Dynesys system (Zimmer Spine, Warsaw, IN) is composed of two titanium pedicle screws connected by a cylindrical polycarbonate urethane. Conquest Hospital. Hastings, United Kingdom. Dynesys® and Dynamic Neutralization® are trademark of Zimmer GmbH. Dynesys® is developed in partnership. The Dynesys® Dynamic Stabilization System (Zimmer Inc., Warsaw, IN, USA) is one of the most frequently used posterior dynamic stabilization.
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Conceived and designed the experiments: There have been few studies comparing the clinical and radiographic outcomes between the Dynesys dynamic stabilization system and posterior lumbar interbody fusion PLIF. The objective of this study is to compare the zlmmer and radiographic outcomes of Dynesys and PLIF for lumbar degenerative disease. Of 96 patients with lumbar degenerative disease included in this retrospectively analysis, 46 were treated with the Dynesys system and 50 underwent PLIF from July to March Clinical and radiographic outcomes were evaluated.
We also evaluated the occurrence of radiographic and symptomatic adjacent segment degeneration ASD.
Dynesys – SPINEMarketGroup
The mean follow-up time in the Dynesys group was At the final follow-up, the Oswestry disability index and visual analogue scale score were significantly improved in both groups. The range of motion ROM of stabilized segments in Dynesys group decreased from 7. The incidence of complications was comparable between groups. Spinal fusion is considered the gold standard for treatment of spinal degenerative disease, although there are several complications associated with this technique, such as nonunion, instrumentation failure, infection, and pain in the donor area if an iliac bone graft is used.
Moreover, increased range of movement ROM at adjacent segments after spinal fusion may increase the risk for adjacent segment degeneration ASD [ 1 ]. To avoid some of these undesirable effects, dynamic stabilization systems have been developed [ 2 ].
The system is designed to stabilize the operated segment, while preserving some mobility, thus avoiding hypermobility of the adjacent segment.
Many clinical studies performed over the past decade have reported positive outcomes in patients with lumbar degenerative disease treated with the Dynesys system [ 45 ]. However, relatively few studies have compared clinical and radiographic outcomes between the Dynesys system and posterior lumbar interbody fusion PLIF [ 6 ].
In addition, long-term reports on the use of the Dynesys system in Chinese populations are comparatively rare. Therefore, the aim of this retrospective study was to compare the clinical and radiographic outcomes of the Dynesys system to those of PLIF for the treatment of lumbar degenerative disc disease in a Chinese population. This retrospective study included 46 consecutive patients who underwent Dynesys stabilization for lumbar degenerative disc disease from July to March The study protocol was approved by the Institutional Review Board of our hospital.
The approval number was Because our study was retrospective and the records of patients were anonymized and de-identified prior to analysis, so we did not have consent from the participants.
Zimmer Dynesys (Implant 384)
Fifty patients who underwent PLIF with the same disease at the same stage were retrospectively matched as a control group. The inclusion criteria and indications were: All patients experienced failure of conservative treatment for at least 3 months before they were considered for surgical intervention. Every patient underwent pre-operative X-ray and magnetic resonance imaging MRI examinations.
All patients were dynseys for a minimum of 48 months.
Stabilization with the Dynesys system was performed as an open procedure with a midline skin incision. General sub-dermal dissection through the same midline skin incision allowed another two fascial incisions at each side. The Dynesys screws were then placed transpedicularly via the Wiltse paraspinal approach without destruction of the facet joints. Standard laminectomies were performed cautiously to preserve the facet joints.
However, for cases of severe stenosis or far lateral stenosis, extensive decompression was performed, during which the medial border of the zimmet facet was partially removed to provide zimker clear view of the involved nerve root. The constructs, polycarbonate-urethane spacers, and tension cords were assembled according to technical suggestions provided by the manufacturer.
Postoperatively, patients in the Dynesys group wore a soft lumbar brace for 3 months [ 7 ]. After the midline incision and subperiosteal dissection of the erector spine muscles, the affected segment was exposed.
Standard laminectomies or extensive decompression was also performed cautiously according to the severity of lumbar degenerative disease. Allograft bone masses were used as the interbody fusion materials at all stabilized segments. Patients in the PLIF group wore a hard lumbar brace for 3 months. All patients received postoperative clinical and dunesys examinations at 3 months, 1 year, and then every year afterward.
The duration of follow-up and surgery, and intraoperative blood loss were retrieved from medical records.
Antero-posterior, lateral, and flexion-extension lateral radiographs of the two groups were obtained preoperatively and at each follow-up visit using the digital PACS radiographic imaging review system.
Radiographic outcomes included segmental ROM and the disc height of the stabilized segments and upper adjacent segments. Because ASD frequently occurred superior to the operated segment, we only evaluated the radiographic outcomes of the upper adjacent segment [ 8 ].
The segmental angulations were measured in the lateral standing lumbar radiography between the inferior surface of the upper vertebra and the superior surface of the lower vertebra. The segmental ROM was calculated as the difference between the segmental angulations in flexion and extension. We also divided each group into two subgroups single and multiple level groups for subgroup analysis of segmental ROM.
The disc height was determined on lateral radiographs by calculating the mean of anterior and zimer disc height. The occurrence of radiographic and symptomatic ASD between the two groups was evaluated as described in a previous study [ 8 ].
Symptomatic ASD was defined as the presence of severe radicular pain and cauda equina symptoms from the upper adjacent segment after a period of postoperative relief.
Zimmer Spine | Dynamic Stabilization System, Spine Implant System, Spine Stabilization
Each radiograph was measured and analyzed independently by two experienced spine surgeons to minimize human error. A senior surgeon resolved disagreements in measurements. All data were analyzed using SPSS The results of improvement differences from baseline pre-op to each follow-up within each group were assessed using the Wilcoxon matched-pairs signed-ranks test. Mean patient age, gender, and follow-up time were similar between groups.
Patient demographics and baseline characteristics are shown in Table 1. The minimum follow-up time was 48 months for each group. There were no significant differences in the levels of the operated segments or composition of disease between the two groups Table 1.
The surgical dynesyd and intraoperative blood loss were both significantly less in the Dynesys group, as compared to those of the PLIF group All radiographic outcomes are presented in Table dynssys. The ROM of stabilized segments in the Dynesys group decreased from 7. Subgroup analysis showed that the number of operated levels single and multiple levels did not affect the results Table 3. The fusion rate was The preoperative lumbar MRI. There were no significant differences in the incidence of asymptomatic screw loosening between the Dynesys and PLIF groups 6 vs.
There was no instance of breakage in either group at the final follow-up. One iatrogenic dural tear occurred intraoperatively in the Dynesys group and two in the PLIF group, which were all managed without further complications. There was one case of superficial wound infection in the Dynesys group and three in the PLIF group, which were treated by conservative therapy.
There were no other complications or reoperation in either group. The result of this study indicated that after a minimum follow-up of 4 years, both Dtnesys and PLIF improved clinical outcomes for lumbar degenerative disease.
Adjacent segment disease after spinal fusion has drawn zimmer attention over the past two decades. Spinal fusion results in increased stress in the adjacent segments and subsequent hypermobility, which may leads to adjacent segment disease[ 1011 ]. This problem can be resolved by the development of dynamic stabilization techniques. The Dynesys system is designed with the intention to neutralize abnormal forces and restore painless function to the spinal segments, while protecting the adjacent segments.
Many studies have reported positive outcomes for patients treated with the Dynesys system [ 4514 ]. They noted that the Dynesys system might be preferable to lumbar fusion for degenerative lumbar disease because it decreased back and leg pain.
However, some studies have indicated that the clinical results with the Dynesys system are no better than those after PLIF. A randomized controlled study performed by Yu et al.
In the present study, the ODI and VAS were significantly improved in both groups at the final follow-ups; however, the differences between the two groups were not significant. We concluded that the Dynesys system was an acceptable alternative to PLIF for the treatment of lumbar degenerative disease. The surgical duration and intraoperative blood loss were both significantly less in the Dynesys group, as compared to those in the PLIF group.
The reason for the shorter surgical duration in the Dynesys group was that there was no need for endplate and autogenous bone preparation or bone grafting. The lower blood loss in the Dynesys group was mainly because the screws were placed via the Wiltse approach and there was less bone and soft tissue dissection [ 19 ]. Although the Dynesys system has been available for more than 10 years, it remains controversial whether this dynamic stabilization system can prevent the occurrence of ASD [ 20 — 22 ].
Two studies by Yu et al. However, Schaeren et al. They also noted that only the segmental ROM at the index level decreased significantly in the PLIF group, while there was no significant difference in the Dynesys group. The results of the current study showed that Dynesys stabilization partially preserved the ROM of the stabilized segments, while that in the PLIF group decreased to zero degrees.
Also, subgroup analysis of segmental ROM according to the operated levels single level and multiple levels showed that these results were similar to the main results. The ROM of the upper segments increased significantly in both groups at the final follow-up, although to a higher degree in the PLIF group. The reason for the lower instance of hypermobility in the upper adjacent segments in the Dynesys group was likely because the Dynesys system could share the load in the operative segment and did not convey an excessive load to the adjacent segments.
The occurrence of radiographic ASDs was significantly lower in the Dynesys group as compared to that in the PLIF group, which might be mainly attributable to the dynamic stabilization of the operated segments and the avoidance of increased stress at the adjacent segment. The complications were comparable between the two groups. In the present study, the incidence of asymptomatic screw loosening was Nonetheless, screw loosening has no adverse effect on clinical improvement.
Furthermore, the fact that Dynesys screws were coated with hydroxyapatite was an attempt to prevent screw loosening. The incidence of other complications, including dural tear and superficial wound infection, was similar between groups.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. National Center for Biotechnology InformationU. Published online Jan