Increase in Paravertebral Muscle Activity in Lumbar Kyphosis Patients by Surface Electromyography Compared With Lumbar Spinal Canal Stenosis Patients and Healthy Volunteers

Paravertebral muscle activity measurement by surface electromyography (EMG) in lumbar degenerative patients and healthy volunteers.Muscle activity was tested in the standing position, and the influence of low back pain and alignment of the lumbar spine was assessed in the patients with lumbar kyphosis (LDK) or canal stenosis.The number of kyphosis patients has increased as the population has grown older. Advanced kyphosis can cause difficulties in maintaining a standing position and affect daily living activities. The most direct cause is the atrophy of erector spinae muscles. The activity of these muscles has not yet been sufficiently evaluated and needs to be assessed objectively for the purpose of diagnosis and treatment.The subjects were kyphosis patients who were 60 years of age or older, age-matched lumbar spinal canal stenosis patients, and healthy volunteers. Muscular activity at the L1-L2 and the L4-L5 intervertebral areas was recorded by surface EMG in the resting standing position and also with a weight load held in the standing position. Muscle activity and muscle fatigue, and the association between the Visual Analogue Scale, the Japanese Orthopaedic Association score for low back pain, and muscle activity, were analyzed.Kyphosis patients had a greater muscle activity in the lower back in the resting standing position and more severe muscle fatigue at the upper lumbar spine in comparison with patients with lumbar spinal canal stenosis. There was no association between muscle activity and clinical findings in patients with LDK although.Our study revealed the constant activity of paravertebral muscles and the susceptibility to muscle fatigue in patients with LDK. The quantification of muscle activity by surface EMG may show the pathology of LDK, and the decrease in muscle activity in the standing position may be a potentially useful index for guiding treatment.