Abstract
Purpose: Postoperative dislocation after revision total hip arthroplasty (rTHA) is a frequent complication. Certain risk factors have been well identified (greater trochanter non-union, history of repeated dislocation or infection, multiple operations), but the role of spinal morphology is not well known. The purpose of this prospective study was to determine the role of spinal morphology on postoperative dislocation.
Material and methods: Between September 2000 and March 2002, 49 patients underwent rTHA. The prospective analysis included a preoperative radiographic evaluation of the spinal morphology for lumbopelvic assessment using the Legave and Duval Beaupère criteria. A standard information card was used pre- intra- and postoperatively to record usual patient- and material-related risk factors of dislocation. Five patients experienced postoperative dislocation despite any apparent defect in implant position.
Results: Mean sacral slope was significantly different (p=0.006) between patients with and without dislocation. This difference remained significant (p=0.017) when limiting the study to the 33 patients who had no associated risk factor postoperatively (history of recurrent dislocation or infection, multiple operations, tight non-union of the greater trochanter).
Discussion: Our study demonstrated the role of lumbar morphology on the risk of postoperative dislocation. Spinal morphology modifies the pelvic orientation and thus landmarks habitually used for implantation. It also affects the amplitude of pelvic movement when moving from the sitting to standing position, requiring hip compensation, particularly extension.
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