Study design: A retrospective study.
Objective: To evaluate the feasibility, efficacy, and safety of laminoplasty with plate fixation at alternating levels through radiologic analysis of the enlarged spinal canal and clinical follow-up.
Summary of background data: Laminoplasty is commonly used to manage cervical myelopathy. Because of the absence of rigid fixation, traditional laminoplasty commonly results in complications, including secondary narrowing of the spinal canal and neurological deterioration. At present, miniplate fixation is promising to prevent reclosure of the opened lamina efficiently by applying plates at each level. However, plates are also used at alternating levels (ie, C3, C5, C7) in clinical settings to reduce the cost of patients. To date, no thorough studies on plates used at alternating levels have been published.
Methods: Forty-two consecutive patients who underwent cervical laminoplasty for the treatment of cervical spondylotic myelopathy with plate fixation at alternating levels between January 2008 and April 2011 were reviewed for this study. Clinical and radiologic outcomes were assessed.
Results: Lateral cervical spine x-rays showed improvements in anteroposterior diameter (APD) of the spinal canal in all levels. No difference of APD was found between alternating fixed levels and unfixed levels preoperatively. Postoperative increased APD in alternating fixed levels was larger than unfixed levels. The mean increased APD in C6 level was smaller than C3, C5, and C7 level (P<0.05). However, there was no difference of the mean increased APD between C4 and C6 levels. Similar results were seen for the mean open angle from computed tomography scan. The mean Japanese Orthopaedic Association (JOA) improvement rate was 58.9%±17.8% on follow-up. However, the available JOA data from all 4 patients with insufficient open angle in unfixed levels exhibited limited improvement of neurological deficit.
Conclusions: Laminoplasty with plate fixation at alternating levels is a safe, relatively fast, and cost-effective surgical method for most patients with cervical myelopathy. However, unfixed levels (C4 and C6) still have the risk of closure of open angle, which could be associated with remaining spinal cord compression. C6 is a much higher risk level compared with C4.