A comparative study on the Dynesys system in the treatment of single-level and multi-level lumbar degenerative diseases

Objective To compare the clinical outcomes of the Dynesys system in the treatment of singlelevel and multi-level lumbar degenerative diseases.Methods The clinical data of 46 patients with lumbar degenerative diseases who were treated by the Dynesys system from July 2008 to March 2011 were retrospectively studied.All patients were divided into single-level group(32 patients) and multiple-level group(14 patients).Clinical outcomes were evaluated using the oswestry disability index(ODI) and visual analogue scale(VAS) scores.Radiological evaluations included the disc height and range of motion(ROM) of stabilized segments and the intervertebral ROM of the upper adjacent segments by lumbar anteroposterior,lateral,flexion,and extension X-rays.Results The average follow-up period was 30 months(range;24-52 months) for all the patients.The ODI and VAS scores were significantly improved in both groups 3 months after the surgery single-level:ODI(20.5±5.7)%,VAS 2.9±1.3;multi-level:ODI(21.2±9.8)%VAS 3.2±1.4 and in the latest follow-up single-level:ODI(12.2±4.3)%,VAS1.4±4.3;multi-level:ODI(15.3±6.9)%,VAS 1.6±0.4(P0.05),which were not different between the 2 groups in the latest follow-up(P0.05).The disc height of stabilized segments was slightly decreased in both groups 3 months after the surgery single-level(11.3±2.7) mm,multi-level(11.1±2.0) mm and in the latest follow-up single-level(10.8±3.1) mm,multi-level(10.3±2.2) mm,but the differences were not statistically significant(P0.05).The ROM of stabilized segments was significantly decreased in both groups 3 months after the surgery single-level(4.3±2.4) °,multi-level(4.6±2.7) ° and in the latest follow-up single-level(4.8±2.2) °,multi-level(5.3±2.0) °(P0.05).The ROM of the upper adjacent segments was slightly increased in both groups 3 months after the surgery single-level(9.1±2.1) °,multi-level(8.5±1.8) °,but the differences were not statistically significant(.P0.05).When compared with that preoperatively,the changes became significant only in the single-level group(10.3±2.7) ° in the latest follow-up.The ROM was higher than that of the multiple-level group(9.1±3.0) °(P0.05).Conclusions Dynesys internal fixation is a good treatment option for single-level and multiple-level lumbar degenerative diseases,with satisfactory short-term clinical outcomes.Partial intervertebral ROM can be preserved,and the ROM of the upper adjacent segments is slightly increased postoperatively,when compared with that preoperatively.It is increased more significantly in the single-level group,which may lead to adjacent segment degeneration.