The outcome and influence of artificial cervical disc replacement on adjacent non-responsible segment instability in patients with cervical spondylosis

English Keywords:Cervical spondylosis  Cervical disc replacement  Adjacent segement  Instability

English Abstract:

  【Abstract】 Objectives: To investigate the clinical efficacy and imaging results of the adjacent segment instability in patients with cervical spondylosis treated by Bryan cervical disc replacement. Methods: A retrospective review was performed on 9 cases suffering from adjacent segment instability before surgery. All 9 cases underwent Bryan artificial cervical disc arthoplasty and were followed up from July 2005 to January 2009 in our hospital. There were 4 males and 5 females with an average age of 33.5 years(range, 26-43 years). Japanese Orthopaedic Association(JOA) score was 10.16±3.17(7-13), and visual analogue pain scale(VAS) was 4.3±2.7(1-7) before surgery. All patients underwent cervical flexion and extension plain film and cervical MRI before surgery. Imaging instability was confirmed in the adjacent segment, which was asymptomatic. C4/5 replacement, 1 cases instability in C5/6; C5/6 replacement 4 cases, 3 cases instability in C4/5, 1 cases instability in C6/7; C6/7 replacement, 2 cases instability in C5/6. The double segment replacement 2 cases, each 1 cases instability in C4/5, C5/6 and C5/6, C6/7, which both are adjacent to the head-end segment. Clinical outcome of surgery was evaluated by JOA, neck pain VAS and Odom before surgery and at 1 week, 3, 6, 12, 24, 36 months after surgery respectively; the range of motion(ROM) of the surgical segment, adjacent unstable segment, C2-C7 and cervical malalignment were assessed by cervical dynamic X-ray before operation and 3, 6, 12, 24, 36 months after surgery. Results: The JOA score, neck pain VAS were improved significantly at each follow-up 3 months later after surgery compared with those of preoperation, difference was statistically significant(P<0.05). Odom score was excellent in 6 cases, good in 1 case, fair in 2 case, good rate of 77.8% 1 week and 3months after surgery, excellent in 6 cases, good in 2 case, fair in 1 case, good rate of 88.9% 6 months after surgery, excellent in 7 cases, good in 1 case, fair in 1 case, good rate of 88.9% 12, 24 and 36 months after surgery. The angular displacement and cervical curve of adjacent unstable segment at 3, 6, 12 months after operation showed no statistically significant difference compared with the preoperative ones(P>0.05), while decreased significantly at 24 and 36 months(P<0.05). ROM of implanted segment and cervical curve at 24 and 36 months after operation increased significantly(P<0.05) compared with preoperative ones. The postoperative ROM of C2-C7 remained unchanged at each follow-up compared with the preoperative ones. During the follow-up, no surgical related complications were noted. Conclusions: The short and medium term clinical result of Bryan artificial cervical disc replacement for cervical spondylosis is reliable, which can relieve adjacent segment instability.