Survival rates for cemented Charnley total hip prostheses and influencing parameters

Aim of the study: to analyse survival of cemented Charnley prostheses, and influencing factors. Material and Methods: 539 patients (mean age: 62 years) undergoing 426 primary, and 200 revision Charnley hip arthroplasties, were examined. The indications for primary operation was idiopathic coxarthrosis in 239 cases (56.1%), and rheumatic coxarthrosis in 56 cases (13.1%). Reasons for revision surgery included aseptic loosening in 123 cases (61.5%), septic loosening in 36 cases (18%), and prosthetic fracture in 13 cases (6.5%). Results: After a mean follow-up of 4.4 years, patients were scored using the Merle d'Aubigne evaluation. The average postoperative score for primary operations was 14.8 points, and for revision surgery 13.1 points. The respective pre-operative scores were 8.2 and 8.1. Radiographic investigation revealed peri-articular calcifications in 28.4% of the primary operations, and in 28.5% of the revisions. Radiolucent lines or protrusions were found in 29.8% of the primary, and in 42.0% of the revisions. At follow-up, 45 implants in 41 patients had been replaced. Kaplan-Meier survival rates for the primary group were 99.6% after one year, 92.8% after five years, 78.3% after 10 years, and 45.9% after 15 years. The respective figures for the revision group were 98.2%, 85.3%, 59.7% and 31.3%. The largest difference was seen in the eleventh year. Patient age had no significant influence for the first 12 years. In the primary group, body mass index showed a significant influence only after 15 years. Analysis of the indications for surgery revealed a slightly higher survival rate in the arthrosis group (84%) vis-a-vis the dysplasia group (83.3%), and a significantly higher rate vis-a-vis patients with rheumatoid arthritis (42%). Clinical relevance: Such factors as age, diagnosis and weight had an influence only over the long term. Significant differences between primary and revision operations were not found.