COMPARISON OF THE WRIGHTINGTON FC HIP WITH THE CHARNLEY LOW-FRICTION ARTHROPLASTY - 10 TO 15-YEAR RESULTS AND SURVIVAL ANALYSIS

Between 1981 and 1986 two groups of patients received either Charnley low-friction arthroplasties or the Wrightington Frusto-Conical hip rep lacement with otherwise identical management before and after operatio n. There were 260 consecutive replacements in 215 patients in the firs t group and 260 consecutive procedures in 211 patients in the second. Both components of each design were cemented and featured a 22.25 mm f emoral head, but the geometry of the stems differed. Of the patients l ost to follow-up, 16 (18 hips) were in the Wrightington series and 24 (36 hips) in the Charnley series, and of those who have died 20 (23 hi ps) were Wrightington and 14 (16 hips) were Charnley. All surviving pa tients have been followed up clinically and radiologically or until re vision was necessary. The mean length of follow-up for original surviv ing components in both series was 140 months (120 to 180). Pain, funct ion and movement were measured by the grading system of Merle D'Aubign e and Postel and showed a marked improvement in both groups. There was little or no pain in 98% of patients in the Wrightington series and 9 6% in the Charnley series, while 93% and 85%, respectively, were entir ely pain free. Trochanteric osteotomy was used in 292 cases overall, w ith a complication rate of 13% due to wire breakage, trochanteric burs itis or trochanteric detachment, requiring a further operation in 5.8% (17 hips). Heterotopic ossification was seen in 40% of cases in which trochanteric osteotomy had been performed (117 hips) but only 3% (10 hips) had clinically significant changes. After the direct lateral app roach heterotopic ossification was seen in 24% (42 hips) with only 2% in class 3 or 4 (4 hips). Femoral osteolysis was more common in the Ch arnley series, occurring in 7.6% of cases (17 hips) as opposed to 2.1% (5 hips) in the Wrightington series. Ten acetabular and seven femoral components have been revised in the Wrightington series and 16 acetab ular and 11 femoral implants in the Charnley series. Survivorship base d on revision for aseptic loosening using the Kaplan-Meier technique s howed survival of the femoral implant at 5, 10 and 15 years of 100%, 9 9% and 98%, respectively in the Wrightington and 100%, 99% and 87% in the Charnley series. The survival of the acetabular component at ill, 12 and 15 years respectively, was 100%, 99% and 95% for the Wrightingt on, and 99%, 98% and 84% for the Charnley. The survival of both the ac etabular and femoral components of the Wrightington system at a mean o f 11.7 years was better than that of the Charnley system, with a lower incidence of radiological loosening of unrevised components.