Surgical Repair is the Recommended Treatment for Acute Full-Thickness Flexor Hallucis Longus Tendon Tears
For an acute full-thickness flexor hallucis longus (FHL) tendon tear, operative repair should be performed to restore active hallux flexion, prevent biomechanical alterations, and optimize functional outcomes. While the available evidence is limited, the literature consistently supports surgical intervention for complete FHL tendon injuries, particularly in active individuals 1, 2.
Treatment Algorithm
Immediate Management
- Confirm the diagnosis through clinical examination demonstrating loss of active hallux interphalangeal (IP) joint flexion and impaired push-off strength
- Obtain MRI if diagnosis is uncertain or to assess the extent of tendon defect and associated injuries 3
- Proceed to surgery promptly in the acute setting (within days to weeks of injury) to facilitate primary repair before tendon retraction and gap formation occur
Surgical Approach Selection
For acute tears with minimal gap (<2-3 cm):
- Primary direct repair is the treatment of choice 1
- Use standard tendon repair techniques with appropriate suture configuration
- This applies when tendon ends can be approximated without excessive tension
For tears with moderate defects or delayed presentation:
- Consider minimally invasive or endoscopic repair techniques when feasible 4
- These approaches offer advantages including earlier recovery, less pain, lower soft tissue complication rates, and better preservation of blood supply 4
For large chronic defects (>10 cm) or failed acute repairs:
- Tendon reconstruction with allograft (such as flexor digitorum longus tendon) may be necessary 3
- Ultrasound-guided tendon localization combined with arthroscopy-assisted techniques can facilitate minimally invasive reconstruction 3
Key Clinical Considerations
Goals of Surgery
The effectiveness of repair depends on clearly defined surgical goals 1:
- Pain relief
- Restoration of active hallux IP joint motion
- Correction of deformity
- Restoration of push-off strength (critical for athletic activities)
Patient-Specific Factors
- Activity level matters: In active individuals and athletes, preservation of native hallux flexion is particularly important 3
- Timing of presentation: Acute injuries allow primary repair; delayed presentation may require more complex reconstruction 3
- Associated injuries: Carefully evaluate for concomitant pathology that may influence surgical planning 1
Important Caveat
Not all FHL tendon injuries require repair 1. The decision should be based on:
- Completeness of the tear (partial vs. full-thickness)
- Patient functional demands and activity level
- Presence of symptoms affecting quality of life
- Associated biomechanical alterations
However, for full-thickness acute tears in symptomatic patients, operative management is strongly favored to prevent long-term functional deficits 2.
Postoperative Management
While specific protocols for FHL repair are not detailed in the available guidelines, principles from Achilles tendon repair can be extrapolated:
- Protected weight-bearing in the early postoperative period
- Gradual mobilization starting at 2-4 weeks to prevent stiffness while protecting the repair
- Progressive rehabilitation focusing on restoration of strength and range of motion
Common Pitfalls to Avoid
- Delayed diagnosis: Loss of active hallux flexion may be subtle; maintain high clinical suspicion in foot trauma patients 2
- Underestimating functional impact: Lack of appropriate management can result in major biomechanical alterations 2
- Inadequate surgical planning: Failure to assess tendon gap size preoperatively may lead to inappropriate surgical technique selection
- Overlooking patient activity demands: Reconstruction strategies should account for the patient's functional requirements 3
The available evidence, though limited to case series and expert opinion, consistently supports operative intervention for acute full-thickness FHL tendon tears to optimize functional outcomes and prevent long-term disability 1, 2.