Measuring Dimensions of Lumbar Intervertebral Discs in Normal Subjects

Introduction: Disc degeneration is a natural aging process characterized by changes in appearance and chemical structure of the disc. This degeneration leads to back pain. In regard to the limitation of current therapeutical methods for patients with degenerated discs, arthroplasty has been suggested as an alternative method. To manufacture artificial discs for Iranians, determining normal lumbar intervertebral disc dimensions is necessary. Thus, we measure the most important dimensions of normal lumbar intervertebral discs in Iranians using Magnetic Resonance Imaging (MRI). Methods: we studied lumbar intervertebral discs of 34 people who were 40-60 years old in Medical Imaging Center of Imam Khomeini Hospital. Out of them, 14 people without herniated disc and any other abnormalities related to spinal column on MRI were selected. There were 7 males and 7 females, and their average age was 48.07 years (range: 40 to 59 years). For accurate measurements, the relevant disc distances were measured by two radiologists and then the mean value for each segment was calculated. Results: The mean (SD) values of anterior intervertebral disc height for L1/L2 to L5/S1 levels were measured and found as follows: 10.82(1.59) mm, 13.09(1.21) mm, 15.21(1.24) mm, 18.14(1.49) mm, 18.71(1.61) mm. The mean (SD) values of middle intervertebral disc height for L1/L2 to L5/S1 levels were measured as follows: 10(1.89) mm, 11.59(1.51) mm, 12.45(1.79) mm, 13.82(1.96) mm, 12.99(2.53) mm. The mean (SD) values of posterior intervertebral disc height for L1/L2 to L5/S1 levels were found as follows: 7.31(1.71) mm, 8.58(1.66) mm, 9.08(1.22) mm, 10.14(1.01) mm, 8.51(1.08) mm. The mean (SD) values of anterior-posterior disc length for L1/L2 to L5/S1 levels were found as follows: 30.23(2.71) mm, 32.03(2.43) mm, 32.86(2.44) mm, 33.08(2.37) mm, 31.33(2.55) mm. The mean (SD) values of transversal disc length for L1/L2 to L5/S1 levels were found as follows: 48.24(2.23) mm, 51.27(1.92) mm, 52.59(1.69) mm, 55.12(1.69) mm, 52.87(2.14) mm. Conclusion: Knowledge of the normal lumbar intervertebral disc dimensions in every society is useful for surgical reconstruction to treat lumbar spine diseases and for medical manufacturers to make proper surgical devices in this regard.