Tendon Injuries Hand and Upper Limb

Understanding the Tendons of the Hand

Tendons are strong, cord-like structures that connect muscle to bone. The muscles that move the fingers and thumb actually sit in the forearm, and their long tendons run across the wrist and hand to reach the fingers. When a muscle contracts, its tendon pulls on the bone and the joint moves. Because these tendons sit close to the skin — especially on the palm side — even a modest cut can divide a tendon completely.

Flexor vs Extensor Tendon Injuries

• Flexor tendons run along the palm side and bend the fingers and thumb. A flexor injury makes it difficult or impossible to bend a finger. Injuries in the finger (the area surgeons call “Zone II” or “no man’s land”) are particularly delicate because the tendons run through tight sheaths and pulleys.
• Extensor tendons run along the back of the hand and straighten the fingers and wrist. A common example is “mallet finger,” where the fingertip droops after the extensor tendon is disrupted.

Identifying exactly which tendon and zone is involved is essential to planning the repair.

Why Cut Tendons Cannot Heal on Their Own

Tendons are under constant tension, like a stretched rubber band. When one is fully cut, the two ends spring apart and cannot rejoin by themselves — which is why complete tendon lacerations almost always require surgery. Because nerves and blood vessels run right beside the tendons, a deep cut can damage them too, sometimes causing numbness or compromising blood supply, which makes prompt assessment important.

Causes

• Cuts from sharp objects (glass, knives, machinery)
• Sports and workplace accidents
• Sudden forceful movements (for example “jersey finger,” where the tendon is pulled off the bone)
• Crush injuries
• Conditions such as rheumatoid arthritis that weaken tendons and can cause them to rupture without obvious trauma

Symptoms and Diagnosis

Typical signs include an open cut on the palm or back of the hand, inability to fully bend or straighten one or more finger joints, pain on movement, swelling, and sometimes numbness if a nerve is also involved. Partial tears can be harder to diagnose — the finger may still move but with pain, weakness, or catching. A careful clinical examination, and sometimes imaging, confirms the diagnosis.

Surgical Treatment Options

Treatment is tailored to the type, location, and timing of the injury:

• Primary tendon repair – direct repair soon after injury, ideally within the first 1–2 weeks, which gives the best results for clean cuts.
• Delayed repair – when a patient presents late, a planned (sometimes staged) repair is arranged.
• Tendon grafting – when a segment of tendon is missing or too damaged to repair directly, a graft bridges the gap.
• Tendon transfer surgery – when the original tendon or its muscle cannot be restored, a working tendon is rerouted to take over the lost movement.

Where nerves are also injured, microsurgical nerve repair is carried out at the same time. These injuries are part of broader hand and upper limb trauma care.