A clinical and radiographic 13-year follow-up study of 138 Charnley hip arthroplasties in patients 50-70 years old: comparison of university hospital data and registry data.

BACKGROUND AND PURPOSE

Arthroplasty registers provide rates of implant survival in large populations based on implant revision. In an unrevised prosthesis population, some patients may have implants with clinically poor outcome or radiographic failure. We therefore evaluated medium-term clinical and radiographic results in patients with charnley hip arthroplasties and compared our results with data from the Norwegian Arthroplasty Register (NAR).

PATIENTS AND METHODS

From 1989 through 1991, 138 Charnley arthroplasties with plain Palacos cement were performed in 123 patients who were 50-70 years old. At follow-up after 13 (12-15) years, 26 patients had died (28 hips). The 84 unrevised patients (93 hips) were interviewed and underwent clinical and radiographic assessment. Prosthesis survival was estimated by the Kaplan- Meier method.

RESULTS

At follow-up, 83% of the patients were completely satisfied with their hip replacement. Mean Harris hip score (HHS) was 83 (SD 15), mean EQ-5D index was 0.75 (SD 0.24) and mean EQ-VAS score was 69 (SD 21). Most clinical assessments had poorer scores for Charnley category C (n = 47) than for Charnley category A + B (n = 46). Function, according to Charnley's modified Merle d'Aubigne and Postel scoring system, was improved compared to preoperative values. The survival at 10 years was 89% (95% CI: 84-95) and at 13 years it was 85% (95% CI: 79-92) with revision for any reason as endpoint. In addition to 20 revised hips, 8 implants were radiographically loose and 13 hips had HHS < 70, giving a clinical success rate of 76%. Only 4 primary operations (0.8%) had not been reported to the NAR, but all revisions had been reported.

INTERPRETATION

Clinical follow-up studies give essential information that is additional to that gained from revision-based outcome studies. To fully appreciate the clinical effectiveness of an implant, specific hip function, patient satisfaction, quality of life, and radiographic analysis must also be considered. The functional status of the patient has an important influence on the clinical outcome after hip replacement.