Study Reassesses Acetabular Overhang Threshold for Iliopsoas Lengthening After Hip Arthroplasty

An 8-mm anterior acetabular overhang threshold has often guided surgery for iliopsoas impingement after total hip arthroplasty, favoring acetabular revision for greater overhang. A retrospective study in The Journal of Bone and Joint Surgery evaluated arthroscopic iliopsoas fractional lengthening performed between 2017 and 2024 in 86 hips among 83 patients. Radiographic overhang was <8 mm in 67 hips and ≥8 mm in 19. Mean follow-up was 2.5 years, with a minimum of one year.

The groups showed no significant differences in preoperative or postoperative pain, hip function, activity, subjective groin pain or hip flexion strength improvement, or satisfaction (all reported p > 0.06). Reoperation rates were 2.9% versus 10.5% in the lower- and higher-overhang groups, respectively (p = 0.210); acetabular revision rates were 1.5% versus 5% (p = 0.387).

The authors propose considering arthroscopic lengthening as first-line surgery after unsuccessful nonoperative management, including with substantial overhang. However, this Level IV retrospective study included only 19 hips with ≥8-mm overhang and did not directly compare lengthening with acetabular revision. Nonsignificant differences do not establish equivalence, particularly given numerically higher reoperation and revision rates in the higher-overhang group.