Patient must remain NPO (nothing by mouth) for at least 8 hours. Perform comprehensive neurovascular assessment, administer prophylactic antibiotics, obtain informed consent, mark the operative site, and complete preoperative laboratory screening including CBC and coagulation profile.
Monitor neurovascular status hourly in the post-anesthesia care unit. Begin supervised physical therapy within 48 hours to prevent adhesion formation. Utilize a strict dorsal blocking splint for 6 weeks. Discharge once pain is controlled and surgical site is stable. Follow up for suture removal and progression of gentle active-passive range of motion exercises.
Comprehensive Guide: Flexor Tendon Repair of the Hand
Flexor tendon repair is a complex orthopedic surgical procedure aimed at restoring the continuity and function of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendons. These structures are the "cables" that allow for finger flexion, and their injury—often resulting from lacerations, crush injuries, or avulsions—requires meticulous surgical intervention and a highly disciplined post-operative rehabilitation program to restore hand dexterity.
1. Introduction and Overview
The flexor system of the hand is divided into five anatomical zones (I–V). The "No Man’s Land" (Zone II), spanning from the distal palmar crease to the insertion of the FDS, is historically the most challenging area to treat due to the confined space within the fibro-osseous sheath and the high risk of adhesion formation. Success in flexor tendon repair is measured not merely by the structural integrity of the repair, but by the ability of the tendon to glide smoothly within its sheath to achieve full range of motion.
2. Technical Specifications & Mechanisms
The Anatomy of the Flexor Apparatus
The flexor mechanism consists of a gliding system of tendons and a pulley system that maintains the tendons against the phalanges.
* FDP: Inserts at the base of the distal phalanx.
* FDS: Splits into two slips to insert on the middle phalanx.
* The Pulley System: Annular (A1–A5) and cruciform pulleys prevent "bowstringing," where the tendon moves away from the bone, significantly decreasing mechanical efficiency.
Surgical Principles
Modern surgical techniques prioritize the "Tendon Repair Trinity":
1. Strength: The repair must be strong enough to withstand early active or passive motion.
2. Gliding: The repair site must be low-profile (minimal bulk) to pass through the pulleys.
3. Biology: Preservation of the vincula (blood supply) is critical to prevent tendon necrosis.
3. Clinical Indications & Usage
Indications for Surgery
Surgical intervention is indicated in the following scenarios:
* Complete Lacerations: Full-thickness cuts resulting in an inability to flex the digit.
* Partial Lacerations: Typically defined as >50% of the tendon width, as these carry a high risk of rupture if left untreated.
* Avulsion Injuries (Jersey Finger): Where the FDP tendon is pulled off the bone, often requiring re-fixation with anchors.
Pre-Operative Preparation
| Phase | Requirement |
|---|---|
| Imaging | Ultrasound or MRI to assess the gap and retraction level. |
| Neurovascular Exam | Assessment of digital nerves and capillary refill. |
| Antibiotics | Prophylactic IV antibiotics (usually Cefazolin) 30–60 minutes pre-incision. |
| Anesthesia | Wide-awake local anesthesia no tourniquet (WALANT) or regional nerve block. |
4. The Procedure: Step-by-Step
Step 1: Exposure and Debridement
- Incision: Bruner (zigzag) incisions are standard to avoid flexion contractures.
- Tendon Retrieval: If the tendon has retracted, a small counter-incision is made in the palm or forearm to retrieve the proximal stump.
Step 2: Core Suture Technique
The core suture provides the primary tensile strength.
* Modified Kessler or Bunnell: Standard core sutures.
* Strands: Current standards favor 4-strand or 6-strand repairs, which are significantly stronger than 2-strand repairs, allowing for early active motion protocols.
Step 3: Epitendinous Suture
A running, circumferential suture (typically 6-0 or 7-0 nylon) is placed around the repair site. This is critical for:
* Smoothing: Reducing the bulk of the repair.
* Strength: Adding ~10-15% to the total repair strength.
* Gap Prevention: Sealing the tendon ends to prevent collagen leakage and adhesion.
Step 4: Pulley Management
If the pulleys are damaged, they must be reconstructed or repaired. If the A2 or A4 pulleys are significantly compromised, reconstruction using a free tendon graft may be necessary.
5. Post-Operative Recovery Protocol
The "Golden Rule" of flexor tendon rehab is the balance between preventing rupture and preventing adhesion.
- Weeks 0–2: Immobilization in a dorsal blocking splint (wrist in 20° flexion, MCP joints in 70° flexion, IP joints extended).
- Weeks 2–4: Passive flexion exercises (Duran or Kleinert protocols).
- Weeks 4–6: Early active motion (EAM) if the repair is robust.
- Weeks 8–12: Gradual strengthening and return to light activities.
- Month 6: Return to heavy lifting and contact sports.
6. Risks, Side Effects, and Contraindications
Potential Complications
- Adhesions: The most common complication, restricting tendon glide.
- Rupture: Often occurs between weeks 3 and 5 when the tendon is softest.
- Flexion Contracture: Permanent stiffness due to prolonged immobilization.
- Infection: Rare, but requires immediate irrigation and debridement.
Contraindications
- Severe Comminuted Fractures: May require stabilization before tendon repair.
- Heavy Contamination: In cases of severe crush injuries, delayed primary repair (secondary repair) may be safer.
- Patient Non-compliance: If the patient cannot follow the strict rehabilitation protocol, the risk of failure is nearly 100%.
7. Alternative Treatments
- Conservative Management: Only for partial lacerations (<30%) where the tendon is stable.
- Tendon Grafting: Used in cases of delayed presentation or failed primary repair (Hunter rod technique).
- Tenolysis: A secondary procedure performed 6+ months post-op to surgically release adhesions if motion is limited.
8. Frequently Asked Questions (FAQ)
1. How long does the surgery take?
Typically 60 to 120 minutes depending on the complexity and the number of digits involved.
2. Can I use my hand immediately after surgery?
No. You will be in a protective splint for at least 6 weeks to ensure the tendon heals securely.
3. What is the most dangerous time for the repair?
Weeks 3 through 5 are critical. The initial inflammatory phase has passed, and the collagen is remodeling; this is when the repair is most susceptible to rupture.
4. Will I regain 100% of my original movement?
While many patients achieve excellent function, some loss of full flexion or extension is common, especially in Zone II injuries.
5. What is the "Jersey Finger"?
It is an avulsion of the FDP tendon from the base of the distal phalanx, commonly occurring in athletes who grab an opponent’s jersey.
6. Does the type of suture material matter?
Yes, non-absorbable, braided sutures (e.g., FiberWire or Ethibond) are preferred for core repairs due to their high tensile strength.
7. Is pain management difficult?
Most patients manage with oral NSAIDs and acetaminophen, though a nerve block may be used for the first 12–24 hours post-op.
8. What happens if the tendon ruptures?
If a rupture occurs, surgical revision is required. However, the outcomes are generally less favorable than the primary repair.
9. Can I drive while wearing the splint?
No. Driving is contraindicated until the splint is removed and your surgeon confirms sufficient grip strength and safety.
10. What is the WALANT technique?
"Wide-Awake Local Anesthesia No Tourniquet." It allows the surgeon to ask the patient to actively flex their finger during surgery to test the repair's gliding and ensure no "catching" occurs.
9. Conclusion
Flexor tendon repair is a demanding field that requires a marriage of surgical precision and patient dedication. The outcomes have improved drastically with the advent of multi-strand core sutures and early active motion protocols. Patients should be counseled that the surgery is only 50% of the journey; the remaining 50% is the diligent adherence to the physical therapy program. By following these evidence-based protocols, surgeons and therapists can maximize the functional recovery of the hand, returning patients to their daily activities with minimal long-term impairment.