Morphometric study of the lower lumbar vertebras and intervertebral discs in the north-eastern population of India using digitized CT scan images

 

 

Abstract              Background: Many people are affected by low backache worldwide. Low back pain could be due to various reasons like improper lumbar vertebral alignment, nerve compression, improper posture, muscle stiffness etc. The anatomy and knowledge of lumbar vertebral dimensions and lumbar intervertebral disc dimensions could be of great value in studying the etiology of backache. Therefore the present study was undertaken to study the dimensions of the L4 and L5 lumbar vertebras as well as that of the L4-5 and L5-S1 lumbar intervetebral discs, as they are the most dependent part of the vertebral column. Method: Computerised Tomographic (CT ) scan images of lumbar region (300 each for male and female) were obtained from radiology department of Tomo Riba Institute of Health and Medical Sciences and Hospital, Naharlagun. The antero-posterior and the transverse diameter and the anterior, central and posterior height of the body of L4 and L5 lumbar vertebras as well as the height and the antero-posterior length of the L4-5 and L5-S1 lumbar intervetebral discs were measured and studied both in males and females of different age groups. Result: It was seen that both the antero-posterior and the transverse diameters of the L4 and L5 vertebral bodies as well as the antero-posterior diameter of the L4-L5 and L5-S1 intervertebral discs were increased with advancing age, whereas the height of the disc was seen to be decreased. Conclusion: It is concluded that with advancing age, the lumbar vertebrae increases in width, whereas the intervertebral disc shows a decrease in height with an increases in width.

Key Words: Backache, Intervertebral disc, Lumbar, Vertebra, CT scan

 

INTRODUCTION

Many people are affected by low backache worldwide. Low back pain could be due to various reasons like improper lumbar vertebral alignment, nerve compression, improper posture, muscle stiffness etc. The anatomy and knowledge of lumbar vertebral dimensions and lumbar intervertebral disc dimensions could be of great value in studying the etiology of backache. Therefore the present study was undertaken to assess the dimensions of the L4 and L5 lumbar vertebras as well as the L4-5 and L5-S1 intervertebral discs (IVD) and correlate them with age and gender. The lower lumbar vertebras and intervertebral discs were chosen for the study as they are the most dependent part of the vertebral column and primarily involved in weight bearing and transmission. In order to obtain more accurate database, digitized computer tomographic (CT) images were studied using the Picture Archiving Communication System (PACS) coupled with its internal measuring system. Ali M et al..¹ established that amongst all referral patients with spinal disorders, most commonly affected was lumbar spine (53.1%) and cervical spine (27.1%) with pain as the most common complaint. Vijay M. Ravindra et al..² documented that 266 million individuals (3.63%) worldwide were found to have degenerative spine disease and low back pain annually.

 

MATERIAL AND METHOD

Computerised Tomographic(CT) scan images of lumbar region (300 each for male and female) were retrospectively obtained from the Radiology departmentof Tomo Riba Institute of Health and Medical Sciences and Hospital, Naharlagun. The CT scans were done using Siemens Somatom Drive dual source MDCT and stored in the Picture Archiving Communication System (PACS). The CT images obtained from the PACS were retrospectively analysed. The study was divided into two groups (male and female) and each was further divided into three subgroups according to the age as 21 to 40 years, 41 to 60 years and above 60 years.

Measurements:

The measurements for antero-posterior and transverse diameter of lumbar vertebra were obtained from axial CT section in bony window. The AP diameter extended from the posterior cortical margin at the basi-vertebral venous plexus to the anterior cortical margin of the vertebra. The maximum transverse diameter was obtained by drawing a perpendicular line to the AP line extending up to the lateral cortical margin of the vertebral body on either side (Fig.1). The measurements for Anterior (A) / Central (C) and Posterior (P) heights of the lumbar vertebral body were obtained on the sagittal CT section in bony window. The Anterior height was obtained by drawing a perpendicular line from the antero-superior end-plate to the inferior end-plate. Similar measurements were done for obtaining the central and posterior heights of the vertebral body by drawing perpendicular lines from the superior to the inferior end-plates (Fig.2).  The measurements for antero-posterior width and height of lumbar intervertebral disc were obtained from sagittal CT section in soft tissue window. The antero-posterior width of lumbar intervertebral disc was obtained by drawing a line connecting the mid-point of the anterior and posterior margin of the intervertebral disc.The height of the intervertebral disc was calculated by drawing a perpendicular line at the mid-point of the intervertebral space (Fig.3).The antero-posterior and the transverse diameter of the L4 and L5 lumbar vertebral bodies (LVB) were measured. The anterior (A), central (C) and posterior (P) height of the L4 and L5 lumbar vertebral bodies (LVB) were measured. The height and the antero -posterior length of the L4-5 and L5-S1 intervetebral discs (IVD) L4-5 and L5-S1 were measured. The measurements obtained were tabulated according to age group in both males and females. The mean and standard deviation was noted and the p-value was calculated using students t-test to find out the significance of the findings.Pearson’s correlation of the above parameters with age was also studied.

 

Figure 1: Measurement of antero-posterior and transverse diameter of vertebra: Axial CT section in bony window

 

Figure 2: Measurement of Anterior (A) / Central (C) and Posterior (P) heights of the lumbar vertebral body: Sagittal CT section in bony window; Figure 3: Measurement of antero-posterior width and height of lumbar intervertebral disc: Sagittal CT section in soft tissue window

RESULT

The study showed an increase in the antero-posterior and the transverse diameters of the L4 and L5 vertebral bodies with increasing age in both males and females, except for the transverse diameter of the L5 lumbar vertebra in females above 60 years. In the female study population, there was a slight decrease from a mean transverse diameter of 42.06 ± 2.85 in the 41-60 years age group to 41.56 ± 3.34 in the above 60 years age group.The study also showed an increase the antero-posterior diameter of the L4-L5 and L5-S1 intervertebral discs with increasing age both in males and females.However, the height of the L4-L5 and L5-S1 IVDs were seen to decrease with advancing age in both males and females (Table No. 1). There was no significant difference in the anterior (A), central (C) and posterior (P) height of the L4 and L5 lumbar vertebral bodies (LVB) and in the dimensions of the L4-L5 and L5-S1 IVDs, when compared between males and females of the same age groups. There was also no significant difference on comparing the three age groups in both males and females (Table No. 2, 3, 4).  The antero-posterior diameter and transverse diameter of L4 and L5 vertebras showed a positive correlation with increasing age in both male and female groups (Table No. 5). The antero-posterior diameter of the L4-L5 and L5-S1 IVDs also showed similar positive correlation with increasing age in both male and female groups (Table No. 5).  The anterior (A), central (C) and posterior (P) height of the L4 and L5 lumbar vertebral bodies (LVB) showed a negative correlation with advancement of age in females except for anterior height of L5 vertebra which showed a positive correlation. The height of the L4-L5 and L5-S1 IVDs showed a negative correlation with advancement of age in females.The anterior (A), central (C) and posterior (P) height of the L4 and L5 lumbar vertebral bodies (LVB) showed a positive correlation with age in males except for anterior (A) height of L5 vertebral body which were seen to be negatively correlated. The height of L4-L5 intervertebral disc showed negative correlation with advancement of age in males (Table No.5).

 

Table 1: Mean dimensions of L4 and L5 vertebral bodies and L4-5 / L5-S1 Intervertebral discs in different age groups in males and females

VBD- VertebVBD- Vertebral Body Dimensions, IVD-Intervertebral Disc, AP-Antero-posterior diameter,   TR-Transverse diameter, A- Anterior Height, C-Central Height, P-Posterior Height, IVDH-Intervertebral Disc Height, IVDL-Intervertebral Disc Length

ral Body Dimensions, IVD-Intervertebral Disc, AP-Antero-posterior diameter,   TR-Transverse diameter, A- Anterior Height, C-Central Height, P-Posterior Height, IVDH-Intervertebral Disc Height, IVDL-Intervertebral Disc Length

 

Table 2: Comparison of the vertebral body and IVD parameters between males and females in different age groups

VBD- Vertebral Body Dimensions, IVD-Intervertebral Disc, AP-Antero-posterior diameter,   TR-Transverse diameter, A- Anterior Height, C-Central Height, P-Posterior Height, IVDH-Intervertebral Disc Height, IVDL-Intervertebral Disc Length, p-value <0.001 is significant.

 

Table 3: Comparison of the vertebral body and IVD parameters in females between different age groups

VBD- Vertebral Body Dimensions, IVD-Intervertebral Disc, AP-Antero-posterior diameter,   TR-Transverse diameter, A- Anterior Height, C-Central Height, P-Posterior Height, IVDH-Intervertebral Disc Height, IVDL-Intervertebral Disc Length, Significant= p-value<0.001.

 

Table 4: Comparison of the vertebral body and IVD parameters in males between different age groups

VBD- Vertebral Body Dimensions, IVD-Intervertebral Disc, AP-Antero-posterior diameter,   TR-Transverse diameter, A- Anterior Height, C-Central Height, P-Posterior Height, IVDH-Intervertebral Disc Height, IVDL-Intervertebral Disc Length, Significant= p-value <0.001.

 

Table 5: Correlation between the vertebral body / IVD parameters and increasing age

VBD- Vertebral Body Dimensions, IVD-Intervertebral Disc, AP-Antero-posterior diameter, TR-Transverse diameter, A- Anterior Height, C-Central Height, P-Posterior Height, IVDH-Intervertebral Disc Height, IVDL-Intervertebral Disc Length

 

 

Height, IVDL-Intervertebral Disc Length