This is a case of a 55 year old female presenting with radial deviation of the thumb metacarpophalangeal (MCP) joint post fall.
Imaging of the thumb MCP jt showed a Stener Lesion with rupture and retraction of the ulnar collateral ligament (UCL). The UCL has retracted proximally past the adductor aponeurosis/adductor pollicis muscle which now prevents the ligament from returning to its proper anatomical position. The ligament folds on itself and appears as a proximal mass like ball of hypoechoic tissue. Surgical intervention is required in the setting of a Stener Lesion to reattach the UCL to its distal attachment.
Stressing MCP joint. Be careful when stressing the joint particularly when there is a UCL injury but no Stener Lesion present. Significant stress of the joint can cause a Stener lesion in an otherwise asymptomatic patient
The adductor aponeurosis can clearly be seen as an echogenic triangle of tissue sitting down over MCP jt with the ruptured and retracted UCL appearing like a small hypoehcoic mass proximally.
The adductor aponeurosis (closed arrow) can be clearly seen with retracted UCL (open arrows) balled up proximally.