RESULTS WITH THE SELF-LOCKING MÜLLER CEMENTED TOTAL HIP PROSTHESIS WITH A 28 MM HEAD: OUTCOME AT TEN YEARS (9–12)

Abstract

Purpose: The purpose of this study was to evaluate ten year outcome of the 28-mm head self-locking cemented Müller THA.

Material and methods: From May 1988 to May 1990, 187 second generation cemented prostheses were implanted via the transgluteal approach for osteoarthritis. The femoral implant was a straight Prostasul 10 implant with a 28-mm modular head and a gamma ray sterilised poly-ethylene cup. At ten years, for the 187 implants: 64 patients had died, 24 patients were contacted by telephone (all with implants in place) nine were lost to follow-up, and 90 implants in 82 patients were reviewed. The reviewed series included 42 women and 49 mean, mean age 65 years. Clinical outcome was noted with the Postel Merle d’Aubigné score (PMA). Radiographical assessment noted lucent lines, granulomas, migrations, wear, and ossification.

Results: Among the 187 implants, two patients required revision: one for infection and the other for posttraumatic dislocation. Among the 82 patients reviewed at ten years, the PMA score was 16.85 (92% good and very good results). Radiographically, the acetabulum showed nine lucent lines measuring greater than 1 mm and progressing between five and ten years, one migration, and two cases of migration as well as three cases of wear greater than 2 mm. Evaluation of the femur showed osteolysis in zone 3 and 4 in one hip and rarified bone in zone 7 in four. Linear penetration of the head in the cup was 0.08 mm/yr. Brooker stage 3 ossifications were found in 27% of the men and 14% of the women.

Discussion: The clinical results were comparable to other series of cemented prostheses. At ten years, potential loosenings were more frequent at the acetabular level with progressive lines always present at five years; and polyethylene wear that was not always associated with osteolysis or granuloma, while osteolysis and granulomas were always associated with wear greater than 2 mm. Furthermore, there was no anatomoclinical relationship and radiographic anomalies did not always have an effect on function. Prevention of ossifications appears to be important, particularly in men.