Risk Factors for Conversion to Total Hip Arthroplasty After Acetabular Fractures Involving the Posterior Wall.

OBJECTIVES

Identify risk factors for early conversion to total hip arthroplasty (THA) in an effort to aid in counseling patients and selecting the optimal treatment for patients who sustain a fracture involving the posterior wall of the acetabulum.

DESIGN

Retrospective cohort analysis.

SETTING

Level I trauma center.

PATIENTS

Patients with acetabular fractures involving the posterior wall managed with open reduction internal fixation at least 4 years out from surgery.

INTERVENTION

Preoperative and postoperative computed tomography scans were reviewed for injury characteristics and reduction quality. Participants were contacted by telephone to document reoperations and functional outcomes including the SF-8 and modified Merle d'Aubigne Hip Scale.

MAIN OUTCOME MEASURE

Conversion to THA.

RESULTS

The overall rate of conversion to THA was 5% at 2 years, 14% at 5 years, and 17% at 9 years. Presence of 5 specific radiographic features was associated with a 50% rate of conversion to THA in contrast to 11% if 4 or less features were present. Among cases with less than 1 mm of diastasis/step-off on postoperative computed tomography scan, there were no THA conversions, 10% conversion for 1-4 mm, and 54% if 4 mm or more of malreduction. There was no difference in SF-8 or modified Merle d'Aubigne scores comparing patients who underwent THA and those who did not.

CONCLUSIONS

Acetabular fractures with posterior wall involvement are associated with a significantly higher rate of conversion to THA if reduction is not near-anatomic. A combination of clinical/radiographic findings is associated with poorer reductions and higher rate of conversion to THA.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.