Background

An increased incidence of periprosthetic osteolysis, resulting in loss of biologic fixation, has been recently reported in contemporary THAs with low-carbide metal-on-metal compared to metal-on-polyethylene couple bearings. A hypersensitivity reaction due to Co and Cr debris is reported as a potential cause for failure of THAs with high-carbide bearings, but there are no evidence-based data for this reaction in low-carbide metal-on-metal bearings.

Background: Recent studies have reported early periprosthetic osteolysis in patients who have been treated with a contemporary metal-on-metal total hip arthroplasty and suggested that metal hypersensitivity associated with an immunologic response to metal may be of etiologic importance. We evaluated the results and histologic findings in patients who underwent revision surgery for a failed contemporary metal-on-metal total hip arthroplasty.

Material and Methods: Two hundred and seventeen total hip arthroplasties (SL-Plus stem and Bicon-Plus cup) with a Sikomet metal-on-metal articulation were implanted in one hundred and ninety four consecutive patients and retrospectively reviewed at mean of 77 months postoperatively. Clinical follow up was performed with the Harris hip score and plain radiographic evaluation was performed. Histologic analysis was performed on the periprosthetic tissues of 14 hips that underwent revision arthroplasty.

Results: The mean Harris hip score improved from 45 preoperatively to 96 at final evaluation. Fourteen (6.4%) hips were revised: 9 for aseptic loosening, 2 for technical failure and three for septic failure. Histologic examination of the retrieved periprosthetic tissues from the eleven patients who underwent revision for aseptic loosening or technical failure showed microscopic metallosis and extensive lymphocytic and plasma cell infiltration around the metal debris. With an endpoint of removal of a component with aseptic loosening, endpoint survivorship was 93% for the stem and 98% for the cup respectively.

Conclusions: Our findings are in agreement with recent publications and support the possibility that periprosthetic osteolysis and aseptic loosening in hips with metal-on-metal articulation are possibly associated with hypersensitivity to metal debris. Prospective, comparative randomized long-term studies are necessary to determine the cause(s) of loosening of this particular articulation.

Introduction & Purpose of Study. The purpose of the present study was to evaluate the clinical, radiographic and histologic results with the Zweymueller total hip arthroplasty (THA) and metal-on-metal articulation. Material and Methods. Between 1994–2003, 380 patients received 415 third-generation Zweymueller-Plus THA with SL-stem and Bicon screw socket for hip osteoarthritis. Ten (5.15%) patients did not return for their last follow-up evaluation for reasons unrelated to their hip operation. This study reports on 217 THAs with follow up more than 60 months. The 217 THAs were implanted in 194 patients (143 women and 51 men), aged 55 ± 9 years, (25–70 years). The most common diagnosis for THA was primary osteoarthritis (48%) followed by secondary osteoarthritis due to developmental hip dysplasia (44%). Results. The follow-up was 77 ±17 months, (60 – 112 months). From the 217 THAs, 14 (6.4%) hips were revised for any reason; the socket in 5(2.3%) and the SL-stem in 9(4.1%) hips. The preoperative Harris hip score of 45±19 was improved to 96 ± 4 postoperatively. 95% of the patients were satisfied or very satisfied with the result of the operation. Revision was made in a total 14(4.6%) hips because of different reasons. The aseptic revision rate was 5%: 4(1.8%) Bicon cups and 7(3%) SL-stems were revised for aseptic loosening. The septic revision rate was 1.4% (3 THAs) and was due to Staph aureus. Periarticular ossification was observed in 32(17%) of the hips (5% Brooker grades III and IV), however without associated disability. The histological examination revealed mild metalosis (Mirra grades 1 and 2) in all revised hips. The cumulative survival for any reason (95% C.I.) was 90% (97% to 71%). The aseptic survival was 91% (97–72%) [95% CI); and specifically for the Bicon socket it was 98 % (100 to 92%); and for the SL-stem 93% (98% to 74%)[CI 95%]. The survival for the men and women was 78.9% and 94.4% respectively (log rank test: chi square P= 0.25). A significant, not statistically significant observation was that men showed lower survival for the stem than women (78.9 vs. 97.5%). Conclusion. This study showed that the medium-term results of Zweymueller total hip arthroplasty with metal-on-metal articulation were inferior particularly for the SL-stem to those obtained with the conventional Zweymueller total hip arthroplasty with polyethylene-ceramic articulation. This could be due either to allergic or mechanical (Sikomet Alloy) reasons.

Aims: To investigate if coralline hydroxyapatite conduct bone formation in human spine. Methods: During revision surgery specimens were taken from the fusion mass from 13 patients, who received spinal instrumentation (Titanium alloy) and fusion with coralline hydroxyapatite. The age of patients at the time of revision surgery was 46±20 years. The time lapsed from the implantation of coralline hydroxyapatite (ProOsteon) was 11±11 months. The indication for revision was infection, pseudarthrosis, technical error, and pain related to hardware. The diagnosis for primary fusion was degenerative disease, spinal trauma and scoliosis. Coralline hydroxyapatite was applied on the posterior decorticated elements of the instrumented spine without any mixture with bone graft. Material from ten different places from the fusion mass was intraoperatively taken and the histological evaluation was made using the Hematoxylin-eosin histological stain. Results: There was a concentration of foreign-body like giant cells & development inflammatory granulomatous tissue around hydroxyapatite granules, which was gradually replaced by dense connective collagen tissue. Both inflammatory granulomatous and collagen tissue showed areas with foreign body reaction. In the cases, where bone has developed, the most initial finding was the presence of osteoblasts & apposition of osteoid in contact to hydroxyapatite granules. In a later phase, cancellous and lamellar bone has developed as a result of secondary ossification. Bone formation was observed in 11/15 cases. Conclusion: Coralline hydroxy-apatite conducts bone and osteoid formation around the implanted coralline hydroxyapatite granules in different areas of the human spine operated for different disorders.

Aim. The aim of this study is to estimate the medium-term results with the Zweymueller metal-on-metal THA in the osteoarthritis of the hip.

Material & Methods. A total of 266 consecutive patients, received 350 third-generation Zweymueller-SL total hip arthroplasties with metal-on-metal articulation for primary or secondary osteoarthritis. The age of the patients at the time of surgery was 55+9 years, (range 25–70 years). Seven (3%) patients did not return for their last follow-up evaluation and they excluded.

Results. The mean follow-up was 67 months (range 49–102 months). The preoperative Harris hip score was 45±19 and increased to 87±4 postoperatively. The invalidity of the patients was significantly improved postoperatively (p< 0.001). In all, 97% of the patients were satisfied or very satisfied with the result of the operation. There was no aseptic loosening noted in this series. Revision was done in 6 (1.8%) hips because of septic loosening (n=5, 1.5%) or technical error (n=1, 0.3%) during implantation. Dislocation of the prosthesis occurred in the early postoperative period in 2 (0.6%) hips because of technical errors during implantation. Periarticular ossification was observed in 30% of the hips (5% Brooker grades III and IV), but without associated disability. During revision surgery, no macroscopic metalosis could be identified in the newly formed hip joint membrane; how ever microscopic evidence for metalosis (Mirra grades 1 and 2) was seen in all revised hips. The survival for Zweymueller screw socket and stem 7.6 years after implantation was 99.4% and 96.8%, respectively.

Conclusion. The reasons of the loosening of Metal-on-Metal Zweymueller THA were the infection or the technical errors during implantation of the socket and nothing about the metal-on-metal articulation.