CASE                               46                               

The patient is an 18-year-old woman who sustained a laceration to the radial side of her index finger at the level of the PIP joint two and a half weeks prior to her office visit. The injury was sustained when a kitchen knife slipped and accidentally caused a 2 cm laceration to this area. On examination, the patient has anesthesia of the radial side of her index finger distal to the injury, but is able to flex at the PIP and DIP joints without difficulty. Surgery is planned for digital nerve exploration and repair.

Which of the following reasons might predict the existence of a nerve gap and worse prognosis following repair?

1. Female gender

2. Time elapsed between injury and surgical intervention

3. Sharp laceration

4. Patient’s age

5. Anatomic location of the laceration

Discussion

The correct answer is (B). Of the factors listed, a time delay to nerve repair is most likely to result in a nerve gap and poor recovery. Female gender is not predictive of a poor outcome. The sharp laceration and the patient’s young age make her a good candidate to experience more complete nerve recovery.

What is the accepted limit of nerve gap for which a nerve conduit can be used?

1. 5 mm

2. 1 cm

3. 2 cm

4. 3 cm

5. 4 cm

Discussion

The correct answer is (D). In a seminal paper, Mackinnon and Dellon demonstrated that clinical results of nerve reconstruction using a nerve conduit were comparable to standard nerve graft techniques up to 3.0 cm. Although newer conduits and synthetic nerve grafts are available and are becoming more widely used in various clinical settings, the largest gap for which conduits are recommended is 3.0 cm.

If autologous nerve is desired for use in a digital nerve graft, which nerve is commonly utilized and expendable in the upper extremity?

1. Radial sensory nerve at the wrist

2. Lateral antebrachial cutaneous nerve proximal to the elbow

3. Anterior interosseous nerve 5 cm distal to the elbow

4. Dorsal ulnar sensory nerve at the wrist

5. Posterior interosseous nerve at the wrist

Discussion

The correct answer is (E). Of the options presented, the posterior interosseous nerve at the wrist provides the best caliber and fascicle match for the digital nerve in zone

1. The radial sensory and dorsal sensory nerves at the wrist should not be harvested for digital nerve reconstruction because of donor site morbidity. The anterior interosseous nerve, although suitable for nerve reconstruction when harvested distally, should not be utilized immediately distal to the elbow because of motor innervation to the FPL and FDP to the index finger. The lateral antebrachial cutaneous nerve can be harvested distally for a good size match to the digital nerve but should not be harvested proximal to the elbow for this purpose.

Objectives: Did you learn...?

Identify factors that contribute to poor recovery in nerve repair? Indicate uses for nerve conduit?

Identify nerves used for autologous nerve grafting?