10-Year Clinical Review of Revision Hip Arthroplasty Following Previous Metal on Metal Hip Procedures With Preoperative Magnetic Resonance Imaging and Metal Ion Analysis: Abductor Tendon Avulsion Predicts Dislocation.

Abstract

There is a paucity of long-term data following the revision of previous metal-on-metal (MoM) hip procedures. We hypothesized that functional and clinical results would be poor and that prerevision serum ion levels and magnetic resonance imaging (MRI) findings could predict the outcome. All patients who had completed a minimum of 10 years following the revision of an MoM hip procedure at our institution were contacted. Data recorded were postrevision complication, rerevision, Oxford Hip Score, and EuroQol-5-Dimension Score, along with prerevision serum ion levels and MRI findings. There were 56 aseptic MoM revisions from a consecutive series of 86 that reached > 10 years of follow up. The mean age at revision surgery was 60 years (range, 31 to 75), and the mean follow up was 138 months (range, 120 to 161). The mean Oxford Hip Score was 37.4 and was lower in the MoM resurfacing group (mean 36.1) versus the MoM total hip arthroplasty group (mean 38.0), P = 0.46. The mean EuroQol-5-Dimension was 8.9. Rerevision rate was 16%, which was associated with the exchange of both components, P = 0.029. The overall dislocation rate was 11, and 5% developed infection. Preoperative MRI was available for 46 hips: abductor tendon avulsion was present in 30% and was positively associated with postoperative dislocation, P = 0.043. Pseudotumor formation was present in 20%. The mean metal ion levels preoperatively were cobalt, 366.1 nmol/L, and chromium, 211.6 nmol/L, with cobalt levels above our mean value of 366.1 nmol/L, associated with Goutallier grades 3/4 abductor insufficiency, P = 0.033 and trending toward association with pseudotumor formation, P = 0.087. Satisfactory patient-reported functional outcomes are attainable at over 10 years following revision surgery for failed MoM hip surgery. However, there is a significant risk of rerevision and dislocation, which may be predicted with MRI evidence of abductor insufficiency and adverse reaction to metal debris.