EP4.18 F-FDG PET/MRI Identifies Previously Unrecognized Pain Generators in Patients with Persistent Pain After Hip Surgery

Abstract Purpose/Background A quarter of patients suffer from post-hip arthroscopy pain (P-HAP). Diagnosis is confounded by overlapping pain generators, post-surgical changes, and limited specificity of imaging. ¹8F-FDG PET/MRI detects metabolically active pathology, its application to P-HAP is evaluated here. Methods This IRB-approved retrospective study enrolled 34 patients (40 hips; 23 female, 11 male; mean age 32.2 years) with P-HAP (duration >6 months; VAS ≥4), and failed standard-of-care. The median interval from arthroscopy to imaging was 19.5 months with average of 1.4 arthroscopies (range 1–3). All scans were interpreted by two board-certified radiologists with more than 10 years of experience. SUVmax values and Z-scores were measured to support findings. Results ¹8F-FDG PET/MRI influenced management in 33/34 patients (97%) by identifying a previously unrecognized diagnosis in 26 (65%) hips, confirming suspicion in 8 (20%) hips, and both in 5 (12.5%) hips. Findings remained indeterminate in 1 (2.5%) case. Hip-related findings were most frequent, involving iliofemoral ligament (n = 33), extracapsular soft tissues (n = 17), iliopsoas bursa (n = 13), greater trochanteric bursa (n = 17), ligamentum teres (n = 10), labrum (n = 7), gluteus medius/minimus (n = 8), ischiofemoral space (n = 7), obturator musculature (n = 5), osteotomy margins (n = 3), ASIS (n = 2), hamstring origin (n = 1), and heterotopic ossification (n = 1). Spinal findings included facet arthropathy (n = 15), vertebral disc disease (n = 15), neural foraminal inflammation (n = 15), pars defects (n = 6), interspinous ligament inflammation (n = 5), sacroiliac joint (n=2), extraforaminal inflammation (n = 1), and Modic changes (n = 1). Additional findings involved peripheral nerves (n = 6), pubic symphysis (n = 1) and post-surgical seroma (n = 2). Hip was excluded as the pain source in 7 patients and spine in 2 patients. Following imaging, 31/34 patients (91.2%) underwent/were scheduled for targeted intervention (ultrasound-guided injections, manipulation-under-anesthesia, revision hip arthroscopy, or total hip arthroplasty). Three patients were referred to spine surgery. Conclusion ¹-F-FDG PET/MRI demonstrated high clinical utility in the evaluation of P-HAP and influenced management in 97% of cases by identifying potential pain generators.