Scranton and McDermott classification of ankle spurs. A, Grade I, synovial impingement. Radiographs show inflammatory reaction with spurs 3 mm. B, Grade II, osteochondral reaction exostosis. Radiographs show spurs larger than 3 mm. No talar spur is seen. C, Grade III, severe exostosis with or without fragmentation. Secondary spur is noted on dorsum of talus, often with fragmentation of osteophytes. D, Grade IV, pantalocrural osteoarthritic destruction. Radiographs suggest degenerative osteoarthritic changes medially, laterally, or posteriorly.