Low back pain: a biomechanical ratioanle based on 'patterns' of disc degeneration

General Posters: no. 01_42INTRODUCTION: Due to the complex etiology of low back pain, it is often difficult to identify the specific factors that contribute to the symptoms of a particular patient. Disc degeneration is associated with the development of low back pain, but its presence is not always synonymous with symptoms. However, studies have suggested that “patterns” of disc degeneration may provide insight into such pain generation rather than the overall presence of degenerative changes. Specifically, individuals with contiguous multilevel disc degeneration have been shown to exhibit higher presence and severity of low back pain as compared to patients with skipped‐level disc degeneration (i.e. healthy discs located in between degenerated discs). The objective of the ...postprin

An in-vivo study exploring correlations between early-to-moderate disc degeneration and flexion mobility in the lumbar spine

Purpose: Early disc degeneration (DD) has been thought to be associated with loss of spine 6 stability. However, before this can be understood in relation to back pain, it is necessary to 7 know the relationship between DD and intervertebral motion in people without pain. This 8 study aimed to find out if early to moderate DD is associated with intervertebral motion in 9 people without back pain. 10 Methods: Ten pain free adults, aged 51-71 received recumbent and weight bearing MRI 11 scans and quantitative fluoroscopy (QF) screenings during recumbent and upright lumbar 12 flexion. Forty individual level and 10 composite (L2-S1) radiographic and MRI DD gradings 13 were recorded and correlated with intervertebral flexion ROM, translation, laxity, and 14 motion sharing inequality and variability for both positions. 15 Results: Kinematic values were similar to previous control studies. DD was evidenced up to 16 moderate levels by both radiographic and MRI grading. Disc height loss correlated slightly, 17 but negatively with flexion during weight bearing flexion (R=-0.356, p=0.0.025). Composite 18 MRI DD and T2 signal loss evidenced similar relationships (R= -0.305, R= -0.267) but did not 19 reach statistical significance (p=0.056, p=0.096). No significant relationships between any 20 other kinematic variables and DD were found. 21 Conclusion: This study found only small, indefinite associations between early-to-moderate 22 DD and intervertebral motion in healthy controls. Motion sharing in the absence of pain 23 was also not related to early DD, consistent with previous control studies. Further research 24 is needed to investigate these relationships in patients. 25 Key words: back pain, disc degeneration, instability, imagin

Changes in vertebral strain energy correlate with increased presence of Schmorl's nodes in multi-level lumbar disk degeneration

Patients with skipped-level disk degeneration (SLDD) were recently reported as having a higher prevalence of Schmorl's nodes than patients with contiguous multi-level disk degeneration (CMDD). Fourteen versions of a nonlinear finite element model of a lumbar spine, representing different patterns of single and multi-level disk degeneration, were simulated under physiological loading. Results show that vertebral strain energy is a possible predictor in the development of Schmorl's nodes. The analysis also shows evidence that the development of Schmorl's nodes may be highly dependent on the location of the degeneration disk, with a higher prevalence at superior levels of the lumbar spine

Low Back Pain: A Biomechanical Rationale Based on "Patterns" of Disc Degeneration

STUDY DESIGN: A nonlinear finite element study of a lumbar spine with different "patterns" of multilevel intervertebral disc degeneration. OBJECTIVE: To determine how different patterns of multilevel disc degeneration influence the biomechanical behavior of the lumbar spine. SUMMARY OF BACKGROUND DATA: Because of the complex etiology of low back pain, it is often difficult to identify the specific factors that contribute to the symptoms of a particular patient. Disc degeneration is associated with the development of low back pain, but its presence is not always synonymous with symptoms. However, studies have suggested that "patterns" of disc degeneration may provide insight into such pain generation rather than the overall presence of degenerative changes. Specifically, individuals with contiguous multilevel disc degeneration have been shown to exhibit higher presence and severity of low back pain than patients with skipped-level disc degeneration (i.e., healthy discs located in between degenerated discs). METHODS: In this study, the biomechanical differences between these patterns were analyzed using a nonlinear finite element model of the lumbar spine. Thirteen separate "patterns" of disc degeneration were evaluated using the model and simulated under normal physiological loading conditions in each of the primary modes of spinal motion. RESULTS: The results showed that stresses and forces of the surrounding ligaments, facets, and pedicles at certain vertebral levels of the spine were generally lower in skipped-level disc degeneration cases than in the contiguous multilevel disc degenerations cases even when the skipped level contained more degenerated discs. CONCLUSION: To our knowledge, this is the first study to illustrate the biomechanics of specific patterns of disc degeneration of the lumbar spine. Using a multilevel disc degeneration model, our study provides insights as to why various patterns of disc degeneration throughout the lumbar spine may affect motion and soft tissue structures as well that may have bearing in the clinical pathway of pain generation. LEVEL OF EVIDENCE: N/A

Biomechanical Rationale for Varia‐Tions in the Prevalence of Low Back Pain and Schmorl's Nodes Found in Different Patterns of Multi‐Level Disc Gegeneration

General PosterINTRODUCTION: Previously published re‐ search has shown that contiguous multi‐ level disc degeneration (CMDD) has been noted to significantly increase the likelihood of severe low back pain in comparison to skipped levels of disc degeneration (SLDD). Clinical studies have also shown that Schmorl's nodes are more common in pat‐ terns of SLDD than with CMDD and that such nodes increase the likelihood of disc degeneration. As such, the purpose of this study was to utilize a nonlinear finite ele‐ ment model of the lumbar spine to investi‐ gate various patterns of multi‐level disc degeneration and to investigate correla‐ tions with clinical incidence of low back pain and Schmorl's nodes. METHODS: A previously validated hexahe‐ dral finite element model of a T12‐S1 lum‐ bar spine was adapted to simulate the 13 cases shown in the figure. The degenerated discs were modeled based on published material properties. Biomechanics data for each SLDD and CMDD case were compared against each other, against the single‐level degeneration cases, and against the control (non‐degenerated) case. These results were also compared with data from a large co‐ hort of patients (the Hong Kong Study) re‐ porting low back pain and MRI prevalence of Schmorl’s nodes. RESULTS: The finite element study indicated that CMDD resulted in higher ligament stresses, pedicle stresses, and facet contact forces as compared to the SLDD conditions. Interestingly, comparisons of sequential patterns of disc degeneration (control vs single level degeneration vs contiguous 2 level degeneration vs skipped level 3 level degeneration) showed that the addition of a skipped‐level degenerated disc to a con‐ tiguous level degenerated case actually de‐ creased stresses. Vertebral strain energy was also shown to be a possible predictor in the development of Schmorl’s nodes. DISCUSSION: These results provide insight into the variation in clinical studies of symp‐ tomatic and asymptomatic multi‐level disc degeneration