TOTAL HIP ARTHROPLASTY : LONG TERM FOLLOW-UP STUDY WITH A CEMENTLESS DOUBLE MOBILITY SOCKET. SURVIVORSHIP AND FAILURE OF 437 HIPS AFTER FIFTEEN YEARS.

Abstract

Background: Early or later dislocation is a frequent complication associated with total hip arthroplasty. The Bousquet’s acetabular component, an original concept of dual mobility socket has been used, for increase stability and mobility. The first mobility is between the femoral head and the polyethylene insert, and the second mobility between the polyethylene and the metal cup socket. The cup, covered with alumina was impacted without cement. The purpose of this study was to evaluate the long-term results of a retrospective series of primary arthroplasty with this cup and a cemented Charnley type femoral component.

Materiel and methods: This study included 437 hip replacements performed between 1984 and 1990, in 389 patients with osteoarthritis (62.5%), dysplasia (11.4%), necrosis (8%), rheumatoid arthritis (5%), post-traumatic and others (13.1%). The average age of the patients at the time of the index procedure was 61 years. The patients were followed at routine intervals for clinical and radiographic review. The clinical results were appreciated with Postel–Merle d’Aubigne score (PMA). Osteolysis was noted according to Gruen zones.

Results: The outcome is known for 345 hips (79%): 164 alive without revision at a mean of 16,5 years follow-up, 137 died without revision, and 44 failures. 92 (21%) were lost at follow up. Revision, for aseptic loosening of femoral or acetabular component, was performed in 30 hips(6.8%). 5 dislocation occurred and were revised: 2 early regarding to technical errors and 3 after 10 years or more of follow up. 7 hips were revised for deep infection, and 2 for unaccountable pain.

At more than 15 years follow-up, the mean PMA hip functional score was 17.1. 66% of the hips was A, 4% were B and 30% were C according to the Charnley’s score. Of the 164 hips in the patients who had survived at least 15 years, 28 had femoral osteolysis in zone 7, and 31 had femoral osteolysis in one (or more) of the other 13 zones. 6 hips had an impingement sign on the neck of the femoral component, without aseptic loosening.

According to Kaplan-Meier analysis, the fifteen year survival rate, was 84.36% with revision for any reason (infection, dislocation, osteolysis…) for end point. The young age of the patients at the time of the index surgery is correlated with loosening.

Conclusion: The long term results of the press fit, double mobility socket with cemented Charnley type femoral stem are good. The prevalence of revision for dislocation is very low in our series. But this concept do not avoid wear, osteolysis and aseptic loosening, specially in young active patients. We can recommand this type of prosthesis for patients over 70 years, and/or with high risk of dislocation.