MORPHOMETRY OF LUMBAR INTERVERTEBRAL DISC WEDGE ANGLE, DISC HEIGHT AND CONCAVITY INDEX IN NORMAL SPINES

BACKGROUND: The lordotic wedging and height of the presacral disc avert detrimental loads and shearing of the lumbar spine. Age and functional degenerations affect these causing spinal disarrays frequently requiring lumbar reconstructive surgery. Reinstating the disc height and wedging to its optimum healthy state is essential for accomplished spinal rehabilitation. The fourth and fth lumbar segments being most predisposed to mechanical pathophysiology and surgical interventions were evaluated in a north-east Indian population. MATERIALS & METHOD: The disc wedge angle, vertebral and disc heights and concavity index were measured in eighty lumbar segments comprising of twenty males and twenty females. RESULTS: The disc-wedge angle, anterior, middle, posterior disc heights and concavity index were as follows: 12.06±1.67°, 12.27±1.25mm,10.83±1.04mm,6.95±0.77mm,0.90±0.01at L4/L5 and 15.65±1.83°, 15.15±1.67mm, 11.32±1.68mm, 6.79±0.79mm, 0.90±0.01 at L5/S1 in males and 13.02±1.66°, 13.03±1.30mm, 11.86±1.23mm, 6.44±0.95mm,0.90±0.01 at L4/L5 and 16.89±1.71°,36.40 ±1.29mm, 16.04± 1.62mm, 12.31± 1.77mm, 6.06±0.94mm and 0.088 ± 0.02 in females. CONCLUSION: The disc wedge angles and anterior and middle disc heights were signicantly higher in females while the vertebral and posterior disc heights and convexity index were larger in males. The larger lordotic wedging of L5/S1 intervertebral disc preserves the spinal conformation. All above dimensions decreased with age in both genders. Our study standardizes quantitative referral data for research, diagnosis and prothesis to resolve the existing discordances.