SURFIX ANCHORED SOCKET FOR HIP DYSPLASIA AND DISLOCATION: RESULTS AFTER MORE THAN FIVE YEARS

Abstract

Purpose: The purpose of this work was to determine the feasibility of using the Surfix anchored hip socket for revision arthroplasty after dysplasia or dislocation.

Material and methods: The series included 45 total hip arthroplasties revised between 1991 and 1995 in 42 patients. Four patients (five hips) had died before five years (at 2, 3, 3, 4 and 4 years) and two others were lost to follow-up (at 1 and 1 year). Thirty-six patients (38 hips) were retained for analysis. There were eight men and 28 women, mean age 60 years (24–74). Mean follow-up was 6.5 years (5–9). There were 20 high or intermediary malformations, 13 severe dysplasias, and five minor dysplasias; 34% had been operated on earlier. The acetabulum was gouged out to the paleoac-etabulum in all cases except one. Primary stability of the acetabulum was achieved with a Surfix anchor. With this anchorage system, the screw that crosses the acetabulum and is screwed into the bone is fixed to the prosthetic socket via a counter-sink placed in the head of the transverse screw. A femur head was used to reconstruct the acetabulum: the entire head was used in two cases, small cubes cut out of the head in 24, and ground head material in 12. The reconstruction bone was driven into the defect between the iliac wing and the implant after its fixation to solidarise the anchorage screws.

Results: There were two cases of regressive sciatic palsy. One case of progressive migration was observed after reconstruction in a patient with a high dislocation who underwent revision at two years for a new Surfix acetabulum. The final result was good but this case was withdrawn from the analysis. Clinical outcome for the 37 remaining patients were: pain 5.9 (35X6 – 2X5), motion 5.8 (33X6 – 3X5 – 1X4), walking 5.6 (26X6 – 10X5 – 1X4). Radiographically, the reconstruction of the bony acetabulum was good with rehabilitation and neocorticalisationof the graft material. There were modifications of the bony condensations and corticalisation around the screws. There were no displacements of the prosthetic socket and no cases with lucent lines.

Discussion: Independent acetabular screws cannot participate in resistance against compression. They become functional and effective when they are solidarised to the socket. They can be anchored in the bony columns allowing very good primary fixation.

Conclusion: The clinical and radiological results confirm the usefulness of the Surfix socket anchor when there is no bony support for the prosthetic socket.