CASE                                8                               

A 17-year-old male sustained an injury to his middle finger while catching a football. When examined by his coach on the field, it was felt to be a sprain, and he continued playing the game. After he finished the game, he was noted to have a

finger bent at the distal interphalangeal joint, and he was unable to straighten it (Fig. 4–7). He was seen in the emergency room where x-ray showed no obvious fracture. He was then splinted and asked to see you in consultation.

Figure 4–7

The most likely diagnosis in this situation is:

1. DIP joint dislocation

2. Flexor profundus avulsion

3. Mallet finger

4. Sprain of the DIP joint

Discussion

The correct answer is (C). This is a typical presentation of a mallet finger. A mallet finger is an injury which affects the insertion of the terminal extensor mechanism onto the base of the distal phalanx. This can present as avulsion of the tendon without a bony fragment being attached (the so-called soft tissue mallet) or there may be avulsion of a bony fragment (also known as a bony mallet). In this instance, the patient had x-rays that did not show any bony injury, so this would qualify as a soft tissue mallet.

The patient is noted to have no ability to extend his DIP joint actively; however, passive extension is full. The patient wishes to continue playing football.

The most appropriate management at this time would be which of the following?

1. Application of a tip protector splint maintaining the DIP joint at neutral and the PIP joint free

2. Closed reduction and percutaneous pin fixation of the DIP joint

3. Open repair of the extensor mechanism

4. Open repair and pinning of the DIP joint

Discussion

The correct answer is (A). A soft tissue mallet, such as this one, can be treated nonoperatively. The patient’s sporting interest should not factor significantly in the decision making process. Should the patient have any degree of subluxation, which would be seen on the lateral radiograph of the finger, then the most appropriate recommendation would be to perform a closed reduction, realign the joint, and pin it. However, in this case where the lateral radiograph does not show any evidence of subluxation and there is no evidence of bony injury, such an injury can be treated effectively with a splint. There are numerous splints available for the treatment of soft tissue mallets. In the experience of this group of authors, a quick-setting, fiberglass cast application, which maintains the DIP joint at neutral and leaves the PIP joint free, is extremely effective in treating this condition. The patient and his family should be cautioned that irrespective of the duration of treatment and irrespective of the method of treatment, in most circumstances this injury heals with a slight dorsal bump and a slight droop with lack of the terminal few degrees of extension.

On the day the patient comes to see you, he is accompanied by one of his colleagues who also sustained a similar injury but whose x-rays show that he has a bony avulsion of the distal phalanx base. The size of the fragment involves about 30% to 40% of the articular surface, and there is no evidence of any joint subluxation.

The most appropriate recommendation for this patient would be which of the following?

1. Open repair of the bony avulsion

2. Closed reduction and percutaneous pin fixation of the bony avulsion

3. Treatment with a splint

4. Open repair and trans-articular pinning

Discussion

The correct answer is (C). This patient has a bony avulsion. While some investigators believe that the size of the fragment is important in the decision-

making about the need for internal fixation, there is no evidence to suggest that fragment size affects the long-term outcome. However, subluxation of the joint does affect long-term outcome as it promotes early degeneration. In this particular instance, the lateral radiograph does not show any evidence of subluxation. Therefore, although this patient has a bony mallet and the fragment appears to be 35% to 40% of the articular surface, this can also be treated nonoperatively. A similar cast, as applied to the other patient, is applied on this patient as well. Most bony mallets tend to heal in a more predictable fashion and over a shorter duration of time (4 weeks), whereas soft tissue mallets tend to require longer duration of splinting. It also appears that bony mallets tend to have a lesser droop and a smaller dorsal bump than soft tissue mallets. In both instances, the indications for internal fixation are the presence of subluxation of the joint. Patients who present early can have the subluxation reduced in the operating room, and the joint may be pinned, disregarding the size of the fragment and allowing the joint to heal in its anatomical position. However, should the subluxation not be reducible, a formal open reduction and joint reduction as well as internal fixation needs to be performed.

Objectives: Did you learn...?

Identify clinical presentation of Mallet finger? Treat Mallet finger?