High Satisfaction Despite 32% Persistent Hip Flexor Weakness After Endoscopic Tenotomy for Iliopsoas Impingement Following Total Hip Arthroplasty.

Abstract

Iliopsoas impingement (IPI) is a serious complication after total hip arthroplasty (THA), causing chronic pain and functional impairment. Endoscopic iliopsoas tenotomy (EIT) is considered among the least invasive options to prevent implant revision. This study aimed to evaluate postoperative outcomes with a focus on pain relief, objective hip flexor strength, and patient satisfaction. We hypothesized that patients would report high satisfaction despite potential persistent strength deficits. This retrospective, consecutive, monocentric, single-surgeon level III study with prospective outcome evaluation included 31 THA patients (mean age 63 years, 18 women/13 men, mean BMI 28) treated with EIT for IPI between 2015 and 2022. The mean follow-up was 37.0 months (range, 24 to 82). The IPI was based on clinical findings and 3-T metal artifact reduction sequences (MARS)-magnetic resonance imaging (MRI), and other causes of painful THA were excluded. Outcome measures included pain (VAS), Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and standardized isometric hip flexion strength testing using a dynamometer, performed on the operated and contralateral limbs in all patients. Pain improved significantly (VAS 8.3 ± 1.3 to 2.9 ± 2.3, P < 0.001) with a postoperative HHS of 75.8 ± 15.8 and WOMAC of 66.2 ± 23.7. Hip flexor strength on the operated side was reduced by 32.4% (Fmax) and 32.6% (Fmean) compared to the contralateral side (P < 0.001), corresponding to a mean limb symmetry index (LSI) of 67.4%. Bilateral THA (11 patients) or previous hip surgeries (six patients) had no effect on pain relief or strength outcomes. Despite this measurable strength deficit, 26 patients - including those who had greater eight mm cup overhang - were satisfied and would choose surgery again. Endoscopic iliopsoas tenotomy is a minimally invasive treatment option for symptomatic IPI, providing high patient satisfaction through reliable pain relief. However, hip flexor weakness may persist and should be discussed during preoperative counseling.