Nerve palsy during femoral lengthening: MRI, electrical, and histologic findings in the central and peripheral nervous systems--a canine model.

Six dog's femurs were lengthened until complete peroneal palsy was present. Ten-24 days later MRIs of the spinal cords were normal. EMGs located lesions at the spinal foramina in five dogs and at the lumbar plexus in one. In all dogs nerve conduction below the lesions was normal and amplitudes were diminished. Muscle histology confirmed neurogenic atrophy. Nerve histology at the sites of the lesions showed myelin and axon changes, but there was no Wallerian degeneration at or distal to those sites. Thus, the nerve lesions were either a variant of Sunderland first degree injury or were developing into second degree.