HIP Surgical Techniques to Enhance Rehabilitation (HIPSTER) : a single-centre, double-blind, parallel three-arm, randomized-controlled, superiority trial.

Aims: The primary aim of this trial is to investigate whether two novel robotic-assisted tendon-sparing posterior approaches to total hip arthroplasty (THA) surgery, the piriformis-sparing posterior approach (PSPA) and the spare piriformis and internus, repair externus technique (SPAIRE), improve early patient outcomes in THA compared with a robotic-assisted standard posterior approach (PA).

Methods: HIP Surgical Techniques to Enhance Rehabilitation (HIPSTER) is a single-centre, double-blind, parallel three-arm, individually randomized, controlled, superiority trial. A total of 309 participants aged over 18 years who have been listed for an elective THA will be recruited. Participants will be randomized in a 1:1:1 ratio to SPAIRE:PSPA:PA, using minimization (with a random element) on sex (males; females), age (< 50 years; ≥ 50 years), and BMI (< 30 kg/m²; ≥ 30 kg/m²). The primary outcome is the patient-reported outcome of Oxford Arthroplasty Early Recovery Score (OARS), assessed six weeks after surgery. Secondary outcome measures include blood biomarkers, activity monitoring, and patient-reported outcome measures.

Conclusion: The trial will assess whether the two novel robotic-assisted tendon-sparing posterior approaches to THA surgery, the PSPA and SPAIRE, improve patient outcomes in THA compared with a robotic-assisted standard PA. If successful, it is anticipated that the results of this trial will provide the evidence necessary to plan a future multicentre, randomized-controlled trial to compare the best-performing tendon-sparing approach (PSPA or SPAIRE) identified in this efficacy trial with the gold standard PA, to assess whether the efficacy results are generalizable across the NHS. At the time of the submission, the trial is currently completing recruitment, and the follow-up will be completed in 2026.