A clinical report of K-Rod dynamic stabilization for 39 lumbar disc protrusion cases

Objective To evaluate the clinical outcomes and imaging changes of discectomy combined with K-Rod dynamic stabilization for lumbar disc protrusion.Methods From January 2009 to November 2011,39 patients with one- or two-level lumbar disc protrusion were surgically treated by discectomy combined with K-Rod dynamic stabilization(group A,n=19) and transforaminal lumbar interbody fusion(TLIF)(group B,n=20) respectively.There were no significant differences in the general data between the 2 groups(P0.05),which were comparable.The surgical results were assessed by the visual analogue scale(VAS) scores and oswestry disability index(ODI) before and after the operation.The disc space height and lumbar range of motion(ROM) were measured dynamically after the operation.Results The patients of group A were followed up for an average of 22 months(range;18-32 months).The patients of group B were followed up for an average of 23 months(range;18-37 months).All the symptoms of back and leg pain in both groups were notably improved in the latest follow-up.Preoperatively the VAS scores and ODI were 5.52±1.58 and(50.83±20.28)%respectively in group A,whereas in the latest follow-up the VAS scores and ODI were 1.16±0.50 and(3.72±3.63)%respectively,which were obviously reduced(P0.001).Preoperatively the VAS scores and ODI were 6.50±1.21 and(60.56±9.92)%respectively in group B,whereas in the latest follow-up the VAS scores and ODI were 2.13±0.69 and(18.61±4.07)%respectively,which were obviously reduced(P0.001).The ROM of operated segments in group A was reduced postoperatively,which was recovered to 60%of its original condition in the latest follow-upi However,the ROM of operated segments in group B became 0° postoperatively.In both groups,the ROM of adjacent segments and the overall ROM of the lumbar maintained at the preoperative level.The disc space height of operated segments in group A was decreased by 10%in the latest follow-up,when compared with the preoperative value,while it maintained at a relatively stable level after the operation.There were no significant differences in the disc space height of adjacent segments between the 2 groups.There were no implant failures,such as looseness or breakage in the fixation system in both groups.Conclusions When compared with fusion,the K-Rod system keeps lumbar physiological curvature and preserves the ROM of involved segments,which has no obvious effects on adjacent segment degeneration,with satisfactory short-term clinical outcomes.However,further observation is needed to evaluate its long-term effects.