CASE                               38                               

The patient is a 5-year-old boy who is referred into the emergency department with an amputation of his dominant right thumb at the level of the MP joint, sustained during a motor vehicle collision in which a sharp piece of metal lacerated and amputated his thumb. He has no other injuries and is hemodynamically stable. On examination, the patient has a sharp amputation of his thumb through the MP joint, and plain films demonstrate no fractures with preservation of the metacarpal head and proximal phalangeal base.

Which of the following are absolute indications for replantation in this patient?

1. Age of the patient

2. Sharp mechanism of injury

3. Amputation of dominant thumb

4. A and C

5. B and C

Discussion

The correct answer is (D). There are absolute and relative indications for digital replantation. Absolute indications include thumb amputation, multiple digit amputations, amputations in a child, and amputations proximal to the wrist. Relative indications include individual digits distal to the insertion of the FDS (in zone 1). A sharp mechanism of injury is more favorable for success, but by itself is not an absolute indication for replantation.

Which of the following is/are true regarding replantation in this patient?

1. Replantation is more likely to be successful because the patient is a child

2. Replantation is less likely to be successful because the patient’s vascular structures are smaller

3. If replantation is successful, the functional outcomes of pediatric patients are superior to that in adults

4. A and C

5. B and C

Discussion

The correct answer is (E). Replantation in children has a lower success rate than in adults. There are many possible reasons for this phenomenon, including more aggressive attempts at replantation in children and the smaller size of vascular structures. If successful, however, the functional results following pediatric replantation are superior to those achieved by adults, possibly due in part to their adaptability and neuroplasticity.

Unfortunately, the replantation is unsuccessful, and the patient is left with absence of the thumb at the level of the MP joint.

Which is the following is the most appropriate reconstruction to offer the patient?

1. No reconstruction

2. Ilizarov thumb lengthening with groin flap reconstruction

3. Toe-to-thumb transfer

4. Pollicization of the index finger

5. Transfer of the contralateral, nondominant thumb

Discussion

The correct answer is (C). The thumb constitutes approximately 50% of hand function, and absence of the thumb at the level of the MP joint is extremely debilitating. The best option for pediatric thumb reconstruction at the MP joint level is a toe-to-thumb transfer. There is some debate about the indications for great toe versus second toe transfer, and each has been performed with success; the choice of donor site is based upon both surgeon experience and patient preference. Thumb lengthening with groin flap reconstruction will provide a longer post for the thumb, but would be inferior to the results of a toe transfer. Pollicization of the index finger is best suited for traumatic absence of the thumb at the CMC joint level.

Objectives: Did you learn...?

Pinpoint the indications for digital replantation?

Describe the various treatment options after failed implantation?