Analysis of Cervical Spine Alignment Change after Modified Kurokawa Cervical Laminoplasty in the Patients with Cervical Myelopathy and Straight Cervical Spine

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 at 2 years follow-up.

Preoperative Range of Motion in Extension May Influence Postoperative Cervical Kyphosis After Laminoplasty

“…3 Laminoplasty destroys the posterior muscle ligament complex (PMLC) of the cervical spine, impairing the ability of the posterior column to share the load. 10,11 The degree of loss of cervical sagittal balance increases in parallel with the extent of surgery on PMLC. In general, the more segments of laminoplasty, the more serious the injury of cervical posterior structure.…”

“…The main physiological function of the posterior cervical ligament complex is to resist posterior tensile stress, making it crucial in maintaining cervical curvature and stability 3 . Laminoplasty destroys the posterior muscle ligament complex (PMLC) of the cervical spine, impairing the ability of the posterior column to share the load 10,11 . The degree of loss of cervical sagittal balance increases in parallel with the extent of surgery on PMLC.…”

The clinical efficacy of laminectomy fusion fixation and posterior single open-door laminoplasty in the treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL): a retrospective study

“…ROM (Range of Motion , Fig. 1 ) : The cervical ROM was mainly measured by taking dynamic X-ray film of CS and measuring C2-7 Cobb Angle in flexion and hyperextension respectively [ 17 ]. Angle of flexion was β; if CS was in reverse, β was negative.…”