No Differences in Patient-reported Outcomes Between the Direct Anterior and Posterolateral Approach for THA: A Randomized Controlled Trial

Background The direct anterior approach (DAA) for THA is seeing wider use because it is purported to deliver a faster postoperative recovery. However, most previous studies comparing the DAA with the posterolateral approach (PLA) were limited by small sample sizes, heterogeneous patient populations, and the use of outcome measures with ceiling effects. Questions/purposes (1) Does the DAA result in a higher proportion of patients achieving the patient acceptable symptom state (PASS) on the Hip Disability and Osteoarthritis Outcome Score (HOOS) after THA compared with the PLA? (2) Are there differences in symptoms, physical function, life activities and participation, health-related quality of life (QoL), or complications between the DAA and PLA in the first postoperative year? Methods A prospective, parallel-group, nonblinded, randomized controlled trial comparing the DAA and PLA for THA was conducted. Patients with primary or secondary osteoarthritis with an indication for THA with an uncemented femoral stem and cemented acetabular component were eligible. Of the 241 patients assessed for eligibility, 53% (128) were included in the study. Fifty-one percent (65 of 128) were randomized to the DAA group, and 49% (63 of 128) were randomized to the PLA group. One patient in each group was lost to follow-up, leaving 98% (64 of 65) and 98% (62 of 63) of patients available for analysis, respectively. There were no between-group differences in baseline or perioperative measurements. The primary outcome was achievement of the PASS on the HOOS at 3 months postoperatively. An a priori sample-size calculation indicated that 60 patients per group were required to detect a 20% difference in PASS achievement between groups (80% power; α = 0.05). With an expected loss to follow-up of 10%, the sample size was set to 65 patients per group. Secondary outcomes included symptoms, physical functioning, participation, and health-related QoL, assessed using patient-reported outcome measures and physical performance tests. Complications were assessed using the Clavien-Dindo classification. Outcomes were assessed preoperatively as well as at 2 weeks, 6 weeks, 3 months, and 1 year postoperatively. Results At 3 months, the proportion of patients achieving the PASS did not differ between the DAA and PLA for any HOOS subscales, including symptoms (65% [41 of 63] versus 63% [39 of 62], OR 1.03 [95% confidence interval (CI) 0.80 to 1.35]; p = 0.80), pain (48% [30 of 63] versus 53% [33 of 62], OR 0.90 [95% CI 0.63 to 1.27]; p = 0.53), activities of daily living (68% [43 of 63] versus 65% [40 of 62], OR 1.06 [95% CI 0.82 to 1.36]; p = 0.66), sports and recreation (55% [34 of 62] versus 58% [36 of 62], OR 0.94 [95% CI 0.69 to 1.29]; p = 0.72), and QoL (73% [46 of 63] versus 71% [44 of 62], OR 1.03 [95% CI 0.83 to 1.28]; p = 0.80). There were no between-group differences in symptoms, physical function, life activities and participation, and health-related QoL at any time point. Complications occurred in 8% (5 of 65) of patients in the DAA group and 2% (1 of 63) of patients in the PLA group (OR 3.05 [95% CI 0.51 to 18.40]; p = 0.21). Conclusion In this randomized controlled trial, the DAA did not improve patient-reported or functional outcomes compared with the PLA during the first postoperative year. In the absence of demonstrated patient-reported or functional benefits of the DAA, surgeons should not represent to patients that the DAA provides advantages in terms of the pace or magnitude of recovery. Future studies powered to detect differences in the risk of complications should be performed to see whether harms are more likely with the DAA than with other surgical approaches. Level of Evidence Level I, therapeutic study.