Supracondylar correction osteotomy to prevent repetitive posterior dislocation of a hip prosthesis.

Recurrent dislocation of a total hip prosthesis can be a challenging and often disappointing problem. This case report describes a 78-year-old woman who had recurrent posterior dislocations of a revision total hip replacement (THR) that occurred on flexion and internal rotation of the hip. The initial THR for posttraumatic osteonecrosis and extensive revision THA were performed through an anterolateral approach. Conservative treatment was not successful in preventing posterior re-dislocation, neither was open surgery in which offset was improved. Investigation under anesthesia by means of an image-intensifier showed that the prosthesis was easily dislocated posteriorly on flexion and internal rotation. On external rotation the hip was completely stable. Flexion-internal rotation is a rare motion which, if the patient is clearly instructed should be avoidable. The mechanism of an anterior dislocation caused by external rotation, extension and adduction is more common, especially since an anterolateral approach was used in all procedures. We describe the surgical technique of performing an supracondylar external rotating osteotomy of the femur to avoid further dislocation. Fixation was performed with a condylar plate fixation of which the proximal part is fixated above the distal point of the femur component to avoid a stress riser. Since the foot and knee of the patient are now internally rotated, the patient is forced to produce an external rotation in the hip to have a normal leg alignment, therefore preventing the internal rotation on which the dislocation occurred. In the prevention of a re-dislocation, solutions other than performing a revision of the THA can successfully solve the problem and should therefore be considered.