REVISION FEMORAL STEM WITH A LONG LOCKED TOTAL PROSTHESIS AND HYDROXYAPATITE COATING: 33 CASES

Abstract

Purpose of the study: The objective of this retrospective analysis was to examine the functional and radiographic results of 33 resvisions for femoral implants using a long locked stem inserted without cement and coated with hydroxyapatite.

Material and methods: Mean follow-up was two years for 33 patient who underwent revison total hip arthroplasty (rTHA) with implantation of a press-fit long locked hydroxyapatite coated femoral stem (Aura or Linea) between 2000 and 2004. The explanted prosthesis was cemented in 23 cases. The reason for revision was femoral loosentng for 60%, femoral fracture for five pateints, and infection for two. According to the SOFCOT 1999 criteria, ten patients had bone defects score grade III or IV. Femorotomy was performed in 21 cases. Patients were reviewed clinically and radiologically. Function was assessed with the Postel-Merle-d’Aubligné (PMA) score and radiographic analysis determined the quality of osteointegration of the implants and the restitution of bone stock.

Results: There were six early complications (one death, one disloction with sciatic paralysis), and six late complications, mainly related to defective locking. The PMA score was less than 3 for only three patients. Twenty-six patients were satisfied or very satisfied and seven patients reported thigh pain which was generally moderate. The locking was released for five prostheses because of failure or pain (relief observed in three cases). Migration was noted in three cases, illustrating their non-integration. For 15 patients, corticalisation around the lower part of the prosthesis suggested implant mobility. This image was observed in all patients who complained of thigh pain (p=0.057). There was a significant increase in the cortical index, reflecting progression of the bone stock favoring the internal cortex.

Conclusion: This type of implant has provided a solution for the difficult problems of explantation and reimplantation of THA. These prostheses provide satisfactory short-term results and a significant improvement in bone stock. There remains the problem of osteointegration of certain implants. Technical factors can contribute to improved clinical results.