[Influence of intraoperative cervical posture in single segmental cervical disc replacement on restoration of...

To study the correlation between the cervical posture in the cervical disc replacement (CDR).

Between January 2008 and August 2010, 51 and the cervical curve restoration in neutral position after surgery. patients underwent single segmental PRESTIGE LP replacement, and the clinical data were retrospectively analyzed. During the surgery, the patient was supinely placed and the lordosis of the cervical spine was mantained with a pillow placed beneath the neck. Of them, 28 were male and 23 were female, aged 30-64 years (mean, 45 years); 32 were diagnosed as having cervical spondylotic myelopathy, 7 having radiculopathy, and 12 having myelopathy and radiculopathy. The disease duration was 3-48 months (mean, 15 months). CDR was performed at C(4, 5) in 5 cases, at C(5, 6) in 42 cases, and at C(6, 7) in 4 cases. The Cobb angles of the cervical alignment, targeted functional spinal unit (FSU), and targeted disc were measured by sagittal X-ray film of the cervical spine in neutral position before and after surgery, as well as the intraoperative C-arm fluroscopy of the cervical spine. Linear correlation and regression were performed to analyze the relation between cervical Cobb angle difference at intraoperation and improvement of the Cobb angles at 3 months after operation.

The cervical Cobb angles at intraoperation and 3 months after operation were larger than those at preoperation (P < 0.05). The difference of the Cobb angle between intra- and pre-operation was (6.72 +/- 9.13) degrees on cervical alignment, (2.10 +/- 5.12) degrees on targeted FSU, and (3.33 +/- 3.75) degrees on targeted disc. At 3 months after operation, the Cobb angle improvement of the cervical alignment, targeted FSU, and targeted disc was (6.30 +/- 7.28), (3.99 +/- 5.37), and (4.29 +/- 5.36) degrees, respectively. There was no significant difference in the Cobb angle improvement between the targeted FSU and the targeted disc (t = -4.391, P = 0.698), and between the targeted disc and the cervical alignment (t = -1.917, P = 0.061), but significant difference was found between the targeted FSU and the cervical alignment (t = -2.623, P = 0.012). The linear correlation between the Cobb angle difference and the Cobb angle improvement of the cervical spine was observed (P < 0.05).

A slightly lordotic cervical posture during CDR is an important factor to maintaining normal physiological lordosis of the cervical spine after surgery.