Hand Injury / Tendon and Nerve Repair | Assessing a cut or crushed hand

Hand trauma often needs microsurgical facilities for small vessel and nerve repair, and nerves are complex structures that may not recover as well as ligaments, tendons or bones; despite optimal treatment, many nerve injuries leave some permanent dysfunction. In severe cases with epineurium damage, surgery may be needed for meaningful recovery. Tendon outcomes also depend on mechanism: clean cuts with the finger extended may need less exposure and allow easier retrieval, while ragged, crushing or multi-structure injuries can cause more swelling and adhesion. A surgeon may also need to protect nearby neurovascular structures during dissection and repair. Careful assessment helps decide whether exploration, repair, or rehabilitation is most appropriate. Outcomes vary by injury severity and patient factors.

Nerves and tendons work together for finger movement. Injured motor nerves can stop the controlled muscle working; for example, radial nerve injury can prevent straightening fingers or thumb and extending the wrist. Many nerves are mixed, so feeling and movement may both be affected. Tendon injuries often occur with open wounds and may involve nerves or blood vessels, so the whole hand needs prompt specialist assessment. Tendon injuries can seriously affect hand function, and appropriate therapy and rehabilitation are essential. Hand trauma treatment varies by injury type. Surgical skill strongly affects tendon outcomes; when experienced tendon surgeons are unavailable, patients should be referred to hand centres with more experience.

The tendon may still move the finger, yet a partial tear can leave a rough edge that catches during gliding and may progress to complete rupture. Evidence distinguishes smaller partial injuries, cut through less than 40% of the cross section, which may be managed without surgery, from larger partial lacerations, where repair can improve gliding and protect the intact portion. Management remains debated, and decisions depend on examination, mechanism and function. Early active motion and synergistic wrist motion are beneficial for healing and remodeling, while postoperative gliding depends on repair method and motion regimen. A strong repair aims to withstand early motion while minimizing resistance to tendon gliding.

After a hand wound, nerves are fragile and can be damaged by pressure, stretching, or cutting. Injury to a nerve can stop signals to and from the brain. This can cause muscles to stop working properly and result in loss of feeling. The fingertip is a precise sensory organ; injury may reduce detailed localization, sometimes causing numbness or vague tingling. A larger branch or nerve trunk injury can create a neuroma, with an acutely sensitive area and impaired sensation farther down; severe pain may limit function. Nerve injuries can be treated to improve outcomes, but nerves recover less well than ligaments, tendons and bones, and some permanent dysfunction can remain despite optimal treatment.

In hand trauma, clinicians inspect the wound and test function, including nerves and tendons, because bleeding vessels in neurovascular bundles may indicate nerve injury rather than a perfusion threat. For the finger itself, warmth, pink colour, capillary refill, signs of venous congestion and pulse oximetry help judge blood flow; readings above 95% suggest no vascular injury. Lower readings, coldness, pallor or congestion may need urgent review. Radiographs may help rule out fractures or foreign bodies, and direct exploration may be needed to find structural damage. These checks are part of a broader clinical assessment, not a diagnosis by themselves, and should be interpreted with the whole injury picture.

Radiographs of the injured finger or hand may help exclude a retained foreign body or underlying fracture. For glass injuries, wound exploration is also recommended for potentially glass-bearing wounds. In one study, sharp lacerations were much less likely to receive plain radiographs than crush or saw injuries, and saw or crush injuries showed higher rates of bony injury or foreign body with changes in management. For fractures, adequate radiographs in three planes are important, and radiographs of the injured digit are preferred over hand films for phalangeal fractures. Clinical judgment should guide imaging because fragments can be missed in real clinical settings.

Musculoskeletal ultrasound in skilled hands allows real-time, dynamic assessment of hand and wrist tendons, such as flexor tendon bowstringing, and can help evaluate soft tissues and locate foreign bodies. Definitive assessment of tendon function requires active participation; in children, examination findings can be unclear and ultrasound has limited accuracy if they are uncooperative. Concurrent nerve and blood-vessel injury should always be assessed. X-rays may help exclude a retained foreign body or fracture. MRI or ultrasound may also show nerve injury and the injury zone, which can help with surgical planning. If doubt remains, exploration under anaesthesia may be needed, and MRI or CT may sometimes be considered.

Human bites often occur as clenched-fist injuries over the knuckle, where a small puncture can involve tendon sheath, joint or bone and may look minor at first. Delayed presentation can require vigorous cleansing, debridement, broad-spectrum intravenous antibiotics and leaving the wound open to heal by secondary intention. Clean cuts allow simpler tendon retrieval and repair, while ragged, crushing or contaminated injuries cause more swelling and adhesion. Nerves are complex and may not recover fully even with optimal treatment. Microsurgical facilities may be needed for small nerve or vessel repair. Bite wounds may need staged repair after infection control. Therefore, the plan depends on contamination, tissue loss and timing, not only the cut.

Primary tendon repair is usually done within 24 hours after cleaning and debridement, but not when contamination, crushing, significant skin loss or multiple severe injuries are present. Clean the wound well and loosely close or cover it; definitive repair can then be delayed. Delayed primary repair after 24 hours and within 10 to 14 days can give comparable results. A 2 to 3 day delay is usually acceptable if thoroughly cleaned, while prolonged delay risks tendon and nerve retraction, especially in zones III, IV and V; securing ends may help. No study validates one best time; a deliberate 4 to 7 day delay may allow infection control and reduced swelling.

Hand tendon zones reflect anatomy and surrounding structures. Zone II, often called no man's land, is difficult because tendons and nearby structures lie close together. Zone III usually has a favorable result, while zone IV may need the transverse carpal ligament divided to see and repair both tendons. Zone V commonly involves multiple tendon and neurovascular injuries, though primary repair is generally successful. Forearm zones can involve muscle, tendon and nerve injuries together. A clean cut usually allows easier retrieval and repair than ragged or crushing injuries, which may cause more swelling and adhesions. Early controlled motion can reduce adhesions and improve strength, but rehabilitation must protect the repair.