Dynamische dorsale Stabilisierung mithilfe des Pedikelschrauben-Systems DYNESYS®

The Effect of Unintended Facet Arthrodesis on the Treatment Outcome of Dynamic Neutralization System for Lumbar Degenerative Diseases

Purpose

This study aimed to examine the influence of unintended facet arthrodesis on the therapeutic effectiveness of the dynamic neutralization system (Dynesys).

Methods

This retrospective study enrolled consecutive patients who underwent posterior decompression and dynamic stabilization for lumbar spondylosis or spinal stenosis. Follow-up assessments included lumbar radiography, lumbar vertebral computerized tomography (CT), visual analog scale (VAS), and Oswestry disability index (ODI). Patients were classified into the facet fusion and non-fusion groups. The differences in the VAS scores for back pain and leg pain, ODI, intervertebral range of motion (ROM) at the surgical segments, and upper adjacent segments were assessed before and after treatment.

Results

A total of 49 patients (29 males and 20 females) aged 31-65 years were enrolled and followed-up for over 40 months. Among the patients, 16 (32.7%) experienced unintended facet arthrodesis and were assigned to the fusion group, whereas the remaining patients were assigned to the non-fusion group. There was a significant increase in the incidence of facet arthrodesis in the surgical segments over time post-surgery (χ2 = 6.2, p < 0.05). The ROM of the surgical and upper adjacent segments, VAS scores for back pain and leg pain, and ODI were all significantly different before and after the operation (p < 0.05), but not between the fusion and non-fusion groups (p > 0.05).

Conclusion

Although unintended facet arthrodesis is common after Dynesys procedure, the presence of facet arthrodesis does not significantly affect the efficacy of Dynesys in treating lumbar degenerative diseases.

Posterior Dynamic Stabilization with Limited Rediscectomy for Recurrent Lumbar Disc Herniation

Objective

Recurrent lumbar disc herniation (RLDH) is the most common cause of sciatica after primary discectomy. The purpose of this study was to evaluate the efficacy of transpedicular dynamic stabilization (TDS) combined with limited rediscectomy in the treatment of single-level RLDH.

Methods

We retrospectively evaluated a consecutive series of 24 middle-aged patients who underwent TDS (Dynesys system) combined with limited rediscectomy (i.e., removing only extruded or loose disc fragments) for single-level Carragee type II and type IV RLDH between April 2012 and September 2017. Clinical results were evaluated with visual analog scale (VAS) for leg and low back pain, Oswestry Disability Index (ODI) scores, and complications. Imaging data include lumbar segment motion and intervertebral height.

Results

The mean follow-up period was 38 months. The VAS and ODI scores were significantly improved at the last follow-up. The average range of motion (ROM) at the stabilized segment was 6.4° before surgery and 4.2° at the last follow-up, with a 78.6% mean preservation (P < 0.05). Intervertebral height at the stabilized segment decreased slightly after surgery (P < 0.05). However, there was no further decline at the last follow-up. There were no cases of reherniation, screw loosening, or segmental instability.

Conclusions

TDS combined with limited rediscectomy resulted in an effective procedure in middle-aged patients with Carragee type II and type IV RLDH. It was able to stabilize the operated segment with partial motion preservation. Moreover, it could maintain disc height and decrease the risk of recurrence in patients with a large posterior annular defect.

Complications associated with the Dynesys dynamic stabilization system: a comprehensive review of the literature

The Dynesys dynamic stabilization system is an alternative to rigid instrumentation and fusion for the treatment of lumbar degenerative disease. Although many outcomes studies have shown good results, currently lacking is a comprehensive report on complications associated with this system, especially in terms of how it compares with reported complication rates of fusion. For the present study, the authors reviewed the literature to find all studies involving the Dynesys dynamic stabilization system that reported complications or adverse events. Twenty-one studies were included for a total of 1166 patients with a mean age of 55.5 years (range 39-71 years) and a mean follow-up period of 33.7 months (range 12.0-81.6 months). Analysis of these studies demonstrated a surgical-site infection rate of 4.3%, pedicle screw loosening rate of 11.7%, pedicle screw fracture rate of 1.6%, and adjacent-segment disease (ASD) rate of 7.0%. Of studies reporting revision surgeries, 11.3% of patients underwent a reoperation. Of patients who developed ASD, 40.6% underwent a reoperation for treatment. The Dynesys dynamic stabilization system appears to have a fairly similar complication-rate profile compared with published literature on lumbar fusion, and is associated with a slightly lower incidence of ASD.

Dynamic stabilization using the Dynesys system versus posterior lumbar interbody fusion for the treatment of degenerative lumbar spinal disease: a clinical and radiological outcomes-based meta-analysis

OBJECTIVE The Dynesys, a pedicle-based dynamic stabilization (PDS) system, was introduced to overcome the drawbacks of fusion procedures. Nevertheless, the theoretical advantages of PDS over fusion have not been clearly confirmed. The aim of this study was to compare clinical and radiological outcomes of patients who underwent PDS using the Dynesys system with those who underwent posterior lumbar interbody fusion (PLIF). METHODS The authors searched PubMed, Embase, Web of Science, and the Cochrane Database. Studies that reported outcomes of patients who underwent PDS or PLIF for the treatment of degenerative lumbar spinal disease were included. The primary efficacy end points were perioperative outcomes. The secondary efficacy end points were changes in the Oswestry Disability Index (ODI) and back and leg pain visual analog scale (VAS) scores and in range of motion (ROM) at the treated and adjacent segments. A meta-analysis was performed to calculate weighted mean differences (WMDs), 95% confidence intervals, Q statistics, and I(2) values. Forest plots were constructed for each analysis group. RESULTS Of the 274 retrieved articles, 7 (which involved 506 participants [Dynesys, 250; PLIF, 256]) met the inclusion criteria. The Dynesys group showed a competitive advantage in mean surgery duration (20.73 minutes, 95% CI 8.76-32.70 minutes), blood loss (81.87 ml, 95% CI 45.11-118.63 ml), and length of hospital stay (1.32 days, 95% CI 0.23-2.41 days). Both the Dynesys and PLIF groups experienced improved ODI and VAS scores after 2 years of follow-up. Regarding the ODI and VAS scores, no statistically significant difference was noted according to surgical procedure (ODI: WMD 0.12, 95% CI -3.48 to 3.72; back pain VAS score: WMD -0.15; 95% CI -0.56 to 0.26; leg pain VAS score: WMD -0.07; 95% CI -0.47 to 0.32). The mean ROM at the adjacent segment increased in both groups, and there was no substantial difference between them (WMD 1.13; 95% CI -0.33 to 2.59). Although the United States is the biggest market for Dynesys, no eligible study from the United States was found, and 4 of 8 enrolled studies were performed in China. The results must be interpreted with caution because of publication bias. During Dynesys implantation, surgeons have to decide the length of the spacer and cord pretension. These values are debatable and can vary according to the surgeon's experience and the patient's condition. Differences between the surgical procedures were not considered in this study. CONCLUSIONS Fusion still remains the method of choice for advanced degeneration and gross instability. However, spinal degenerative disease with or without Grade I spondylolisthesis, particularly in patients who require a quicker recovery, will likely constitute the main indication for PDS using the Dynesys system.

Long-term Outcome After Monosegmental L4/5 Stabilization for Degenerative Spondylolisthesis With the Dynesys Device

STUDY DESIGN

Retrospective analysis of prospectively collected clinical data.

OBJECTIVE

To assess the long-term outcome of patients with monosegmental L4/5 degenerative spondylolisthesis treated with the dynamic Dynesys device.

SUMMARY OF BACKGROUND DATA

The Dynesys system has been used as a semirigid, lumbar dorsal pedicular stabilization device since 1994. Good short-term results have been reported, but little is known about the long-term outcome after treatment for degenerative spondylolisthesis at the L4/5 level.

METHODS

A total of 39 consecutive patients with symptomatic degenerative lumbar spondylolisthesis at the L4/5 level were treated with bilateral decompression and Dynesys instrumentation. At a mean follow-up of 7.2 years (range, 5.0-11.2 y), they underwent clinical and radiographic evaluation and quality of life assessment.

RESULTS

At final follow-up, back pain improved in 89% and leg pain improved in 86% of patients compared with preoperative status. Eighty-three percent of patients reported global subjective improvement. Ninety-two percent would undergo the surgery again. Eight patients (21%) required further surgery because of symptomatic adjacent segment disease (6 cases), late-onset infection (1 case), and screw breakage (1 case). In 9 cases, radiologic progression of spondylolisthesis at the operated segment was found. Seventy-four percent of operated segments showed limited flexion-extension range of <4 degrees. Adjacent segment pathology, although without clinical correlation, was diagnosed at the L5/S1 (17.9%) and L3/4 (28.2%) segments. In 4 cases, asymptomatic screw loosening was observed.

CONCLUSIONS

Monosegmental Dynesys instrumentation of degenerative spondylolisthesis at L4/5 shows good long-term results. The rate of secondary surgeries is comparable to other dorsal instrumentation devices. Residual range of motion in the stabilized segment is reduced, and the rate of radiologic and symptomatic adjacent segment degeneration is low. Patient satisfaction is high. Dynesys stabilization of symptomatic L4/5 degenerative spondylolisthesis is a possible alternative to other stabilization devices.

Outcome of a dynamic neutralization system for the spine

One hundred fourteen patients (66 men and 48 women; mean age, 49 years) underwent spine stabilization using a dynamic neutralization system between January 1999 and August 2010 for degenerative disk disease, spinal instability, or spinal stenosis. Mean follow-up was 6.8 years (range, 1-11 years). Seven patients were lost to follow-up. Radiological examination and clinical evaluation, including the Oswestry Disability Index, the Roland-Morris Disability Questionnaire, and patient satisfaction, were performed.Mean Oswestry Disability Index score improved from 57% (severe disability) preoperatively to 22% (moderate disability) postoperatively. Mean Roland-Morris Disability Questionnaire score improved from 52% preoperatively to 35% postoperatively; 79 (74%) patients declared themselves very satisfied with the end result of the operation. Postoperatively, 27 (25%) patients experienced complications, including screw loosening (n=22), infection (n=2), back (n=5) and leg (n=2) pain, and endplate vertebral fracture (n=1). Three patients with screw loosening, 2 with deep infection, and 1 with severe persistent back and leg pain underwent rigid spine arthrodesis.Dynamic neutralization systems can be considered for degenerative disk disease, spinal instability, and stenosis. Patient satisfaction with the procedure is excellent. However, in the long term, the complication rate, most commonly screw loosening, is high and reoperations are common. In this setting, long-term follow-up is recommended, and the use of this system should be reconsidered.