Thumb UCL Tear on MRI & ultrasound: Imaging Findings
A thumb UCL tear, often called skier's thumb or gamekeeper's thumb, injures the ligament that stabilizes the inside of the thumb MCP joint. X-rays look for an avulsion fracture and joint alignment. MRI or ultrasound can show whether the ligament is partially torn, completely torn, or displaced superficial to the adductor aponeurosis as a Stener lesion, a pattern that often changes management.
Common Symptoms
- Pain and swelling on the inner side of the thumb MCP joint after a fall or ski injury
- Weak pinch, difficulty gripping keys, or thumb instability during grasping
- Tenderness at the thumb ulnar collateral ligament attachment
- Possible small avulsion fragment near the base of the thumb proximal phalanx
What We Look For on Imaging
- Avulsion fragment at the ulnar base of the thumb proximal phalanx
- Partial or complete UCL discontinuity on MRI or ultrasound
- Displaced ligament stump suggesting a Stener lesion
- MCP joint widening, subluxation, or associated volar plate injury
- Bone bruise, edema, or chronic ligament thickening after repeated injury
Frequently Asked Questions
What is a Stener lesion?
A Stener lesion occurs when the torn thumb UCL is displaced superficial to the adductor aponeurosis, preventing normal healing back to its attachment. MRI and ultrasound can help identify this displacement, but treatment decisions should be made by a hand specialist with the exam findings.
Is ultrasound enough for a thumb UCL tear?
High-quality dynamic ultrasound can be very useful when performed by an experienced operator. MRI provides a broader view of the ligament, bone edema, joint alignment, and associated injuries. The best test depends on local expertise and the clinical question.
Sources
- Stener B. Displacement of the ruptured ulnar collateral ligament of the metacarpo-phalangeal joint of the thumb. J Bone Joint Surg Br. 1962;44-B(4):869-879.
- Hinke DH, Erickson SJ, Chamoy L, Timins ME. Ulnar collateral ligament of the thumb: MR findings in cadavers, volunteers, and patients with ligamentous injury (gamekeeper's thumb). AJR Am J Roentgenol. 1994;163(6):1431-1434.
- Melville DM, Jacobson JA, Fessell DP. Ultrasound of the thumb ulnar collateral ligament: technique and pathology. AJR Am J Roentgenol. 2014;202(2):W168.
- Daley D, Geary M, Gaston RG. Thumb metacarpophalangeal ulnar and radial collateral ligament injuries. Clin Sports Med. 2020;39(2):443-455.
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Skier's or gamekeeper's thumb? Learn how MRI and ultrasound show a thumb UCL tear, what a Stener lesion is and why it can change treatment.
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