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