Spinal Sagittal Imbalance In Patients With Lumbar Disc Herniation

BackgroundNowadays spinal sagittal imbalance is a hot topic. There has been an increasing recognition of the importance of sagittal spinopelvic alignment in patients with spinal diseases as it relates to clinical outcomes. Many kinds of diseases result in spinal sagittal imbalance including spinal deformity (scoliosis and kyphosis), spinal fracture (injury and pathology), spinal infection (tuberculosis spondylitis and brucellar spondylitis), spinal degenerative diseases (lumbar disc herniation, lumbar spondylolisthesis, lumbar stenosis).Spinal sagittal imbalance is a widely acknowledged problem, but there is insufficient knowledge regarding the factors that contribute to its occurrence. Whether it is a structural spinopelvic sagittal imbalance or a compensated one is difficult to recognize. We take patients with lumbar disc herniation (LDH) as the model to identify the mechanism of the spinal sagittal imbalance.ObjectivesThe aim of this study is to illustrate the spinopelvic sagittal characteristics and identity the role of spinal musculature in the mechanism of sagittal imbalance in patients with lumbar disc herniation by analyzing the spinopelvic parameters and the electromyography parameters.MethodsThis review focused on a group of 25 adults with spinal sagittal imbalance who initially presented to our clinic for treatment of LDH, followed by posterior discectomy between 2012 and 2013. Radiographic measurements included trunk shift and sagittal profile. The strength of the spinal musculature preoperatively and postoperatively was compared by some specific measurements recorded by electromyography (EMG). All the patients have received more than 1 year’s follow-up and no complications was noted.ResultsAll the patients restored sagittal balance immediately after lumbar discectomy. The mean SVA preoperatively (11.6±6.6cm) were significantly larger than those values postoperatively (-0.5±2.6cm). The preoperative mean thoracic kyphotic angle was (24.7±11.3°) and decreased to (22.0±9.8°) postoperatively. The mean lumbar lordotic angle and sacral slope angle before surgery (25.3±14.0° and 25.6±9.5°, respectively) were significantly smaller than those after surgery (42.4±10.2° and 30.4±8.7°, respectively), while preoperative pelvic tilting angle (20.7°±7.8°) was larger than the postoperative one (15.8±5.5°). The largest recruitment oder on the level of T7-T8, T12-L1 and the herniated level all improved significantly from (0.43+0.24mv,0.46+0.21mv,0.32+0.17mv, respectively) preoperatively to (0.76+0.34mv,0.73+0.17mv,0.95+0.31mv, respectively) postoperatively. The mean ODI was 77.8% before surgery to 4.2% at the final follow-up.ConclusionsSome patients with lumbosacral nerve compression syndrome caused by the LDH tend to be in a passive scoliotic position with spinal sagittal imbalance. Compensatory mechanism of spinal sagittal imbalance mainly includes a loss of lumbar lordosis, an increase of thoracic kyphosis and pelvis tilt. Spinal musculature plays an important role in spinal sagittal imbalance in patients with LDH. The spinal sagittal imbalance caused by LDH is a kind of compensated sagittal imbalance. Early posterior discectomy can provide a great opportunity for spontaneous correction of sagittal imbalance.