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Objective: The Isobar TTL dynamic fixation system has demonstrated favorable outcomes in the short-term treatment of lumbar degenerative disc diseases (LDDs). However, there is a paucity of extensive research on the long-term effects of this system on LDDs. This study aimed to evaluate the long-term clinical and radiological outcomes of patients with LDDs who underwent treatment utilizing the Isobar TTL dynamic fixation system., Methods: The study analyzed the outcomes of 40 patients with LDDs who underwent posterior lumbar decompression and received single-segment Isobar TTL dynamic internal fixation at our hospital between June 2010 and December 2016. The evaluation of clinical therapeutic effect involved assessing postoperative pain levels using the visual analogue scale (VAS) and Oswestry disability index (ODI), both before surgery, 3 months after, and the final follow-up. To determine the preservation of functional motion in dynamically stable segments, we measured the range of motion (ROM) and disc height of stabilized and adjacent segments preoperatively and during the final follow-up. Additionally, we investigated the occurrence of adjacent segment degeneration (ASD)., Results: Forty patients were evaluated, with an average age of 44.65 years and an average follow-up period of 79.37 months. Fourteen patients belonged to the spondylolisthesis group, while the remaining 26 were categorized under the stenosis or herniated disc group. The preoperative ROM of the stabilized segment exhibited a significant reduction from 8.15° ± 2.77° to 5.00° ± 1.82° at the final follow-up (p < 0.001). In contrast, there was a slight elevation in the ROM of the adjacent segment during the final follow-up, increasing from 7.68° ± 2.25° before surgery to 9.36° ± 1.98° (p < 0.001). The intervertebral space height (IH) in the stabilized segment exhibited a significant increase from 10.56 ± 1.99 mm before surgery to 11.39 ± 1.90 mm at the one-week postoperative follow-up (p < 0.001). Conversely, there was a notable decrease in the IH of the adjacent segment from 11.09 ± 1.82 mm preoperatively to 10.86 ± 1.79 mm at the one-week follow-up after surgery (p < 0.001). The incidence of ASD was 15% (6/40) after an average follow-up period of 79.37 months, with a rate of 15.38% (4/26) in the stenosis or herniated disc group and 14.29% (2/14) in the spondylolisthesis group; however, no statistically significant difference was observed in the occurrence of ASD among these groups (p > 0.05)., Conclusion: The Isobar TTL dynamic fixation system is an effective treatment for LDDs, improving pain relief, quality of life (QoL) and maintaining stabilized segmental motion. It has demonstrated excellent long-term clinical and radiographic results., (© 2024 The Authors. Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.)

Background: Hybrid fixators with quite different joint design concepts have been widely to suppress adjacent segment degeneration problems. The kinematic and kinetic responses of the adjacent and transition segments and contact behaviors at the bone-screw interfaces served as the objective of this study., Methods: The moderately degenerated L4/L5 and mildly degenerative L3/L4 segments were respectively immobilized by a static fixator and further bridged by the rod-rod (Isobar) and screw-spacer (Dynesys) fixator. The joint stiffness and mobility of the rod-rod system and the cable pretension of the screw-spacer system were systematically varied., Findings: The flexion of the screw-spacer system provided higher mobility to the transition segment, reducing adjacent-segment problems. The cable pretension had a minor effect on the construct behavior. However, due to limited joint mobility, the rod-rod system showed higher constraints to the transition segment and induced more adjacent-segment compensations. The increased mobility of the rod-rod joint caused it to behave as a more dynamic fixator that increased adjacent-segment compensations at the transition segment. Comparatively, increasing the joint mobility showed more significant effects on the construct behaviors than decreasing the joint stiffness. Furthermore, increased constraint by the rod-rod joint induced higher stress and risk of loosening at the bone-screw interfaces INTERPRETATION: If the protection of the transition segment is the major concern, the rod-rod system can be used to constrain the intervertebral motion and share the higher loads through the fixator. Otherwise, the screw-spacer system is recommended in situations where higher loads onto the transition disc are allowable., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Shang-Chih Lin reports was provided by Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan. Yu-Kun Xu reports was provided by Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan. Pei-Wei Weng reports was provided by Department of Orthopedics, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan. Shih-Hao Chen reports was provided by Tzu Chi General Hospital at Taichung and Tzu Chi University, Taiwan., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

OBJECTIVE Pedicle screw-based dynamic stabilization has been an alternative to conventional lumbar fusion for the surgical management of low-grade spondylolisthesis. However, the true effect of dynamic stabilization on adjacent-segment degeneration (ASD) remains undetermined. Authors of this study aimed to investigate the incidence of ASD and to compare the clinical outcomes of dynamic stabilization and minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). METHODS The records of consecutive patients with Meyerding grade I degenerative spondylolisthesis who had undergone surgical management at L4-5 in the period from 2007 to 2014 were retrospectively reviewed. Patients were divided into two groups according to the surgery performed: Dynesys dynamic stabilization (DDS) group and MI-TLIF group. Pre- and postoperative radiological evaluations, including radiography, CT, and MRI studies, were compared. Adjacent discs were evaluated using 4 radiological parameters: instability (antero- or retrolisthesis), disc degeneration (Pfirrmann classification), endplate degeneration (Modic classification), and range of motion (ROM). Clinical outcomes, measured with the visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and the Japanese Orthopaedic Association (JOA) scores, were also compared. RESULTS A total of 79 patients with L4-5 degenerative spondylolisthesis were included in the analysis. During a mean follow-up of 35.2 months (range 24-89 months), there were 56 patients in the DDS group and 23 in the MI-TLIF group. Prior to surgery, both groups were very similar in demographic, radiological, and clinical data. Postoperation, both groups had similarly significant improvement in clinical outcomes (VAS, ODI, and JOA scores) at each time point of evaluation. There was a lower chance of disc degeneration (Pfirrmann classification) of the adjacent discs in the DDS group than in the MI-TLIF group (17% vs 37%, p = 0.01). However, the DDS and MI-TLIF groups had similar rates of instability (15.2% vs 17.4%, respectively, p = 0.92) and endplate degeneration (1.8% vs 6.5%, p = 0.30) at the cranial (L3-4) and caudal (L5-S1) adjacent levels after surgery. The mean ROM in the cranial and caudal levels was also similar in the two groups. None of the patients required secondary surgery for any ASD (defined by radiological criteria). CONCLUSIONS The clinical improvements after DDS were similar to those following MI-TLIF for L4-5 Meyerding grade I degenerative spondylolisthesis at 3 years postoperation. According to radiological evaluations, there was a lower chance of disc degeneration in the adjacent levels of the patients who had undergone DDS. However, other radiological signs of ASD, including instability, endplate degeneration, and ROM, were similar between the two groups. Although none of the patients in the present series required secondary surgery, a longer follow-up and a larger number of patients would be necessary to corroborate the protective effect of DDS against ASD.

Dynesys (Dynamic Neutralization System) was designed to overcome the shortcomings of fusion. The Dynesys top loading (DTL) system is a new alternative Dynesys system that can be applied via a minimally invasive procedure. This study aimed to ascertain whether DTL is a suitable device for motion preservation and prevention of instability, and to compare the clinical and radiological outcomes between DTL and Dynesys. In this study, 12 patients were treated with Dynesys and 21 patients were treated with DTL. Back and leg pain were evaluated using the visual analog scale. The Oswestry Disability Index was used to evaluate the patients' function. Range of motion (ROM) at the operative level and for the whole lumbar spine was measured pre- and postoperatively. The length of wound, blood loss, length of hospital stay, and operation duration were also compared. All patients were followed up for 12-76 months. Scores on the visual analog scale and Oswestry Disability Index were significantly improved postoperatively. The median ROM of the whole spine and index level ROM in all patients showed 12.5% and 79.6% loss, respectively. The DTL group exhibited significantly better results in terms of blood loss, wound length, and operation duration, in addition to early ambulation. In conclusion, Dynesys and DTL are semirigid fixation systems that can significantly improve clinical symptoms and signs. Our results suggested that DTL was better than Dynesys as a result of it being a minimally invasive procedure. However, further study with large sample sizes and longer follow-up durations is required to validate the effects of these dynamic stabilizers., (Copyright © 2016. Published by Elsevier Taiwan.)

OBJECTIVE In the past decade, dynamic stabilization has been an emerging option of surgical treatment for lumbar spondylosis. However, the application of this dynamic construct for mild spondylolisthesis and its clinical outcomes remain uncertain. This study aimed to compare the outcomes of Dynesys dynamic stabilization (DDS) with minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) for the management of single-level spondylolisthesis at L4-5. METHODS This study retrospectively reviewed 91 consecutive patients with Meyerding Grade I spondylolisthesis at L4-5 who were managed with surgery. Patients were divided into 2 groups: DDS and MI-TLIF. The DDS group was composed of patients who underwent standard laminectomy and the DDS system. The MI-TLIF group was composed of patients who underwent MI-TLIF. Clinical outcomes were evaluated by visual analog scale for back and leg pain, Oswestry Disability Index, and Japanese Orthopaedic Association scores at each time point of evaluation. Evaluations included radiographs and CT scans for every patient for 2 years after surgery. RESULTS A total of 86 patients with L4-5 spondylolisthesis completed the follow-up of more than 2 years and were included in the analysis (follow-up rate of 94.5%). There were 64 patients in the DDS group and 22 patients in the MI-TLIF group, and the overall mean follow-up was 32.7 months. Between the 2 groups, there were no differences in demographic data (e.g., age, sex, and body mass index) or preoperative clinical evaluations (e.g., visual analog scale back and leg pain, Oswestry Disability Index, and Japanese Orthopaedic Association scores). The mean estimated blood loss of the MI-TLIF group was lower, whereas the operation time was longer compared with the DDS group (both p < 0.001). For both groups, clinical outcomes were significantly improved at 6, 12, 18, and 24 months after surgery compared with preoperative clinical status. Moreover, there were no differences between the 2 groups in clinical outcomes at each evaluation time point. Radiological evaluations were also similar and the complication rates were equally low in both groups. CONCLUSIONS At 32.7 months postoperation, the clinical and radiological outcomes of DDS were similar to those of MI-TLIF for Grade I degenerative spondylolisthesis at L4-5. DDS might be an alternative to standard arthrodesis in mild lumbar spondylolisthesis. However, unlike fusion, dynamic implants have issues of wearing and loosening in the long term. Thus, the comparable results between the 2 groups in this study require longer follow-up to corroborate.

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.

OBJECTIVE Dynamic stabilization devices are designed to stabilize the spine while preserving some motion. However, there have been reports demonstrating limited motion at the instrumented level of the lumbar spine after Dynesys dynamic stabilization (DDS). The causes of this limited motion and its actual effects on outcomes after DDS remain elusive. In this study, the authors investigate the incidence of unintended facet arthrodesis after DDS and clinical outcomes. METHODS This retrospective study included 80 consecutive patients with 1- or 2-level lumbar spinal stenosis who underwent laminectomy and DDS. All medical records, radiological data, and clinical evaluations were analyzed. Imaging studies included pre- and postoperative radiographs, MR images, and CT scans. Clinical outcomes were measured by a visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and Japanese Orthopaedic Association (JOA) scores. Furthermore, all patients had undergone postoperative CT for the detection of unintended arthrodesis of the facets at the indexed level, and range of motion was measured on standing dynamic radiographs. RESULTS A total of 70 patients (87.5%) with a mean age of 64.0 years completed the minimum 24-month postoperative follow-up (mean duration 29.9 months). Unintended facet arthrodesis at the DDS instrumented level was demonstrated by CT in 38 (54.3%) of the 70 patients. The mean age of patients who had facet arthrodesis was 9.8 years greater than that of the patients who did not (68.3 vs 58.5 years, p = 0.009). There were no significant differences in clinical outcomes, including VAS back and leg pain, ODI, and JOA scores between patients with and without the unintended facet arthrodesis. Furthermore, those patients older than 60 years were more likely to have unintended facet arthrodesis (OR 12.42) and immobile spinal segments (OR 2.96) after DDS. Regardless of whether unintended facet arthrodesis was present or not, clinical evaluations demonstrated improvement in all patients (all p < 0.05). CONCLUSIONS During the follow-up of more than 2 years, unintended facet arthrodesis was demonstrated in 54.3% of the patients who underwent 1- or 2-level DDS. Older patients (age > 60 years) were more likely to have unintended facet arthrodesis and subsequent immobile spinal segments. However, unintended facet arthrodesis did not affect the clinical outcomes during the study period. Further evaluations are needed to clarify the actual significance of this phenomenon.

Introduction: Middle- and long-term outcomes of multi-segmental lumbar spinal stenosis treated with Dynesys stabilization (DS) have rarely been reported. Older age and multi-segmental degeneration may be positive factors in achieving satisfactory outcomes following DS. The present study aimed to compare the middle- and long-term outcomes of DS with lumbar fusion for treatment of multi-segmental lumbar spinal stenosis (ms-LSS) in elderly patients.Materials and Methods: This study retrospectively analyzed patients with ms-LSS treated by DS or lumbar fusion from January 2011 to April 2013. Twenty-two patients were included in the Dynesys group, and 44 patients treated by lumbar fusion and rigid fixation were included in the fusion group. Clinical outcomes were assessed by VAS and ODI. Radiological outcomes were measured by range of motion (ROM) of stabilized segments and the proximal adjacent segment, intervertebral disc height (DH) and L1-S1 lumbar lordosis angle (LL). Modified Pfirrmann grade score was used to access disc degeneration.Outcomes: The mean follow-up time of the Dynesys group and fusion group was 68.50 ± 6.40 and 70.14 ± 7.26 months, respectively. Baseline data were similar between the two groups. There were no significant differences between the two groups in terms of improvement of clinical outcomes (VAS and ODI). DS preserved a certain degree of ROM (3.74 ± 2.00) of surgical segments. ROM of proximal adjacent segment underwent an increase in both groups at the final follow-up. The DH of the surgical segments and proximal adjacent segment in both groups was significantly lower than that before surgery (P = 0.000). LL of both groups improved (P = 0.000), and there was no significant difference between the two groups. The modified Pfirrmann score of proximal adjacent segment of both groups increased at the final follow-up. The fusion group underwent a more significant increase (P = 0.000), whereas the inter-group difference showed no significance (P = 0.090).Conclusion: DS is a safe and effective surgical treatment of multi-segmental lumbar spinal stenosis in the elderly population. DS preserves a certain degree of mobility of surgical segments. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Few studies compared radiographic and clinical outcomes between posterior dynamic stabilization (PDS) and posterior lumbar intervertebral fusion (PLIF) in treating degenerative disc disease (DDD). Methods: A total of 176 consecutive patients who underwent posterior instrumented spinal surgery for degenerative disc disease between January 2007 and January 2009 were prospectively divided into two groups--PDS and PLIF. All patients included in the analysis were followed up for 3 years. Demographic distribution, perioperative complications, and radiographic and clinical outcomes were compared between the two groups. Results: The amount of intraoperative blood loss and drained volume was significantly greater in the PLIF group compared with the PDS group (881.1 ml versus 737.4 ml, = 0.004). The length of stay of patients who had PLIF p surgery (20.9 days) was significantly longer ( = 0.033) than that of patients who underwent PDS surgery (18.9 days). p Patients with PLIF surgery had higher total costs than those with PDS surgery (US$12826.8 versus US$11654.5, p = 0.002). No statistically significant differences existed in back visual analogue scale (VAS), leg VAS, or Oswestry disability index (ODI) scores between the PDS and PLIF groups of patients at each time point. Conclusions: Compared with PLIF, PDS have advantages on blood loss, length of stay in hospital, total charges, and radiographic outcomes, but no advantages on leg and back VAS or ODI scores. High-quality randomized controlled trials are still required in the future. [ABSTRACT FROM AUTHOR]