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.

The growing interest in the development of spinal implants has led to an increasing need for biomechanical studies. Porcine spines are commonly used in such studies. Quantitative data of the normal porcine tho-racolumbar spine is lacking, yet these data are crucial to discussion of such studies. In this study we aim to provide such a database to highlight the differences between the porcine and human specimen with a view to help plan future studies contemplating their use.

6 adult (18-24 month old, 60-80 kilograms) male porcine spines were dissected of soft tissue. The lowest thoracic and all the lumbar vertebrae were studied (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 Micro-soft Excel. Results were compared with available data on human vertebra (Zindrick et al 1987;Panjabi et al 1991,1992; 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 body height of the porcine vertebra was 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 specimen. 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. The results for the measured parameters and their comparison to human specimen will be presented.

Results from our study provides a database of anatomical measurements for the porcine vertebrae and highlights the differences with the human specimen. The data would help design future studies contemplating the use of pig spines. Biomechanical studies involving interbody cages, disc replacements and pedicle screw systems should take into account the differences and match implant size accordingly. It also provides valuable information for geometric and Finite Element Modelling of the porcine spine. Further, the results are useful in extrapolation of data from experiments which have used the porcine model.