Conditions Treated

Thumb Ulnar Collateral Ligament Injury

Ulnar Collateral Ligament Injury of the thumb occurs when the thumb is overstretched away from the hand causing either a sprain, partial or full-thickness tear to the stabilising ligament. This can occur from a single forceful incident such as being hit by a cricket ball or from a fall. It is often called a ‘skier’s thumb” as the ligament can be overstretched in a fall while holding ski poles. Less commonly it can be caused by ongoing overuse (Gamekeeper’s thumb).

The ulnar collateral ligament is important for thumb stability during pinch and gripping activities.

What is the ulnar collateral ligament injury thumb?

Most thumb sprains involve the ulnar collateral ligament which is located on the inside of the knuckle joint. A tear to this ligament can be painful and make the thumb feel unstable. It may also weaken the ability to grasp ob the thjects using the thumb and index finger. These injuries can also include an avulsion fracture.

Ligament injuries are classically divided into three categories:

  • Grade 1 injury: the ligament is strained, but intact with relatively normal resistance to forces (“no laxity”)
  • Grade 2 injury: the ligament is partially torn with reduced resistance to forces (“increased laxity”)
  • Grade 3 injury: the ligament is completely ruptured.


A thumb UCL injury can result from a fall onto an outstretched hand that causes the thumb to bend away from the palm or from a blow to the inside of the thumb, for example from a ball.  A thumb UCL injury is most common in sports such as skiing, snowboarding, basketball, football etc

Signs & Symptoms

Pain is a common symptom of a thumb UCL injury, though you may or may not feel pain right away. The degree of pain and other symptoms will depend on the severity of your injury. Other common symptoms include:

  • Pain that worsens when moving your thumb
  • Bruising, swelling, and tenderness at the base of the thumb
  • Thumb feels loose and not secure
  • Weakness when gripping or squeezing with the thumb and index finger
  • A lump and swelling on the inside of the thumb


Your treating doctor may recommend an x-ray, ultrasound or other imaging to assist with diagnosing and grading the injury. For treatment see a hand therapist who is skilled at assessing the injury and stability of the injured thumb. Partial tears can be treated conservatively by a hand therapist with the fabrication of a custom made thermoplastic splint.  Depending on the severity of the injury this may be required for 4-6 weeks full time. After this, the therapist will assist with exercises aimed at regaining movement and strength.

Complete tears are likely to require surgical reattachment.

Melbourne Hand Therapy Can Help You

Our therapists at Melbourne hand therapy are experts at managing this injury from the acute phase through to the rehabilitation phase. Our aim is to heal the injury as quickly as possible to allow for a return to all normal functional activities including work, sports and recreation. We work closely with Melbourne’s best hand surgeons and can organise a timely referral if surgery is required.