Changes of posture and muscle activities in the trunk and legs during walking in patients with lumbar spinal stenosis after decompression surgery. A preliminary report

Neurogenic intermittent claudication is a main symptom in lumbar spinal stenosis (LSS), and postural change is often observed during walking. This study aimed to identify the changes in posture and muscle activity in the trunk and legs during walking in patients with LSS by examining 6 patients who had undergone decompression surgery. None of them had significant paralysis. Gait analysis using Vicon motion capture system® with electromyographic recordings of the paravertebral muscles (PVM) and vastus lateralis muscle (VL) was performed preoperatively and 2 weeks postoperatively. Results showed that the thorax angle indicating the degree of trunk flexion after walking decreased significantly and the pelvic angle tended to decrease after surgery. However, there were no difference in the spine angle, which is a measure of the motion of the thoraco-lumbar spine among the evaluations. The knee angle increased significantly after surgery both at the beginning and at the end of walking, but the angles of the hip and ankle did not change significantly after surgery. Knee torques increased significantly after surgery both at the beginning and at the end of walking. The activity of the PVM decreased and that of the VL increased after surgery. The results indicate that patients with LSS walk in a forward-bending position without flexing the spine, which can be one of the neurologic symptoms. Increases in knee torque and VL activity seemed to reflect the increase of walking speed, and the decrease of PVM activity appeared to be caused by postural improvement after surgery.