Indications and Outcomes of Conversion Total Hip Arthroplasty via the Anterior and Posterior Approaches.

Abstract

In primary total hip arthroplasty (THA), the decision of performing an anterior-based or posterior approach is debatable and depends on surgeon comfort and experience, as well as patient-specific factors. Conversion THA (convTHA) presents unique challenges given the presence of implants and alteration of native anatomy. While convTHA has historically been performed through a posterior approach, there is renewed interest in anterior-based approaches given their rising popularity in primary THA. In this retrospective cohort analysis of 80 patients, 47 had anterior-based and 33 had posterior convTHA. Patient and procedure characteristics including age, sex, race, body mass index, American Society of Anesthesiologists score, indication for convTHA, duration from index procedure, staged hardware removal (when applicable), procedure duration, and use of multiple incisions were compared. Outcome measures included complication and revision rates, length of stay and discharge disposition. Statistical analyses were performed using Student's t-tests, Chi-square tests, and multivariate regressions. Percutaneous screws constituted the majority (51.1%) of prior implants in the anterior cohort, while sliding hip screws were highest among the posterior cohort (42.9%) (P < 0). Anterior-based approach had a lower length of stay (2.3 versus 3.4 days, P = 0.04), complication rate (10.6 versus 39.4%, P < 0.001), and revision rate (4.3 versus 17.1%, P < 0.001). On multivariate regressions, only complication rate was significantly different with an odds ratio of 0.2 for the anterior approach (confidence interval 0.05 to 0.7, P = 0.013). Anterior convTHA is a safe and effective technique for simple convTHA, such as in patients who had prior percutaneous screw fixation, but commonly requires a separate incision to facilitate implant removal. For more complex convTHA, posterior approach can incorporate previous incisions for removal of larger implants, but may correspond with greater use of revision-type femoral implants and a higher complication profile.