Effect of anterior versus posterior in situ decompression on ulnar nerve subluxation.

We sought to determine the effect anterior versus posterior in situ decompression with 360° external neurolysis on ulnar nerve subluxation. Ten cadaveric specimens were used, with anterior release performed on 5 specimens and posterior release the other 5 specimens. Each specimen was released for 4 cm centered over the cubital tunnel followed by 12 cm, 20 cm, and 20 cm with 360° external neurolysis. After release, the elbow was brought through a range of motion from 0° to 140° of flexion. Compared with posterior release, anterior release demonstrated significantly more total subluxation of the ulnar nerve for all release types from 80° to 120° of flexion (P<.05). At 140° of flexion, the 4-cm release, the 12-cm release, and the 20-cm release with 360° external neurolysis also demonstrated significantly more total subluxation with anterior release (P<.05). Ulnar nerve subluxation was significantly lower with posterior release, compared with anterior release for limited and complete in situ decompression.

Unusual case of isolated lunate fracture without ligamentous injury.

Fractures of the lunate are rare injuries that usually result from high-energy trauma and are typically associated with other carpal and ligamentous injuries. The incidence of lunate fractures has been cited as 0.5% to 6.5% of all carpal fractures. These fractures are not frequently reported in the literature, and no consensus exists on the treatment of these injuries in the acute and chronic setting. The mechanism typically producing this fracture is a loading force applied to a dorsiflexed, ulnarly deviated wrist such that the capitate is driven downward into the lunate.No prior reports exist in the literature of an isolated fracture of the lunate without perilunate dislocation or ligament disruption. This article reports a case of an isolated displaced transverse shear fracture of the lunate seen 3 months after initial injury, which was successfully treated using a volar and dorsal combined approach and open reduction and internal fixation using microscrews. Bony union across the fracture site was obtained by 7-week follow-up and continued to show improved consolidation through 10-month follow-up. The patient had decreased pain, normal range of motion, and no radiographic evidence of lunate osteonecrosis on most recent follow-up despite the delayed presentation and degree of fracture displacement. This case demonstrates a previously unreported type of wrist injury.

Disorders of the immature carpus.

Carpal disorders in children are often associated with developmental abnormalities of structures surrounding the wrist. In addition, carpal ossification throughout childhood has unique influences on pediatric carpal injury. Because the immature carpus is composed of unossified cartilage, carpal abnormalities in young children are frequently undetectable on plain radiographs. Clinical suspicion of an abnormality may elicit further imaging with MRI, which can provide detailed information about cartilaginous structures.

Effect of exercise on microsurgical hand tremor.

This study investigated the effects of upper-body and aerobic/lower-body-only (nonupper-body) exercise on microsurgical hand tremor. Subjects were given a task of holding a microsurgical needle tip over a small target, with video-microscopic documentation immediately before and 0, 2, 4, 8, and 24 h after either upper-body or nonupper-body (aerobic) exercise. Tremor was quantified by the amount of time the needle was maintained within a 100 x 100-microm target zone and the number of times the needle extruded from the zone. Both upper-body and aerobic-only exercise groups had significant increases in tremor immediately after exercise (P < 0.02), with a return to baseline tremor 2 h after exercise in the aerobic group and only a slightly prolonged return to baseline (by 4 h) in the majority of upper-body exercise subjects. These findings demonstrate that microsurgical hand tremor increases following exercise, but returns to baseline within 4 h in the majority of individuals, particularly after aerobic-only workouts.