MCP deformity LIGAMENTS: No significant abnormality noted.TENDONS: There is buckling, increased signal, and thickening of the ulnar collateral ligament of the thumb however there is no significant increased signal within the surrounding bone or soft tissue. The radial collateral ligament is intact.The flexor pollicis longus appears normal at its insertion however more proximally it is enlarged and demonstrates increased signal throughout the remaining visualized portion into the flexor compartment. It is not well seen within the flexor compartment. Additionally, there is fluid signal surrounding the flexor pollicis longus as it courses between the flexor compartment and its insertion.BONES: There is severe osteoarthritic changes of the first metacarpal phalangeal joint.
1. Probable partial tearing of the ulnar collateral ligament which is likely chronic in nature given the lack of edema and inflammation in the surrounding area.2. Increased signal and thickening of the flexor pollicis longus as it enters the flexor compartment suggesting intrasubstance tearing. The tendon is not well seen within the flexor compartment which is suspicious of a proximal tear and retraction of the tendon.3. Tenosynovitis of the flexor pollicis longus.