REVISION OF THE WELL FIXED BIRMINGHAM HIP RESURFACING ACETABULAR COMPONENT: RESULTS USING A NOVEL DEVICE

Abstract

Introduction: While the explant device has made revision of uncemented acetabular components technically easier, the unique design of the Birmingham Hip Resurfacing(BHR) acetabular component precludes the use of the standard explant extractor. The dual radius geometry of this socket causes impingement and damage to the curved blade of this device.

A novel adaptor was designed to correct for the differential radii and enable removal of the well fixed BHR socket with the explant. We present the results of our initial experience with this device.

Method: A prospective study was performed to evaluate the effectiveness of this device for revising the well fixed BHR socket. All cases were performed by a single surgeon via a posterior approach.

The explant cup extractor was used with its standard centering head and curved blades. The size of the explanted cup, last reamer size and size of the implanted component were recorded

Results: Three males and 7 females were included. Their average age was 58.1 years (48–65). Average time to revision of the BHR sockets was 24.2 months (7–40). Average explanted cup size was 51mm (46–58) and final reamer size 53.8mm (51–59). Average final socket size was54.8 (50–62). Overall there was a mean 2.8.mm size difference between the explanted cup and the final reamer.

Discussion: The thickness of the blade of the explant was 2mm therefore only 0.8 mm of bone was lost on average. The device enables a simple reproducible removal of the well fixed BHR sockets with preservation of acetabular bone stock.