INTRODUCTION

The uncertainty of the biological effects of wear and corrosion from Metal-on-metal (MoM) implants has initiated a debate on their safety and use. Generally, the release of wear particles from MoM hip implants can clinically manifest in aseptic osteolysis. In our study, the effect of MoM-wear particles and particle originated Co and Cr ions on mesenchymal stromal cells (MSCs) was investigated [1]. The lead hypotheses were that (1) dissociated Co and Cr, originated from MoM-wear particles, accumulate in the bone marrow and (2) apparently impair the osteogenic function of local MSCs. This impairment could be one element contributing to the manifestation of periprosthetic osteolyses.

Introduction

Total hip arthroplasty (THR) with non-cemented or hybrid fixation remains one of the most successful procedures performed today. The aim of this study was to assess the safety and efficacy of a hydroxyapatite (HA) coated, hemispherical cup.

Introduction

Total hip arthroplasty (THR) is one of the most successful procedures performed today. Uncemented acetabular components have by and large replaced cemented cups. As such, optimal fixation, bony ingrowth with longevity, and safety is highly demanded. In this study, we look at the safety and efficacy of the Stryker® Trident PSL™ acetabular component based on radiographic and clinical analysis.

Bicompartmental arthritis involving the medial and patellofemoral compartments of the knee is a common pattern that has often been treated with total knee arthroplasty.

However, the success of unicompartmental and patellofemoral arthroplasty for unicompartmental arthritis, as well as an interest in bone and ligament conservation for earlier stages of arthritis, has led to an interest in bicompartmental arthroplasty. The purpose of this study is to review the clinical, functional, and radiographic results of modular bicompartmental arthroplasty.

Twelve consecutive modular bicompartmental arthroplasties, using separate contemporary unicompartmental tibiofemoral and patellofemoral prostheses, were performed by the senior author. Clinical and functional data including range of motion (ROM), WOMAC and Knee Society (KS) scores were collected pre-operatively and post-operatively at 6 weeks, 12 weeks and annually. Radiographs were taken preoperatively and at the 6 week and annual postoperative visits. The average patient age at the time of surgery was 63 (range, 47 to 72); seven patients were women.

At most recent follow-up, the mean knee ROM improved from 100 degrees of flexion pre-operatively (range, 90 to 110) to a mean of 126 degrees of flexion (range, 115 to 130) (p < 0.0001). Improvements in WOMAC scores were statistically significant (p = 0.02). Statistically significant improvements in Knee Society scores were also observed (p = 0.03). No radiographs showed evidence of loosening, polyethylene wear or progressive lateral compartment degenerative arthritis. There were no complications in the peri-operative period.

Modular bicompartmental arthroplasty is an effective method for treating arthritis of the knee restricted to the medial and patellofemoral compartments. Early results using contemporary prostheses are encouraging and should prompt further mid-and long-term study.

Introduction: We present a clinical and radiology follow-up of the uncemented titanium coated monobloc Robert Mathys (RM) Acetabular Component (Mathys AG Bettlach, Bettlach, Switzerland).

The acetabular component is a monobloc hemispherical cup manufactured from Ultra High Molecular Weight Polyethylene (UHMWPE), with a pure titanium particle coated surface. With heat and pressure, the particles are blasted into the polyethylene surface. The coating promote osseointegration. Stability of the cup is provided by 2 anchoring pegs on the weight bearing part on its outer surface. The inclination of pegs and holes diverge by 5 degrees providing a press-fit effect that increases the rigidity of the primary fixation and this is supplemented by screws inserted through the periphery of the cup. Tow cups designs are available, a full-profile and a bevelled cup. In all cases the bevelled cup was used. The purpose of this study was to assess the clinical performance with 15 years of this cup.

Methods: In this study, the status of the uncemented titanium coated RM cup placed in patients who underwent a primary total hip replacement between January 1, 1988 and December 31, 2001 was determined. A total of 1876 cups (1584 patients) were placed in patients with a permanent residence in Berlin. The femoral component was either an uncemented or a cemented stem in an supine lateral approach with either a 28 or 32mm diameter head. The majority of the heads were ceramic and stainless steel.

The diagnosis was osteoarthritis, rheumatic arthritis, femur neck fracture, developmental dysplasia of the hip (DDH). 1034 patients were contacted by telephone. Out of this patients group 539 patients (678 cups) were evaluated by clinical examination (HHS), radiographic investigation and social evaluation by the WOMAC and NHS score. 451 patients who had died unrelated to the operation. Lost of follow up were 65 patients (69 Cups) and 34 patients (48 cups) had to be revised.

Results: The cumulative survival rate of the RM cup is 98.2 percent at 5 years, 97.5 percent at 10 years and 96.9 percent at 15 years. The survival rate in the ceramic head group is 98.7 at 15 years and by using stainless steel head 91.7 at 15 years. Reseaon for re-opertion was in 34 patients aseptic loosening, 8 patients had infection. Dislocation, malpsition and periprosthetik fracture in 2 patients. In the group with clinical evaluation, the HHS was in 80.2 percent of all patients good and ecellent, 9,7 percent had a moderate result and 10,1 percent had a poor result.

Discussion/Conclusion: The low failure rate for loosening demonstrates that this implant has excellent ongrowth and fixation potential. The RM Cup has been shown to function well at up to 15 years post implantation. Its success may in part be due to the one-piece design.

Objectives: Retrospective case control study of management and outcome of periprosthetic femoral fractures, from the lower limb reconstruction unit in Exeter.

Material and Methods: 144 fractures over a period of 20 years were reviewed. The Vancouver classification system wasd used to clasify the fractures. The prosthesis length was measured pre and post-peratively. The use of impaction grafting technique for inadequate bone quality of the surrounding bone was assessed (type B3 fractures). The use of Dall/Miles, DCP and Mennen plates was also assessed. Healing was defined using radiological and clinical criteria and where available the Harris Hip Score. Chi-square test with p< 0.05 was used for the statistical analysis of the Results:

Results: When the Vancouver system was applied 2.85% of the fractures were classified as type A, 87.2% as type B and 10% as type C. Within the type B group 13.2% were subtype B1, 12% subtype B2 and 62% subtype B3. 1 out of 6 Mennen, 4 out of 16 Dall/Miles and 2 out of 20 DCP plates failed. Overall 68% healing, 5% non-union, 4% infection, 23% re-fracture rate at 12 months follow-up. Better healing was achieved when impaction grafting was used for B3 fractures (p=0.001). Better healing was achieved when the revision stem was bypassing the most distal fracture line by at least 2 ipsilateral femoral diameters and impaction grafting was used for B3 fractuires (p=0.01).

Conclusion: Impaction Grafting can compensate for the inadequate bone in type B3 fractures and appears to promote union. Revision stem should bypass the most distal fracture line by at least 2 cortical diameters to achieve healing.