Early functional outcomes of a conjoined tendon-preserving posterior approach in robotic arm-assisted total hip arthroplasty: A retrospective cohort study

Purpose Minimally invasive surgery (MIS) techniques in total hip arthroplasty (THA) seek faster recovery. The conjoined tendon-preserving posterior (CPP) approach has recently been introduced as a MIS posterior technique; however, evidence regarding its clinical benefits in THA remains limited. To determine whether the CPP approach shortens the time to independent walking without limping and improves early postoperative clinical outcomes compared with the conventional posterolateral (PL) and piriformis muscle-sparing PL (P-PL) approaches in patients undergoing robotic arm-assisted THA. Methods This retrospective cohort study included 100 consecutive patients who underwent robotic arm-assisted primary THA using one of the three approaches: PL (n = 33), P-PL (n = 34), or CPP approach (n = 33). Time to independent ambulation with two canes (T1) and with or without a single cane (T2) was recorded postoperatively. Patient-reported outcomes were assessed preoperatively and up to 1 year postoperatively using the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). Results The CPP group achieved independent walking significantly earlier than the PL and P-PL groups (T1: 5.1 vs. 10.9/9.1 days; T2: 14.3 vs. 24.7/24.5 days, all p < 0.001). CPP group showed significantly higher JHEQ movement scores from 3 months postoperatively and lower dissatisfaction scores at 6 and 12 months, with no significant differences in pain scores. Conclusion The CPP approach significantly accelerated postoperative gait recovery and improved early functional outcomes compared with conventional posterior approaches, likely due to preservation of short external rotators and the posterior capsule. Further large-scale, prospective studies are warranted to confirm these findings.