Analysis of clinical effect and radiographic outcomes of Isobar TTL system for two-segment lumbar degenerative disease: a retrospective study

Long-term Outcome of Isobar TTL System for the Treatment of Lumbar Degenerative Disc Diseases

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.

Biomechanical Study of Minimally Invasive Nonfusion Surgery for Treatment of Disc Herniation Associated with Adjacent Segment Disease: A Finite Element Analysis

OBJECTIVE

We explored the biomechanical changes of 2 conventional minimally invasive nonfusion surgical methods for treating disc herniation in adjacent segment disease using 3-dimensional finite element analysis.

METHODS

A model comprising L3 to the sacrum was validated and used to establish an L4-L5 fusion model, and an adjacent segment disease (ASD) model was developed by modifying the material properties of the intervertebral discs. The ASD model was used to simulate 2 conventional minimally invasive nonfusion surgical methods, which resulted in the creation of 2 postoperative models (M1 and M2). The range of motion and the equivalent stress for each model were recorded under 6 different working conditions. The data are descriptive and were analyzed comparatively under a normal load.

RESULTS

Compared with the ASD group, the range of motion of the adjacent segment in the M1 and M2 groups remained unaffected. However, significant Von-Mises stress changes were found in the annulus fibrosus and nucleus pulposus (NP), especially during extension, ipsilateral bending, and rotation. Stress in the NP also shifted toward the surgical incision in the annulus fibrosus during these movements. The maximum Von-Mises stress in the NP of the cephalic segment increased more than did that of the caudal segment.

CONCLUSIONS

Minimal nonfusion surgery for ASD might not affect adjacent segment stability significantly. Nonetheless, it can lead to segmental degeneration deterioration and postoperative recurrence. The cephalic segment is affected more than the caudal segment. Therefore, consideration of disc degeneration and appropriate selection of surgical methods for ASD are crucial.

Clinical Outcomes of Isobar TTL System with Isthmic Bone Grafting and Pedicle Screw-Vertebral Plate Hook with Direct Repair of Defect for Lumbar Spondylolysis: A Matched-Pair Case Control Study

OBJECTIVE

Although direct isthmic repair, such as PSVPH, did not affect the mobility of the fixed segment and adjacent segment, it has a relatively low rate of isthmic fusion compared with conventional fusion. The Isobar TTL dynamic internal fixation system has been widely used in clinical practice and has achieved satisfactory clinical results. However, the use of the Isobar TTL system in combination with direct isthmic repair for lumbar spondylolysis has rarely been reported. The aim of this study was to compare the clinical and radiologic outcomes between patients who underwent Isobar TTL system and PSVPH with direct repair of defect for lumbar spondylolysis.

METHODS

Stepwise propensity score matching (PSM) for age and sex were performed to keep comparable clinical data between groups in this retrospective and matched-pair case control study. A total of 50 patients diagnosed with lumbar spondylolysis underwent surgical implantation of the Isobar TTL group (n = 25) or PSVPH group (n = 25) from June 2009 to June 2016. Clinical outcomes were assessed using the Oswestry disability index (ODI), and visual analog score (VAS). Radiographic evaluations included range of motion (ROM) and the disc heights of stabilized segment and adjacent segment, adjacent segment degeneration (ASD) and bony fusion. Three-dimensional reconstruction of lumbar CT scan was obtained to evaluate bone fusion of the isthmic at final follow-up. The independent Student's t test and chi-square test were applied to compare the differences between groups.

RESULTS

A total of 25 patients from TTL group were matched to 25 patients in PSVPH group for age, sex, body mass index (BMI), defect side, spondylolisthesis meyerding, and follow-up duration. The intervertebral space height (IH) of stabilized segment at postoperative 1 week and final follow-up in the TTL group was higher than those in the PSVPH group, respectively (P = 0.030; P = 0.013). The ROM of stabilized segment at final follow-up in the TTL group was significantly lower than that in the PSVPH group (P < 0.001). The bony fusion rate at the final follow-up was 88.0% (22/25 cages) in the TTL group and 80.0% (20/25 cages) in the PSVPH group. The ODI score at final follow-up in the TTL group was significantly lower than that in the PSVPH group (P = 0.007).

CONCLUSION

Overall, our data suggest that the Isobar TTL system outcomes are comparable to those in the PSVPH, with a similar high bony fusion rate as PSVPH, especially its wider indications as a new surgery.

Biomechanical and clinical research of Isobar semi-rigid stabilization devices for lumbar degenerative diseases: a systematic review

While lumbar spinal fusion using rigid rods is a prevalent surgical technique, it can lead to complications such as adjacent segment disease (ASDis). Dynamic stabilization devices serve to maintain physiological spinal motion and alleviate painful stress, yet they are accompanied by a substantial incidence of construct failure and subsequent reoperation. Compared to traditional rigid devices, Isobar TTL semi-rigid stabilization devices demonstrate equivalent stiffness and effective stabilization capabilities. Furthermore, when contrasted with dynamic stabilization techniques, semi-rigid stabilization offers improved load distribution, a broader range of motion within the fixed segment, and reduced mechanical failure rates. This paper will review and evaluate the clinical and biomechanical performance of Isobar TTL semi-rigid stabilization devices. A literature search using the PubMed, EMBASE, CNKI, Wanfang, VIP, and Cochrane Library databases identified studies that met the eligibility criteria. Twenty-eight clinical studies and nine biomechanical studies were included in this systematic review. The VAS, the ODI, and Japanese Orthopedic Association scoring improved significantly in most studies. UCLA grading scale, Pfirrmann grading, and modified Pfirrmann grading of the upper adjacent segments improved significantly in most studies. The occurrence rate of ASD was low. In biomechanical studies, Isobar TTL demonstrated a superior load sharing distribution, a larger fixed segment range of motion, and reduced stress at the rod-screw/screw-bone interfaces compared with titanium rods. While findings from mechanical studies provided promising results, the clinical studies exhibited low methodological quality. As a result, the available evidence does not possess sufficient strength to substantiate superior outcomes with Isobar semi-rigid system in comparison to titanium rods. To establish more conclusive conclusions, further investigations incorporating improved protocols, larger sample sizes, and extended follow-up durations are warranted.

Correlation between surgical segment mobility and paravertebral muscle fatty infiltration of upper adjacent segment in single-segment LDD patients: retrospective study at a minimum 2 years' follow-up

OBJECTIVE

The purpose of this study was to investigate the relationship between surgical segment mobility and fatty infiltration of the adjacent segment paravertebral muscles in patients with single-segment lumbar degenerative disease (LDD) who underwent decompression with fusion or dynamic stabilization.

METHODS

Retrospective analysis of patients who underwent lumbar decompression combined with titanium rod fixation intertransverse fusion (PITF group), Isobar TTL dynamic stabilization (TTL group) or Isobar EVO dynamic stabilization (EVO group) for single-segment lumbar degenerative disease, from March 2012 to July 2018. The preoperative and final follow-up clinical indexes C-LDSI and the measured imaging indexes (range of motion of the surgical segment and the upper adjacent segment, and Goutallier grade of the upper adjacent segment) were counted, and the differences between the preoperative and final follow-up indexes were compared.

RESULTS

According to the inclusion and exclusion criteria, 68 patients were included in this study, 21 in the PITF group, 24 in the TTL group, and 23 in the EVO group. At the final follow-up, the C-LSDI score had significantly higher in the PITF group than the TTL and EVO groups, and the C-LSDI score was a very strongly negatively correlated with ROM of surgical segment (r=-0.7968, p < 0.001). There was a strong negative correlation between surgical segment and upper adjacent segment mobility (r = -0.6959, p < 0.001). And there was a very strong negative correlation between ROM of surgical segment and upper adjacent segment paravertebral muscle Goutallier classification (r = -0.8092, p < 0.001), whereas the ROM of the upper adjacent segment was strong positive correlated with the Goutallier classification (r = 0.6703, P < 0.001).

CONCLUSION

Compared with decompression combined with rigid fusion, decompression combined with dynamic fixation for single-segment lumbar degenerative disease can significantly reduce postoperative low back stiffness. And a certain range of increased mobility of the dynamic stabilization device can effectively reduce the compensatory mobility of the upper adjacent segment and slow down the fatty infiltration of the paravertebral muscle in the adjacent segment.

Comparison between single-segment Isobar EVO dynamic stabilization and Isobar TTL dynamic stabilization in the treatment of lumbar degenerative diseases: a single center retrospective study over 4 years

Objective

Posterior instrumented fusion is the most widely accepted surgical treatment for spinal stenosis and disc herniation. However, fusion can affect daily activities due to lumbar stiffness. In recent years, dynamic stabilization has been introduced to overcome the drawbacks of fusion, however, it is inconclusive whether dynamic stabilization requires the maintenance of a level of activity that is closer to the physiological state of activity for better clinical efficacy. The purpose of this study was to compare the effectiveness of dynamic stabilization with different levels of activity (Isobar EVO and TTL) in the treatment of spinal stenosis and disc herniation.

Methods

This study retrospectively reviewed 80 consecutive patients with lumbar degenerative diseases who were undergoing surgical treatment between March 2014 and July 2018. 41 patients (EVO group) and 39 patients (TTL group) underwent fenestrated decompression with Isobar EVO stabilization and Isobar TTL stabilization, respectively. Clinical outcomes, radiographic data, and postoperative complications were compared between the two groups.

Results

At an average follow-up of 52.23 ± 2.97 months, there were no significant differences in the oswestry disability index (ODI) (P > 0.05). The visual analog scale for back pain (VAS_back) and visual analog scale for the leg pain (VAS_leg) of the EVO group were lower compared with the TTL group (P < 0.05). The range of motion (ROM) of operated segments were significantly higher in the EVO group as compared to the TTL group (P < 0.05). The intervertebral space height (ISH) of upper adjacent segments were significantly higher in the EVO group as compared to the TTL group (P < 0.05). The overall complications were less in the EVO group, but the difference was not statistically significant (P > 0.05).

Conclusion

Both Isobar EVO dynamic stabilization and TTL dynamic stabilization can improve clinical outcomes of patients with spinal stenosis and disc herniation. Isobar EVO has advantages over Isobar TTL in terms of improving low back and leg pain, maintaining mobility of the operated segment, and preventing further degeneration of the upper adjacent segment.

Biomechanical analysis of lumbar nonfusion dynamic stabilization using a pedicle screw-based dynamic stabilizer or an interspinous process spacer

This study aimed to investigate and compare the effects of two widely used nonfusion posterior dynamic stabilization (NPDS) devices, pedicle screw-based dynamic stabilizer (PSDS) and interspinous process spacer (IPS), on biomechanics of the implanted lumbar spine under static and vibration loadings. The finite element model of healthy human lumbosacral segment was modified to incorporate NPDS device insertion at L4-L5 segment. Bioflex and DIAM were used as PSDS-based and IPS-based NPDS devices, respectively. As a comparison, lumbar interbody fusion with rigid stabilization was also simulated at L4-L5. For static loading, segmental range of motion (ROM) of the models under moments of four physiological motions was computed using hybrid testing protocol. For vibration loading, resonant modes and dynamic stress of the models under vertical excitation were extracted through random response analysis. The results showed that compared with the rigid fusion model, ROM of the nonfusion models was higher at L4-L5 level but lower at adjacent levels (L1- L2, L2-L3, L3-L4, L5-S1). Compared with the Bioflex model, the DIAM model produced higher ROM at L4-L5 level but lower ROM at adjacent levels, especially under lateral bending and axial rotation; resonant frequency of the DIAM model was slightly lower; dynamic response of nucleus stress at L4-L5 level was slightly higher for the DIAM model, and the dynamic stress at adjacent levels was no obvious difference between the nonfusion models. This study reveals biomechanical differences between the Bioflex and DIAM systems, which may provide references for selecting surgical approaches in clinical practice.

Intervertebral Disc Degeneration: Functional Analysis of Bite Force and Masseter and Temporal Muscles Thickness

Intervertebral disc degeneration is a pathological condition associated with the intervertebral disc and is related to functional alterations in the human body. This study aimed to evaluate the maximum molar bite force and masseter and temporal muscles thickness in individuals with intervertebral disc degeneration. Thirty-two individuals were divided into two groups: those with degeneration of intervertebral discs (n=16) and those without degeneration (n=16). The maximum molar bite force (on the right and left sides) was measured using a dynamometer. Masseter and temporal muscle thickness during mandibular task rest and dental clenching in maximum voluntary contraction were analysed using ultrasound. Significant differences in the left molar bite force (p=0.04) were observed between the groups (Student's t-test, p&lt;0.05). The intervertebral disc degeneration group had a lower maximum molar bite force. No significant differences in muscle thickness were observed between the masseter and temporal muscles in either group. However, based on clinical observations, the group with intervertebral disc degeneration presented less masseter muscle thickness and greater temporal muscle thickness in both mandibular tasks. Degenerative disease of the intervertebral discs promoted morphofunctional changes in the stomatognathic system, especially in maximum molar bite force and masticatory muscle thickness. This study provides insight into the interaction between spinal pathology and the stomatognathic system, which is important for healthcare professionals who treat patients with functional degeneration.

Effects of posterior lumbar nonfusion surgery with isobar devices versus posterior lumbar interbody fusion surgery on clinical and radiological features in patients with lumbar degenerative diseases: a meta-analysis

Purpose

The aim of this study was to systematically evaluate the efficacy of posterior lumbar isobar nonfusion with isobar devices versus posterior lumbar interbody fusion (PLIF) in the treatment of patients with lumbar degenerative diseases (LDDs).

Materials and method

We performed a literature review and meta-analysis in accordance with the Cochrane methodology. The analysis included a Group Reading Assessment and Diagnostic Evaluation assessments, Jadad Quality Score evaluations, and Risk of Bias in Randomized Studies of Interventions assessments. The PubMed, Ovid, EMBASE, Web of Science, MEDLINE, CNKI, VIP and WanFang databases were searched to collect and compare relevant randomized controlled trials and cohort studies of isobar nonfusion and PLIF in the treatment of lumbar degenerative diseases. The retrieval time was from database inception to June 2021. Two evaluators independently screened the literature, extracted data, and evaluated the quality of the included studies. Outcome measures of interest included low back pain, disability, and radiological features. The protocol for this systematic review was registered on INPLASY (2021110059) and is available in full on inplasy.com (https://inplasy.com/inplasy-2021-11-0059/).

Results

Of the 7 RCTs, 394 patients met the inclusion criteria. The meta-analysis results showed that isobar nonfusion surgery shortened the surgical duration (P = 0.03), reducing intraoperative bleeding (P = 0.001), retained the ROM of surgical segment (P < 0.00001) and the ROM of the lumbar spine (P < 0.00001), and reduced the incidence of ASD (P = 0.0001). However, no significant difference in the postoperative ODI index (P = 0.81), VAS score of LBP (P = 0.59, VAS score of lower limb pain (P = 0.05, and JOA score (P = 0.27) was noted.

Conclusions

Posterior lumbar nonfusion surgery with isobar devices is superior to PLIF in shortening the surgical duration, reducing intraoperative bleeding, retaining the ROM of surgical segments and the lumbar spine to a certain extent, and preventing ASD. Given the possible publication bias, we recommend further large-scale studies.

The effect of posterior lumbar dynamic fixation and intervertebral fusion on paraspinal muscles

BACKGROUND

The aim of this study was to analyze the effect of unilateral K-rod dynamic internal fixation on paraspinal muscles for lumbar degenerative diseases.

METHODS

This study retrospectively collected 52 patients who underwent lumbar surgery with the K-rod group or PLIF. The operation time, intraoperative blood loss, postoperative drainage volume, postoperative exercise time were compared in the two groups. The visual analog scale (VAS) score and the oswestry dysfunction index (ODI) were employed to evaluate the clinical outcomes. The functional cross-sectional area (FCSA) of the paraspinal muscles and paraspinal muscles fat infiltration were measured to assess on the paraspinal muscles.

RESULTS

As compared with the PLIF group, the operation time, the postoperative time in the field, and the average postoperative hospital stay in the K-rod internal fixation group were significantly shortened. At the last follow-up, both the groups showed significant improvement in the VAS score and ODI. The FCSA atrophy of the upper and lower adjacent segments (UAS and LAS) of the K-rod internal group was significantly less than that of the PLIF group. The extent of increase in the fatty infiltration of the paraspinal muscles in the K-rod group was significantly lesser than that in the PLIF group. The postoperative low back pain of the two groups of patients was significantly positively correlated with the FCSA atrophy.

CONCLUSIONS

As compared to PLIF, the posterior lumbar unilateral K-rod dynamic internal fixation showed significantly lesser paraspinal muscle atrophy and fatty infiltration, which were significantly positively correlated with postoperative low back pain.

Selection of the fusion and fixation range in the intervertebral surgery to correct thoracolumbar and lumbar tuberculosis: a retrospective clinical study

Background

To compare the diseased verses the non-diseased intervertebral surgery used in the treatment of thoracolumbar and lumbar spinal tuberculosis and to explore the best choice of fusion of fixation range.

Methods

Two hundred twenty-one patients with thoracolumbar and lumbar tuberculosis were categorized into two groups. One hundred eighteen patients underwent the diseased intervertebral surgery (lesion vertebral pedicle fixation, Group A) and 103 patients underwent the non-diseased intervertebral surgery (1 or 2 vertebral fixation above and below the affected vertebra, group B). Spinal tuberculosis diagnosis was confirmed in both groups of patients before lesion removal, bone graft fusion, and internal fixation. Clinical data and efficacy of the two surgical methods were then evaluated.

Results

The mean follow-up duration for both procedures was 65 months (50–68 months range). There were no significant differences in laboratory examinations, VAS scores, and the Cobb angle correction rate and the angle loss. However, significant differences existed in the operation time, blood loss, serosanguineous drainage volume, and blood transfusion requirement between the two groups. The diseased intervertebral surgery group performed significantly better than the non-diseased intervertebral surgery group in all of these areas. In both cases, the bone graft fused completely with the normal bone by the last follow-up, occuring at 50–86 months post surgery.

Conclusion

The diseased intervertebral surgery is a safe and feasible option for the treatment of thoracolumbar and lumbar tuberculosis. It effectively restores the physiological curvature of the spine and reduces the degeneration of adjacent vertebral bodies in the spinal column.