High-yield overview

Repair of ruptured ulnar collateral ligament of the thumb MCP joint — acute suture anchor repair and chronic free graft reconstruction | intermediate

Surgical Imaging

Non-displaced UCL tear versus Stener lesion — Non-displaced UCL tear (can heal in a cast) versus a Stener lesion, where the adductor aponeurosis is interposed between the retracted ligament stump and its insertion — preventing healing and mandating surgery.Credit: AI-generated medical image · OrthoVellum

Thumb UCL repair with suture anchor — Thumb UCL repair with a suture anchor at the proximal phalanx footprint, adductor aponeurosis reflected. The dorsal sensory branch of the radial nerve is at risk in the lazy-S incision.Credit: AI-generated medical image · OrthoVellum

Thumb UCL valgus stress testing in extension and 30 degrees flexion — Valgus stress testing: stressing in full extension assesses the proper and accessory collaterals plus volar plate, while 30° of MCP flexion isolates the proper UCL. Greater than 30° of radial deviation, or more than 15° more than the contralateral thumb, indicates a complete rupture.Credit: AI-generated medical image · OrthoVellum

Critical Exam Traps and Danger Structures

Stener Lesion — When Surgery is Mandatory

Definition: The torn UCL end folds back proximally and lies SUPERFICIAL to the adductor aponeurosis. The aponeurosis then interposes between the UCL stump and its insertion on the proximal phalanx base — preventing any possibility of spontaneous healing.

Implication: A Stener lesion cannot heal non-operatively. Surgery is MANDATORY. Attempted conservative treatment results in chronic UCL insufficiency with progressive MCP instability, pinch weakness, and early arthritis.

Valgus Stress Test Technique

Correct technique: Apply radial-directed (valgus) stress to the thumb MCP joint with the joint in (1) full extension — tests accessory UCL — and (2) 30 degrees flexion — tests proper UCL. Compare to the contralateral thumb.

Criteria for complete tear: Greater than 35 degrees absolute laxity in flexion, OR greater than 15 degrees side-to-side difference. If laxity is present in both extension AND flexion, both bands are likely torn (complete UCL rupture).

MRI Indications and Findings

Indications: Clinically complete tear (laxity criteria met), patient with complete tear but uncertain Stener status, chronic injury where tissue quality needs assessment before planning repair vs reconstruction.

Stener lesion on MRI: The UCL stump appears proximal to the adductor aponeurosis on axial and coronal sequences — the 'yo-yo sign'. Pooled diagnostic accuracy (meta-analysis): MRI sensitivity 93%, specificity 98%; ultrasound sensitivity 95%, specificity 94%. Ultrasound with dynamic valgus stress is an appropriate first-line lower-cost alternative in experienced hands.

Acute vs Chronic — Repair vs Reconstruction

Acute (less than 6 weeks): Direct repair with suture anchors to proximal phalanx base. Tissue is identifiable and strong enough to hold anchors. Success greater than 90%.

Chronic (greater than 6 weeks): UCL is attenuated, shortened, scarred. Direct repair usually not possible. Options: (1) free tendon graft reconstruction (palmaris longus or plantaris — gold standard), (2) adductor aponeurosis advancement (if tissue quality reasonable), (3) primary MCP arthrodesis in elderly with severe arthritis.

Radial Collateral Ligament (RCL) — Less Common but Same Principles

Incidence: RCL tears account for less than 10% of thumb collateral ligament injuries. Mechanism: forced ulnar deviation (adduction stress).

Surgical consideration: Thenar branch of radial nerve runs close to the radial aspect of the thumb MCP — at risk with a radial incision for RCL repair. Identify the nerve before dividing any tissue on the radial side. Stener equivalent with adductor intrinsic muscle can occur with RCL injuries.

Post-op K-Wire Protection

Purpose: A 1.4 mm K-wire may be placed across the MCP joint in slight flexion after repair to protect the repair from inadvertent valgus stress during early healing (first 3-4 weeks).

Decision: Not universally required. Indicated when tissue quality is borderline, repair tension is marginal, or patient compliance is uncertain. Patients must be warned about pin site infection and the need for pin removal at 4 weeks.

Mnemonic

S.T.E.N.E.RSTENER — Diagnosis and Management

Mnemonic

U.C.LUCL — Anatomy and Repair

Surgical Indications

Acute UCL Injury (less than 6 weeks)

Absolute surgical indication:

Complete UCL tear with confirmed or likely Stener lesion
Valgus stress test: greater than 35 degrees absolute laxity OR greater than 15 degrees side-to-side difference in 30 degrees flexion
MRI confirming Stener lesion displacement

Relative surgical indication:

Complete UCL tear without imaging confirmation of Stener lesion in young active patients (high-demand use of thumb)
Associated avulsion fracture at proximal phalanx base with more than 2 mm displacement or more than 20% articular surface involvement

Non-operative treatment appropriate:

Incomplete UCL tear (partial tear) with less than 15 degrees side-to-side difference — immobilise in short thumb spica for 4-6 weeks
Complete UCL tear without Stener lesion confirmed on MRI in reliable patients (rare)

Chronic UCL Insufficiency (greater than 6 weeks — Gamekeeper's Thumb)

Chronic instability with functional pinch and grip weakness
Pain at MCP joint with lateral stress activities
Inability to perform key pinch (thumb-index tip-to-tip)
Failed conservative treatment (splinting, activity modification) for greater than 3 months
Pre-arthritic joint (MCP joint cartilage must be preserved — if severe arthritis, arthrodesis preferred)

Contraindications

Absolute:

Active infection
Severe MCP joint arthritis (consider MCP arthrodesis instead)
Poor soft tissue coverage or wound healing concerns

Relative:

Elderly low-demand patient with chronic UCL insufficiency (conservative functional adaptation may be acceptable)
Medical comorbidities precluding anaesthesia

Evidence Summary

Stener Lesion Prevalence and Stress-Test Thresholds

In Heyman's prospective series, a Stener lesion was found in 15 of 17 (87%) thumbs that demonstrated greater than 35 degrees of valgus laxity in extension — confirming that gross instability strongly predicts a displaced (operative) ligament.
Reported Stener prevalence across complete tears ranges 60-87% in the wider literature — the majority of clinically complete tears therefore warrant surgical evaluation.
Diagnostic thresholds (validated biomechanically and clinically): complete tear when the proximal phalanx angulates 30-35 degrees or more in either full extension or 30 degrees flexion, OR a side-to-side difference greater than 15 degrees, OR absence of a firm end-point.

Imaging Accuracy

Pooled meta-analysis (15 studies, 422 thumbs): MRI sensitivity 93%, specificity 98%; ultrasound sensitivity 95%, specificity 94%. Ultrasound is an appropriate first-line modality where expertise exists.

Acute vs Chronic Operative Outcomes

Acute anchor/transosseous repair within 6 weeks reliably restores stability with good/excellent functional outcomes in most series.
Free tendon graft reconstruction for chronic insufficiency restores grip and pinch strength to near-symmetrical values with low residual laxity rates in cohort studies (see EvidenceCards below).

Injuries of the ulnar collateral ligament of the thumb MCP joint: biomechanical and prospective clinical studies on valgus stress testing

Level II

Heyman P, Gelberman RH, Duncan K, Hipp JA • Clinical Orthopaedics and Related Research

Clinical Implication: Stress testing in BOTH extension (accessory ligament) and 30 degrees flexion (proper ligament) is essential; gross laxity (greater than 35 degrees, or absent end-point) predicts a complete, often displaced, tear that requires operative exploration.

Verify on PubMed (PMID 8519106)

Management of thumb metacarpophalangeal ulnar collateral ligament injuries

Level V

Rhee PC, Jones DB, Kakar S • Journal of Bone and Joint Surgery (American Volume)

Clinical Implication: Provides the standard decision framework: partial vs complete, acute vs chronic, repair vs reconstruction vs arthrodesis — the backbone of operative planning for thumb UCL injury.

Verify on PubMed (PMID 23138242)

Diagnostic accuracy of ultrasound and MRI in detecting Stener lesions of the thumb: systematic review and meta-analysis

Level I

Qamhawi Z, Shah K, Kiernan G, Furniss D, Teh J, Azzopardi C • Journal of Hand Surgery (European Volume)

Clinical Implication: Either MRI or dynamic ultrasound can reliably confirm a Stener lesion pre-operatively; ultrasound is a lower-cost first-line test where operator expertise exists, with MRI reserved for equivocal cases or tissue-quality assessment.

Verify on PubMed (PMID 33596684)

Comparison of results after surgical repair of acute and chronic ulnar collateral ligament injury of the thumb

Level III

Basar H, Basar B, Kaplan T, Erol B, Tetik C • Chirurgie de la Main (Hand Surgery and Rehabilitation)

Clinical Implication: Free tendon graft reconstruction restores near-symmetrical strength and stability for chronic/irreparable UCL injury, while displaced avulsion fractures can be managed by closed reduction and percutaneous K-wire fixation.

Verify on PubMed (PMID 25458468)

Collateral ligament injuries of the thumb metacarpophalangeal joint

Level V

Tang P • Journal of the American Academy of Orthopaedic Surgeons

Clinical Implication: Confirms the examination thresholds used for surgical decision-making and the acute-repair / chronic-reconstruction / arthrodesis treatment ladder for both ulnar and radial collateral ligament injuries.

Verify on PubMed (PMID 21536628)

Treatment Options by Timing and Pathology

Clinical Decision Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 28-year-old skier presents to the emergency department after a fall 4 hours ago. He has acute pain, swelling, and tenderness over the ulnar side of the right thumb MCP joint. On stress testing, radial deviation in 30 degrees MCP flexion is 40 degrees (contralateral 20 degrees — so 20 degrees side-to-side difference). There is also end-point laxity in full extension. What is the diagnosis and how do you manage this?"

PRACTICAL APPROACH

This presentation is consistent with a complete ulnar collateral ligament tear of the thumb MCP joint with a likely Stener lesion. The stress test demonstrates 20 degrees of side-to-side laxity in flexion — this exceeds the threshold of 15 degrees — confirming a complete UCL rupture. The presence of laxity in both flexion AND extension suggests both the proper and accessory bands are involved. **Stener lesion**: In 64-87% of complete UCL tears a Stener lesion is present. In this injury, the torn UCL distal stump has retracted and been caught by the adductor aponeurosis, leaving the aponeurosis interposed between the UCL and its insertion site on the proximal phalanx. This prevents spontaneous healing — surgery is required. **Imaging**: I would request an MRI of the thumb to confirm the Stener lesion. On axial and coronal sequences the UCL stump will appear superficial to the adductor aponeurosis (the 'yo-yo sign'). I would also request plain X-rays to exclude an avulsion fracture — if a bony Stener is present with more than 2 mm displacement or more than 20% articular surface involvement, the same operative repair applies to the bony fragment. **Management — Operative**: Given the confirmed complete tear with likely Stener lesion, I would proceed to surgical repair within days (not urgent on an emergency list — can be done on the elective trauma list within 7-10 days). Under WALANT or regional block with arm tourniquet: - Dorso-ulnar incision over the thumb MCP joint (3-4 cm) - Protect superficial radial nerve branches in the subcutaneous plane - Reflect (do not divide) the adductor aponeurosis - If Stener lesion present, reduce the UCL stump to beneath the aponeurosis - Place mini-suture anchor (1.3-1.5 mm) at the UCL footprint on the proximal phalanx base (ulnar-palmar corner) - Repair UCL stump to anchor with locking suture configuration, MCP joint in 10-15 degrees flexion - Close aponeurosis as a second layer - Short thumb spica splint for 4 weeks, IP joint free **Post-operative rehabilitation**: K-wire optional for this young active patient with good tissue quality. IP joint mobilisation from day 1. Active MCP ROM from week 4. Return to skiing: 12-16 weeks with protective thumb splint for sport.

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 55-year-old farmer presents with a 6-week history of pain and instability of the right thumb MCP joint after an injury sustained while pulling a calf. He reports ongoing weakness with pinch and grip. On examination there is MCP joint instability with 25 degrees of laxity side-to-side in 30 degrees flexion. MRI shows chronic UCL changes with an attenuated and scarred ligament. What are the surgical options and how do you choose between them?"

PRACTICAL APPROACH

This is a chronic UCL insufficiency — Gamekeeper's thumb in the classical occupational setting. At 6 weeks the UCL has retracted, scarred, and is too attenuated to allow direct end-to-end repair. The surgical options are: **Option 1 — Free tendon graft reconstruction (GOLD STANDARD)**: Reconstruct the UCL using a free tendon graft (palmaris longus preferred — same arm, 12-15 cm, harvest through 2 small forearm incisions). Bone tunnels are drilled through the metacarpal head (origin) and proximal phalanx base (insertion). The graft is passed through in a figure-of-eight or loop configuration, tensioned with the MCP in 10-15 degrees flexion, and fixed with interference screws or transosseous sutures. The adductor aponeurosis is closed over the reconstruction. Expected outcomes: cohort studies report restoration of near-symmetrical grip and pinch strength with low residual laxity (Basar 2014, PMID 25458468 — 16 of 19 fully stable, the remainder with mild laxity); return to manual work 12-14 weeks. **Option 2 — Adductor advancement**: If the UCL remnant and adductor tissue are of reasonable quality, the adductor aponeurosis and associated UCL remnant can be advanced distally and re-attached to the proximal phalanx base with suture anchors. This avoids the need for a tendon graft and a separate donor site. Suitable for patients with reasonable residual tissue quality and moderate demand. Expected outcomes: 70-80% good/excellent — slightly lower than graft reconstruction; simpler and quicker procedure. **Option 3 — MCP joint arthrodesis**: Indicated only if there is significant pre-existing MCP arthritis, cartilage damage, or failed previous reconstruction. Provides reliable stability but eliminates MCP motion. The farmer's occupational demands make this a last resort — some MCP flexion is important for gripping tools. **My recommendation for this patient**: For a 55-year-old manual farmer with a 6-week-old injury, absent significant arthritis on X-ray and MRI, I would perform free tendon graft reconstruction using the palmaris longus. This offers the best chance of restoring stability and pinch strength to meet his occupational demands. I would counsel him on K-wire protection for 6 weeks, total recovery 4-5 months before return to full farming activity, and the 10-20% chance of some residual mild laxity.

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A patient is 4 months after acute UCL repair with suture anchors. She complains of ongoing pinch weakness and the physiotherapist reports that grip strength is only 60% of the contralateral side. On examination, there is mild residual laxity at the thumb MCP in 30 degrees flexion (10 degrees side-to-side difference). How do you assess and manage this?"

PRACTICAL APPROACH

At 4 months post-repair, 60% grip strength with mild residual laxity raises three diagnostic possibilities that I must systematically differentiate: (1) repair failure/elongation, (2) delayed rehabilitation and deconditioning, (3) associated pathology (carpal tunnel syndrome, EPL adhesion, or FPL scarring affecting power grip). **Clinical assessment**: - Stress test: 10 degrees side-to-side laxity is below the complete tear threshold (greater than 15 degrees). This may represent a partial elongation of the repair under load — stable but not fully tight. - Range of motion: assess MCP and IP ROM. Stiffness from prolonged immobilisation can restrict grip even with a sound repair. - Strength: formal Jamar dynamometry for grip and key pinch. 60% at 4 months is below expected (should be 75-85% by this stage in most patients). - Nerve function: two-point discrimination at thumb tip and dorsum — exclude superficial radial nerve injury (neuroma causing pain-limited grip). **Investigations**: MRI to assess anchor position, graft/repair integrity, and any tissue elongation. If MRI shows intact repair with no significant laxity — this is a rehabilitation issue. If MRI shows repair elongation or anchor pull-out — this requires intervention. **Management by cause**: If rehabilitation delay: Intensified hand therapy protocol — progressive grip strengthening, pinch rehabilitation, functional activities. Expected full recovery by 6-9 months. Reassess at 6 months with final dynamometry. If repair elongation (mild): If less than 15 degrees side-to-side and functional — accept and continue rehabilitation. Dynamic splinting for sport/high-risk activities. Repeat stress test at 6 months. If repair failure (greater than 15 degrees side-to-side, pain, functional limitation): Revision reconstruction with free tendon graft. Discuss realistic expectations — revision surgery outcomes are slightly lower than primary (65-75% good results). **My approach**: At this stage I would reassure this patient if MRI confirms repair integrity, intensify hand therapy, and reassess at 6 months before considering any revision. The 10 degrees laxity does not meet the revision threshold; the weakness is likely rehabilitation-based.