[Prevention of prothesis dislocation after the revision of total hip arthroplasty]

To explore the role of reconstruction of the posterior capsule and external rotators in prevention of postoperative dislocation in total hip arthroplasty revision following the posterolateral approach.

Forty-five patients (47 hips) with the mean age of 65 years (55 to 78 years)of failed total hip arthroplasty were revised following the posterolateral approach. Posterior capsule was sutured to the anterosuperior portion of the capsule from where it had been detached, and the external rotators were then reattached to the soft tissue at the tip of the greater trochanter using 1.0 silk suture in surgery. The dislocation rate and risk factors were reviewed retrospectively to determine if closing the posterior capsule resulted in fewer dislocations. The femoral prosthesis and acetabular prosthesis were revised in 29 patients (31 hips), the liner was exchanged in 5 patients (5 hips), and the acetabular prosthesis or femoral components were revised in 10 patients (10 hips) and one patient (one hip) respectively. The procedure was the patient's first revision in 29 patients (30 hips), the second revision in 15 patients (16 hips), and the third revision in one patient(one hip). Radiographic evaluation included lower limb discrepancy, acetabular phase, femoral offset, anteversion angle, prosthetic loosening before and after revision. Function evaluation based on Harris score system.

All patients were followed up with an average of 2.7 years. None of the patients sustained dislocation or infection, except one patient felt the anterior instability but without dislocation, X-ray revealed the acetabular component was in excessively anteversion. Lower leg discrepancy, acetabular abduction, anteversion femoral offest and collodiaphyseal angle were restored to normal level after operation on the basis of X-ray. One of the acetabular components and one of the femoral components were loose without dislocation. The Harris hip score improved from (49.13 +/- 15.53) points preoperatively to (83.59 +/- 6.93) points at the final follow-up (P < 0.05). According to Harris functional evaluation, 36 hip got an excellent result, 5 good, 5 fair and 1 bad.

The historically high dislocation rate with the posterolateral approach for total hip arthroplasty revision can be reduced by careful soft tissue balancing,correction of implant alignment, meticulously closure of the posterior capsule, and reattaching the external rotators.