MRI Classification of Subtalar Joint Osteoarthritis Using a Novel Scoring System

Abstract

Background: Plain radiography usual method to detect degeneration in the subtalar and talonavicluar joints. MRI is a better way to fully characterise non-ossified structures, such as articular cartilage, marrow tissue and synovial fluid and therefore detect changes of arthritis. The motivation behind this study was to develop a quantitative way to score arthritic changes to the subtalar and talonavicular joints using MRI. The developed system will then be used as a research tool and in the close assessment and monitoring of patients with hindfoot degenerative disease. Methods: The MRI scans of thirty consecutive subjects with foot and ankle pain were retrospectively evaluated. Images were interpreted independently by three musculoskeletal radiologists in order to determine intra-observer reliability as well as the inter-observer reliability of the score. Five features of osteoarthritis were scored in the Subtalar joint and the Talonavicular joint. These were cartilage morphology, subarticular marrow, subarticular cyst, marginal osteophytes and synovitis. Results: For the 30 MRI scans the mean score for the Subtalar joint ranged from 11.7 to 14.4 and for the Talonavicular joint ranged from 3.7 to 5.6. The inter-observer correlation for the Subtalar joint between the three readers ranged between 0.53 and 0.83 for the individual features but overall was excellent at 0.76. For the Talonavicular joint the total correlation was good at 0.67. The inter-observer ICC for the total score was 0.75 which showed excellent agreement between the three readers. The total intra-observer correlation was excellent. Conclusions: The current work has shown excellent reliability for the scoring system. It will be a useful tool to diagnose and monitor disease progression of the Subtalar and Talonavicluar joints.