The Kinematics and Spondylosis of the Lumbar Spine Vary Depending on the Levels of Motion Segments in Individuals With Low Back Pain

The Mid-term Outcome of Intervertebral Disc Degeneration After Direct Vertebral Rotation in Adolescent Idiopathic Scoliosis: Magnetic Resonance Imaging-based Analysis for a Mean 11.6-year Follow-up

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To evaluate the mid-term effect of intervertebral disc degeneration (DD) in patients with adolescent idiopathic scoliosis (AIS) who underwent pedicle screw instrumentation (PSI) and rod derotation (RD) with direct vertebral rotation (DVR).

SUMMARY OF BACKGROUND DATA

Posterior spinal fusion is a mainstay of surgical treatment in AIS, and DVR is considered a main corrective maneuver for vertebral rotation. However, the mid-term effect of intervertebral DD after DVR is still unknown in AIS.

METHODS

A total of 336 vertebrae for 48 patients with AIS who underwent PSI and RD with DVR were retrospectively assessed for intervertebral DD. They were divided into two groups based upon intervertebral DD, defined as Pfirmann grade more than IV. The Pfirrmann grade and modic change were evaluated at the disc above the uppermost instrumented vertebra (UIV), the disc below the lowest instrumented vertebra (LIV), and the lumbar disc levels.

RESULTS

With the 11.6 years of mean follow-up, 41.7% (20/48) of patients exhibited DD, while modic changes were observed in 4.2% (2/48) of the included patients. The discs below the LIV, L4-5, and L5-S1 were significantly shown to have an increasing trend of Pfirmann grade. The preoperative thoracic kyphosis was significantly lower in the DD group (22.0°) than in the non-DD group (31.4°) ( P = 0.025) and negatively correlated with DD ( r = -0.482, P = 0.018). The Pfirrmann grade of L5-S1 showed a high level of correlation with DD ( r = 0.604, P < 0.001).

CONCLUSIONS

The degenerative change at the disc below the LIV, L4-5, and L5-S1 levels was observed following PSI and RD with DVR. Thoracic hypokyphosis may negatively influence intervertebral discs in patients with AIS required for deformity correction. Therefore, the restoration of thoracic kyphosis is important to prevent long-term DD in AIS.

Prevalence, distribution characteristic and risk factors of lumbar vertebral axial rotation in patients with lumbar disc herniation: a retrospective study

This retrospective study aimed to investigate the impact of lumbar disc herniation (LDH) on vertebral axial rotation (VAR) in the lumbar spine, focusing on both close and distant neighboring vertebrae. A total of 516 patients with LDH and an equal number of healthy individuals were included in the study, matched for age and gender. The degree of axial rotation for each lumbar spine vertebra was assessed using the Nash-Moe index. The results revealed that the prevalence of VAR in the lumbar spine was significantly higher in the LDH group compared to the Control group (65.7% vs 46.7%, P < 0.001). Among the LDH group, the L2 vertebra had the highest frequency of VAR (49.5%), followed by L1 (45.1%), and then L3 to L5 (33.6%, 8.9%, 3.1%, respectively). A similar pattern was observed in the Control group (L2, 39.8%; L1, 34.6%; L3, 23.2%; L4, 3.1%; L5, 0.8%). Furthermore, the study found that disc herniation was associated with a higher incidence of VAR not only in close neighboring vertebrae but also in distant neighboring vertebrae. This indicates that the biomechanical influence of LDH extends beyond just the immediate adjacent vertebrae. To identify potential risk factors for VAR in LDH patients, multivariate analysis was performed. The results revealed that age was an independent risk factor for VAR (OR 1.022, 95% CI [1.011, 1.034], P < 0.001). However, the duration of symptoms and presence of back pain were not found to be significant risk factors for VAR.

EMG Validation of a Subject-Specific Thoracolumbar Spine Musculoskeletal Model During Dynamic Activities in Older Adults

Musculoskeletal models can uniquely estimate in vivo demands and injury risk. In this study, we aimed to compare muscle activations from subject-specific thoracolumbar spine OpenSim models with recorded muscle activity from electromyography (EMG) during five dynamic tasks. Specifically, 11 older adults (mean = 65 years, SD = 9) lifted a crate weighted to 10% of their body mass in axial rotation, 2-handed sagittal lift, 1-handed sagittal lift, and lateral bending, and simulated a window opening task. EMG measurements of back and abdominal muscles were directly compared to equivalent model-predicted activity for temporal similarity via maximum absolute normalized cross-correlation (MANCC) coefficients and for magnitude differences via root-mean-square errors (RMSE), across all combinations of participants, dynamic tasks, and muscle groups. We found that across most of the tasks the model reasonably predicted temporal behavior of back extensor muscles (median MANCC = 0.92 ± 0.07) but moderate temporal similarity was observed for abdominal muscles (median MANCC = 0.60 ± 0.20). Activation magnitude was comparable to previous modeling studies, and median RMSE was 0.18 ± 0.08 for back extensor muscles. Overall, these results indicate that our thoracolumbar spine model can be used to estimate subject-specific in vivo muscular activations for these dynamic lifting tasks.

The association between spondylolisthesis and decreased muscle health throughout the lumbar spine for patients with operative lumbar spinal stenosis

PURPOSE

There are data underlining the relationship between muscle health and spine related pathology, but little data regarding changes in paralumbar muscle associated with lumbar spondylolisthesis. We aimed to define changes in paralumbar muscle health associated with spondylolisthesis.

METHODS

A retrospective review was performed on consecutive patients with lumbar spine pathology requiring an operation. A pre-operative lumbar MRI was analysed for muscle health measurements including lumbar indentation value (LIV), paralumbar cross-sectional area divided by body mass index (PL-CSA/BMI), and Goutallier classification of fatty atrophy. All measurements were taken from an axial slice of a T2-weighted image at lumbar disc spaces. Baseline health-related quality of life scores (HRQOLs), narcotic use and areas of stenosis were tracked. We performed Chi-square analyses and student's t test to determine statistically significant differences between cohorts.

RESULTS

There were 307 patients (average age 56.1 ± 16.7 years, 141 females) included within our analysis. 112 patients had spondylolisthesis. There were no differences in baseline HRQOLs between the spondylolisthesis cohort (SC) and non-spondylolisthesis cohort (non-SC). There were significantly worse PL-CSA/BMI at L2-L3 (p = 0.03), L3-L4 (p = 0.04) and L4-L5 (p = 0.02) for the SC. Goutallier classification of paralumbar muscle was worse for SC at L1-L2 (p = 0.04) and at L4-L5 (p < 0.001). Increased grade of spondylolisthesis was associated with worse PL-CSA at L1-L2 (p = 0.02), L2-L3 (p = 0.03) and L3-L4 (p = 0.05). Similarly, there were worse Goutallier classification scores associated with higher-grade spondylolisthesis at all levels (p < 0.05).

CONCLUSION

There are significant detrimental changes to paralumbar muscle health throughout the lumbar spine associated with spondylolisthesis.

The Influence of Kinematic Constraints on Model Performance During Inverse Kinematics Analysis of the Thoracolumbar Spine

Motion analysis is increasingly applied to spine musculoskeletal models using kinematic constraints to estimate individual intervertebral joint movements, which cannot be directly measured from the skin surface markers. Traditionally, kinematic constraints have allowed a single spinal degree of freedom (DOF) in each direction, and there has been little examination of how different kinematic constraints affect evaluations of spine motion. Thus, the objective of this study was to evaluate the performance of different kinematic constraints for inverse kinematics analysis. We collected motion analysis marker data in seven healthy participants (4F, 3M, aged 27–67) during flexion–extension, lateral bending, and axial rotation tasks. Inverse kinematics analyses were performed on subject-specific models with 17 thoracolumbar joints allowing 51 rotational DOF (51DOF) and corresponding models including seven sets of kinematic constraints that limited spine motion from 3 to 9DOF. Outcomes included: (1) root mean square (RMS) error of spine markers (measured vs. model); (2) lag-one autocorrelation coefficients to assess smoothness of angular motions; (3) maximum range of motion (ROM) of intervertebral joints in three directions of motion (FE, LB, AR) to assess whether they are physiologically reasonable; and (4) segmental spine angles in static ROM trials. We found that RMS error of spine markers was higher with constraints than without (p < 0.0001) but did not notably improve kinematic constraints above 6DOF. Compared to segmental angles calculated directly from spine markers, models with kinematic constraints had moderate to good intraclass correlation coefficients (ICCs) for flexion–extension and lateral bending, though weak to moderate ICCs for axial rotation. Adding more DOF to kinematic constraints did not improve performance in matching segmental angles. Kinematic constraints with 4–6DOF produced similar levels of smoothness across all tasks and generally improved smoothness compared to 9DOF or unconstrained (51DOF) models. Our results also revealed that the maximum joint ROMs predicted using 4–6DOF constraints were largely within physiologically acceptable ranges throughout the spine and in all directions of motions. We conclude that a kinematic constraint with 5DOF can produce smooth spine motions with physiologically reasonable joint ROMs and relatively low marker error.

Lumbar Intervertebral Kinematics During an Unstable Sitting Task and Its Association With Standing-Induced Low Back Pain

People developing transient low back pain during standing have altered control of their spine and hips during standing tasks, but the transfer of these responses to other tasks has not been assessed. This study used video fluoroscopy to assess lumbar spine intervertebral kinematics of people who do and do not develop standing-induced low back pain during a seated chair-tilting task. A total of 9 females and 8 males were categorized as pain developers (5 females and 3 males) or nonpain developers (4 females and 5 males) using a 2-hour standing exposure; pain developers reported transient low back pain and nonpain developers did not. Participants were imaged with sagittal plane fluoroscopy at 25 Hz while cyclically tilting their pelvises anteriorly and posteriorly on an unstable chair. Intervertebral angles, relative contributions, and anterior-posterior translations were measured for the L3/L4, L4/L5, and L5/S1 joints and compared between sexes, pain groups, joints, and tilting directions. Female pain developers experienced more extension in their L5/S1 joints in both tilting directions compared with female nonpain developers, a finding not present in males. The specificity in intervertebral kinematics to sex-pain group combinations suggests that these subgroups of pain developers and nonpain developers may implement different control strategies.

Three-Dimensional Spinal Position With and Without Manual Distraction Load Increases Spinal Height

OBJECTIVE

The purpose of this study was to investigate if spinal height increases using 3-dimensional (3-D) spinal position with and without manual distraction load and to assess the correlation between spine height changes and degrees of trunk rotation.

METHODS

Fifty-six participants were randomly placed in one of two groups: (1) 3-D spinal position with manual distraction load, and (2) without manual distraction load. Spinal height was measured before and after the interventions using a stadiometer. For the statistical analysis, we used a 2 (Loading status: pre- versus post-intervention height) X 2 (3-D spinal position: with versus without manual distraction load) repeated measures Analysis of Variance (ANOVA) was used to identify significant interaction and main effects. Paired t-tests were used to calculate differences in spinal height changes between the two interventions. Pearson correlation coefficient was used to measure correlations between changes in spinal heights and degrees of trunk rotation.

RESULTS

Mean spinal height increase with 3-D spinal position with and without manual distraction load was 6.30 mm (±6.22) and 5.69 mm (±4.13), respectively. No significant interaction effect was present between loading status and 3-D spinal position but a significant main effect in loading status was. Paired t-tests revealed significant differences in spinal heights between pre-and post-3-D spinal position with and without manual distraction load. No significant correlation was measured between trunk rotation and spinal height changes.

CONCLUSION

3-D spinal position with or without distraction load increased spinal height. This suggests that 3-D spinal positioning without manual distraction could be used in home settings to help maintain intervertebral disc (IVD) health.

Temporary axial rotation stabilization for lumbar disc herniation surgery with the ARO® spinal system: a prospective analysis of safety and clinical efficacy

Background

Decompressive surgery has a failure rate of between 25% and 32% based on patient reported improvement in clinical symptoms. Significant back pain is associated with 53% of failures of decompressive surgery, while also being associated with abnormal axial rotation motion. We report on the clinical performance of subjects receiving a novel axial rotation stabilization implant (ARO Spinal System, ARO Medical), while undergoing a surgical decompression for a herniated lumbar disc, a condition associated with low back pain and abnormal movement.

Methods

This Danish Medicines Agency and Ethics Committee approved clinical trial prospectively investigated the use of the ARO^® Spinal System as part of lumbar discectomy surgery in 20 patients. All subjects had a single level posterolateral lumbar herniation with symptoms lasting more than 6 weeks. They underwent an open discectomy at the symptomatic level, and received the implant.

Results

No complications with the implant were observed. Four serious adverse events not related to the devices were reported, one subject had reoperation at 3 months. Leg pain median VAS score decreased from 70 to 2 at 1 year (P=0.01) back pain median VAS score from 48 to 6 (P=0.04). Satisfaction with surgery was 88%. Oswestry Disability Index scored likewise improvement going from 38 pre-operative to 5 at 1 year. Follow-up rate was excellent 100%.

Conclusions

Discectomy with the ARO Spinal System proves equally safe as a standard discectomy at 1 year follow-up. The subjects had significant improvements in both leg and back pain. In addition, they did better than historical controls, though not statistically so in this patient sample.