SAGITTAL BAND INJURIES
Extensor Hood Disruption | MCP Instability | Radial vs Ulnar Subluxation
Rayan Classification (Severity)
Critical Must-Knows
- Sagittal bands stabilize EDC at MCP level - rupture causes subluxation into intermetacarpal valley
- Long and middle fingers most affected due to absence of juncturae support
- Ulnar subluxation (90%) more common than radial - EDC displaces ulnarly with MCP flexion
- Rayan Type I-II often respond to extension splinting alone for 4-6 weeks
- Chronic cases (greater than 6 weeks) usually require surgical reconstruction
Examiner's Pearls
- "Painful snapping at MCP with active extension = sagittal band injury until proven otherwise
- "Elson test positive (weak MCP extension) with normal PIP/DIP extension = differentiate from central slip
- "Surgical repair within 3 weeks has better outcomes than delayed reconstruction
- "Juncturae tendinum can mask single finger EDC injury - examine each finger independently
Critical Sagittal Band Exam Points
Anatomy and Pathomechanics
Sagittal bands are transverse fibers originating from volar plate that wrap around EDC to stabilize it dorsally over MCP. Rupture allows EDC to subluxate into intermetacarpal valley (usually ulnarly). Loss of MCP extension power.
Clinical Diagnosis
Classic triad: Pain over MCP with active extension, palpable/visible tendon subluxation (snap), weak active MCP extension. EDC tendon displaces ulnarly with MCP flexion and snaps back with extension.
Surgical Repair
Direct repair best for acute injuries (within 3 weeks). Techniques: Direct suture, juncturae transfer, free tendon graft. Goal: Restore EDC centralization and MCP extension strength.
Rehabilitation
Early diagnosis critical - Type I-II often heal with 4-6 weeks extension splinting. Chronic injuries (greater than 6 weeks) develop scarring and require reconstruction with worse outcomes.
Quick Decision Guide
| Rayan Type | Clinical Features | Primary Treatment | Key Pearl |
|---|---|---|---|
| Type I (Partial) | Pain, NO subluxation, maintains extension | Splint MCP extension 4-6 weeks | Conservative treatment successful in 80% |
| Type II (Complete, reducible) | Subluxation with flexion, reduces with extension | Splint vs early surgery if active | Surgery preferred for athletes, manual laborers |
| Type III (Irreducible) | Tendon locked in intermetacarpal valley | Surgical reduction and repair | Cannot extend MCP actively |
STEELSagittal Band Anatomy (Extensor Hood Components)
Memory Hook:STEEL represents the strength of the extensor hood - Sagittal bands are the foundation that keep the mechanism centralized!
SNAPClinical Examination Findings
Memory Hook:SNAP - you can feel and hear the tendon SNAP as it subluxates and reduces!
CRAFTSurgical Repair Options
Memory Hook:CRAFT represents the surgical skill needed - multiple techniques available, goal is to CRAFT a stable centralized extensor mechanism!
Overview and Epidemiology
Sagittal band injuries represent a relatively uncommon but functionally significant hand injury, disrupting the delicate balance of the extensor mechanism at the MCP joint level. The long and middle fingers are most commonly affected due to their relative lack of support from juncturae tendinum and greater metacarpal mobility.
Why Sagittal Bands Matter
Sagittal bands act as the dorsal stabilizers of the extensor tendon at the MCP joint, preventing subluxation into the intermetacarpal valleys during finger flexion and extension. Without intact sagittal bands, the mechanical advantage of the extensor digitorum communis is lost, resulting in weak MCP extension despite intact tendon continuity.
Demographics
- Age: Peak 30-50 years (athletic and occupational injuries)
- Gender: Male predominance 3:1
- Mechanism: Forced flexion against resistance (punching), laceration, rheumatoid arthritis
- Digits: Long finger (40%), middle finger (30%), index (20%), ring (10%), small (rare)
Clinical Impact
- Function: Weak grasp and release due to loss of MCP extension power
- Pain: Snapping causes discomfort with gripping activities
- Work: Manual laborers and athletes most affected
- Outcomes: 85% achieve good function if treated within 3 weeks, drops to 60% if chronic
Anatomy and Pathomechanics
Extensor Hood Complexity at MCP Joint
The sagittal band is NOT a simple ligament but rather a complex confluence of transverse fibers from the volar plate, longitudinal fibers from the interosseous fascia, and contributions from the juncturae tendinum. This creates a dynamic stabilization system that centralizes the EDC during the full arc of MCP motion.
Sagittal Band Anatomy
Structure
Origin: Volar plate of MCP joint, interosseous fascia
Course: Wrap around radial and ulnar sides of EDC tendon
Insertion: Merge with extensor hood dorsally, anchoring EDC to metacarpal
Thickness: Radial band thicker and stronger than ulnar (explains why ulnar disruption more common)
Function
Stabilization: Prevent EDC subluxation into intermetacarpal valley
Force transmission: Transfer intrinsic muscle forces to extensor mechanism
MCP extension: Act as direct MCP extensors (independent of EDC)
Dynamic centering: Maintain EDC position through full ROM
Biomechanics of Subluxation
| Phase of Motion | Normal Mechanism | After Radial Band Rupture | After Ulnar Band Rupture |
|---|---|---|---|
| MCP extension (rest) | EDC centralized dorsally | EDC displaces radially (rare) | EDC displaces ulnarly (common) |
| MCP flexion (gripping) | EDC maintained dorsal by sagittal bands | EDC subluxates radially over metacarpal head | EDC subluxates ulnarly into valley (90% of cases) |
| Active extension | Smooth EDC excursion, strong extension | Painful snap as tendon reduces radially | Painful snap as tendon reduces from ulnar valley, weak extension |
Why Ulnar Subluxation Predominates
90% of sagittal band injuries result in ulnar EDC subluxation because: 1) Radial sagittal band is thicker and stronger than ulnar, 2) Ulnar intrinsic muscles (3rd palmar interosseous) are weaker than radial, 3) Normal resting tension of EDC favors ulnar displacement when restraints are lost.
Relationship to Other Structures
The sagittal band is intimately related to the juncturae tendinum (interconnections between adjacent EDC tendons). Juncturae can partially compensate for sagittal band disruption in some cases, explaining why index and small fingers (with strongest juncturae) are less commonly symptomatic.
Classification Systems
Rayan Classification of Sagittal Band Injuries
The Rayan classification (most widely used) is based on severity and reducibility of EDC subluxation. This guides treatment decisions.
| Type | Pathology | Clinical Findings | Treatment | Prognosis |
|---|---|---|---|---|
| Type I | Partial tear or attenuated sagittal band | Pain, mild swelling, NO visible subluxation, active extension maintained | Splint MCP extension 4-6 weeks, NSAIDS | 85-90% excellent outcomes |
| Type II | Complete tear, tendon subluxates but reducible | Visible/palpable subluxation with MCP flexion, painful snap with extension, weak active extension | Splinting vs surgery (consider surgery for athletes, manual workers) | 80% good with splinting, 90% with surgery |
| Type III | Complete tear, tendon locked in intermetacarpal valley | Tendon permanently displaced, cannot actively extend MCP, may have flexion contracture | Surgical reduction and repair/reconstruction REQUIRED | 70-80% good outcomes (worse if chronic greater than 6 weeks) |
Type II vs Type III Distinction
The key distinction is reducibility. Type II subluxates with MCP flexion but reduces with extension (dynamic instability). Type III is locked in subluxated position (static deformity). Type III CANNOT achieve active MCP extension and requires surgery.
Clinical Assessment
History
- Mechanism: Forced MCP flexion (punching, ball sports), direct trauma, spontaneous (RA)
- Symptoms: Painful snapping at MCP, weakness extending finger, swelling over MCP
- Timing: Acute (days), subacute (weeks), chronic (months)
- Hand dominance: Affects treatment urgency
- Occupation: Manual labor vs desk work
- Red flags: Rheumatoid arthritis (pathologic rupture), multiple finger involvement
Examination
- Look: Swelling over MCP, finger posture at rest
- Feel: Tenderness over radial or ulnar sagittal band, palpable snap with motion
- Move: Active MCP extension (weak), observe for tendon subluxation, check PIP/DIP extension (normal)
- Special tests: Dynamic subluxation test, resisted MCP extension
- Neurovascular: Intact (not a feature of isolated sagittal band injury)
Special Tests
Clinical Examination Maneuvers
Technique: Ask patient to make a fist (flex all MCPs), then actively extend fingers.
Positive test: Visible or palpable EDC tendon subluxation (usually ulnarly) with MCP flexion, followed by painful snap as tendon reduces with active extension.
Observer: Place finger over dorsal MCP to feel tendon displacement.
Interpretation: Confirms sagittal band disruption allowing dynamic instability.
Technique: Stabilize proximal phalanx in slight flexion, ask patient to extend MCP against examiner resistance.
Positive test: Weak extension with pain at MCP (compares to normal adjacent fingers).
Note: PIP and DIP extension should be NORMAL (rules out central slip injury).
Interpretation: Loss of mechanical advantage due to EDC eccentric position.
Standard Elson: Flex PIP over table edge, ask patient to extend PIP against resistance.
In sagittal band injury: PIP extends normally (central slip intact), but MCP extension weak.
Contrast: Central slip injury shows weak PIP extension with rigid DIP extension.
Interpretation: Helps differentiate MCP-level pathology from PIP-level central slip rupture.
Differential Diagnosis
Key differentials to exclude:
- Central slip rupture (Zone III): Weak PIP extension, positive Elson test, risk of boutonniere
- EDC laceration (Zone V): Complete loss of MCP extension, visible wound
- MCP joint arthritis: Stiffness, limited ROM, radiographic changes
- Extensor tendon rupture in RA: Multiple fingers, systemic disease, atraumatic
Distinguishing feature: Sagittal band injury has DYNAMIC subluxation with painful snap, normal PIP/DIP extension, and weak but present MCP extension.
Investigations
Imaging Protocol
Views: PA, lateral, oblique of affected digit
Purpose: Exclude bony pathology, assess MCP joint
Findings: Usually NORMAL (soft tissue injury), may show MCP joint space narrowing if chronic arthritis
Stress views: Dynamic lateral with active MCP flexion may show tendon subluxation (rarely needed)
Advantages: Dynamic real-time assessment of EDC subluxation, assess sagittal band integrity
Technique: Dorsal longitudinal view over MCP, ask patient to flex/extend MCP, observe EDC movement
Positive findings: EDC displacement into intermetacarpal valley with MCP flexion, discontinuity of sagittal band fibers
Availability: Operator-dependent, not widely used but increasing
Indications: Chronic cases, atypical presentation, pre-operative planning
Findings: Disruption of sagittal band fibers, fluid in MCP joint, EDC tendon position
Utility: Can assess tissue quality for surgical planning (acute vs chronic scarring)
Cost: Expensive, rarely necessary if clinical diagnosis clear
Clinical Diagnosis is Key
Sagittal band injuries are clinical diagnoses. Imaging is primarily to exclude other pathology (fracture, arthritis) rather than to confirm sagittal band rupture. The dynamic subluxation test is more sensitive and specific than any imaging modality.
Management Algorithm
Conservative Treatment Indications
Ideal Candidates
- Rayan Type I: Partial tear, no subluxation
- Rayan Type II: Reducible subluxation, low-demand patient
- Acute presentation: Within 2-3 weeks of injury
- Patient factors: Non-manual occupation, older age, medical comorbidities
Contraindications
- Rayan Type III: Irreducible subluxation
- Chronic injury: Greater than 6 weeks
- High-demand patients: Athletes, manual laborers who need reliable grip strength
- Failed splinting: Recurrent subluxation after adequate trial
Splinting Protocol
Splint type: Custom thermoplastic dorsal blocking splint OR aluminum foam commercial splint
Position: MCP in FULL extension (0 degrees), PIP and DIP joints free to move
Wear schedule: Continuous 24 hours/day (remove only for hygiene)
Activities: No gripping, lifting, or forceful hand use
Monitoring: Weekly follow-up to assess compliance, skin integrity, adjust splint
Daytime: Remove for light activities if no pain or subluxation
Nighttime: Continue splinting during sleep
Exercises: Gentle active ROM, blocked MCP extension (protect repair)
Avoid: Forceful gripping, weight-bearing on hand
Splint: Discontinue if MCP stable and no pain
Therapy: Progressive grip strengthening with putty, therapy balls
Monitor: Any recurrence of snapping or subluxation
Return to activity: Gradual, based on symptom tolerance
Goal: 80% grip strength, no pain, no subluxation
Work: Return to manual labor if criteria met
Sports: Protective taping for contact sports for additional 4 weeks
Follow-up: If symptoms recur, consider surgical reconstruction
Success Rates for Conservative Treatment
Rayan Type I: 85-90% success with splinting. Rayan Type II: 70-80% success (higher failure in manual laborers and athletes). Rayan Type III: Splinting contraindicated - requires surgery. Overall, early presentation (within 3 weeks) has best non-operative outcomes.
Surgical Technique
Patient Positioning
Setup Checklist
Supine on operating table with hand table.
- Shoulder abducted 80-90 degrees
- Elbow extended on arm board
- Forearm pronated (dorsal hand up)
- Wrist neutral to slight extension
Forearm tourniquet preferred for better visualization.
- Pressure: 200-225 mmHg
- Exsanguination: Elevation 2 minutes OR Esmarch bandage
- Limit: 90 minutes (most cases completed in 30-45 minutes)
- Prep from fingertips to mid-forearm with betadine or chlorhexidine
- Transparent hand drape allows visualization of finger motion intraoperatively
- Expose all digits to assess juncturae and EDC continuity
Consent Points
- Recurrence: 10-15% (higher in chronic cases)
- Stiffness: 10% (especially if immobilized prolonged)
- Infection: 2-5% (low risk)
- MCP joint stiffness: 5-10% if overly tight repair
- Need for revision: 10% (juncturae transfer or reconstruction)
- Incomplete return of strength: 15-20%
Equipment Checklist
- Instruments: Hand surgery set, fine scissors, forceps
- Sutures: 3-0 or 4-0 braided non-absorbable (sagittal band repair), 5-0 nylon (skin)
- Magnification: Loupe 2.5-3.5x (not mandatory but helpful)
- Tendon graft: Palmaris longus harvested if reconstruction needed
- Splint materials: Thermoplastic for postoperative extension splint
Complications
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Recurrent subluxation | 10-15% | Chronic injury, inadequate repair tension, early mobilization, heavy manual labor | Revision repair with juncturae augmentation or tendon graft reconstruction |
| MCP stiffness (extension contracture) | 10% | Over-tight repair, prolonged immobilization greater than 6 weeks | Hand therapy with passive flexion stretching, rarely requires surgical release |
| Loss of MCP flexion | 5-10% | Excessive scar formation, adhesions | Aggressive hand therapy, tenolysis if persistent at 6 months |
| Infection | 2-5% | Open injury, diabetes, immunosuppression | Antibiotics, irrigation and debridement if deep, delayed repair |
| Dorsal sensory nerve injury | 3-5% | Iatrogenic during dissection | Neuroma excision and burial if symptomatic painful neuroma |
| Incomplete return of grip strength | 15-20% | Chronic injury, muscle atrophy, patient factors | Prolonged hand therapy (up to 6 months), accept functional outcome |
Preventing Recurrence
The most common complication is recurrent EDC subluxation (10-15%). Prevention strategies: 1) Adequate tissue tension at repair (EDC centralized with MCP extended), 2) Augmentation with juncturae transfer in subacute/chronic cases, 3) Strict compliance with 4-6 week immobilization, 4) Gradual return to heavy activity over 12 weeks.
Postoperative Care and Rehabilitation
Postoperative Rehabilitation Timeline
Splint: MCP extension splint worn continuously (24/7).
Remove only: For wound care by therapist (suture removal at 10-14 days).
PIP/DIP ROM: Encouraged to prevent stiffness in adjacent joints.
Activity: No gripping, no weight-bearing on hand.
Follow-up: Wound check at 10-14 days, therapy initiation at 2 weeks.
Splint: Remove for supervised therapy sessions only.
Exercises: Gentle active MCP flexion and extension within pain-free range.
Blocked exercises: Isolate MCP ROM (stabilize proximal phalanx).
Splint between exercises: Maintain extension between sessions and at night.
Goal: Achieve 60-70 degrees MCP flexion without pain or subluxation.
Wean splint: Discontinue daytime splinting, continue nighttime.
Exercises: Full active ROM, composite fist, intrinsic stretching.
Light resistance: Putty exercises, soft therapy balls.
Monitor: Any recurrence of snapping or subluxation (if occurs, return to splinting).
Discontinue splint: If full ROM and no subluxation.
Progressive resistance: Grip strengthening with graded resistance.
Work simulation: Activity-specific exercises for return to work.
Goal: 80% grip strength compared to contralateral hand.
Work: Return to manual labor if strength criteria met.
Sports: Gradual return, protective taping for contact sports for additional 4 weeks.
Final outcome: Expect 85-90% of baseline function.
Importance of Compliance
Patient compliance with the 4-6 week immobilization is CRITICAL. Early mobilization (before 4 weeks) significantly increases risk of recurrent subluxation. Therapist-supervised progression ensures safe return to activity without overstressing repair.
Outcomes and Prognosis
| Treatment | Patient Group | Expected Outcomes | Predictors of Poor Outcome |
|---|---|---|---|
| Splinting (Type I-II acute) | Low-demand, office workers | 80-85% good, minimal recurrence | Manual labor, poor compliance, presentation greater than 3 weeks |
| Direct repair (Type II-III acute) | Athletes, manual workers | 90% return to sport/work at pre-injury level | Delayed surgery greater than 6 weeks, inadequate tension at repair |
| Reconstruction (chronic greater than 6 weeks) | All patients | 60-70% good, higher stiffness and recurrence | Greater than 6 months delay, multiple previous failed repairs, rheumatoid arthritis |
Factors Predicting Success
Best outcomes: Acute presentation (within 3 weeks), Rayan Type I-II, surgical repair with adequate tension, patient compliance with immobilization, experienced hand surgeon and therapist. Worst outcomes: Chronic injury (greater than 6 weeks), failed prior repair, rheumatoid arthritis, manual laborer who returns to heavy work too early.
Evidence Base and Key Studies
Classification and Treatment of Sagittal Band Injuries
- Case series: 37 patients with sagittal band injuries
- Proposed classification: Type I (partial), Type II (complete reducible), Type III (complete irreducible)
- Type I: 90% success with splinting alone (4-6 weeks)
- Type II: 70% success with splinting, 90% with surgery
- Type III: Surgery required, 80% good outcomes with direct repair
Long-term Outcomes of Sagittal Band Reconstruction
- Retrospective review: 28 patients with chronic sagittal band injuries treated surgically
- Mean follow-up: 4.2 years
- Techniques: Direct repair (12), juncturae transfer (10), tendon graft (6)
- Good to excellent outcomes: 71% (direct repair 83%, juncturae 80%, graft 50%)
- Recurrence rate: 14% overall (graft reconstruction 33%, direct repair 8%)
Extensor Tendon Subluxation in Rheumatoid Arthritis
- Review article on extensor tendon subluxation in RA
- Sagittal band attenuation from chronic synovitis leads to progressive EDC ulnar subluxation
- Multiple digits often affected (contrast to trauma which is usually single digit)
- Treatment: Early synovectomy and sagittal band reconstruction, late cases may require tendon transfers
Sonographic Assessment of Sagittal Band Injuries
- Ultrasound reliably demonstrates sagittal band tears and extensor tendon subluxation
- Dynamic examination during finger flexion shows tendon displacement
- Radial sagittal band thicker than ulnar, correlating with ulnar rupture predominance
- High-resolution US can show partial vs complete tears
Juncturae Tendinum Transfer for Chronic Sagittal Band Injuries
- Juncturae tendinum transfer provides dynamic extensor tendon stabilization
- Technique preserves natural anatomy and provides active centering force
- Results comparable to direct repair in acute injuries
- Preferred for chronic injuries where primary repair tissue quality is poor
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Acute Sagittal Band Injury (~2-3 min)
"A 35-year-old manual laborer presents 5 days after punching a wall in anger. He has pain over the dorsum of his right long finger MCP joint and complains of a snapping sensation when he makes a fist. On examination, you observe the EDC tendon subluxating ulnarly with MCP flexion and snapping back with extension. He has weak but present active MCP extension. What is your assessment and management?"
Scenario 2: Failed Conservative Management (~3-4 min)
"A 42-year-old female was treated with MCP extension splinting for 6 weeks for a Rayan Type II sagittal band injury of her index finger. She was initially compliant but now, 2 weeks after discontinuing the splint, she has recurrent painful snapping and visible EDC subluxation with gripping. She is frustrated and wants definitive treatment. How would you manage this case?"
Scenario 3: Chronic Sagittal Band Injury (~2-3 min)
"A 55-year-old patient with rheumatoid arthritis presents with progressive ulnar subluxation of the EDC tendons of her long and ring fingers over the past 6 months. She has difficulty extending her MCPs and reports that the tendons slip off the side of the knuckles when she tries to grip. Examination shows fixed ulnar subluxation of EDC with inability to actively extend the MCPs. How would you manage this?"
MCQ Practice Points
Rayan Classification Question
Q: A patient has visible EDC tendon subluxation with MCP flexion that reduces with extension, and weak but present active MCP extension. What is the Rayan classification and recommended treatment? A: Rayan Type II (complete tear with reducible subluxation). Treatment depends on patient factors: splinting for low-demand patients (70-80% success), surgical repair for high-demand patients/athletes/manual laborers (90% success).
Anatomy Question
Q: Why is ulnar subluxation of the EDC more common than radial subluxation in sagittal band injuries? A: Three reasons: 1) The radial sagittal band is thicker and stronger than the ulnar band, 2) Ulnar intrinsic muscles (palmar interossei) are weaker than radial, 3) Normal resting tension of EDC favors ulnar displacement when restraints lost. Result: 90% of sagittal band injuries cause ulnar EDC subluxation.
Surgical Timing Question
Q: What is the optimal timing for surgical repair of sagittal band injuries and why? A: 1-3 weeks from injury is optimal. Tissue quality is good (minimal scarring), direct repair is possible, and outcomes are best (90% good results). Beyond 6 weeks, dense scarring and tissue attenuation make direct repair difficult and outcomes worse (70% good), often requiring reconstruction with tendon graft.
Differential Diagnosis Question
Q: How do you differentiate sagittal band injury from central slip rupture on clinical examination? A: Key differences: Sagittal band injury has weak MCP extension with NORMAL PIP and DIP extension, dynamic tendon subluxation visible at MCP level, and negative Elson test. Central slip injury has weak PIP extension, positive Elson test (rigid DIP extension with PIP flexion), and risk of boutonniere deformity. Anatomic level: sagittal band = MCP, central slip = PIP.
Rehabilitation Question
Q: What is the critical immobilization period after sagittal band repair and why? A: 4-6 weeks of continuous MCP extension splinting is critical. The sagittal band is under significant tension during gripping and early mobilization (before 4 weeks) causes repair failure and recurrent subluxation (occurs in 20-30% if mobilized early). PIP and DIP joints should remain free to prevent stiffness.
Australian Context and Medicolegal Considerations
Occupational Injuries
- WorkCover: Common mechanism is punching injury (assault vs occupational)
- Claim requirements: Document mechanism clearly (work-related vs personal altercation)
- Return to work: Light duties possible at 4-6 weeks, full manual labor 10-12 weeks
- Functional capacity: Formal assessment required for heavy manual labor clearance
Rheumatoid Arthritis Context
- PBS medications: DMARDs (methotrexate, biologics) for RA control
- Multidisciplinary: Rheumatology co-management essential
- Surgical timing: Control disease activity before elective reconstruction
- Prognosis: Discuss realistic outcomes (inferior to traumatic injuries)
Medicolegal Considerations
Key documentation requirements:
- Mechanism of injury (assault, occupational, spontaneous in RA)
- Rayan classification (guides treatment and prognosis discussion)
- Discussion of operative vs non-operative options with success rates
- Patient occupation and activity level (affects treatment recommendation)
- Informed consent: Recurrence risk (10-15%), stiffness, incomplete return of strength
Common litigation issues:
- Failed conservative management without early surgical referral (manual laborers need surgery)
- Inadequate patient education about splint compliance (leads to treatment failure)
- Over-tight repair causing MCP extension contracture (technical error)
- Missed diagnosis (treated as simple contusion, presents chronically with fixed subluxation)
SAGITTAL BAND INJURIES
High-Yield Exam Summary
Key Anatomy
- •Sagittal bands = transverse fibers from volar plate wrapping around EDC to stabilize at MCP level
- •Radial band thicker than ulnar (explains 90% ulnar subluxation)
- •Long and middle fingers most affected (lack juncturae support)
- •Function: Centralize EDC, prevent subluxation into intermetacarpal valley, transmit intrinsic forces
Rayan Classification
- •Type I = Partial tear, NO subluxation, active extension maintained → Splint 4-6 weeks
- •Type II = Complete tear, REDUCIBLE subluxation → Splint (low-demand) vs Surgery (high-demand)
- •Type III = Complete tear, IRREDUCIBLE subluxation → Surgery required
- •Dynamic subluxation test: EDC displaces ulnarly with MCP flexion, snaps back with extension
Treatment Algorithm
- •Type I: Splint MCP extension 4-6 weeks (85-90% success)
- •Type II: Surgery for athletes/manual workers, splinting for office workers
- •Type III: Surgical reduction and repair (cannot extend MCP actively)
- •Chronic (greater than 6 weeks): Reconstruction with tendon graft (worse outcomes 60-70%)
- •Optimal surgical timing: 1-3 weeks (90% good outcomes)
Surgical Pearls
- •Direct repair: Horizontal mattress sutures with 3-0 non-absorbable, tension with MCP extended
- •Juncturae transfer: Augment weak tissue by transferring adjacent juncturae
- •Tendon graft: Palmaris longus reconstruction for chronic/RA cases
- •Critical: Appropriate tensioning (too loose = re-subluxation, too tight = extension contracture)
- •Test repair: Passive MCP flexion to 90 degrees should not cause subluxation
Rehabilitation
- •Immobilization: MCP extension splint 4-6 weeks CONTINUOUSLY (PIP/DIP free)
- •Early mobilization before 4 weeks increases recurrence risk 20-30%
- •Weeks 4-6: Protected supervised ROM
- •Weeks 6-12: Progressive strengthening
- •Return to manual work: 10-12 weeks
Outcomes and Complications
- •Acute repair: 85-90% good outcomes
- •Chronic reconstruction: 60-70% good outcomes
- •Recurrence: 10-15% (higher in chronic cases, inadequate repair tension)
- •MCP stiffness: 10% (over-tight repair)
- •Predictors of poor outcome: Chronic injury greater than 6 weeks, RA, failed previous repair, manual labor with early return to work