A Randomized Clinical Trial of Direct Anterior versus Mini-Posterior Total Hip Arthroplasty: Small, Early Functional Differences Did Not Lead to Meaningful Clinical Differences at 7.5 Years

Introduction Our previously reported randomized clinical trial of direct anterior approach (DAA) versus mini-posterior approach (MPA) total hip arthroplasty (THA) showed slightly faster initial recovery for patients who had a DAA and no differences in complications or clinical or radiographic outcomes beyond 8 weeks. The aims of the current study were to determine if early advantages of DAA led to meaningful clinical differences beyond 5 years and to identify differences in midterm complications. Methods Of 101 original patients, 93 were eligible for follow-up at a mean 7.5 years (range, 2.1 to 10). Clinical outcomes were compared with Harris Hip, 12-Item Short Form Health Survey (SF-12), and Hip Disability and Osteoarthritis Outcomes Scores (HOOS) scores and sub-scores, complications, reoperations, and revisions. Results Harris Hip scores were similar (95.3 ± 6.0 versus 93.5 ± 10.3 for DAA and MPA, respectively, P = 0.79). The SF-12 physical and mental scores were similar (46.2 ± 9.3 versus 46.2 ± 10.6, P = 0.79, and 52.3 ± 7.1 versus 55.2 ± 4.5, P = 0.07 in the DAA and MPA groups, respectively). The HOOS scores were similar (97.4 ± 7.9 versus 96.3 ± 6.7 for DAA and MPA, respectively, P = 0.07). The HOOS quality of life subscores were 96.9 ± 10.8 versus 92.3 ± 16.0 for DAA and MPA, respectively (P = 0.046). No clinical outcome met the minimally clinically important difference. There were 4 surgical complications in the DAA group (1 femoral loosening requiring revision, 1 dislocation treated closed, and 2 wound dehiscences requiring debridement), and 6 surgical complications in the MPA group (3 dislocations, 2 treated closed, and 1 revised to dual-mobility; 2 intraoperative fractures treated with a cable; and 1 wound dehiscence treated nonoperatively). Conclusions At a mean of 7.5 years, this RCT demonstrated no clinically meaningful differences in outcomes, complications, reoperations, or revisions between DAA and MPA THA.