Pain at the base of the thumb after a skiing fall may come from the ligament, a fracture, or both. Swelling and difficulty gripping need assessment. AAOS
What is injured in skier’s thumb?
The ulnar collateral ligament lies at the base of the thumb, on the side facing the index finger. It helps keep the thumb stable during gripping. A fall that forces the thumb away from the hand can stretch or tear it; a ski pole may contribute to this movement.
Sometimes the ligament pulls away a small piece of bone: an avulsion fracture. In children, possible growth plate involvement must also be considered. These are different findings and need to be distinguished during diagnosis. RCH
Is a normal X-ray enough?
An X-ray looks for a fracture and assesses its position. It does not directly show whether the ligament is intact: the image may look normal despite a significant ligament injury.
Examination assesses pain and stability. Do not try bending the thumb sideways at home. A specialist may request ultrasound or MRI when uncertainty remains; these tests are not always needed. AAOS
Cast, splint or surgery
Partial, stable injuries can be protected with a cast or splint that also immobilises the thumb. The choice and follow-up depend on the injury.
Marked instability, a complete tear or a displaced bone fragment requires specialist assessment of whether surgery is indicated. One particular problem is a Stener lesion: tissue lies between the torn ligament and its attachment, preventing it from healing back in the correct position. BSSH
In children, however, a displaced fragment does not automatically mean an operation is needed. A retrospective study of paediatric avulsion fractures reported healing with immobilisation alone in some cases that met conventional surgical criteria. It was not a randomised trial and does not establish that immobilisation and surgery are interchangeable. Examination, imaging and follow-up all inform the decision. Huynh and colleagues
When to seek care and return to sport
Pain, swelling and difficulty using the thumb after an injury need prompt assessment. An obvious deformity, a blue or numb digit, or a wound with visible bone needs urgent assessment in an emergency department. While waiting, avoid loading the hand or trying to straighten the digit. NHS
Returning to skiing depends on the injury, treatment and recovery of stability and function. Less pain or wearing a splint does not establish readiness for another fall: return to sport should be agreed with the treating clinician. Lurie Children’s
For the broader context, see injuries and fractures in children and growth plate fractures.
Dr Daniele Priano — Paediatric Orthopaedics. General information: this does not replace an individual medical assessment.
References
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Royal Children’s Hospital Melbourne. Thumb Fractures – Emergency Department.
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Ann & Robert H. Lurie Children’s Hospital of Chicago. Skier’s or Gamekeeper’s Thumb.
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American Academy of Orthopaedic Surgeons (AAOS), OrthoInfo. Sprained Thumb.
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British Society for Surgery of the Hand. Skier’s thumb.
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Huynh MNQ, Tang K, Cheung K. A Comparison of Conservative and Operative Management of Thumb Ulnar Collateral Ligament Avulsion Fractures in Children. Hand (N Y). 2020;15(6):812–817. DOI: 10.1177/1558944719831237. PMID: 30857433.
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NHS. Broken finger or thumb.
Online sources accessed on 12 November 2026.
