Intervertebral Disc Rehydration after Lumbar Dynamic Stabilization: Magnetic Resonance Image Evaluation with a Mean Followup of Four Years

Abstract

Objective. To compare the clinical and radiographic outcomes in patients of different ages who underwent the Dynesys stabilization. Methods. This retrospective study included 72 patients (mean age 61.4 years) with one- or two-level lumbar spinal stenosis who underwent laminectomy and the Dynesys (Zimmer Spine, Minneapolis) dynamic stabilization system. Thirty-seven patients were younger than 65-year old while the other 35 were older. Mean followup was 46.7 months. Pre- and postoperative radiographic and clinical evaluations were analyzed. Results. The mean calibrated disc signal (CDS) at the index level was significantly improved from 60.2 ± 25.2 preoperatively to 66.9 ± 26.0 postoperatively (P > 0.001). Screw loosening occurred in 22.2% of patients and 5.1% of screws. The improvement in CDS at index level was seen to be significant in younger patients but not in older patients. Overall, the mean visual analogue scale (VAS) of back pain, VAS of leg pain, and the Oswestry disability index (ODI) scores improved significantly after operation. There were no significant differences in pre- and postoperative VAS and ODI and screw loosening rates between the younger and older patients. Conclusions. There is significant clinical improvement after laminectomy and dynamic stabilization for symptomatic lumbar spinal stenosis. Intervertebral disc rehydration was seen in younger patients.

Dynesys dynamic stabilization–related facet arthrodesis

“…7 The T2-weighted MRI signals of discs increased significantly in younger patients at the mean follow-up of 46.7 months. The Dynesys system was designed to shift the load from the intervertebral disc to the artificial spacer and cord.…”

“…Thus, recovery or rehydration of the degenerative discs might be expected in selected patients after DDS. 7 Although several reports have demonstrated promising short-to midterm outcomes of DDS, the concerns with regard to nonfusion instrumentation are durability (e.g., screw loosening) and long-term effects. 7,8,16,32 Nevertheless, substantial rates of screw loosening have been reported for DDS without adverse effects.…”

“…7 Although several reports have demonstrated promising short-to midterm outcomes of DDS, the concerns with regard to nonfusion instrumentation are durability (e.g., screw loosening) and long-term effects. 7,8,16,32 Nevertheless, substantial rates of screw loosening have been reported for DDS without adverse effects. 7,8,16,26,27,32 Interestingly, several reports have demonstrated that only minimal segmental spinal motion was preserved in patients who underwent DDS.…”

“…7,8,16,32 Nevertheless, substantial rates of screw loosening have been reported for DDS without adverse effects. 7,8,16,26,27,32 Interestingly, several reports have demonstrated that only minimal segmental spinal motion was preserved in patients who underwent DDS. 5,8,13,21,23,24,28 The actual cause of this limited motion remains elusive, and the effects of DDS on surrounding structures have not been fully addressed.…”

Dynamic stabilization for L4–5 spondylolisthesis: comparison with minimally invasive transforaminal lumbar interbody fusion with more than 2 years of follow-up

“…Dynamic stabilization methods include interspinous devices and pedicle screw-based stabilization systems. The Dynesys dynamic stabilization (DDS; Zimmer Bio met) system is the subject of many published reports on its application for the management of lumbar degenerative disc disease, 6,13,31,32 spondylolisthesis, 7,8,10,20,22 and even de generative scoliosis. 3,4,15 However, the application of these dynamic constructs for spondylolisthesis and its clinical outcomes remain unclear.…”