Objective To study the correlation between the cervical posture in the cervical disc replacement (CDR) and the cervical curve restoration in neutral position after surgery. Methods Between January 2008 and August 2010, 51 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 C4, 5 in 5 cases, at C5, 6 in 42 cases, and at C6, 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. Results The cervical Cobb angles at intraoperation and 3 months after operation were larger than those at preoperation (P lt; 0.05). The difference of the Cobb angle between intra- and pre-operation was (6.72 ± 9.13)° on cervical alignment, (2.10 ± 5.12)° on targeted FSU, and (3.33 ± 3.75)° 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)°, respectively. There was no significant difference in the Cobb angle improvement between the targeted FSU and the targeted disc (t= — 0.391, 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 lt; 0.05). Conclusion A slightly lordotic cervical posture during CDR is an important factor to maintaining normal physiological lordosis of the cervical spine after surgery.
ObjectiveTo evaluate the effectiveness of cervical disc replacement for cervical myelopathy. MethodsBetween October 2006 and October 2008, 20 patients (26 segments) with cervical myelopathy underwent single-level (14 segments) or bi-level (6 segments) cervical disc replacement. There were 8 males and 12 females with an average age of 46 years (range, 26-65 years). The disease duration ranged 2-18 months (mean, 7 months). The effectiveness was evaluated using visual analogue scale (VAS) score, cervical range of motion (ROM), and the Odom et al. criteria. Heterotopic ossification (HO), osteophyte formation, and prosthesis loosening were observed. ResultsAll incisions healed by first intention, with no severe complication. Twenty patients were followed up 30-48 months (mean, 34 months). At 28 months after operation, according to Odom et al. criteria, the results were excellent in 17 cases and good in 3 cases. The VAS scores of the neck, shoulder, and upper limb were significantly improved when compared with preoperative scores (P lt; 0.05). At 30 months after operation, X-ray films showed that 20 replaced segments were mobile and ROM was (10.6 ± 4.5)°, showing no significant difference (P gt; 0.05) when compared with that of upper adjacent segment (10.8 ± 3.7)° and lower adjacent segment (7.5 ± 4.2)°. HO occurred in 10 cases (13 segments). No displacement, subsidence, or loosening occurred except 1 case of retrodisplacement of the prosthesis. ConclusionCervical disc replacement can obtain good effectiveness. It can maintain normal cervical ROM and physiological curvature. But it needs further long-term follow-up to evaluate the function and the influence on the adjacent segments.