Tendon Injuries

Hand tendons are the fibrous cables connecting muscles to bones, enabling finger movement. Flexor tendons (within the palm and finger pulley system) power finger curling (closing the fist); extensor tendons (on the back of the hand) straighten the fingers. Tendon injuries — most commonly lacerations from sharp objects (knife cuts, glass) — sever this continuity, causing specific functional deficits: a cut flexor digitorum profundus (FDP) tendon disables the distal finger joint; cut FDP + FDS (superficialis) prevents all finger flexion. Extensor tendon cuts cause inability to straighten the finger or a "mallet finger" drop at the fingertip. Without timely repair, fibrous retraction, adhesion formation, and joint stiffness make secondary reconstruction significantly more complex.

Primary repair (within 24 hours of injury) is strongly preferred — the tendon ends are fresh, easy to identify, and have not yet retracted deep into the palm or forearm. Delayed primary repair (24 to 72 hours) is acceptable when wound contamination, swelling, or initial emergency management prevent immediate surgery. Secondary repair (after 72 hours) is technically more challenging as tendon ends retract and scarring begins. For injuries presenting after 3 to 4 weeks where primary repair is impossible, tendon grafting (harvesting a spare tendon from the forearm — palmaris longus — or foot to bridge the gap) is performed as a staged procedure.

Zone II (the "No Man's Land" described by Sterling Bunnell) spans from the distal palmar crease to the middle finger joint (PIP). Within this zone, both flexor tendons (FDS and FDP) run in intimate proximity through a tight fibro-osseous tunnel lined with the pulleys (A1 through A5) critical for mechanical efficiency. Any scarring between the two tendons or between them and the pulley system creates adhesions that prevent independent tendon gliding and rob the repair of full finger flexion. Meticulous core repair (4-strand or 6-strand techniques), delicate sheath repair, and rigorous controlled early active motion hand therapy protocols are essential for optimal outcomes in Zone II.

Immobilization of a repaired tendon leads to proliferative adhesion formation between the tendon and surrounding sheath within days — permanently limiting glide. Evidence-based hand therapy protocols (Kleinert, Duran, or Belfast/Modified Early Active Motion protocols) begin within 24 to 72 hours of surgery under the strict supervision of a certified hand therapist. These protocols use a dorsal protective splint to prevent accidental extension while permitting carefully controlled active flexion exercises that stress the repair sufficiently to stimulate intrinsic tendon healing without gapping. Adherence to the prescribed programme is the primary determinant of functional outcome.

Tenolysis is a secondary surgical procedure performed 3 to 6 months after primary repair when dense adhesions — despite optimal hand therapy — prevent adequate tendon excursion and finger flexion. The procedure surgically releases the adhesion bands tethering the tendon to surrounding structures under local anaesthesia (so the patient can actively flex during the procedure to confirm excursion). An immediate post-operative active motion protocol is mandatory to prevent re-adhesion formation in the days following tenolysis. Tenolysis is only offered when: the tendon repair itself is confirmed intact, passive finger motion is full, and the patient is motivated and capable of intensive post-operative therapy.