[Effect of Bryan cervical disc replacement on cervical curvature and replacement segment in treating cervical spondylosis].

Objective: To investigate the effect of Bryan cervical disc replacement on cervical curvature and replacement segment in the treatment of cervical spondylosis, and analyze its clinical efficacy.

Methods: Forty-nine patients underwent Bryan artificial cervical disc replacement from August 2010 to August 2013 were retrospectively analyzed. There were 26 males and 23 females, aged from 27 to 66 years old with an average of 48.5 years. Including 21 cases of nerve root type, 16 cases of spinal cord type, 12 cases of mixed type. And 21 cases were single segment replacement, 28 cases were double segments replacement. Preoperative and postoperative pain was compared using visual analogue scale(VAS);cervical function was observed by Japanese Orthopedic Association Scores (JOA) and Neck Disability Index (NDI);cervical lordosis curvature, function spinal unit(FSU) curvature, activities of replacement and adjacent segment, FSU activity were measured by cervical X-rays. Clinical effects were evaluated by the Odom method.

Results: All the patients were followed up for 18.5 to 37.3 months with an average of 33.1 months. Pvoperative VAS, JOA, NDI scores were 7.08±1.55, 5.2±1.9, 39.96±7.06 before operation, 3.76±2.33, 13.20±1.20, 25.20±6.64 at 3 months after operation, and 2.80±1.50, 14.3±1.6, 24.24±7.89 at the last follow-up. Patients at three months and the last follow-up after operation were obviously improved in their VAS, JOA, and NDI scores (<0.05). There was no significant difference between the scores at last follow-up and 3 months after operation. Cervical lordosis changed from (10.64±4.26)° preoperatively to (13.68±4.56) ° at the last follow-up;the FSU curvature from (5.40±0.41) °to (9.92±2.00) °at the last follow-up (<0.05). The range of motion of the cervical spine preoperatively, 3 month postoperatively, and at the last follow-up were(70.84±6.17)°, (60.00±6.58)°, (71.48±4.61)°; FSU activities were(12.00±0.49)°, (9.36±0.26)°, (12.52±0.33)°;the activities of replacement segment were (10.48±0.67)°, (7.24±0.34)°, (9.28±0.36)°;the activities of upper segment of replacement were (10.52±0.60)°, (8.60±0.30)°, (10.44±0.43)°;the activities of lower segment of replacement were (8.48±0.40)°, (6.56±0.36)°, (9.60±0.39)°;there were significant differences in above items preoperatively and 3 months postoperatively(<0.05); and there were no significant difference preoperatively and at the last follow-up(>0.05). Pharyngeal discomfort and hoarseness occurred in 5 cases, and were recovered within 2 weeks after operation;heterotopic ossification occurred in 1 case at 6 months after operation;displacement of prosthesis occurred in 1 case at 12 months after operation. Based on Odom standard to evaluate the clinical outcome, 20 cases obtained excellent results, with 27 good, 2 general.

Conclusions: Bryan artificial cervical disc replacement not only generate good clinical effects, but may also restore the cervical lordosis and FSU curvature, while retaining the activities of replacement segment, and restoring overall cervical biomechanical functions.