Short-term clinical observation of the Dynesys neutralization system for the treatment of degenerative disease of the lumbar vertebrae

Innovative technologies in thoracolumbar and lumbar spine surgery failing to reach standard of care: state-of-art review

PURPOSE

To evaluate previously popular technologies in the field of spine surgery, and to better understand their advantages and limitations to the current standards of care. Spine surgery is an ever-evolving field that serves to resolve various spinal pathologies in patients of all ages. While there are established treatments for various conditions, such as lumbar spinal stenosis, idiopathic scoliosis, and degenerative lumbar disease, there is always further research and development in these areas to produce innovative technologies that can lead to better outcomes. As this process progresses, we must remind ourselves of previously tried and tested inventions and their outcomes that have fallen short of becoming a standard to ensure we are able to learn lessons from the past.

METHODS

A thorough literature review was conducted with the aim of compiling literature of previously utilized technologies in spine surgery. Biomedical databases were utilized to gather relevant articles including PubMed, MEDLINE, and EMBASE. Emphasis was placed on gathering articles with technologies or therapeutics aimed at treating common spinal pathologies including lumbar spinal stenosis (LSS), adolescent idiopathic scoliosis (AIS), and other degenerative lumbar spine diseases. The keywords used were: "failed technologies", "historical technologies", "spine surgery", "spinal stenosis", "adolescent idiopathic scoliosis", and "degenerative lumbar spine disease". A total of 47 articles were gathered after initial review.

RESULTS

Different technologies pertaining to spine surgery were identified and critically evaluated. Some of these technologies included X-STOP, Vertiflex, Vertebral Body Stapling, and Dynesys. These technologies were evaluated for their strengths and limitations across their spinal pathology applications. While each type of technology had their benefits, the data tended to be mixed with various limitations across studies.

CONCLUSION

These technologies have been trialed in the field of spine surgery across various spinal pathologies, but still prove of limited efficacy and shortcomings to the current standards of care.

Spontaneous regression of a large sequestered lumbar disc herniation: a case report and literature review

Lumbar disc herniation is a common disorder in adults that is accompanied by lower back and radicular pain. A 32-year-old man visited our clinic with 1-week history of persistent lower back pain and weakness in his right big toe. Magnetic resonance imaging (MRI) of his lumbar spine revealed herniated discs at L3/L4, L5/S1 and L4/L5, where a right-sided intraspinal mass lesion deep to the L4 vertebral body was causing compression of the nerve root. The patient underwent conservative treatment and reported no symptoms referrable to his back or leg 4 months later. Follow-up MRI showed no herniation of the nucleus pulposus at the L4/L5 level or lesion deep to the vertebral body of L4, whereas no changes had occurred to the status of the herniated L3/L4 and L5/S1 discs. The present case and a literature review show that a sequestered lumbar disc herniation can regress within a relatively short timeframe without surgery. The authors emphasise the utility of conservative therapy for patients who do not have a definitive surgical indication.

Lumbar Stabilization with DSS-HPS® System: Radiological Outcomes and Correlation with Adjacent Segment Degeneration

Arthrodesis has always been considered the main treatment of degenerative lumbar disease. Adjacent segment degeneration is one of the major topics related to fusion surgery. Non-fusion surgery may prevent this because of the protective effect of persisting segmental motion. The aims of the study were (1) to describe the radiological outcomes in the adjacent vertebral segment after lumbar stabilization with DSS-HPS^® system and (2) to verify the hypothesis that this system prevents the degeneration of the adjacent segment. This is a retrospective monocentric analysis of twenty-seven patients affected by degenerative lumbar disease underwent spinal hybrid stabilization with the DSS-HPS^® system between January 2016 and January 2019. All patients completed 1-year radiological follow-up. Preoperative X-rays and magnetic resonance images, as well as postoperative radiographs at 1, 6 and 12 months, were evaluated by one single observer. Pre- and post-operative anterior and posterior disc height at the dynamic (DL) and adjacent level (AL) were measured; segmental angle (SA) of the dynamized level were measured. There was a statistically significant decrease of both anterior (p = 0.0003 for the DL, p = 0.036 for the AL) and posterior disc height (p = 0.00000 for the DL, p = 0.00032 for the AL); there were a statistically significant variations of the segmental angle (p = 0.00000). Eleven cases (40.7%) of radiological progression of disc degeneration were found. The DSS-HPS^® system does not seem to reduce progression of lumbar disc degeneration in a radiologic evaluation, both in the dynamized and adjacent level.

Dynamic Stabilization Surgery in Patients with Spinal Stenosis: Long-term Outcomes and the Future

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

The purpose of this study was to analyze the long-term results for patients with lumbar spinal stenosis (LSS) treated with dynamic stabilization (DS) and to consider how we can improve the results.

SUMMARY OF BACKGROUND DATA

Few studies have reported long-term outcomes of DS surgery for LSS with or without spondylolisthesis.

METHODS

A single-center, single-surgeon consecutive series of LSS patients who underwent DS surgery with at least 5 years of follow-up were retrospectively reviewed. Twenty-seven patients were included in the LSS group and 38 patients in the spondylolisthesis group. Patient characteristics, operative data, radiographic parameters, clinical outcomes, and complications were analyzed at baseline and follow-up.

RESULTS

In the LSS group, all radiographic parameters (e.g., disc height, segmental lordosis, segmental range of motion [ROM] at the index level and proximal adjacent level, global lordosis, and global ROM) were maintained well until the last follow-up. In the spondylolisthesis group, global lordosis decreased from 36.5° ± 8.2° to 32.6° ± 6.0° at the last follow-up (P = 0.039), and global ROM decreased from 22.1° ± 6.9° to 18.8° ± 7.1° at the last follow-up (P = 0.012). In both groups, back pain, leg pain, and Oswestry Disability Index scores showed significant and sustained improvements. Screw loosening occurred in three patients (11.1%) in the LSS group and five patients (13.2%) in the spondylolisthesis group. Symptomatic adjacent segment degeneration (ASD) occurred in two patients (7.4%) in the LSS group and three patients (7.9%) in the spondylolisthesis group.

CONCLUSION

Decompression and DS surgery for LSS with or without spondylolisthesis showed favorable long-term surgical outcomes with an acceptable rate of complications and ASD. However, an improved physiological DS system should be developed.Level of Evidence: 4.

Dynesys system vs posterior decompression and fusion for the treatment of lumbar degenerative diseases

BACKGROUND

The Dynesys dynamic stabilization system is an alternative to rigid instrumentation and fusion for the treatment of lumbar degenerative disease. The purpose of this study is to evaluate the clinical efficacy between Dynesys and posterior decompression and fusion for lumbar degenerative diseases.

METHODS

The computer was used to retrieve the Cochrane library, Medline, Embase, CNKI, Wanfang database and Chinese biomedical literature database; and the references and main Chinese and English Department of orthopedics journals were manually searched. All the prospective or retrospective comparative studies on the clinical efficacy and safety of Dynesys and posterior decompression and fusion were collected, so as to evaluate the methodological quality of the study and to extract the data. The RevMan 5.2 software was used for data analysis.

RESULTS

A total of 17 studies were included in the meta-analysis. There were no significant differences in Oswestry disability index and visual analogue score for leg pain, visual analogue score for back pain, L2-S1 ROM between Dynesys and fusion group. Operation time, blood loss, length of stay and complications in the Dynesys group were significantly less than that in the fusion group. Adjacent-segment degeneration in the fusion group was significantly higher than that in the Dynesys group. In addition, postoperative operated segment ROM was significantly less in the fusion group as compared to the Dynesys group.

CONCLUSIONS

Our meta-analysis suggests that Dynesys system acquires comparable clinical outcomes compared to fusion in the treatment of lumbar degenerative diseases. Moreover, compared with fusion, Dynesys could remain ROM of surgical segments with less operation time, blood loss, length of stay, adjacent-segment degeneration, and lower complication. Further studies with large samples, long term follow up and well-designed are needed to assess the two procedures in the future.

Long-Term Outcome of Dynesys Dynamic Stabilization for Lumbar Spinal Stenosis

Background:

Many clinical studies over the past decade have indicated positive outcomes for patients treated with Dynesys dynamic stabilization for lumbar degenerative disease. However, long-term outcomes of Dynesys for lumbar spinal stenosis are rarely reported. The aim of this study was to analyze the long-term clinical and radiologic outcomes for patients with lumbar spinal stenosis treated with Dynesys stabilization.

Methods:

Thirty-eight patients with lumbar spinal stenosis were treated with Dynesys stabilization from July 2008 to March 2010. The minimal duration of follow-up was 72 months. The patients were divided into stenosis and spondylolisthesis groups according to degenerative spondylolisthesis. Clinical outcomes were evaluated using the Oswestry Disability Index (ODI) and visual analog scale (VAS). Radiographic evaluations included range of motion (ROM) and the disc heights of stabilized segments and the upper adjacent segments. We also evaluated the occurrence of radiographic and symptomatic adjacent segment degeneration (ASD).

Results:

There were 23 patients in stenosis group and 15 patients in spondylolisthesis group. The ODI scores were significantly improved at the final follow-up evaluation, as compared to the baseline values (16.1 ± 5.7 vs. 57. 2 ± 14.2, t = 61.41, P < 0.01). The VAS scores for back and leg pain were significantly improved from 4.82 ± 0.89 and 4.04 ± 0.82 preoperatively to 0.93 ± 0.61 and 0.54 ± 0.51 postoperatively (t = 6.59, P < 0.01, and t = 5.91, P < 0.01, respectively). There were no differences between the two groups with respect to VAS and ODI scores. The ROM of stabilized segments decreased significantly from 7.8° ± 2.4° to 4.5° ± 1.5° (t = 7.18, P < 0.05), while the upper adjacent segments increased significantly from 8.3° ± 2.4° to 10.4° ± 2.4° (t = 2.87, P = 0.01). The change in disc height of stabilized segments was not significant (11.9 ± 2.1 preoperatively vs. 12.5 ± 1.5 postoperatively, t = 1.43, P = 0.15), whereas the decrease in disc height of the upper adjacent segments was significant (12.5 ± 2.0 preoperatively vs. 11.0 ± 1.7 postoperatively, t = 2.94, P = 0.01). The occurrence of radiographic and symptomatic ASD was 16% (6/38) and 3% (1/38), respectively.

Conclusions:

Decompression and Dynesys stabilization for lumbar stenosis with or without spondylolisthesis showed good long-term clinical and radiographic results. Lumbar stenosis with or without Grade I spondylolisthesis, particularly in patients <60 years of age with mild-to-moderate lumbar disc degeneration, would be one of the main indications for the Dynesys system.

Spontaneous regression of herniated nucleus pulposus: The clinical findings of 76 patients

Lumbar disc hernia is common disease, affecting about 5% of the population. Many studies to date reported regression of disc herniation without surgical intervention.Medical records of the patients who applied to the spine clinic in an outpatient setting were retrospectively reviewed. Age, sex, radiological findings, neurological examinations, and medical treatments of the patients were evaluated.Male patients constituted 52.6% of the cases (n = 40) and 47.4% (n = 36) were female. The ages of the patients ranged from 25 to 82 years, with a mean of 48.5 ± 12.1 years. Visual analog scale (VAS) measurements ranged from 0 to 8 and the mean was determined as 2.65 ± 1.98. The VAS score of pain severity of 12 (15.78%) cases was 0, VAS score of 39 (51.31%) cases was 1 to 3, VAS score of 20 (26.31%) cases was 4 to 6, VAS score of 5 (6.57%) cases was 7 to 10. Eighteen (23.68%) of the cases underwent neuropathic pain treatment for more than 6 months. Fifteen (19.7%) patients also developed permanent motor deficits.Findings of our study show that there was no direct association between radiological improvement and clinical improvement. Indication for surgery still existed in a high number of patients, substantial of which developed permanent motor deficits. Current results suggest that we need to advise our patients in favor of early surgery as soon as indication for surgery is established upon neurological and radiological examination.

Minimum ten-year follow-up of spinal stenosis with degenerative spondylolisthesis treated with decompression and dynamic stabilization

Background

The Dynesys system remains the most widely implanted posterior non-fusion pedicle screw system. Various study designs used in investigations with good to excellent short- and mid-term results have been reported in the current literature. However, there is a lack of information concerning long-term outcomes following treatment for spinal stenosis with degenerative spondylolisthesis.

Methods

The aim of our study was twofold. Firstly, to assess whether the dynamic stabilization in situ with the Dynesys System without bone grafting provides enough stability to prevent progression of spondylolisthesis and secondarily to maintain significant clinical improvement in a long-term follow-up (FU). Therefore, the consecutive patients due to inclusion criterions underwent interlaminar decompression and stabilization with Dynesys instrumentation. Patients were evaluated clinically and radiologically after a minimum FU of 10 years.

Results

At FU, the mean low back pain (LBP) post-operatively and leg pain (LP) post-operatively on visual analog scale (VAS) and North American Spine Society (NASS) improved significantly (P<0.001) compared to preoperative examination. The mean value of NASS neurogenic symptoms (19.13% and 4.72%) and activity subscores were 23.13% and 10.74% respectively. In plain and functional radiographs the mean listhesis grade in neutral position was 11.11%, 11.8% in reclination and 11.63% in inclination. There were 17 and 8 patients with progressing degenerative osteochondrosis/listhesis at adjacent segments.

Conclusions

Decompression and single and double level dynamic in situ stabilization with the Dynesys System demonstrate good clinical and radiological long-term results in elderly patients.

Electrophysiological Study for Nerve Root Entrapment in Patients With Isthmic Spondylolisthesis

STUDY DESIGN

A case series study.

OBJECTIVE

To investigate the electrophysiological location of nerve root entrapment in patients with isthmic spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Although the lesion of the nerve root in patients with isthmic spondylolisthesis has been thought to be located at the pars interarticularis due to proliferation of fibrous cartilage, there is no electrophysiological study in relation to this accomplished fact.

METHODS

We performed an electrophysiological study in 12 patients with isthmic spondylolisthesis during surgery. All patients presented with low-grade isthmic spondylolisthesis and unilateral radiculopathy, and underwent single-level posterior lumbar interbody fusion with instrumentation. After a total facetectomy, nerve root action potentials were recorded by stimulating the ipsilateral peroneal nerve at the popliteal fossa. Four needle electrodes were inserted into the affected nerve root at the intraspinal canal, pars interarticularis, disk level, and extralateral to the disk. The waveforms that showed either a positive waveform pattern or polyphasic waveform pattern were regarded as abnormal potentials. We also confirmed surgical records and preoperative images to investigate the relationship to the electrophysiological findings.

RESULTS

An abnormal waveform pattern was demonstrated at the pars interarticularis in 6 patients, at the disk level in 5, and at the extralateral site in 1. On the basis of the electrophysiological findings of this study, the nerve root lesion was not always found on only the pars interarticularis in patients with isthmic spondylolisthesis. A relationship between the electrophysiological findings and surgical records or preoperative images was not found.

CONCLUSIONS

The electrophysiological investigation in this study shows that the nerve root entrapment in patients with isthmic spondylolisthesis occurs not only at the pars interarticularis but also distal to the isthmus. This study suggests the possibility of insufficiency of decompression only at the pars interarticularis for patients with isthmic spondylolisthesis.

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.

Nonfusion Does Not Prevent Adjacent Segment Disease: Dynesys Long-term Outcomes With Minimum Five-year Follow-up

STUDY DESIGN

Case series.

OBJECTIVE

The aim of this study was to determine the relationship between fusion and adjacent segment disease via Dynesys long-term outcomes.

SUMMARY OF BACKGROUND DATA

Dynesys is a dynamic stabilization system meant to improve symptoms by stabilizing the spine without fusion and avoiding the development of adjacent segment disease. However, few studies have evaluated long-term outcomes.

METHODS

All patients were operated on with Dynesys from 2006 to 2009 by a single surgeon at a single institution. We prospectively collected 18 variables among the following categories: patient characteristics, comorbidities, surgical indications, and OR variables. We analyzed two primary endpoints: solid fusion on X-ray and clinical adjacent segment disease (ASD) both at 5 years. Secondary endpoints were time to fusion, time to ASD, reoperation, Oswestry disability index (ODI), and visual analogue scale (VAS) leg pain. We conducted a multivariate analysis via the random forest method. Mann-Whitney U test and Fisher exact test were then used to qualify relationship between variables.

RESULTS

We had 52 patients to review in the database. Eight had preexisting ASD. Mean follow-up was 92 months (median 87 months). Fifteen had ASD (29%) during follow-up at a mean 45 months (Median 35 months). Nine had a solid fusion (17%), 2 of which also had ASD. Mean time to fusion was 65 months (median 71 months). Differences in improvement of ODI (P = 0.005) and VAS leg pain (P = 0.002) were significant favoring patients without ASD. The multivariate analysis revealed four variables associated with ASD: prior ASD (OR 11.3, P = 0.005), neurological deficit (OR 8.5, P = 0.018), revision OR (OR 8.5, P = 0.018), and multilevel degeneration (OR 0.184, P = 0.026). No variable was associated with fusion.

CONCLUSION

Dynesys was associated with a high rate of ASD over long-term follow-up despite maintaining a low fusion rate. Prior ASD was the strongest predictor of progressive ASD.

LEVEL OF EVIDENCE

3.

Comparison of the Dynesys Dynamic Stabilization System and Posterior Lumbar Interbody Fusion for Lumbar Degenerative Disease

BACKGROUND

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 clinical and radiographic outcomes of Dynesys and PLIF for lumbar degenerative disease.

METHODS

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 2008 to March 2011. Clinical and radiographic outcomes were evaluated. We also evaluated the occurrence of radiographic and symptomatic adjacent segment degeneration (ASD).

RESULTS

The mean follow-up time in the Dynesys group was 53.6 ± 5.3 months, while that in the PLIF group was 55.2 ± 6.8 months. 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 7.1 ± 2.2° to 4.9 ± 2.2° (P < 0.05), while that of in PLIF group decreased from 7.3 ± 2.3° to 0° (P < 0.05). The ROM of the upper segments increased significantly in both groups at the final follow-up, the ROM was higher in the PLIF group. There were significantly more radiographic ASDs in the PLIF group than in the Dynesys group. The incidence of complications was comparable between groups.

CONCLUSIONS

Both Dynesys and PLIF can improve the clinical outcomes for lumbar degenerative disease. Compared to PLIF, Dynesys stabilization partially preserves the ROM of the stabilized segments, limits hypermobility in the upper adjacent segment, and may prevent the occurrence of ASD.

Short-term effects of a dynamic neutralization system (Dynesys) for multi-segmental lumbar disc herniation

PURPOSE

To determine the safety and short-term curative effects of internal fixation using a dynamic neutralization system (Dynesys) for multi-segmental lumbar disc herniation (ms-LDH) with the control group treated by posterior lumbar interbody fusion (PLIF).

METHODS

Forty-five patients with ms-LDH were selected as study group treated with Dynesys and 40 patients as control group with PLIF. The surgical efficacy was evaluated by comparing the visual analogue scale (VAS) scores, the Oswestry Disability Index (ODI) scores and the ROMs of the adjacent segment before and after surgery. The postoperative complications related to the implants were identified.

RESULTS

All patients were followed up for an average duration of over 30 months. Dynesys stabilization resulted in significantly higher preservation of motion at the index level (p < 0.001), and significantly less (p < 0.05) hypermobility at the adjacent segments. VAS for back and leg pain and ODI improved significantly (p < 0.05) with both the methods, but there was no significant difference between the groups.

CONCLUSIONS

The non-fusion fixation system Dynesys is safe and effective regarding short-term curative effects for the treatment of ms-LDH.

Role of dynesys as pedicle-based nonfusion stabilization for degenerative disc disorders

Posterior nonfusion pedicle-screw-based stabilization remains a controversial area of spine surgery. To date, the Dynesys system remains the most widely implanted posterior nonfusion pedicle screw system. We review the history of Dynesys and discuss clinical outcome studies and biomechanical evaluations regarding the Dynesys system. Indications for surgery and controversies are discussed. Recommendations are made regarding technical implantation.

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.

Lumbar degenerative disc disease: current and future concepts of diagnosis and management

Low back pain as a result of degenerative disc disease imparts a large socioeconomic impact on the health care system. Traditional concepts for treatment of lumbar disc degeneration have aimed at symptomatic relief by limiting motion in the lumbar spine, but novel treatment strategies involving stem cells, growth factors, and gene therapy have the theoretical potential to prevent, slow, or even reverse disc degeneration. Understanding the pathophysiological basis of disc degeneration is essential for the development of treatment strategies that target the underlying mechanisms of disc degeneration rather than the downstream symptom of pain. Such strategies ideally aim to induce disc regeneration or to replace the degenerated disc. However, at present, treatment options for degenerative disc disease remain suboptimal, and development and outcomes of novel treatment options currently have to be considered unpredictable.