BACKGROUND:The majority of studies focus on the lesions of spinal cord injury, while little evidence is available on the change of morphology and structure of distal nerve, muscle and motor endplates fol owing spinal cord injury.
OBJECTIVE:To investigate the time window change of the morphology of motor neurons and skeletal muscles caudal to the lesion after spinal cord injury in rats.
METHODS:Fifty healthy adult Sprague-Dawley rats were randomly divided into three groups:control group (n=5;without treatment), sham operation group (n=10), and spinal cord injury group (n=35). The sham operated rats only received laminectomy. In the spinal cord injury group, rats were subject to complete T 10 spinal cord injury by total laminectomy and cord transverse resection. Then the morphological change including sciatic nerve, motor endplate and median gastrocnemius was observed for each group at 1, 2, 4, 12, 24 weeks after injury.
RESULTS AND CONCLUSION:(1) The myelin sheath layers of sciatic nerve were separated partial y at 4 weeks in rats with spinal cord injury, the myelin sheaths were fragmented with the regeneration of thin-myelinated and unmyelinated axons at 12 weeks. There was a decrease in myelinated axons and an increase in thin-myelinated and unmyelinated axons at 24 weeks. (2) The synaptic gutters of motor endplate, the presynaptic and postsynaptic membrane and synaptic space were distinct at 4 weeks in rats with spinal cord injury, the degenerated motor endplates coexsisted with the intact ones at 12 weeks. The motor endplate disappeared at 24 weeks. (3) There was a slight decrease in muscle cross-sectional area at 2 weeks in rats with spinal cord injury, but no structural change was found, the membrane of myocytes was partial y weakened at 4 weeks, the border of myocytes was obscure with hyperplasia of connective tissue at 12 weeks, and myocytes gathered and in fusion at 24 weeks. As natural history of completely transected spinal cord injury in rats, there were significant changes in morphology of peripheral nerve, motor endplate and skeletal muscles caudal to the lesion at 12 weeks, and the changes were destructive at 24 weeks.

Objective:To observe the effect of early weightbearing after anterior cruciate ligament reconstruction (ACLR) on lower limb motor function, activation of the knee muscles and the stability of the knee joint.Methods:Forty-four persons who had received ACLR were divided at random into a control group and an experiment group, each of 22. In addition to conventional rehabilitation treatment after surgery, the control group underwent weightbearing training from the 8th day after the surgery, while the experimental group began weight-bearing training from the 3rd postoperative day. Both groups had their motor functioning evaluated using the International Knee Scoring Committee (IKDC) knee subjective evaluation form 3 days after the operation, and then 6 and 12 weeks later. Their pain perceptions were quantified on the same schedule using visual analogue scoring (VAS), and protractor measurements documented active range of motion (AROM). Electromyography (AEMG) of the medial head and rectus femoris muscle was also performed, and the stability of the knee joint was assessed using the KT-1000 test.Results:After the intervention, the average IKDC score, VAS score, knee extension and flexion AROMs, medial quadriceps head AEMG ratio, and rectus femoris muscle AEMG ratio improved to different degrees in the two groups. At 6 weeks the average pain score, knee extension and flexion ranges of motion, quadriceps medial head AEMG ratio, and rectus femoris AEMG ratio of the experimental group were all better than the control group′s averages. At 12 weeks the average IKDC subjective knee function score in the experimental group was also superior.Conclusions:Supplementing conventional rehabilitation with early weight-bearing can significantly improve the recovery from anterior cruciate ligament reconstruction. Beginning on day 3 after the operation gives the best results.