Management of peripheral nerve defects: external fixator-assisted primary neurorrhaphy.

BACKGROUND: Controlled joint extension followed by gradual distraction with use of an external fixator may facilitate primary repair of peripheral nerve defects by permitting end-to-end repair without tension. The hypothesis of the present study was that gradual lengthening of nerve repairs with use of incremental distraction would provide superior results compared with grafting or repair under tension. METHODS: A median nerve segment measuring four times the diameter of the nerve was resected in thirty-six rabbits to create a 7-mm gap in the nerve. Neurorrhaphy was performed with use of one of three techniques. In Group 1 (cable graft), a tension-free medial antebrachial cutaneous graft was placed to allow full range of motion of the elbow postoperatively. In Group 2 (end-to-end repair without distraction), the elbow was externally fixed in hyperflexion and the nerve was repaired end-to-end. At fourteen days, the fixator was removed and unprotected elbow motion was permitted. In Group 3 (end-to-end repair with gradual distraction), the elbow was externally fixed in hyperflexion and primary neurorrhaphy was performed. At fourteen days, the elbow was extended 10 degrees every other day with use of the articulated external fixator until full extension was achieved. Median nerve amplitude, latency, and nerve-conduction velocity; flexor digitorum superficialis single-twitch force generation and maximum tetanic force generation; muscle mass; and elbow range of motion were measured at three or six months. In addition, histologic analysis of the median nerve distal to the repair site and the morphometry of the neuromuscular junction in the flexor digitorum superficialis were performed at six months. RESULTS: All rabbits regained full active and passive range of motion. At three months, the nerve-conduction velocities in Groups 2 and 3 were significantly greater than that in Group 1. At six months, the nerve-conduction velocities and amplitudes in Group 3 were significantly greater than those in Groups 1 and 2. At six months, the tetanic force in Group 3 was significantly greater than those in Groups 1 and 2. There were no significant differences in muscle mass among the groups. There were no significant differences in histological findings among the three groups, although there was a trend toward larger fiber size in Group 3 as compared with the other two groups. The neuromuscular junctions in Group 3 had a significantly larger surface area than did those in Group 1 (p = 0.002) and Group 2 (p = 0.034). CONCLUSION: The use of an articulated external fixator and controlled gradual distraction appears to facilitate the treatment of peripheral nerve defects.

Arthroscopic resection of the common extensor origin: anatomic considerations.

This study examines the intra-articular anatomy and safe zones for arthroscopic resection of the common extensor origin for the treatment of lateral epicondylitis. The extensor complex was arthroscopically debrided in 7 cadaveric elbows to determine the percentage of each tendinous origin that was resectable. Elbow stability was assessed, and safe zones of resection were determined. The extensor carpi radialis brevis and extensor digitorum communis origin was resected a mean of 100% and 90%, respectively. Elbow stability was maintained when resection did not extend posteriorly to an intra-articular line bisecting the radial head. Posterolateral rotatory instability occurred when debridement was continued posteriorly to the axis of the radial head. In conclusion, complete resection of the extensor carpi radialis brevis-extensor digitorum communis common origin is achievable via standard arthroscopic techniques. The lateral ulnar collateral ligament remains intact and elbow stability is maintained when debridement of the extensor origin does not extend posteriorly to a line bisecting the radial head.

Radius pull test: predictor of longitudinal forearm instability.

BACKGROUND: Longitudinal instability of the forearm (the Essex-Lopresti lesion) following radial head excision may be difficult to detect. This cadaveric study examines a stress test that can be performed in the operating room to identify injury to the ligamentous structures of the forearm. METHODS: Twelve cadaveric upper extremities were randomized into two groups and underwent radial head resection. Group 1 underwent sequential transection of the triangular fibrocartilage complex and the interosseous membrane. Group 2 underwent sequential transection of the interosseous membrane and the triangular fibrocartilage complex. Ulnar variance and radial migration were examined with use of fluoroscopy of the wrist before, during, and after the application of a 9.1-kg load via longitudinal traction on the proximal part of the radius. RESULTS: Group 1 demonstrated no significant changes in proximal radial migration with load (compared with the findings after radial head resection alone) after transection of the triangular fibrocartilage complex. However, Group 2 demonstrated significant changes in proximal radial migration with load after transection of the interosseous membrane (p = 0.03; median, 3.5 mm). In both groups, transection of both the triangular fibrocartilage complex and the interosseous membrane resulted in significant changes in proximal radial migration with load (p = 0.001; median, 9.5 mm). When the load was removed, specimens were ulnar positive (median, 3.0 mm), with no specimen returning to the preload position of ulnar variance (p = 0.001). CONCLUSION: After radial head resection, 3 mm of proximal radial migration with longitudinal traction indicated disruption of the interosseous membrane. In all specimens, proximal radial migration of > or =6 mm with load indicated gross longitudinal instability with disruption of all ligamentous structures of the forearm.

Technique for iliopsoas ultrasound-guided active electromyography-directed botulinum a toxin injection in cerebral palsy.

Symptomatic hip flexion deformity secondary to iliopsoas spasticity may interfere with gait, impair sitting balance, or contribute to hip subluxation or dislocation. A nonsurgical, minimally invasive technique to ameliorate iliopsoas spasticity is presented. The technique uses intramuscular injections of botulinum A toxin to provide selective neuromuscular blockade of the iliacus or psoas muscles or both. Because of the anatomic location of the target muscles, this technique uses ultrasound guidance for needle placement. Active electromyographic stimulation is used to verify the needle position adjacent to active myoneural interfaces. The authors' experience to date includes the treatment of 28 patients (53 hips). Use of this technique has resulted in improved hip range of motion. No intraoperative or postoperative adverse events or complications have been observed.