Fact-sheet: Ulnar collateral ligament tear of the thumb
Updated on 03/12/2018 at 5:19 PM
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Definition
The ulnar collateral ligament of the thumb (UCL) is covered by the adductor aponeurosis (AA), a superficial aponeurotic extension of the adductor that slides over the ligament
In case of complete rupture with retraction of the UCL, the UCL stump passes over the AA: this is the Stener lesion, which prevents healing
Mechanism of injury: forced abduction
Clinical features
Pain on the medial and/or dorsal aspect of the MCP joint, +/- edema: no correlation between pain and edema and the severity of the sprain
Abnormal laxity = severe sprain = surgery
But clinical testing is difficult in the acute setting (pain): value of ultrasound
Radiography
Look for avulsion fractures on the medial aspect of the base of P1
Ultrasound
Availability, dynamic and comparative study
Mild sprain: hypoechoic thickening, Doppler hyperemia
Moderate sprain: partial tear, hypoechoic nodular area not involving the full thickness of the ligament
Severe sprain without Stener lesion: complete tear. Careful dynamic MCP abduction maneuver, the AA slides over the UCL: flexion-extension maneuver of the PIP joint
Severe sprain with Stener lesion: the AA is incarcerated within the UCL, retracted into a ball at its attachment, the AA does not slide during flexion-extension maneuvers of the PIP joint
MRI
Thickening, inflammatory T2 hyperintensity
Ball-like retraction of the UCL in Stener lesion
Classification
Ebrahim injury classification (5 stages):
-1= normal
-2= mild sprain: stretched ligament without rupture
-3= moderate sprain: partial tear
-4= severe sprain, complete rupture without Stener lesion
-5= severe sprain, complete rupture with Stener lesion