Ultrasound-Guided Obturator Nerve-Targeted Physical Therapy for Persistent Buttock Pain After Hip Arthroscopy for Femoroacetabular Impingement: A Report of Two Cases

Femoroacetabular impingement (FAI) can present with buttock pain even after hip arthroscopy. While arthroscopy often improves pain and function, some patients continue to experience persistent postoperative symptoms. Case 1: A woman in her 40s presented with buttock pain specifically induced during walking, eight months after arthroscopy for a labral tear. The FABER (Flexion, Abduction and External Rotation) test reproduced buttock pain (numerical rating scale (NRS) 5), with increased knee-to-floor distance (KFD), poor external obturator (EO) contraction, and localized tenderness elicited under ultrasound-guided sonopalpation of the obturator nerve (ON), EO, and internal obturator. Case 2: A man in his 30s reported severe buttock pain during hip abduction-external rotation 11 months after arthroscopy. The FABER test reproduced pain (NRS 7), with increased KFD, diminished EO contraction, and tenderness around the ON and EO on ultrasound-guided sonopalpation. Both patients underwent weekly ultrasound-guided manual therapy with EO activation and biweekly ON hydrodissection using 10 mL of 0.09% lidocaine solution, followed by dynamic stretch-slack maneuvers. Both demonstrated immediate improvement in FABER-induced buttock pain, shortened KFD, and enhanced EO contraction after each session. In Case 1, buttock pain during walking resolved after the fourth session without recurrence. In Case 2, progressive improvement began at the second session, with complete recovery of daily activities. These cases suggest that impaired gliding of ON articular branches may contribute to postoperative buttock pain after hip arthroscopy. Ultrasound-guided ON hydrodissection with EO activation and targeted nerve-gliding maneuvers may offer an effective therapeutic approach. Limitations include the small number of cases, qualitative evaluation without validated outcome scores, and short-term follow-up.