ASEPTIC SOCKET LOOSENING. PRODUCING CONSISTENT PATTERNS OF FAILURE AND PREDICTABLE OPTIONS FOR RECONSTRUCTION

Abstract

Aim: To determine if it is possible to predict the pattern of socket failure from the first post-operative x-rays.

Methods: A retrospective review was performed of patients undergoing revision hip surgery for aseptic socket loosening. An assessment was made of the pattern of failure and socket migration. Operative details of bone defects and reconstructions required were noted.

Results: 55 patients were identified with an average age of 46.2 years at primary surgery. The average socket survival was 16.14 years. There was no association between the patient’s age or original diagnosis and the duration of socket survival.

Supero-medial migration was seen in 27 (49%) of cases, demarcation without migration was seen in 18 cases (33%) and supero-lateral migration was seen in 7 (13%) cases. There were 2 (4%) socket fatigue fractures due to wear. There was 1 (2%) patient with a worn socket and no loosening.

Reconstruction was achieved by impaction bone grafting alone in 25 cases, IBG and a block allograft in 9 cases, cement alone in 8 cases and IBG with a rim mesh in 4 cases.

In cases where the supero-lateral margin of the socket was covered by host bone, failure always occurred by demarcation alone or in association with supero-medial migration. Rim defects significant enough to require reconstruction were seen in only 4 of these 45 patients (9%). Failure by supero-lateral migration was only seen in the cases of DDH where the socket was left uncovered or where the socket had fractured.

Conclusions: In this young age group series cemented acetabular components performed well, failed predictably and were relatively straightforward to reconstruct.

The pattern of socket failure can be reliably predicted from the original post-operative x-rays. Care should be taken to ensure adequate supero-lateral coverage in order that demarcation and migration leave an intact rim for reconstruction.