Abstract
Laminoplasty is widely used to decompress the spinal cord in patients with multilevel cervical lesions. Straight cervical alignment may not be a good candidate for laminoplasty because of postoperation progression of kyphosis and loss of cervical spine range of motion (ROM). However, clinical outcomes of laminoplasty did not show a strong and consistent effect based on cervical sagittal alignment. Moreover, the kyphosis progression and ROM change after operation for the patients with preoperative strange cervical alignment are still unclear. This study is to evaluate the change of cervical alignment and ROM in patients with straight cervical alignment after modified Kurokawa cervical laminoplasty. Thirty patients with multiple-level cervical spondylosis (CSM) and straight cervical alignment were included. All patients underwent laminoplasty with the reconstruction of the spinous process-ligament-muscular complex (SPLMC). The modified JOA score was analyzed for clinical assessment. The change of cervical alignment, ROM, T1 slope, and intervertebral disc space Cobb angle were analyzed for radiological assessment. The average JOA score at preoperative and 2 years follow-up were 7.8 ± 1.4 and 13.6 ± 2.1, respectively. The recovery ratio was 63%. At the 2 years follow-up, there were 18 patients who acquired lordotic cervical alignment. 10 patients remained as straight cervical curve, and 2 patients' cervical alignment developed mild kyphosis. 28 out of 30 patients showed improvement of cervical alignment. The cervical alignment was improved from 1.29 ± 10.04° preoperative to 9.58 ± 8.65° postoperative. However, the ROM decreased from 36.8 ± 18.92 preoperative to 25.08 ± 12.10° postoperative. A positive correlation was found between the C2/4 angle change and cervical alignment change, T1 slope and cervical alignment, cervical alignment, and neutral position flexion reserved ROM. A negative correlation was found between the C1/2 angle change and cervical alignment change. Laminoplasty with a reconstruction of SPLMC followed by appropriate postoperative muscle exercises may be an encouraging way to maintain or improve physiological alignment and prevent postoperation kyphosis deformity for the CSM patients with straight cervical alignment at 2 years follow-up.
Highlights
Degenerative diseases of the cervical spine are increasing among the geriatric population, and surgical treatment is becoming more common [1]
Previous studies showed that cervical sagittal alignment plays an important role in the clinical outcomes of laminoplasty
The straight or kyphotic curvature of the cervical spine is not recommended as a good indication for laminoplasty because the laminoplasty may not create enough posterior migration of the spinal cord
Summary
Degenerative diseases of the cervical spine are increasing among the geriatric population, and surgical treatment is becoming more common [1]. Double door laminoplasty has been widely used to treat patients with myelopathy due to cervical intervertebral disc herniation, spinal canal stenosis, and multiple-segment ossification of the posterior longitudinal ligament ossification This surgical technique preserves the integrity of the posterior bone-ligament structure, maintains the stability immediately after surgery [2]. Kim et al [9] reported that radiological and clinical outcomes were compared after laminoplasty between the group of patients who had cervical kyphosis with Cobb angle < 10° and the cervical lordosis group He found that there was no significant difference between the two groups. In this regard, the authors hypothesize that by properly maintaining and reconstructing the spinous processligament-muscle complex (SPLMC) during laminoplasty surgery, followed by postoperative muscle strengthening exercises, the formation of kyphosis can be decreased and even the preoperative mild kyphotic or straight alignment can be improved. By analyzing the changes of cervical spine radiological parameters, this study intends to confirm whether the straight alignment of the cervical spine would be a proper indication for laminoplasty
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