ANATOMY OF THE PORCINE AND HUMAN THORACOLUMBAR VERTEBRAE

Abstract

With the development of new implants there is an increasing need for biomechanical studies. The problem of obtaining human specimen is well appreciated. Porcine spines are commonly used. To date there are no studies delineating the anatomy of porcine thoracolumbar vertebrae. The objective of this study is to provide a comprehensive database of measurements for the porcine thoracolumbar vertebrae with a view to help plan future studies contemplating their use.

6 adult porcine spines from 18–24 month old male pigs weighing 60 to 80 kilograms were obtained and dissected of soft tissue. The lowest thoracic and all the lumbar vertebrae were used in our experiment (n=42). 15 anatomical parameters from each vertebra were measured by 2 independent observers using digital calipers (Draper® PVC150D, accuracy ± 0.03mm). The mean, SD and SEM were calculated using Microsoft Excel. Results were compared with available data on human vertebra (Panjabi et al 1991,1992; Zindrick et al 1987; Kumar et al 2000).

The inter class correlation coefficient for the observers was 0.997. The intra-observer agreement was statistically robust (0.994). The vertebral bodies of the porcine vertebra were larger while both the upper and lower endplate depth and width were smaller than the human specimens. The pedicle width and depth was greater than the human specimens. The spinal canal length and depth of the porcine spine were smaller than humans indicating a narrow spinal canal. The spinous process length showed an increase from T16 to L1. This was in contrast to human spinous process.

This study provides a comprehensive database of anatomical measurements for the porcine thoracolumbar vertebra and highlights the differences in morphometry. These should borne in mind when designing studies using porcine spines and the implants matched accordingly. The measurements are also useful when extrapolating data from studies where porcine spines have been used.