Effect of preserving paraspinal muscles on postoperative axial pain in the selective cervical laminoplasty

Study Design. A retrospective clinical study. Objective. To evaluate the effect of preservation of paraspinal muscles attached at the spinous process of C2 or C7 in selective laminoplasty on postoperative axial pain. Summary of Background Data. Several methods of modified laminoplasty such as selective decompression and/or reconstruction of detached paraspinal muscles have been reported. It is still unclear, however, which posterior muscles need to be preserved to reduce postoperative problems. Methods. The study group consisted of 145 patients who underwent cervical laminoplasty. The level of decompression was decided based on preoperative cervical magnetic resonance imaging. The level of detachment of muscle from the spinous process was from 1 cranial to the decompression level and to the same level caudal to the level of decompression. Clinical outcome was evaluated based on improvement ratio of Japanese Orthopedic Association (JOA) score. In addition, the risk factors for postoperative axial pain were examined by multivariate logistic regression analysis. Results. In 113 patients, C2 paraspinal muscles were detached, with elevation of the C3 lamina, and the improvement ratio of JOA score was 56.0%. In 32 patients, the muscles were preserved, without elevation of the C3 lamina, with corresponding ratio of 54.8%. In 112 patients, C7 paraspinal muscles were detached, with elevation of the C7 lamina, and in 33 patients the muscles were preserved; the improvement ratios of JOA score for these groups were 56.7% and 52.4%, respectively. There were no significant differences in clinical outcome among the groups. Older age (odds ratios: 0.17, 95% confidence intervals: 0.04-0.72) and preservation of muscles attached at the C2 spinous process (OR: 0.13, 95% CI: 0.02-0.98) decreased the risk of postoperative axial pain. Conclusion. Muscle-preserving selective laminoplasty yielded clinical outcomes equivalent to those of conventional C3-C7 laminoplasty in cervical compression myelopathy. Preservation of the muscles attached at C2 resulted in reduction of postoperative axial pain.