Ski thumb (UCL rupture)

What is the ski thumb? Anatomy and function

The metacarpophalangeal joint (MCP I) of the thumb is stabilized by two collateral ligaments: the ulnar (UCL) on the side facing the palm and the radial (RCL) on the opposite side. The UCL prevents the thumb from opening excessively (valgus) - essential for strong gripping and the so-called tweezer grip function.

In the ski thumb, the UCL tears partially or completely. In the event of a complete rupture, the end of the ligament can slide under the tendon plate of the adductor pollicis (Stener lesion). Then the ligament cannot grow back spontaneously and stability remains limited unless targeted treatment is provided.

• Task of the UCL: Valgus stability of the thumb joint
• Meaning in everyday life: turning keys, opening bottles, writing, holding tools
• Injury types: Strain (Grade I), partial tear (Grade II), complete tear (Grade III), possibly with bony avulsion (avulsion fracture)

Causes and typical symptoms

The cause is usually a fall with your thumb getting caught on the handle of the ski or pole, which suddenly opens outwards. Something similar happens with ball and contact sports (e.g. handball, soccer goalkeeper) or with handlebars/rackets. More rarely, repeated overload leads to chronic damage (“Gamekeeper’s thumb”).

• Acute pain on the ulnar side of the thumb joint
• Swelling, bruising (often increasing after hours)
• Pain during grip and forceps grip movements
• Feeling of instability or “unfolding” of the joint
• Loss of strength when clamping objects (e.g. paper between thumb and index finger)
• Occasionally tingling/numbness (irritation of the sensitive nerve branches)

Warning signs: when to clarify immediately?

Some signs indicate a relevant ligament injury or accompanying damage and should be clarified promptly by orthopedic/hand surgery:

• Significant instability or visible “unfolding” of the thumb
• Severe swelling with pronounced bruising and pain at rest
• Sensory disturbances (numbness, tingling) or paleness/coldness of the thumb
• Open injuries or suspected fracture
• Persistent loss of grasping function after 24-48 hours

Diagnostics in practice

In our practice in Hamburg-Winterhude, we first take a detailed accident history and check the visual findings, swelling and pressure pain points. The assessment of stability in the valgus stress test is crucial.

• Valgus stress test in approx. 30° flexion of the MCP I: assessment of hingeability and fixed end point
• Comparison with the opposite side to differentiate individual ligament laxity
• Palpation of the ligament region: palpable thickening/displacement (indication of Stener lesion)
• Neurovascular examination (blood flow, sensitivity)

Imaging complements the clinical examination: X-rays are used to exclude/detect bony avulsions or accompanying fractures. High-resolution sonography allows dynamic assessment of ligament continuity, especially in experienced hands. An MRI is useful if the findings are unclear, a Stener lesion is suspected or surgery is planned.

• X-ray: avulsion fracture? Joint position? if necessary, stress recordings
• Sonography: continuity, retraction, hematoma; dynamic stress test
• MRI: Soft tissue detail, reliable detection of Stener lesion and accompanying pathologies

Classification (simplified clinical classification):

Conservative treatment (standard for stable injuries)

For grade I and many grade II injuries, conservative treatment is the first choice. The aim is to reduce pain, protect the ligament and gradually build up function without overloading the UCL.

• Acute measures after PECH/RICE: break, ice (intermittent, pay attention to skin protection), compression, elevation
• Immobilization: Thumb spica splint or cast, usually 4-6 weeks (depending on stability and progression)
• Pain management as required (e.g. local cooling measures; medication after medical consultation)
• Early hand therapy: edema-reducing measures, joint-preserving mobilization without valgus stress
• During the course: functional training, grip and tweezer grip development, proprioceptive training
• Taping/orthotic protection when returning to sport/exercise after release

Follow-up checks are important to check stability and adjust the duration of immobilization individually. If instability persists or a Stener lesion is evident, surgical treatment should be considered.

Regenerative procedures: In selected cases, additional measures such as platelet-rich plasma (PRP) can be discussed to accompany the pain and healing phase. The evidence is heterogeneous; In the case of structurally unstable ruptures, such procedures do not replace necessary surgery.

When does an operation make sense?

Surgery is particularly considered for grade III injuries with instability, confirmed Stener lesions, relevant avulsion fractures or if sufficient stability cannot be achieved conservatively. The procedure should be carried out as quickly as possible in the case of fresh ruptures.

• Complete rupture with no fixed end point
• Stener lesion (interposed adductor aponeurosis)
• Bony avulsion with relevant fragment dislocation or joint involvement
• High functional demands (e.g. certain professional groups, competitive sports) – always in the context of the objective findings

Surgical techniques depend on the findings: soft tissue suturing and refixation of the UCL (often with suture anchors or transosseous sutures), bony refixation with screws/wires for avulsion fractures, occasionally ligament augmentation (e.g. “internal brace”). In the case of chronic instability, ligament reconstruction with tendon transfer (e.g. palmaris longus) may be necessary.

• Postoperative: Immobilization in the thumb spica for approx. 4 weeks
• Then step by step mobilization with hand therapy
• Functional development until you are cleared for sport depending on the healing process (often after 10-12+ weeks)

Possible risks of any operation include: Bleeding, infection, wound healing problems, nerve irritation, persistent stiffness, CRPS or residual instability. We discuss the benefits and risks individually and based on evidence.

Rehabilitation, return to sport and everyday life

The follow-up treatment follows a structured timetable based on the findings and stage of healing. What is important is: no early valgus stress, progressive build-up of load, reliable home exercises and close follow-up checks.

• Everyday life: early use of the hand for light activities is desirable - as long as it is painless and without abducting strain on the thumb
• Sport: depending on stability and sport; With conservative therapy often after 6-8 weeks, after surgery more often after 10-12+ weeks
• Ability to work: individual; Office work usually early, manual work later (see below)

Differentiation from other injuries

Not every painful thumb injury is a ski thumb. The following diagnoses must be considered:

• Radial collateral ligament (RCL) injury at MCP I
• Palmar plate/capsule injury
• MCP-I dislocation or subluxation
• Avulsion fractures or intra-articular fractures (e.g. bony ligament avulsion)
• Injuries to the first metacarpal (e.g. Bennett/Rolando fracture – at the saddle joint)
• Bruise, bone marrow edema, nerve contusion

Prevention and tips for everyday life and sport

• Skis: use the pole loops correctly or, if necessary, ski without loops to avoid getting caught
• Protective gloves and warm hands maintain responsiveness
• Sport-specific warm-up and hand coordination training
• Taping/orthosis for previous ligament injuries in risky situations
• If you fall: Do not catch your hand if you can avoid it - train your core and leg muscles to fall safely
• Choose handlebar/racquet grips ergonomically; no handles that are too big, spread your thumbs apart

Everyday life, work and fitness for sport

The return to everyday life and work depends on the degree of injury, type of therapy and individual healing. Safety comes first – especially in activities with a risk of falling, vibration or pinching.

• Office work/computer: often possible after a few days, if necessary with a splint
• Craft/production/care: depending on the level of stress after 4-8 weeks (conservative) or 6-12+ weeks (post-operative)
• Driving the vehicle: only when safe steering/braking without pain is guaranteed and there is no impediment to immobilization; please seek medical advice
• Everyday life: Open bottles/jars with two hands, avoid heavy bags, use non-slip aids
• Sports: low-contact sports earlier, contact sports/skiing later and only after clearance; If necessary, use tape/orthosis

Your supply in Hamburg-Winterhude

As an orthopedic specialist practice at Dorotheenstrasse 48, 22301 Hamburg, we treat acute hand injuries promptly. Our focus is on well-founded diagnostics - including dynamic sonography - and gradual, conservatively oriented therapy. We discuss surgical options transparently if they make medical sense (e.g. in cases of instability or Stener lesions).

• Evidence-based decision support and realistic expectation management
• Individual splint care and close collaboration with hand therapy
• Structured rehabilitation plans and follow-up checks
• If surgery is indicated: collegial hand surgical co-treatment and aftercare coordination

Bring any previous findings or images (X-ray/MRI) with you, if available. Together we will determine the appropriate, safe procedure - with the aim of reliably restoring function and suitability for everyday use.