Evaluation of Hip Disorders Using Magnetic Resonance Imaging

Abstract

Introduction: The hip joint is a major weight-bearing joint in the human body. It is often difficult to assess painful hip disorders clinically. This necessitates the need for imaging to arrive at an accurate diagnosis. Magnetic Resonance Imaging (MRI) is an imaging modality with good soft tissue contrast and resolution for evaluating hip pathologies. Aim: To identify and study the spectrum of imaging features in various hip disorders in adults and to establish a differential diagnosis using MRI. Materials and Methods: A hospital based cross-sectional study was done from June 2017 to May 2018 in a tertiary care centre of Southern India, where 70 patients who presented with unilateral or bilateral hip pain were evaluated with MRI. Demographic data including the patients age and sex was collected. The clinical features with which the patients presented were recorded. Conventional radiographic imaging of bilateral hip bone in antero-posterior and lateral views were obtained. Specialized imaging using appropriate MRI sequences in various imaging planes were obtained. The collected data was analysed and the differential diagnoses described. Data analysis was done by descriptive statistics using Microsoft Excel and Epi Info. Results were presented as mean (maximum-minimum) and percentage. Results: Out of 70 patients, majority of them were in the 20-29 years age group, with a male preponderance overall and also in the study subgroups. Unilateral hip involvement was more common than bilateral. The most common clinical presentation was hip pain. The commonest hip disorder encountered was Avascular Necrosis (AVN) of the femoral head (n=50), followed by Osteoarthritis (OA) (n=10), Tubercular (TB) arthritis (n=4), Transient Osteoporosis of Hip (TOH) (n=2), Metastasis (n=2), Synovial osteochondromatosis (n=1) and Perthe’s disease (n=1). Each of the conditions showed specific age group in which it commonly occurred. Bone Marrow Oedema (BME), joint effusion, soft tissue signal intensity changes, synovial thickening and enhancement, articular surface changes and subchondral changes were the spectrum of imaging features which occurred in various hip disorders studied. Double line sign was pathognomic of AVN of femoral head. MRI was more sensitive than conventional radiography in the identification of presence of hip disorders like AVN in early stages and TOH. Conclusion: MRI enables assessment of articular structures, soft tissues and osseous structures of the hip joint that can be affected by disease. It helps in better staging of various hip disorders like AVN, OA, Perthe’s, etc. It can help diagnose early stages of AVN and TOH, where it can be missed on conventional radiograph and Computed Tomography (CT). Hence, its role in the evaluation of painful hip disorders in adults is invaluable

Keywords

• articular structures
• avascular necrosis
• bone marrow oedema
• differential diagnosis