrict this surgical option indications to level III and IV cases of femoral loosening.

Kinematics of a cementless mobile bearing posterior cruciate ligament-retaining total knee arthroplasty.

Mobile bearing (MB) total knee arthroplasty (TKA) was developed to provide low contact stress and unconstrained joint motion. We studied a consecutive series of 41 knees with mobile-bearing, posterior cruciate-retaining (CR) TKAs to determine if kinematics resembled normal knees or if kinematics changed over time. Patients were studied at 3 and 21 months average follow-up with weight-bearing radiographs at full extension, 30 degrees flexion and maximum flexion. Shape-matching techniques were used to measure TKA kinematics. Implant hyperextension, maximum flexion and total ROM increased with follow-up. Tibial rotation and condylar translations did not change with time. The medial condyle did not translate from extension to 30 degrees, but translated 5 mm anteriorly from 30 degrees to maximum flexion. Lateral condylar translation was 3 mm posterior from extension to 30 degrees, with no translation from 30 degrees to maximum flexion. Tibiofemoral kinematics in CR-MB-TKAs were stable over time, but did not replicate motions observed in healthy knees. The mobile tibial insert showed rotation and translation at both follow-up examinations, but the patterns of translation were not predictable.

Mobile-bearing insert translational and rotational kinematics in a PCL-retaining total knee arthroplasty.

INTRODUCTION: Total knee prostheses with a mobile-bearing insert were developed to provide nonconstrained joint range of motion while reducing friction forces. The purpose of this study was, based on weightbearing X-rays, to evaluate the mobility of the polyethylene tibial insert in relation to the femoral and tibial components. We studied the results of a cementless total knee arthroplasty (TKA) retaining the posterior cruciate ligament (PCL), with a mobile-bearing platform in rotation and anteroposterior translation (Innex Anterior-Posterior Glide, Zimmer) with a mean 23-month follow-up duration after surgery. HYPOTHESIS: Both anterior-posterior tibiofemoral translation and intraprosthetic axial rotation occur between the mobile polyethylene insert and the tibial endplate. MATERIAL AND METHOD: In a series of 51 primary TKA, the three-dimensional (3D) kinematics of the femoral, tibial, and mobile insert components were determined using a computerized matching system between the prosthetic 3D models and the radiographic images of the implants on three lateral follow-up weightbearing knee X-rays: films were taken in full extension, at 45 degrees flexion, and at maximum flexion. RESULTS: There was a statistically significant increase in the internal rotation of the mobile tray with flexion, (up to a mean -3+/-3 degrees between the femoral box and the mobile tray [p<0.0001] and up to a mean -5+/-7 degrees between the tibial tray and the mobile tray [p<0.0001]). The mobile tray did not translate in relation to the tibial endplate from extension to 45 degrees flexion (0+/-2 mm [range: -5 to 6 mm]). However, from 45 degrees to maximum flexion, a statistically significant mean 1+/-2 mm (range: -2 to 9 mm) of anterior translation (p<0.0001) was found. DISCUSSION: The extent of insert mobility varies from one study to another. Some have reported relatively limited mobility stemming from a superior surface that is not highly congruent, (thus allowing anterior-posterior and mediolateral translation through gliding of the femur in contact with the insert). Other studies have reported mobile-bearing tray mobility in relation to the tibial endplate and minimal rotation at the femoral component level. In this series of PCL retaining TKA with a mobile-bearing platform, the mobile-bearing platform showed a progressive increase in internal rotation during flexion. Most of this rotational mobility occurred between the mobile platform and the tibial endplate, confirming our hypothesis. However, with flexion, the femoral component increased its mobility relatively to the platform. During flexion, an anterior-posterior translation occurred between the femoral implant and the tibial insert, and between the tibial insert and the tibial endplate, but the direction of the mobile tibial insert translation remained unpredictable with this nonconstrained implant design used. LEVEL OF EVIDENCE: Level IV. Prospective non-controlled therapeutic study.

[Preliminary and multidisciplinary study of three Coptic mummies of the Testut-Latarjet museum at Lyon]. / Etude pluridisciplinaire et préliminaire de trois momies coptes du Musée Testut-Latarjet de Lyon.

In 1901 Albert Gayet raked up from Antinoe three mummies exhibited to day at the Anatomy Museum of Lyon. The study of the three mummies was made in detail as to their dress, anthropometric and scannographic findings. The clothes were characteristic of coptic civilization. The radiographic date gave a life span of around 40 years. The X-ray imagery shows the remains of cerebral and visceral organs. The sexual criteria are thought to be those of two women and undetermined for the child. Later, several investigations like endoscopic autopsy, tooth microscopy and chromosomic map will be necessary.