CASE                                9                               

A 34-year-old female got into an altercation in a pub. During the course of the altercation, she struck a mirror sustaining a laceration to the dorsal aspect of her hand as shown in Figure 4–8. She presents to you now a few days out from the injury with difficulty in hand function. She is otherwise healthy, has no other medical problems, and has been in a splint to the fingertips.

Figure 4–8

The most likely cause of her dysfunction is:

1. Splint-related stiffness affecting all the joints in the hand

2. Pain inhibition leading to loss of function in the hand

3. Extensor tendon lacerations of the middle and ring fingers

4. Reflex sympathetic dystrophy

5. None of the above

Discussion

The correct answer is (C). This patient has sustained a laceration across the dorsal aspect of the MP joint of the hand. When the hand is formed into a fist, the extensor tendons are immediately subcutaneous. It is therefore extremely common for any laceration in this area, which runs across the long axis of the extensor mechanism, to sever the extensor mechanism of the fingers partially if not completely. The appearance is fairly typical. In most circumstances, patients are unable to extend their fingers fully at the metacarpophalangeal joint. Should there be any doubt about the ability to extend the metacarpophalangeal joints, infiltration of local anesthetic in this area and an examination in the office can reveal the weakness of extension. The ability to maintain extension against resistance is also a good test, and patients who have partial injury will often times be unable to maintain extension against resistance, the so-called piano key sign.

You have made a clinical diagnosis of extensor tendon injury. The most appropriate form of management at this stage would be which of the following?

1. Short-arm cast with the metacarpophalangeal joints at neutral and the interphalangeal joints free

2. Short-arm cast to the fingertips with all joints at neutral

3. Exploration and open repair of affected structures

4. Dynamic splinting with early range of motion program

Discussion

The correct answer is (C). This patient has a clinical examination consistent with extensor tendon lacerations. It must be noted that weak extension is often times possible even if the laceration involves a substantial amount of the extensor tendon. Another reason to have weak extension is for the patient to be able to extend the digit through the juncturae. The juncturae attach to the extensor mechanism, and should there be a laceration proximal to the junctura, then the patient may still be able to demonstrate extension of the affected digit by using the extensor of the neighboring digit and pulling through the junctura. In this particular circumstance, the patient’s hand needs to be explored further, and the extensor mechanism needs to be repaired.

The patient is taken to the operating room and the extensor mechanism of the middle and ring fingers are noted to be completely lacerated. After repair, the patient is called back to the office for a postoperative follow-up on the fifth day following surgery.

At this stage, the most appropriate form of postoperative rehabilitation and management would be which of the following?

1. Short-arm cast, MCP joints at neutral, and PIP joints free

2. Dynamic splinting with range of motion program

3. Short-arm splint with MCP joint at neutral, and PIP joints free

4. All of the above

Discussion

The correct answer is (D). While surgeon preferences may dictate which type of rehabilitation is performed on the patient, there is no conclusive evidence to show the superiority of one method of rehabilitation of extensor tendon injuries in this particular zone. Extensor tendon injuries are classified into zones 1 through 8 with the odd numbers lying over the distal interphalangeal (DIP), proximal interphalangeal (PIP), metacarpohalangeal (MCP) and the wrist joint, respectively, whereas the even numbers lie over the middle phalanx, proximal phalanx,

metacarpals and proximal to the wrist. Extensor tendon injuries in zones 4 and 5 are commonly seen in patients who sustain punching injuries against a sharp object as described in this case. Postoperatively, after repair, these injuries can be immobilized for a period of 3 weeks before starting a range of motion program, and the immobilization can be done either in a splint or a cast. On the other hand, there is some data to suggest that early rehabilitation with dynamic splinting protocol is superior in terms of early recovery of motion.

Objectives: Did you learn...?

Pinpoint the clinical presentation of extensor tendon laceration? Treat extensor tendon lacerations?

Establish appropriate postoperative rehabilitation?