Investigation of Reaction Forces in the Thoracolumbar Fascia during Different Activities: A Mechanistic Numerical Study

Spinal instability remains a complex phenomenon to study while the cause of low back pain continues to challenge researchers. The role of fascia in biomechanics adds to the complexity of spine biomechanics but offers a new window from which to investigate our spines. Specifically, the thoracolumbar fascia may have an important role in spine biomechanics, and thus the purpose of this study was to access the mechanical influence of the thoracolumbar fascia on spine biomechanics during different simulated activities. A numerical finite element model of the lumbar spine inclusive of the intra-abdominal and intra-muscular regions as well as the thoracolumbar fascia was constructed and validated. Four different loading scenarios were simulated while deformation, stress, pressure, and reaction forces between the thoracolumbar fascia and spine were measured. Model validation was accomplished through comparison to in vivo and ex vivo published studies. Force transmission between the thoracolumbar fascia and the spine increased 40% comparing kyphotic and squatting lifting patterns. Further, the importance of reciprocating paraspinal and intra-abdominal pressures was demonstrated. It was also found that tension in the thoracolumbar fascia remains even in a simulated prone position. This numerical analysis allowed for an objective interpretation of the loads conveyed through the thoracolumbar fascia in different positional or lifting scenarios. Based on validation studies, it would appear to be a viable experimental platform from which insight can be derived. The loads in the thoracolumbar fascia vary considerably based on simulated tasks and are linked to the pressures in the paraspinal and intra-abdominal regions.

A Self-Contained 3D Biomechanical Analysis Lab for Complete Automatic Spine and Full Skeleton Assessment of Posture, Gait and Run

Quantitative functional assessment of Posture and Motion Analysis of the entire skeleton and spine is highly desirable. Nonetheless, in most studies focused on posture and movement biomechanics, the spine is only grossly depicted because of its required level of complexity. Approaches integrating pressure measurement devices with stereophotogrammetric systems have been presented in the literature, but spine biomechanics studies have rarely been linked to baropodometry. A new multi-sensor system called GOALS-E.G.G. (Global Opto-electronic Approach for Locomotion and Spine-Expert Gait Guru), integrating a fully genlock-synched baropodometric treadmill with a stereophotogrammetric device, is introduced to overcome the above-described limitations. The GOALS-EGG extends the features of a complete 3D parametric biomechanical skeleton model, developed in an original way for static 3D posture analysis, to kinematic and kinetic analysis of movement, gait and run. By integrating baropodometric data, the model allows the estimation of lower limb net-joint forces, torques and muscle power. Net forces and torques are also assessed at intervertebral levels. All the elaborations are completely automatised up to the mean behaviour extraction for both posture and cyclic-repetitive tasks, allowing the clinician/researcher to perform, per each patient, multiple postural/movement tests and compare them in a unified statistically reliable framework.

Video analysis of spine biomechanics as an objective method of functional diagnostics

The present scientific review of medical and technical literature presents the attempt to assess modern technological stage of spine biomechanical hardware diagnostics in terms of its objectivity, as well as diagnostic and prognostic value on the example of etiopathogenesis analysis of spine degenerative-dystrophic diseases. A set of structural and extra vertebral factors contributing to the onset and progression of spine degenerative-dystrophic diseases was identifi ed to determine diagnostic and prognostic value studying particular literature sources, which use empirical and mathematical research methods. Central indicator value of intersegmental compression-distractive kinetics and loads shift s related to these factors was also determined. When considering the objectivity of spine biomechanics video analysis, the reliability of kinetics and spinal motion segments kinematics was separately assessed. Furthermore, impropriety of the latter was established in terms of reliability and repeatability of diagnostic results. Only vertical force indicator is valid in kinetics, reflecting intersegmental compression load, due to the sufficient objectivity and weak dependence of its values on the type of computer mathematical models used by commercial systems of video motion analysis. Walking is optimal motional act for calculating vertical force by modern optoelectronic soft ware and hardware systems.

Instrumentation following intradural tumor resection: A case analyses and literature review

Background: Resection of intradural spinal tumors typically utilizes a posterior approach and often contributes to significant biomechanical instability and sagittal deformity. Methods: We searched PubMed for studies regarding pre- and postoperative spine biomechanics/alignment in patients with intradural tumors undergoing posterior decompressions. Results: Three patients underwent posterior decompressions with instrumented fusions to preserve good sagittal alignment postoperatively. Variables analyzed in this study included the extent of preoperative and postoperative deformity, the number of surgical levels decompressed and fused, the different frequencies of instability following the resection of cervical versus thoracic versus lumbar lesions, and whether pediatric patients were most likely to develop instability. Conclusion: Simultaneously performing instrumented fusions following posterior spinal decompressions for tumor removal proved optimal in preventing postoperative spinal deformity. Further, “open” surgical procedures offered more optimal/definitive tumor removal versus minimally invasive approaches, and the greater operative exposure and resultant increased risk for instability were remediated by performing simultaneous fusion.

The Effect of Compression Applied Through Constrained Lateral Eccentricity on the Failure Mechanics and Flexibility of the Human Cervical Spine

In contrast to sagittal plane spine biomechanics, little is known about the response of the cervical spine to axial compression with lateral eccentricity of the applied force. This study evaluated the effect of lateral eccentricity on kinetics, kinematics, canal occlusion, injuries and flexibility of the cervical spine in translationally-constrained axial impacts. Eighteen functional spinal units were subjected to flexibility tests before and after an impact. Impact axial compression was applied at one of three lateral eccentricity levels based on percentage of vertebral body width (low = 5%, medium = 50%, high = 150%). Injuries were graded by dissection. Correlations between intrinsic specimen properties and injury scores were examined for each eccentricity group. Low lateral force eccentricity produced predominantly bone injuries, clinically recognised as compression injuries, while medium and high eccentricity produced mostly contralateral ligament and/or disc injuries, an asymmetric pattern typical of lateral loading. Mean compression force at injury decreased with increasing lateral eccentricity (low = 3098 N, medium = 2337 N and high = 683 N). Mean ipsilateral bending moments at injury were higher at medium (28.3 Nm) and high (22.9 Nm) eccentricity compared to low eccentricity specimens (0.1 Nm), p<0.05. Ipsilateral bony injury was related to vertebral body area (r = -0.974, p = 0.001) and disc degeneration (r = 0.851, p = 0.032) at medium eccentricity. Facet degeneration was correlated with central bony injury at high eccentricity (r = 0.834, p = 0.036). These results deepen cervical spine biomechanics knowledge in circumstances with coronal plane loads.