Cervical alignment, range of motion, and instability after cervical laminoplasty.

It has been reported that flexibility of the neck decreases after cervical laminoplasty. It also is known that kyphosis can be an unfavorable result after posterior decompression surgery of the cervical spine. To examine whether a decrease in cervical mobility resulting from contracture of the cervical spine helps prevent postoperative kyphotic alignment, changes in radiographic findings after cervical expansive laminoplasty were evaluated. There was a strong correlation postoperatively between range of motion of the cervical spine and cervical lordotic alignment, namely, the more that cervical mobility was maintained, the more that cervical lordosis was preserved. This relationship was not found preoperatively. A postoperative increase in the number of unstable vertebrae was found only in a few patients and was not associated with any deterioration in clinical outcome. The current results suggest that postoperative cervical lordosis is preserved not through intervertebral soft tissue contracture or bony fusion, but through more dynamic factors such as muscles or ligaments, therefore implicating the importance of early removal of cervical orthosis and early postoperative rehabilitation.