Abstract
BACKGROUND: Avascular necrosis (AVN) of the hip, also known as osteonecrosis or ischemic necrosis, is cellular necrosis of bone and marrow elements. Although clinical evaluation is the first step in assessing the hip joint, imaging is fundamental for accurate diagnosis and staging of AVN. OBJECTIVE: We aim to assess the role of magnetic resonance imaging (MRI) in evaluating AVN of the hip, describe imaging features, and classify AVN using various classification systems. METHODS: A cross-sectional study was conducted over two years at the Department of Radiodiagnosis, Aarupadai Veedu Medical College and Hospital, Puducherry, a tertiary healthcare center situated in Southern India. The study included 50 patients referred for MRI of the hip joint with suspected unilateral or bilateral hip joint pathology, with or without pain. The participants' demographic data, clinical presentations, and MRI findings were recorded. Data were collected, and Statistical Package for the Social Sciences version 28 (IBM Corp., Armonk, NY) was used for all statistical analyses. RESULTS: The study comprised 50 patients, with a significant male predominance (62%, n=31) and a male-to-female ratio of 1.63:1. The mean age of the patients was 41.2 years, ranging from 20 to 63 years. Idiopathic AVN was the most common risk factor, accounting for 36% of cases, followed by alcohol consumption (32%), steroid use (28%), and trauma (8%). Notably, 34% (n=17) of the patients had a history of COVID-19 prior to AVN symptom onset. Among the 50 cases with 80 hips affected by AVN, the majority (60%, n=30) had bilateral hip involvement, while 22% (n=11) had unilateral right hip involvement and 18% (n=9) had unilateral left hip involvement. The most common chief complaint in our study was hip pain, which was present in 43 (86%) cases. According to the Association Research Circulation Osseous (ARCO) classification of AVN, we observed that stage I AVN was detected in 11 (13.75%) hips, stage II AVN in 19 (23.75%), stage IIIA AVN in 21 (26.25%), stage IIIB AVN in eight (10%), and stage IV AVN in 21 (26.25%). CONCLUSION: The ARCO classification system is superior in assessing disease severity. The modified Kerboul's angle is useful for assessing femoral head deformity. The radiologic staging of the disease is of great importance for the identification and risk stratification in pre-collapse stages, prognosis, adequate treatment planning, and post-operative follow-up.