• Injuries in zone 2 (middle of middle phalynx to distal palmar crease) have a poor prognosis.
• Although flexor tendon repair in these areas is successful in children under eight years of age, a satisfactory result in an adult is difficult to attain, and a primary repair in this area should be carried out by a surgeon experienced in tendon surgery.
Zone 1: middle of middle phalanx to insertion of FDP – flexor sheath has only FDP
Zone 2: Distal palmar crease to middle of middle phalanx. FDS and FDP contained in proximal part of the fibrous flexor tendon sheaths.
Zone 3: Distal limit of flexor retinaculum to distal palmar crease. FDS and FDP lying free in palm. Repair outcome usually good.
Zone 4: Flexor tendons in carpal tunnel. Repair usually does well, but there is a tendancy to adhesion formation
Zone 5: Proximal to flexor retinaculum: Results of repair are usually satisfactory.
Are flexor tendon injuries an emergency
• They should not be repired in ED and if the hand surgeon is not available they should be irrigated and sutured closed and prophylactic antibiotics started. They should be repaired primarily within three weeks.
• The ideal time to perform repair is within 24 hours.
• After 2 weeks the tendon sheaths become scarred and the musculo-tendinous units retract.
What are the principles of operative repair
• Repair in OR
• Incisions: Volar Zigzag
• Haemostasis, debridement and removal of debris and non-viable tissue
• A laceration of <30% tendon diameter is treated with trimming to prevent triggering, but repair is not required.
• A laceration >50% is treated as a complete laceration with suture repair (having <50% of its original strength).
• I use a modified Kessler repair. 4/0 Nylon is used for internal suture and a 6/0 continious epitendinous suture.
• Digital arteries and nerves should be repaired under microscope.
• After repair the limb is placed in a dorsal splint with 30 degrees of wrist flexion, 70 degress of MCP flexion and DIP and PIP fully extended
• Regimented hand therapy regimen is required for follow-up which involve gradual mobilization up to 12 weeks after injury