nerve repair technique may prove useful in clinical situations involving peripheral nerve defects

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Abstract From J Bone Joint Surg Am. 2004 Jul;86-A(7):1405-13.

Management of peripheral nerve defects: external fixator-assisted

primary neurorrhaphy.

Ruch DS, Deal DN, Ma J, AM, Castle JA, FO, EV, Yoder

JS, Rushing JT, TL, Koman LA.

Department of Orthopaedic Surgery, Watlington Hall, 4th Floor, Medical

Center Boulevard, Wake Forest University School of Medicine,

Winston-Salem, NC 27157.

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. Clinical Relevance: This nerve repair technique may prove

useful in clinical situations involving peripheral nerve defects.