Posterolateral fusion versus Dynesys dynamic stabilization: Retrospective study at a minimum 5.5years' follow-up

The Future of Motion Preservation and Arthroplasty in the Degenerative Lumbar Spine

The lumbar degenerative cascade is a pathological process that affects most of the aging adult population and has significant negative economic consequences. Lumbar fusion surgery remains a mainstay of treatment for refractory degenerative disease but carries significant long-term consequences. More recently, lumbar arthroplasty and motion-sparing technology has become an increasingly popular alternative surgical option in carefully indicated patients. Arthroplasty technology carries the theoretical benefits of spinal segment motion preservation and decreased degeneration of adjacent segments as compared to traditional fusion procedures. This article will review the lumbar degenerative cascade and its related anatomic considerations, current management strategies and the challenges surrounding lumbar spinal fusion, including adjacent segment disease. This article will also review the theoretical benefits of lumbar arthroplasty and motion preservation. Furthermore, this paper will highlight the current state of lumbar arthroplasty, including current concepts of implant design, limitations, outcomes and ongoing development. It will review the development and current state of artificial disk arthroplasty, total joint arthroplasty and posterior column motion-preserving implants, including flexible rods and facet joint replacement.

COMPARISON OF DYNESYS AND HYBRID SYSTEM FOR MULTI-SEGMENTAL LDD

Objective

To compare effectiveness of Dynesys and hybrid system in treating patients with multi-segmental lumbar degenerative disease (LDD).

Methods

Patients involved in this retrospective study were divided into Dynesys (n = 22) and Hybrid (n = 13) groups. Clinical outcomes were evaluated using Oswestry Disability Index (ODI), and Visual Analogue Scale (VAS). Radiologic evaluations included X-ray, MRI, and CT. Furthermore, different complications were analyzed.

Results

At the last follow-up, ODI and VAS of each group were improved (p < 0.05), and the range of motion (ROM) of operating segments decreased. However, Dynesys group preserved a larger extent of ROM at the final follow-up (p < 0.05). ROM of the upper adjacent segment was increased in both groups (p < 0.05), while the disc heights were decreased at the final follow-up (p < 0.05). Besides, Dynesys group had a more obvious decrease in the disc height of dynamic segments (p < 0.05). No significant difference existed in complications between both groups (p > 0. 05).

Conclusion

In our study, similar satisfactory results were obtained in both groups. Both surgical procedures can be employed as effective treatments for middle-aged and physically active patients with multi-segmental LDD. Level of Evidence III; Retrospective Comparative Study.

Prediction of Screw Loosening After Dynamic Pedicle Screw Fixation With Lumbar Polyetheretherketone Rods Using Magnetic Resonance Imaging-Based Vertebral Bone Quality Score

OBJECTIVE

To investigate the correlation between magnetic resonance imaging-based vertebral bone quality (VBQ) score and screw loosening after dynamic pedicle screw fixation with polyetheretherketone (PEEK) rods, and evaluate its predictive value.

METHODS

A retrospective analysis was conducted on the patients who underwent dynamic pedicle screw fixation with PEEK rods from March 2017 to June 2022. Data on age, sex, body mass index, hypertension, diabetes, hyperlipidemia history, long-term smoking, alcohol consumption, VBQ score, L1-4 average Hounsfield unit (HU) value, surgical fixation length, and the lowest instrumented vertebra were collected. Logistic regression analysis was employed to assess the relationship between VBQ score and pedicle screw loosening (PSL).

RESULTS

A total of 24 patients experienced PSL after surgery (20.5%). PSL group and non-PSL group showed statistical differences in age, number of fixed segments, fixation to the sacrum, L1-4 average HU value, and VBQ score (p < 0.05). The VBQ score in the PSL group was higher than that in the non-PSL group (3.56 ± 0.45 vs. 2.77 ± 0.31, p < 0.001). In logistic regression analysis, VBQ score (odds ratio, 3.425; 95% confidence interval, 1.552-8.279) were identified as independent risk factors for screw loosening. The area under the receiver operating characteristic curve for VBQ score predicting PSL was 0.819 (p < 0.05), with the optimal threshold of 3.15 (sensitivity, 83.1%; specificity, 80.5%).

CONCLUSION

The VBQ score can independently predict postoperative screw loosening in patients undergoing lumbar dynamic pedicle screw fixation with PEEK rods, and its predictive value is comparable to HU value.

Clinical and radiological analysis of the effects of three different lumbar transpedicular dynamic stabilization system on disc degeneration and regeneration

Objective

This study aims to assess the clinical outcomes of three transpedicular dynamic systems in treating degenerative disc disease and evaluate their impact on both clinical and radiological aspects of the operated and adjacent segments.

Materials and methods

A total of 111 patients who underwent posterior transpedicular short-segment dynamic system procedures for treatment of degenerative disc disease were included. The patients were categorized into three groups, namely, Group 1 (Dynesys system, n = 38), Group 2 (Safinaz screw + PEEK rod, n = 37), and Group 3 (Safinaz screw + titanium rod, n = 36). Disc regeneration in the operated segment and disc degeneration in the operated, upper, and lower adjacent segments were assessed using the Pfirrmann Classification.

Results

Postoperatively, a statistically significant difference was observed in visual analog scale and Oswestry Disability Index scores (p < 0.001). However, no statistically significant difference was seen in disc degeneration/regeneration and degeneration scores of the upper and lower adjacent segments between the preoperative and postoperative groups (p = 0.763, p = 0.518, p = 0.201). Notably, a positive effect on disc regeneration at the operated level (32.4%) was observed. No significant differences were found between the groups in terms of operation rates, screw loosening, and screw breakage after adjacent segment disease (p > 0.05).

Conclusion

In patients without advanced degeneration, all three dynamic systems demonstrated the ability to prevent degeneration in the adjacent and operated segments while promoting regeneration in the operated segment. Beyond inhibiting abnormal movement in painful segments, maintaining physiological motion and providing axial distraction in the operated segment emerged as key mechanisms supporting regeneration.

Comparison of Cortical Bone Trajectory to Pedicle-Based Dynamic Stabilization: An Analysis of 291 Patients

Objective: Pedicle-based dynamic stabilization (DS) has gained popularity outside of America. Although pedicle screw (PS) loosening has always been a concern, it is reportedly innocuous. Cortical bone trajectory (CBT) screw is an emerging option with less invasiveness and similar effectiveness to PS in short-segment lumbar fusion. This study aimed to verify the use of CBT for DS by comparing the outcomes between pedicle- and CBT-based DS.Methods: Consecutive patients with lumbar spondylosis or low-grade spondylolisthesis who underwent 1- or 2-level DS between L3–5 with a minimum follow-up of 24 months were reviewed. Screw loosening was determined by computed tomography and the incidences were compared.Results: A total of 291 patients who underwent Dynesys DS (235 pedicle- and 56 CBT-based, respectively) were compared. The demographics and preoperative conditions were similar. All the clinical outcomes improved at 24-month postoperation, while the CBT-based group had less operation time and blood loss than the pedicle-based group. The rates of screw loosening were lower in the CBT-based (5.4% per screw and 12.5% per patient) than the pedicle-based group (9% per screw and 26.4% per patient). Furthermore, there were no differences in the clinical outcomes and complication profiles.Conclusion: The CBT-based DS for 1- or 2-level lumbar degeneration demonstrated equivalent clinical improvement as the pedicle-based DS. The adaption of CBT-based screws for DS could be a less invasive approach (shorter operation time and less blood loss), with lower chances of screw loosening than the conventional PS-based DS.

Medium and long-term radiographic and clinical outcomes of Dynesys dynamic stabilization versus instrumented fusion for degenerative lumbar spine diseases

BACKGROUND

Dynesys stabilization (DS) is utilized to preserve mobility at the instrumental segments and prevent adjacent segment pathology in clinical practice. However, the advantages of DS method in medium and long-term follow-up remain controversial.

OBJECTIVE

To compare the radiographic and clinical outcomes between DS and instrumented fusion in the treatment of degenerative lumbar spine disease with or without grade I spondylolisthesis with a minimum follow-up period of 2 years.

METHODS

We conducted a comprehensive search of PubMed, EMBASE, Cochrane, and Web of Science databases, Chinese National Knowledge Databases, and Wanfang Database for potentially eligible articles. Clinical outcomes were assessed in terms of VAS and ODI scores, screw loosening and breakage, and surgical revision. Radiographic outcomes were assessed in terms of postoperative range of movement (ROM) and disc heigh. Moreover, adjacent segment degeneration (ASDeg) and adjacent segment disease (ASDis) were evaluated.

RESULTS

Seventeen studies with 1296 patients were included in the meta-analysis. The DS group was associated with significantly lower postoperative VAS scores for low-back and leg pain, and lower rate of surgical revision than the fusion group. Moreover, the Dynesys group showed significantly less ASDeg than the fusion group but showed no significant advantage over the fusion group in terms of preventing ASDis. Additionally, the ROM at the stabilized segments of the fusion group decreased significantly and that at the adjacent segments increased significantly compared with those of the DS group.

CONCLUSION

DS showed comparable clinical outcomes and provided benefits in preserving the motion at the stabilized segments, thus limiting the hypermobility at the adjacent segments and preventing ASDeg compared with the fusion method in degenerative disease with or without grade I spondylolisthesis.

Arthrodesis versus dynamic neutralization: A short/mid- and long-term retrospective evaluation in degenerative disk disease treatment

Study Design

This was a retrospective comparative study.

Objectives

The aim of this study was to perform a clinical and radiological retrospective evaluation of the most used techniques for the lumbar degenerative disk disease (DDD) treatment: arthrodesis versus dynamic neutralization (DN)-Dynesys dynamic stabilization system.

Methods

The study included 58 consecutive patients affected by lumbar DDD, 28 treated with rigid stabilization and 30 with DN at our department between 2003 and 2013. The clinical evaluation was performed through the Visual Analog Scale (VAS) and the Oswestry Disability Index (ODI). The radiographic evaluation was performed through standard and dynamic X-ray projections and magnetic resonance imaging.

Results

Both techniques determined a clinical improvement in the postoperative period compared to the preoperative one. There were no significant differences between the postoperative VAS of the two techniques. The DN group postoperative ODI percentage showed a significant improvement (P = 0.026) compared to the arthrodesis group. During the follow-up, no clinically significant differences were highlighted between the two techniques. At a long term follow up period, radiographic results showed, in both groups, a L3-L4 disk mean height reduction and an increase of segmental and lumbar lordosis without significant differences between the two techniques. During an average of 96-month follow-up period, 5 (18%) patients developed an adjacent segment disease in the arthrodesis group and 6 (20%) patients developed this syndrome in the DN group.

Conclusions

We are confident in recommending arthrodesis and DN as effective techniques for lumbar DDD treatment. Both techniques are potentially burdened, with similar frequency, by the development of long-term adjacent segment disease.

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.

Is Dynesys dynamic stabilization system superior to posterior lumbar fusion in the treatment of lumbar degenerative diseases?

Dynesys, a pedicle-based dynamic stabilization system, was introduced to overcome some undesirable complications of fusion procedures. Nevertheless, the theoretical advantages of Dynesys over fusion have not been clearly confirmed. The purpose of this editorial was to compare clinical and radiological outcomes of patients who underwent Dynesys system with those who underwent posterior lumbar fusion according to the existing literature and to see if the application of the Dynesys system is superior to the traditional lumbar fusion surgery. According to published clinical reports, the short-term effects of the Dynesys dynamic stabilization system are similar to that of traditional lumbar fusion surgery. Three comparative studies of Dynesys dynamic stabilization and fusion surgery with medium-term follow-up are encouraging. However, the results from four single-treatment-arm and small-sample studies of case series with long-term follow-up were not encouraging. In the present circumstances, it is not possible to conclude that the Dynesys dynamic stabilization system is superior to fusion surgery for lumbar degenerative diseases.

Current incidence of adjacent segment pathology following lumbar fusion versus motion-preserving procedures: a systematic review and meta-analysis of recent projections

BACKGROUND CONTEXT

Lumbar fusion has shown to be an effective surgical management option when indicated, improving patient outcomes and functional status. However, concerns of adjacent segment pathology (ASP) due to reduced mobility at the operated segment have fostered the emergence of motion-preserving procedures (MPP).

PURPOSE

To assess rates of radiographic adjacent segment degeneration (ASDeg) and symptomatic adjacent segment disease (ASDis) as well as reoperation rates due to ASP in patients who have undergone lumbar fusion compared to motion-preservation for degenerative disorders.

STUDY DESIGN

Systematic Review and Meta-Analysis.

METHODS

Following PRISMA guidelines, a systematic review and meta-analysis was conducted to find current (1/2012-12/2019) retrospective cohort studies and randomized controlled trials evaluating rates of ASDeg, ASDis, and reoperations due to lumbar ASP.

RESULTS

A total of 1,751 patients (791 underwent fusion surgery and 960 motion-preserving procedures) in 19 publications were included in the final analysis. Overall incidence rates of ASDeg, ASDis, and reoperation rates were 27.8%, 7.6%, and 4.6%, respectively. Results showed no significant difference between the lumbar fusion versus MPP cohorts in incidence of ASDeg (36.4% vs. 19.2%, p: 0.06), ASDis (10.7% vs. 4.42%, p: 0.25), or reoperation due to ASP (7.40% vs. 1.80%, p: 0.19). Fixed-effects analysis revealed patients who underwent MPP had significantly lower odds of ASDeg (OR: 2.57, CI: 1.95, 3.35, p<.05) and reoperations (OR: 3.18, CI: 1.63, 6.21, p<.05) compared to lumbar fusion patients.

CONCLUSIONS

This meta-analysis revealed no statistically significant difference in incidence of ASDeg, ASDis, or reoperations due to ASP for patients after lumbar fusion versus MPP. Weighted analysis, however, showed that MPP patients had significantly lower odds of ASDeg and reoperations due to ASP. While previous studies have established the biomechanical efficacy of MPP on cadaveric models, further high-quality studies are required to evaluate the long-term consequences of these procedures on patient-reported outcomes, postoperative complications, and associated inpatient/outpatient costs.

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.

Finite element simulation and clinical follow-up of lumbar spine biomechanics with dynamic fixations

Arthrodesis is a recommended treatment in advanced stages of degenerative disc disease. Despite dynamic fixations were designed to prevent abnormal motions with better physiological load transmission, improving lumbar pain and reducing stress on adjacent segments, contradictory results have been obtained. This study was designed to compare differences in the biomechanical behaviour between the healthy lumbar spine and the spine with DYNESYS and DIAM fixation, respectively, at L4-L5 level. Behaviour under flexion, extension, lateral bending and axial rotation are compared using healthy lumbar spine as reference. Three 3D finite element models of lumbar spine (healthy, DYNESYS and DIAM implemented, respectively) were developed, together a clinical follow-up of 58 patients operated on for degenerative disc disease. DYNESYS produced higher variations of motion with a maximum value for lateral bending, decreasing intradiscal pressure and facet joint forces at instrumented level, whereas screw insertion zones concentrated stress. DIAM increased movement during flexion, decreased it in another three movements, and produced stress concentration at the apophyses at instrumented level. Dynamic systems, used as single systems without vertebral fusion, could be a good alternative to degenerative disc disease for grade II and grade III of Pfirrmann.