bubble_chart Overview

Hand tendon injuries are mostly open, with lacerations being the most common, often accompanied by neurovascular injuries or bone and joint injuries. Closed lacerations can also occur. After a tendon rupture, the corresponding joint loses its function. For example, if the flexor digitorum superficialis tendon is ruptured, the proximal interphalangeal joint of the corresponding finger cannot flex; if the flexor digitorum profundus tendon is ruptured, the distal interphalangeal joint cannot flex; if both the flexor digitorum superficialis and profundus tendons are ruptured, neither the proximal nor the distal interphalangeal joints can flex. Since the intrinsic hand muscles remain intact, the flexion of the metacarpophalangeal joint is not affected. Ruptures of the extensor tendons at different locations result in the inability to extend the corresponding joints and may lead to deformities.

bubble_chart Treatment Measures

(1) Deep Tendon Insertion Zone (Zone I): From the middle part of the middle phalanx to the insertion point of the deep tendon. This zone contains only the flexor digitorum profundus tendon. If ruptured, early repair should be attempted, with direct suturing of the ruptured ends. If the rupture occurs within 1 cm of the insertion point, the tendon end can be advanced, i.e., the distal segment is cut, and the proximal end is reattached to the insertion point.

(2) Tendon Sheath Zone (Zone II): From the beginning of the tendon sheath to the attachment point of the flexor digitorum superficialis (i.e., the middle part of the middle phalanx). In this segment, the deep and superficial flexor tendons are confined within a narrow tendon sheath, making them prone to adhesion after injury, difficult to manage, and often resulting in poor outcomes. Hence, it is also known as the "no man's land." Currently, it is generally recommended that if the flexor digitorum superficialis tendon is ruptured due to traction, it may not need to be sutured to avoid adhesion. If both the deep and superficial tendons are ruptured, only the deep tendon should be sutured, while the superficial tendon is excised, preserving the tendon sheath and pulley. Some also advocate for the simultaneous repair of both deep and superficial flexor tendons.

(3) Palmar Zone (Zone III): The area distal to the transverse carpal ligament up to where the tendons enter the tendon sheath. In the palm, the lumbrical muscle attaches to the radial side of the deep tendon, limiting the retraction of the proximal tendon after rupture. If both deep and superficial tendons are ruptured in the lumbrical muscle zone, they can be sutured simultaneously, with the lumbrical muscle wrapping around the deep tendon to prevent adhesion with the superficial tendon. From the lumbrical muscle to the tendon sheath segment, only the deep tendon is sutured, and the superficial tendon is excised.

(4) Carpal Tunnel Zone (Zone IV): Nine tendons and the median nerve are crowded within the carpal tunnel, which has limited space. The median nerve is superficial and often injured along with the tendons. During treatment, the transverse carpal ligament should be incised, and only the deep tendon and the flexor pollicis longus tendon should be sutured, while the superficial tendons are excised to increase space. The suture sites should not be on the same plane. The median nerve must also be sutured simultaneously.

(5) Forearm Zone (Zone V): From the origin of the tendons to the proximal end of the carpal tunnel, i.e., the lower third of the forearm. In this zone, the flexor tendons are protected by the paratenon and surrounding soft tissues, reducing the chance of adhesion. If the flexor tendons are injured in this zone, primary suturing should be performed, often yielding good results. However, when multiple deep and superficial flexor tendons are ruptured, the suture sites should be staggered to reduce adhesion.

Rupture of the flexor pollicis longus tendon should also be repaired primarily. At the level of the metacarpophalangeal joint, the tendon is sandwiched between two sesamoid bones, making it prone to adhesion. For ruptures at this level, the tendon is not directly sutured. Instead, the distal segment is excised, and the tendon is lengthened at the musculotendinous junction above the wrist. The distal segment is advanced and reattached to the insertion point. Alternatively, the flexor digitorum superficialis tendon of the ring finger can be transferred to replace the flexor pollicis longus tendon. For ruptures within 1 cm of the insertion point, tendon advancement is typically used without lengthening the tendon.