Abstract:

BACKGROUND: Surgeons usually predict the size and number of nucleus pulposus (NP) prosthesis before operation according to the diameters of lumbar intervertebral disc measured on medical images.
OBJECTIVE: To measure and analyze height of lumbar intervertebral space, lumbar disc and NP diameters in normal for obtaining basic data of intervertebral disc related to artificial prosthetic nucleus.
METHODS: Totally 157 lumbar spine X-ray films (Lateral views) of normal adult were randomly selected. Anterior, middle and posterior heights of lumbar intervertebral space were measured on X-ray films. A total of 106 lumbar Magnatic Resonance Imaging (MRI) images of normal adult were randomly selected for measuring transverse diameter and antero-posterior diameter (A-P diameter) of NP and lumbar disc.
RESULTS AND CONCLUSION: ① X-ray film: from upper to lower, the height of intervertebral space increased gradually. Posterior height of lumbar intervertebral space was low. It ranged between 7 mm and 9 mm, approximately 50% at L2/3, L3/4, and L4/5, about 39.5% at L5/S1. ② MRI images: from L2/3 to L5/S1, the transverse diameter and A-P diameter of lumbar disc enlarged in turn. About 46.7% A-P diameter of lumbar discs were more than 37 mm. However, only 49.0% were proved that the A-P diameters of NP were more than 24 mm. In this study, the average transverse diameter of NP was 33.5 mm, the average A-P diameter was 23.4 mm. The A-P diameters of NP were all more than 12 mm. Among these, about 22.9% were more than 24 mm. The results indicated that single prosthetic disc nucleus (PDN) is suitable for most Chinese patients, and the height of 7 mm of PDN is commonly chosen. The A-P diameter of lumbar disc ranging from 37 mm is demonstrated unreliable to predict double PDN replacement before operation in Chinese.