CASE                                2                               

An 18-month-old, male child comes to your office accompanied by his parents who have recently noticed that while he is using his hand, he appears unable to extend his thumb fully (Fig. 4–2A). The child is able to use his hand very well, does not appear to be in any pain, does not cry or fuss, and his sibling does not have a similar problem. Of note, the child was born full-term, and the mother reports that she had not seen this when the child was born. The other side remains unaffected. The x-ray is shown in Figure 4–2B.

Figure 4–2 A–B

The most likely diagnosis is:

1. Failure of development of extensive pollicis longus

2. Post-traumatic flexion contracture of the interphalangeal joint

3. Scar formation of the interphalangeal flexion crease

4. Trigger thumb

5. None of the above

Discussion

The correct answer is (D). This is a well-described and typical presentation for a trigger thumb in a child. Traditionally, trigger thumb was referred to as a congenital trigger thumb. However, there is increasing data showing that a large number of children who present with trigger thumb do not necessarily have it noted at birth. It has also been noted that developmental trigger thumb can occur in children. The exact nature of its causation remains unclear.

The parents are inquiring about treatment options and are confused about what the next step in treatment should be.

The most appropriate advice to give the patient’s parents would be:

1. Nothing needs to be done

2. The child will grow out of it

3. Surgery within the next week

4. Surgery within the next month

5. Observation for 6 months, and if there is no further improvement, then consider surgery

Discussion

The correct answer is (E). Longitudinal studies on the natural history of trigger thumb suggest that most trigger thumbs that do not resolve by the age of 2 years, are likely to persist and are more likely to require surgical release. A thumb with a flexion contracture is an extremely common form of presentation, and the classical triggering with clicking and popping of the thumb in adults is not frequently noted in children.

The parents are also concerned about a swelling that they noticed over the volar aspect of the thumb, and they wonder if the child is developing a cyst in this area.

After you examine the child, the most likely explanation for the swelling would be:

1. Flexor sheath ganglion

2. Hypertrophic sesamoid

3. Notta’s node

4. Subluxed metacarpophalangeal (MP) joint

5. None of the above

Discussion

The correct answer is (C). Pediatric patients with trigger thumb oftentimes will present with a localized thickening or a globular swelling over the volar aspect of the MP joint at the level of the A1 pulley. This is called a Notta’s node. It represents a thickening of the proximal pollicis longus and at the level of the A1 pulley as a response to the pulley’s stenotic condition. In most circumstances, this thickening resolves with the passage of time after the A1 pulley has been released surgically. The patient and the parents need re-assurance that this is part of the entire process, does not represent a separate, pathological process, and that resolution is commonplace after A1 pulley release.

The patient returns to you at the age of 2½ years with no resolution of the thumb flexion deformity. At that stage, you elect to operatively release the A1 pulley of the thumb.

The structure which is most vulnerable to injury during the operative procedure is:

1. The flexor pollicis longus

2. The volar plate

3. The radial digital nerve

4. The ulnar digital nerve

5. All of the above

Discussion

The correct answer is (C). The radial digital nerve lies immediately subcutaneous along the MP flexion crease of the thumb. It must be noted that anatomically, when faced with the thumb in the palm up position, the flexor pollicis longus and the A1 pulley lie slightly more ulnar than would be obvious. Therefore, the incision has to be made at the MP joint flexion crease, slightly ulnar than expected. If the incision is placed a little more radial than planned, the surgeon is likely to encounter the radial digital nerve, and if not careful, the radial digital nerve which lies immediately subcutaneous is likely to get injured. The same condition applies to the adult trigger thumb release as well. During the consenting process for surgery, it is vital that patients who undergo trigger thumb release be alerted to the possibility of this occurrence, however rare.

Objectives: Did you learn...?

Identify the clinical presentation of trigger thumb in a child?

Treat initially for trigger thumb?

Idenfity structures at risk during surgery?