To Lengthen or Revise: Reevaluating Anterior Acetabular Overhang Thresholds in Iliopsoas Impingement After Total Hip Arthroplasty

Background: Iliopsoas impingement (IPI) is a known cause of persistent anterior hip pain following total hip arthroplasty (THA). Management of IPI has often relied on an 8-mm anterior acetabular overhang threshold to guide operative treatment, favoring acetabular revision for greater overhang and iliopsoas tenotomy for lesser overhang. These thresholds were initially established on the basis of the outcomes of open tenotomy, and now, with an improved understanding of IPI and the advent of arthroscopic iliopsoas fractional lengthening (IPFL), a review of the 8-mm threshold is warranted. Methods: A retrospective review was performed to identify patients who underwent arthroscopic IPFL following primary THA between 2017 and 2024, with a minimum follow-up of 1 year. Acetabular overhang was measured for all patients using cross-table lateral radiographs, and patients were stratified into <8-mm and ≥8-mm cohorts. Patient-reported outcome measures, reoperations, revisions, and complications were collected and analyzed on the basis of both the classic 8-mm threshold and continuous statistical methods. Results: We evaluated 86 hips undergoing IPFL. There were 83 patients (30 men and 53 women), with a mean age of 63.0 ± 11.2 years; with regard to race, 80 patients were White, 1 patient was Black or African American, and 2 patients listed other race or chose not to disclose. The acetabular overhang was <8 mm for 67 hips and ≥8 mm for 19 hips. The mean follow-up was 2.5 ± 1.6 years (range, 1 to 7.5 years). When comparing patients with <8-mm and ≥8-mm acetabular overhang, we observed no significant differences (p > 0.06) in the preoperative and postoperative visual analog scale (VAS) pain scores, modified Harris hip score, Single Assessment Numeric Evaluation (SANE) score, Tegner activity level, subjective groin pain improvement, subjective hip flexion strength improvement, and overall satisfaction. Reoperation (2.9% compared with 10.5%; p = 0.210) and acetabular revision rates (1.5% compared with 5%; p = 0.387) were not significantly different between the <8-mm and ≥8-mm overhang groups. Conclusions: Arthroscopic IPFL provided satisfactory outcomes for patients with IPI, independent of the magnitude of acetabular overhang. IPFL should be considered for first-line surgical management of IPI refractory to nonoperative management, even in the setting of substantial acetabular overhang, given positive outcomes and low rates of subsequent acetabular revision. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.