Obturator nerve transfer to repair lumbosacral plexus nerve root avulsion injuries: anatomic study and clinical application.

Abstract

Objective To provide an effective and safe motor donor nerve for the treatment of lumbosacral plexus nerve root avulsion injuries. Methods The obturator nerve, lumbar plexus and sacral plexus on both sides were exposed on 15 cadaver specimens. The length of obturator nerve was measured from its origin to entrance of the foramen obturatum. The transverse diameter and thickness of the obturator nerve and femoral nerve on both sides were measured individually. The obturator nerve and femoral nerve of each specimen was cut into histological slice, and the amount of myelinated nerve fiber was counted respectively. There were five patients including 4 patients with traumatic lumbosacral plexus nerve root avulsion injuries and 1 patient with lumbar plexus nerve root injuries. The contralateral obturator nerve as motor donor nerve transferred through the retroperitoneal route and direct coaptation with the femoral nerve was performed in 4 cases, and ipsilateral obturator nerve was transferred to the S1 nerve root in 1 case. Results The length, transverse diameter and thickness of the obturator nerve was (10.5±0.9) cm, (2.03±0.37) mm and (2.78±0.29) mm individually. The transverse diameter and thickness of femoral nerve were (3.79±0.58) mm, (6.53±0.61) mm individually. The obturator nerve contained 5974±1996 myelinated nerve fibers and the femoral nerve contained 15 860±4350 myelinated nerve fibers. In 3-7 d after the operation, the muscle strength of adduction on the donor lower limber was decreased to grade 2-3. The functional recovery of muscle strength of quadriceps reconstructed by contralateral obturator nerve transfer recovered to grade 4 in 2 cases, grade 2 in 1 case and grade 1 in 1 case between 8 months to 5 years postoperatively. The muscle strength of triceps surae and finger flexor reconstructed by ipsilateral obturator nerve transferring to S1 nerve root recovered to grade 3 after 11 months postoperatively. Conclusion The contralateral or ipsilateral obturator nerve can be used as a new and effective donor nerve for transferring to repair the lumbosacral plexus nerve root avulsion injuries, and there is no obvious deficit on the function of donor lower limber adduction. Key words: Lumbosacral plexus; Wounds and injuries; Nerve transfer; Obturator nerve