[Clinical application of dynamic neutralization system (K-Rod) in treating multisegmental lumbar degenerative...

To evaluate the clinical effects of dynamic neutralization system (K-Rod) in treating multisegmental lumbar degenerative disease.

From October 2011 to October 2013, 20 patients with multisegmental lumbar degenerative disease were treated with dynamic neutralization system (K-Rod). There were 8 males and 12 females with an average age of 45.4 years old (ranged from 31 to 65) and an average course of 3.8 years (ranged from 9 months to 6.25 years). All patients had the history of low back and legs pain. Among them, 10 cases were far lateral lumbar disc herniation, 7 cases were lumbar spinal stenosis, 3 cases were lumbar spondylolisthesis (degree I in 2 cases and degree II in 1 case). Every patient had only one responsible segment which causing the symptom would have to be rigidly fixed during operations, and the adjacent intervertebral disc of the responsible segments at least 1 segment has already obvious degenerated. All patients underwent the operation to relieve compressed nerves and reconstruct spinal stability with K-Rod system (the responsible segments were fixed with interbody fusion, and the adjacent segments were fixed with dynamic stabilization). Visual analogue scale (VAS), Japanese Orthopaedic Association Scores (JOA) and Oswestry Disability Index (ODI) were used to evaluate the clinical effects. Imaging data were used to analyze the range of motion (ROM), intervertebral disc height and intervertebral disc signal (according to modified Pfirrmann grading system) in degenerative adjacent segment.

All patients were followed up for more than 1 year, and preoperative symptoms obviously relieved. There were significant differences in VAS, JOA, ODI between preoperative and postoperative (postoperative at 1 week and 1 year) (P<0.05). Radiological examination showed that all responsible segments had already fused, and no looseness, displacement and breakage of internal fixations were found. Postoperative at 1 year, the ROM of adjacent segments were decreased (P<0.05). There was no significant difference in intervertebral disc height between preoperative and postoperative at 1 year (P>0.05). According to modified Pfirrmann grading system to classification for the 25 disks of adjacent segment, 8 disks (32%) got improvement, 15 disks (60%) got no change and 2 disks (8%) got aggravation at 1 year after operation.

Dynamic neutralization system (K-Rod) combined with interbody fusion could obtain short-term clinical effects in the treatment of multisegmental lumbar degenerative disease.