Magnetic Resonance Imaging in Evaluation of Avascular Necrosis of Femoral Head

Introduction: Avascular necrosis (AVN) of the femoral head is one of the common causes of pain and disability of hip. Impairedblood supply and increased intraosseous pressure are predominantly responsible for the necrotic process, which eventuallyresults in collapse of the femoral head. Magnetic resonance imaging (MRI) is the preferred investigation for the evaluation of AVN.Aims and Objectives: This study aims to assess the role of MRI in the evaluation of clinically suspected cases of AVN of hipand to describe the imaging features along with proper staging.Materials and Methods: In this prospective study, 100 patients of all age groups with clinically suspected cases of AVN offemoral head were evaluated by MRI hip in the Department of Radiodiagnosis, Gandhi Medical College and Hamidia Hospitalover a period of 1 year. Detailed history and associated risk factors were asked from all patients. MRI hip was then performedon 1.5 Tesla Hitachi ECHELON SMART - 523 MRI machine using the required protocol and sequences. The imaging findingswere studied and proper staging was given.Results: In our study of 100 cases of AVN, 132 femoral heads were involved (unilateral 68 and bilateral 32 cases). The most commonrisk factor associated was alcohol consumption. The most common quadrant of femoral head affected was anterosuperior (49.3%). Themost common stage of AVN was found to be Grade III – 39.4% (Ficat and Arlet classification), Type C – 47% (Mitchell’s classification),and Stage IIIC – 37.8% (Steinberg classification). MRI could detect early AVN in 50 femoral heads, in which radiographs were normal.Conclusion: This study concludes that MRI is the modality of choice for diagnosing and staging AVN. Early diagnosis andappropriate treatment is associated with better outcome.