Initial Experiences With a New MRI Scoring System for Differentiating Advanced Femoral Osteonecrosis From Tubercular Arthritis

• Orthopedics
• November 2014 – Volume 37 · Issue 11: e1014-e1020
• DOI: 10.3928/01477447-20141023-59

Abstract

The purpose of this study was to formulate a magnetic resonance imaging–based scoring system for differentiating tuberculous arthritis from advanced osteonecrosis of the femoral head. Magnetic resonance imaging findings in 18 hips with tuberculous arthritis and 36 hips with advanced osteonecrosis of the femoral head were reviewed retrospectively. Confirmation of tuberculous arthritis was based on enzyme-linked immunosorbent assay and/or synovial biopsy. Osteonecrosis was confirmed either by histopathology or eventual radiographic evidence on follow-up. The findings were analyzed with an emphasis on the changes in femoral head marrow, joint cavity, synovium, acetabulum, and contrast enhancement patterns. A score of 2 was assigned for the presence of each of the following: T2 hyperintensity of the femoral head, synovial hypertrophy, articular cartilage erosion, unilateral involvement of the femoral head, acetabular edema/sclerosis, and enhancement of the involved head. A score of 1 was assigned for each of the following: joint effusion, edema of adjacent marrow, and enhancement of adjacent soft tissue. A cutoff value of 10 of 15 points was considered to be positive for tuberculous arthritis. Sixteen of 18 cases of tuberculous arthritis were correctly identifiable on the basis of this scoring system. The 2 remaining cases had a score of 9. No case of osteonecrosis of the femoral head scored more than 9. A score of 10 for a positive diagnosis of tuberculous arthritis had a sensitivity of 88.89% and specificity of 100%. Positive and negative predictive values were 1 and 0.94, respectively. Statistical significance for each of the parameters and the entire model was established with logistic regression analysis. This new scoring system is effective in solving the imaging dilemma pertinent to endemic regions.

The authors are from the Department of Radiodiagnosis (VV, IA, EU), Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh; the Department of Radiodiagnosis (ADP), Chettinad Medical College Hospital and Research Centre, Chennai; and the Department of Microbiology (MH), Hamdard Institute of Medical Sciences and Research, New Delhi, India.