What is the treatment for a lacerated extensor tendon at the index finger?

Treatment of Lacerated Extensor Tendon at Left Index Finger

Surgical repair using a modified Kessler technique with 4-0 nylon suture is the definitive treatment for complete extensor tendon lacerations of the index finger, followed by 4 weeks of wrist splinting in extension and then early controlled motion rehabilitation. 1

Immediate Surgical Management

Primary Repair Technique

• Perform primary surgical repair using a modified Kessler suture technique with 4-0 nylon suture, which provides optimal stability at the tendon repair site 1
• Surgical repair should be performed within the first week after injury (repair can be successfully done even 6 days post-injury) 2
• Complete lacerations require surgical repair; partial lacerations involving less than 50% of tendon width may be managed conservatively with splinting alone 3

Zone-Specific Considerations for Index Finger

The index finger extensor mechanism can be injured at different zones, each with distinct prognosis:

• Zone III (PIP joint level): Central slip injuries at this level have poorer outcomes (worse results compared to zones 3 and 5) and require meticulous repair to prevent boutonniere deformity 1, 4
• Zone IV (proximal phalanx): Also associated with worse outcomes compared to zones 3 and 5 1
• Zone V (MCP joint level): Best outcomes achieved at this level (88% good-to-excellent results) 1
• Zone VI (metacarpal/hand level): Excellent outcomes when properly managed 2, 1

Post-Operative Immobilization Protocol

Initial Immobilization Phase

• Immobilize the wrist and affected finger in extension for 4 weeks post-operatively using a short-arm cast or static extension splint 2, 1
• This traditional conservative approach prevents excessive tension on the repair site during initial healing 2

Rehabilitation Protocol

Early Controlled Motion (Preferred Approach)

After the 4-week immobilization period, two evidence-based approaches exist:

Option 1: Early Controlled Motion with Dynamic Splinting

• Begin early controlled motion immediately after cast removal 5
• Use dynamic splinting or a relative motion with dorsal hood orthosis (RMDH) for zone III injuries 4
• This approach achieves similar total active motion (TAM) and total passive motion (TPM) as static splinting, with no significant difference in complication rates 5

Option 2: Static Extension Splinting with Gradual Motion

• Continue static extension splinting except during supervised exercise 2, 5
• Gradually introduce active motion under close monitoring 2

Critical Monitoring During Rehabilitation

Watch for Extensor Lag Development (8-10 days into rehabilitation):

• Extensor lag (active extension less than passive extension) indicates excessive scar lengthening at the repair site 2
• If extensor lag develops or increases: immediately discontinue all flexion stretching exercises 2
• Emphasize active extension exercises only 2
• Rest the joint in extension using a static splint except during exercise 2
• Once extensor lag improves, increase vigor of active extension to promote tendon gliding and elongate restricting adhesions 2

Exercise Progression

• Monitor both active and passive range of motion carefully at each visit 2
• Progress from gentle active extension to more vigorous exercises as extensor lag resolves 2
• Full range of motion and return to work typically achieved within 12 months 1

Common Pitfalls to Avoid

• Do not confuse acute traumatic tendon laceration with chronic tendinosis: The guidelines on tendinosis 6, 7 address degenerative overuse conditions, not acute traumatic lacerations requiring surgical repair
• Do not delay surgical repair: Primary repair within the first week yields optimal results 2, 1
• Do not continue flexion stretching if extensor lag develops: This worsens scar lengthening and compromises repair integrity 2
• Do not use NSAIDs or corticosteroid injections for acute tendon lacerations: These are only indicated for chronic tendinosis, not acute traumatic injuries requiring surgical repair 6, 7

Imaging Considerations

• MRI is the ideal imaging modality for evaluating tendon injuries and surgical planning, with sensitivity of 28-85% for detecting extensor hood injuries 8
• Standard radiographs should be obtained to rule out associated fractures or bony abnormalities 8

Expected Outcomes

• Zone V injuries (MCP level) achieve 88% good-to-excellent results 1
• Zone III and IV injuries have lower success rates, requiring more intensive rehabilitation 1
• Wound infections and re-ruptures are rare with proper technique 1
• Full return to work at full duty is achievable with appropriate management 2