Module 7 - Hand Injuries

Tendon Injuries

Tendon lacerations are amongst the most common injuries to be seen in the Emergency Room. They must be considered any time a laceration occurs of the course of a flexor or extensor tendon in the hand. Examination to diagnose a flexor extensor tendon laceration is straight forward. The inability to flex the DIP joint of the finger while holding the other digits immobile suggests an injury to the flexor digitorum profunds tendon. Inability to flex the IP joint of the thumb suggests flexor pollicis longus laceration. Flexor digitorum sublimis laceration is suggested by the inability to flex the PIP joint. Inability to extend any joint suggests an extensor tendon laceration.

Flexor Tendon Injuries - B. Miller, L. Sigurdson (Microsoft PowerPoint)

 

A. Flexor Tendon Lacerations

Zones of injury

There are Five zones of flexor tendon injuries:

• Zone 1: Distal to the insertion of the sublimis tendon n the middle phalanx.
• Zone 2: Between the sublimis insertion and the proximal end of the flexor sheath.
• Zone 3: Mid-palm.
• Zone 4: Carpal tunnel.
• Zone 5: Distal forearm.

Zone 2 is called no-man's land since two flexor tendons run through the flexor sheath in this area and the prognosis after a flexor tendon injury in this area is generally worse than the other areas.

Flexor tendon sheath: The flexor tendon sheath is composed of five annular and three cruciate pulleys which control the flexor tendons during finger flexion and extension. It is important to preserve the A2 and A4 pulleys after flexor tendon injuries to avoid bowstringing (associated with weakness and poor range of motion).

Flexor tendon repair: It is difficult to obtain excellent results after flexor tendon lacerations due to the anatomy of the flexor tendons within the flexor sheath. The essential features of the repair include atraumatic tissue handling, a blood-free field, magnification, and anatomic repair. Generally, these criteria are satisfied only in the main operating room and it is generally recommended that hand surgeons perform flexor tendon repairs.

 

B. Extensor Tendon Lacerations

Extensor tendon injuries are common and occur on the dorsum of the hand or fingers. It is important to understand the anatomy of these tendons prior to repair. On the dorsum of the hand, there are a number of extensor tendon as well as juncturae tendinum. On the dorsum of the finger, the extensor anatomy consists of a central slip which attaches on the dorsal lip of the middle phalanx, the lateral bands of the extensor tendon. As well, there are a number of important ligaments including the triangular ligament, the sagittal band, and the retinacular ligaments. The anatomy of the extensor tendons over the wrist joint is complex and is included in six compartments.

Extensor tendon repairs: Extensor tendon lacerations can often be repaired in the Emergency Room. Meticulous surgical technique including hemostatsis , a blood-free field, good lighting and instruments is essential. Usually the tendonsare repaired using a 4-0 non-absorbable suture such and Mersilene or Ticron. Local anesthesia and a tourniquet are used. Exposure can be obtained using a longitudinal or zig-zag incision over the proximal and distal ends of the tendon. Once the tendon is repaired, splinting is needed for three to four weeks. Following this, a referral to physiotherapy for active and passive range of motion exercises is usually needed.

Author: Dr. SF Morris