Define Tendon Injuries of the Hand. Describe its management and complications.

Definition & Anatomy

Tendon injuries of the hand — division of the flexor or extensor tendons — are common after lacerations and are functionally important because tendons transmit the power of the forearm muscles to move the digits. Repair is challenging because tendons must glide smoothly within their sheaths, and scarring (adhesions) readily limits movement.

Flexor Tendon Injuries & Zones

The flexor surface has each digit served by flexor digitorum profundus (FDP) and superficialis (FDS). Injuries are described by zones (I–V). Zone II — where both FDS and FDP run together within the tight fibro-osseous flexor sheath — was historically called ‘no man’s land’ because repairs here adhere and give poor results. Diagnosis is by testing FDP (dip flexion) and FDS (PIP flexion with the other fingers held extended) individually.

Extensor Tendon Injuries

Extensor tendons are more superficial and injured by dorsal lacerations. Classic closed injuries include mallet finger (avulsion of the terminal extensor from the distal phalanx — a dropped dip that cannot actively extend) and boutonnière deformity (central slip rupture at the PIP). Extensor repairs generally do better than flexor repairs.

Management

The principles are meticulous primary repair of the divided tendon (core plus epitendinous sutures) where the wound is clean, careful repair of the sheath/pulleys, and a controlled rehabilitation programme to allow the repair to heal while early protected movement prevents adhesions. Some closed extensor injuries (mallet finger) are treated by splinting in extension. Late/failed injuries may need tendon grafting, tenolysis or tendon transfer. Associated nerve and vessel injuries are repaired at the same time.

Principles of Repair & Rehabilitation

Successful tendon surgery depends on more than the suture itself. The repair must be strong enough to permit early movement yet handle the tendon atraumatically to preserve its blood supply and gliding surface; the pulleys (especially A2 and A4) are preserved to prevent bow-stringing; and any injured digital nerves and vessels are repaired at the same sitting. A supervised early controlled-motion rehabilitation programme then balances the competing needs of protecting the healing repair and preventing the adhesions that would otherwise tether the tendon.

Complications

The characteristic complications are adhesions (limiting glide and movement, the commonest problem, especially in Zone II), rupture of the repair (from overly aggressive early loading), joint stiffness and flexion contracture, and bow-stringing if the pulleys are lost. Persistent loss of movement after healing may require tenolysis (release of adhesions), staged tendon grafting or tendon transfer.

Zone II was called no man's land for its poor repair results.

• Flexor/extensor tendon division common after lacerations; repair aims to restore smooth glide.
• Flexor zones I–V; Zone II (‘no man’s land’, FDS+FDP in the sheath) has the poorest results.
• Test FDP (dip flexion) and FDS (PIP flexion) separately; extensor injuries: mallet finger, boutonnière.
• Primary repair (core + epitendinous sutures) + controlled early-motion rehab to prevent adhesions.
• Mallet finger → extension splinting; late failures → graft/tenolysis/transfer.