Patient must adhere to strict NPO status for at least 8 hours prior to surgery. Pre-operative assessment includes complete blood count, coagulation profile, ECG, and cardiac clearance. Antibiotic prophylaxis is administered within 60 minutes of the incision. Informed consent must be obtained, and the surgical site verified and marked.
Post-operative care includes elevation of the hand to reduce edema, administration of IV analgesia, and wound inspection. A volar splint is applied for immobilization. Physical therapy consultation for early controlled mobilization is essential starting at 48 hours post-op. Discharge criteria include stable vital signs, controlled pain, and adequate wound healing status.
Comprehensive Guide: Flexor Tendon Repair
Flexor tendon repair is a sophisticated surgical intervention designed to restore the continuity and function of the flexor tendons in the hand, which are responsible for the flexion (bending) of the fingers and thumb. Given the complex anatomy of the hand—specifically the "no man’s land" or Zone II—this procedure requires meticulous surgical technique, deep anatomical knowledge, and a highly structured postoperative rehabilitation protocol.
1. Introduction & Overview
The flexor tendon system consists of the flexor digitorum profundus (FDP) and the flexor digitorum superficialis (FDS). These tendons glide through a series of fibro-osseous tunnels (pulleys) that keep them flush against the bone, maximizing mechanical efficiency. When these tendons are lacerated, the fingers lose the ability to flex, leading to significant functional impairment.
Flexor tendon repair is not merely a "stitching" process; it is a reconstructive procedure that must balance two competing needs:
1. Tensile Strength: The repair must be strong enough to withstand the forces of early active motion.
2. Gliding Function: The repair must be smooth and low-profile enough to pass through the tight annular pulleys without catching or triggering.
2. Technical Specifications & Mechanisms
The Anatomy of the Repair
Modern flexor tendon repair relies on the "core suture" technique combined with an epitendinous (peripheral) suture.
- Core Suture: Typically uses a 3-0 or 4-0 non-absorbable, braided suture. Common configurations include the Kessler, Modified Kessler, Bunnell, or cruciate (six-strand) repairs.
- Epitendinous Suture: A 6-0 or 7-0 monofilament suture placed circumferentially around the repair site. This is critical for smoothing the junction, reducing gap formation, and increasing the overall tensile strength of the construct.
The Role of Pulleys
The annular pulleys (A1 through A5) are critical structures. During surgery, the surgeon must ensure that the repair does not "bunch up" against the A2 or A4 pulleys, which are the most biomechanically significant.
| Suture Technique | Tensile Strength | Gliding Resistance | Clinical Application |
|---|---|---|---|
| Two-strand | Low | Low | Pediatric or low-tension zones |
| Four-strand | Moderate | Moderate | Standard adult repair |
| Six-strand | High | Higher | Early active mobilization protocols |
3. Clinical Indications & Usage
Indications for Surgery
- Complete Lacerations: Traumatic division of the tendon (e.g., glass cuts, saw injuries).
- Partial Lacerations: If the laceration involves >60% of the tendon diameter, surgical repair or debridement is generally indicated to prevent subsequent rupture.
- Closed Ruptures: Often associated with rheumatoid arthritis or attrition over a bony spur (e.g., Rupture of the FPL tendon over the scaphoid).
Contraindications
- Gross Infection: If the wound is heavily contaminated, formal debridement is required before definitive repair.
- Severe Comminution: If the distal phalanx is shattered, tendon insertion site integrity must be addressed first.
- Patient Compliance: Postoperative rehabilitation is mandatory. Patients unable to follow a strict hand therapy regimen are poor candidates for aggressive early-motion protocols.
4. Pre-Operative Preparation
- Clinical Assessment: Evaluation of neurovascular status (two-point discrimination, capillary refill).
- Imaging: Radiographs to rule out associated fractures or foreign bodies (glass, metal).
- Tetanus Prophylaxis: Standard for all traumatic hand lacerations.
- Antibiotic Prophylaxis: First-generation cephalosporins are the standard of care to cover Staphylococcus aureus.
- Anesthesia: Typically performed under regional anesthesia (e.g., axillary block or WALANT—Wide Awake Local Anesthesia No Tourniquet). WALANT is increasingly popular as it allows the surgeon to test the tendon glide intraoperatively.
5. Surgical Procedure: Step-by-Step
Step 1: Exposure
A Bruner incision (zigzag) is utilized to prevent longitudinal scar contractures across the flexion creases.
Step 2: Tendon Retrieval
If the proximal tendon stump has retracted into the forearm, a secondary incision or a tendon passer is used to retrieve the tendon through the pulley system.
Step 3: Core Suture Placement
The surgeon uses a traumatic-free needle to place the core sutures. Accuracy is paramount; the sutures must be placed deep enough to hold but spaced to avoid crushing the tendon collagen.
Step 4: Epitendinous Suturing
The tendon ends are brought together. The epitendinous suture is placed to invert the tendon ends, reducing friction against the pulley walls.
Step 5: Testing
The surgeon performs "passive" flexion and extension to ensure there is no "catch" at the pulley sites. If using WALANT, the patient is asked to actively flex the finger.
Step 6: Closure
The skin is closed carefully to avoid tension. A bulky, compressive dressing is applied, followed by a dorsal blocking splint.
6. Post-Operative Recovery Protocol
The goal of rehabilitation is to prevent adhesion formation (the tendon "sticking" to the sheath) while protecting the repair from rupture.
- Phase I (Weeks 0-3): Immobilization in a dorsal blocking splint (wrist in 20° flexion, MCP joints in 70° flexion). Passive flexion exercises are performed to ensure the tendon glides.
- Phase II (Weeks 4-6): Transition to "Place and Hold" exercises. The patient passively places the finger in flexion and holds it using their own muscle force.
- Phase III (Weeks 6-8): Transition to active range of motion (AROM).
- Phase IV (Weeks 8-12): Strengthening. Resisted exercises are initiated.
7. Potential Complications
- Tendon Rupture: The most feared complication. Usually occurs between weeks 2 and 4 when the repair strength is at its nadir.
- Adhesion Formation: Leads to stiffness. Often requires secondary tenolysis (surgical release of scar tissue).
- Infection: Can be catastrophic for tendon gliding; requires urgent I&D and IV antibiotics.
- Triggering: If the repair site is too bulky, it will catch on the pulley, causing a "triggering" sensation.
8. Alternative Treatments
- Primary Tenorrhaphy: Standard surgical repair (covered above).
- Tendon Grafting: If the repair is delayed or the tendon bed is scarred, a two-stage reconstruction using a Hunter Rod (silicone rod) to create a new sheath, followed by a free tendon graft (e.g., palmaris longus), may be necessary.
- Tendon Transfer: If the muscle-tendon unit is non-functional, a transfer from another functional muscle may be required.
9. Frequently Asked Questions (FAQ)
1. What is "No Man’s Land"?
Zone II of the hand, extending from the A1 pulley to the insertion of the FDS. It is notoriously difficult to treat because the tendons are closely confined within the narrow fibrous sheath, making adhesions very likely.
2. Can I use my hand immediately after surgery?
Absolutely not. The repair is at its weakest during the first 3 weeks. You must adhere strictly to your splinting schedule.
3. What is the success rate of this surgery?
Success rates are high (often >85-90%) in centers of excellence, provided the patient is compliant with hand therapy.
4. How long does the surgery take?
Typically 60 to 90 minutes, depending on the complexity of the laceration and the number of tendons involved.
5. Will I have full range of motion?
Most patients regain functional range of motion, but achieving "perfect" pre-injury mobility is rare due to the inherent formation of scar tissue.
6. What if my finger gets stuck?
This is a sign of an adhesion or a bulky repair. Consult your surgeon; you may need formal hand therapy or, in rare cases, a tenolysis.
7. Why do I need a dorsal blocking splint?
It prevents the finger from extending fully, which would put dangerous tension on the new repair.
8. Is this procedure painful?
Post-operative pain is usually managed with NSAIDs and elevation. Nerve blocks are often used for the first 24 hours.
9. What is the "Place and Hold" technique?
It is a safe way to start using the tendon without the full force of a contraction, reducing the risk of pulling the stitches out.
10. Can smoking affect my recovery?
Yes. Nicotine causes vasoconstriction, which reduces blood flow to the healing tendon, significantly increasing the risk of rupture and complications.
10. Summary and Clinical Outlook
Flexor tendon repair remains one of the most demanding procedures in hand surgery. The transition from "immobilization" to "early active motion" has revolutionized outcomes, allowing patients to regain function faster. However, the surgeon’s technical precision and the patient’s commitment to rehabilitation are the dual pillars upon which success rests. Future developments in bio-resorbable sutures and tendon-healing biological scaffolds continue to push the boundaries of what is possible in tendon reconstruction.