What it is

Thumb ulnar collateral ligament injury is a sprain or tear at the base of the thumb, where the ligament stabilises pinch and grip. It typically follows a fall with the thumb forced outward or a sudden pull on the thumb during a sporting activity. Pain and weakness reduce pinch and key tasks.

Most partial sprains recover with bracing and rehabilitation. Complete ruptures or Stener lesions need surgical review.

What happens when it occurs

Valgus force separates the joint, stretching or tearing the ligament. Early protection in a thumb spica brace allows healing. Strength and control return in stages.

Common causes and risk factors

  • Ski falls with poles, football and rugby contact, ball handling incidents
  • Falls onto the hand during daily tasks
  • Previous thumb injuries

Who is most affected

Active adults and adolescents in field and snow sports. Dominant hands are often involved.

Typical symptoms

  • Pain and swelling at the base of the thumb
  • Weak pinch and grip
  • Instability or catching in higher-grade injuries

When to seek care

If pain and weakness follow a fall, or if the thumb feels unstable. Early imaging improves decisions.

How we diagnose

Valgus stress testing at the thumb joint, comparison with the other side, and ultrasound or MRI to check for a complete tear or Stener lesion.

Management

  • Thumb spica brace and activity modification
  • Range and gentle strength once pain allows
  • Progressive pinch and grip training
  • Surgical repair when a complete rupture or a Stener lesion is present

Rehabilitation milestones

Phase 1 weeks 0 to 2: brace protection, swelling control, gentle range out of brace.

Phase 2 weeks 2 to 6: progressive strength, pinch practice, task drills.

Phase 3 weeks 6 to 12: return to sport skills with protection as required.

Readiness to progress

  • Stable valgus test without pain
  • Pinch and grip strength within 90 per cent
  • Sport drills completed without following day symptoms

Prevention

  • Use pole straps safely and release when falling
  • Protect the thumb in contact sports during early return
  • Maintain forearm and intrinsic hand strength

Australia snapshot

  • Common in football codes and at ski resorts
  • Bracing and early imaging guide care
  • Most partial injuries recover without surgery

Latest insights

Early protection prevents laxity. Strength and control restore a reliable pinch.

Do not delay imaging if instability is suspected.

Frequently Asked Questions

The torn ligament flips above a tendon and cannot heal in its original position. It needs surgical repair.

Often four to six weeks for partial sprains, with staged weaning.

Yes, with the brace and task changes while pain settles.