Extensor tendon lacerations are caused by an injury to the finger, hand or arm. The injury is typically the result of a traumatic event that results in the lacerations, i.e. deep cuts.
The anatomy of the extensor tendons (tendons that extend or straighten your finger) is very complex.
The extensor tendons, in general, are thinner than the powerful flexor tendons and glide together as a sheet over the finger. The extensor mechanism is very complex, elegant, and delicate.
Lacerations, i.e. deep cuts, of the extensor tendon may be classified by their location. Common locations are:
Lacerations can also vary in their causes and their presentation. For example:
One thing we must keep in mind when evaluating patients is that there are also intertendinous connections between the extensor tendons to the different fingers called Juncturae Tendineae. These are located proximal to the MCP joint in the back of the hand. The extensor tendons for the adjacent finger can pull on the affected tendon through its juncturae, and mask a tendon laceration. Therefore, it’s our responsibility as medical professionals to make this distinction.
With that in mind, diagnosis of extensor tendon lacerations involves careful examination of the hand and testing for extensor function.
Small tendon lacerations that involve only part of the tendon may be treated conservatively after repairing the skin. Splinting or buddy-taping to an adjacent finger may be used while the tendon is healing and allow finger motion.
In cases where the finger extension is weak or absent, surgery is usually required to restore function. In the surgery, the laceration is usually extended slightly to allow exposure and access to the ends of the tendon. The wound is explored and any other injured structures are repaired. The tendon is then repaired with several small but strong sutures. Afterwards, a protective dressing and splint are applied. Range of motion of the tendon is allowed when the tendon is sufficiently healed. This will vary from case the case, depending on the strength of both the tendon and the repair at that location. After the tendon is healed, aggressive therapy will be used to regain motion and strength.
This surgery is usually performed as an outpatient procedure with local standby or twilight anesthesia or axillary block. Risks with this injury and surgery include anesthesia-related risks, wound healing problems or infection, stiffness of the finger, or failure of the repair. In cases of scarring, a later surgery to free the tendon (tenolysis) or joint (capsulotomy) may be required.
In cases where a portion of the extensor tendon has been lost (such as a grinder injury) or cannot be repaired, an extensor tendon graft or transfer may be required. In this situation, a portion of extensor tendon from another donor area is spliced into the extensor tendon for repair. In cases of a transfer, an extensor tendon is rerouted to the necessary finger along with its muscle to substitute for the damaged extensor tendon.