How should a flexor tendon injury be evaluated and managed?

Flexor Tendon Injury: Evaluation and Management

For flexor tendon injuries, perform a thorough physical examination to identify the zone of injury and associated pathology, obtain plain radiographs initially, use MRI for surgical planning (sensitivity 92-100% for tendon injuries), and proceed with early surgical repair using at least a 4-strand core technique followed by early active motion within 3-5 days postoperatively.

Initial Evaluation

Clinical Assessment

Examine specifically for:

• Zone of injury (zones I-V, with zone II being most challenging for outcomes) 1, 2
• Concomitant fractures, neurovascular injuries, or nerve deficits 1
• Level of tendon retraction in complete tears
• Presence of wound contamination or infection 3
• Mechanism of injury (sharp vs. crush)

Imaging Algorithm

Step 1: Plain Radiographs

• Obtain initial radiographs in all cases to identify fractures or radiopaque foreign bodies 4

Step 2: MRI for Surgical Planning

• MRI is the ideal imaging modality for flexor tendon injuries 4
• Provides 92% sensitivity and 100% specificity for flexor tendon injuries in cadaveric studies 4
• Demonstrates 100% sensitivity and specificity for diagnosis of tendon re-tears after repair 4
• Critical for identifying:
  • Location of retracted proximal tendon stump (determines if primary repair vs. reconstruction is feasible) 5
  • Quality of tendon stump 4
  • Pulley system injuries (A2 and A4 pulleys identified in 100% of cases) 4
  • Peritendinous adhesions (91% sensitivity) 4

Step 3: Ultrasound (Alternative)

• Dynamic US can visualize tendon injuries but is less comprehensive than MRI 4
• Useful for pulley system assessment 4

Surgical Management

Timing

Early repair is optimal 2, 6

• Primary repair should be performed as soon as feasible
• Delay repair if infection is present - wait until granulation tissue develops 3
• For contaminated wounds: administer empiric antibiotics; do not use prophylactic antibiotics in clean wounds 3
• Pyogenic flexor tenosynovitis requires immediate surgical intervention 3

Surgical Technique (Based on 2026 IFSSH Consensus)

The following technical principles are critical 7:

1. Core Repair Strength

   • Use at least a 4-strand technique (6-strand preferred) 2, 7
   • Provides strong, solid repair necessary for early active motion

2. Suture Technique

   • Add epitendinous suture for additional strength and gliding properties 2
   • Do NOT use traditional running peripheral sutures with 6-strand repairs 7
   • Do NOT place knots between tendon stumps - knots are foreign bodies 7

3. Pulley Management

   • Perform pulley venting as needed 2
   • Preserve A2 and A4 pulleys when possible

4. Special Considerations for Zone II

   • Most difficult zone to achieve acceptable outcomes 2
   • Requires meticulous attention to repair technique 2

Secondary Reconstruction Options 7

Decision Algorithm:

• One-stage tendon grafting: For patients WITHOUT extensive pulley destruction 7

  • Can use early active motion postoperatively 7

• Two-stage tendon reconstruction: For patients requiring pulley reconstruction 7

  • Stage 1: Pulley reconstruction
  • Stage 2: Tendon grafting

• Tendon transfer: Required if nerve function is lost 3

Postoperative Rehabilitation

Early active range of motion is essential 2, 6:

• Begin within 3-5 days of surgery 2
• Critical for optimizing outcomes and preventing adhesions 1
• Abandon traditional place-and-hold exercises 7

Common Pitfalls

1. Delaying surgery in infected wounds without adequate debridement - leads to poor outcomes 3
2. Using weak repair techniques - necessitates prolonged immobilization and increases adhesion risk 2, 7
3. Inadequate rehabilitation - results in stiffness and adhesion formation 1, 8
4. Attempting primary repair with extensive pulley damage - should proceed to staged reconstruction 7
5. Placing knots between tendon stumps - creates foreign body reaction 7

Prognostic Factors

Outcomes depend on 8:

• Zone of injury (Zone II worst prognosis)
• Mechanism of injury
• Presence of concomitant injuries
• Time to surgery
• Quality of tendon repair
• Adherence to rehabilitation protocol