ILIOPSOAS INTERPOSITION CAPSULOPLASTY: A NOVEL SOFT-TISSUE-PRESERVING TECHNIQUE FOR ILIOPSOAS IMPINGEMENT AFTER TOTAL HIP ARTHROPLASTY

Introduction Iliopsoas impingement after total hip arthroplasty (THA) may occur due to mechanical conflict between the iliopsoas tendon and the anterior rim of the acetabular component. The condition represents a diagnostic and therapeutic challenge, as it is often difficult to identify and conventional treatment with iliopsoas tenotomy can lead to persistent weakness and marked muscle atrophy (1). We describe a novel iliopsoas interposition capsuloplasty, in which the hip capsule is utilized as a biological interposition layer between the psoas tendon and the acetabular component. Methods The hip capsule and iliopsoas notch are approached through the Smith-Petersen interval. In cases of anterior cup prominence or visible tendon-cup conflict, the anterior capsule is partially released, rotated, and interposed between the iliopsoas tendon and the acetabular component. Fixation is achieved using three suture anchors. When capsular quality is insufficient, an Achilles tendon allograft is employed to reinforce the anterosuperior segment. We report on twenty patients who underwent iliopsoas interposition capsuloplasty for iliopsoas impingement following THA. Results Twenty patients (mean age 65.7 years; 13 female [65%]) underwent the procedure, with a mean follow-up of 22.5 months. Postoperative MRI confirmed the structural integrity of the interposed capsule. Mean VAS pain scores improved from 7.7 ± 0.6 to 3.5 ± 2.5 postoperatively (Δ = 4.3 ± 2.9). The mean Global Perceived Effect was 5.3 ± 1.3 on a 0–7 scale, indicating that most patients experienced a moderate to good improvement after surgery. One patient (5%) required revision due to trunnionosis. These preliminary findings suggest that interposition capsuloplasty provides substantial pain relief while preserving iliopsoas muscle function. Conclusion Iliopsoas interposition capsuloplasty is a feasible and functionally favorable soft-tissue-preserving technique for managing iliopsoas impingement after THA. By maintaining iliopsoas function and preventing prosthesis-tendon contact, it offers a promising alternative to iliopsoas tenotomy, particularly in cases with muscle atrophy or complex revision settings.