Anatomic basis of anterior and posterior instrumentation of the spine: morphometric study

A morphometric study of the linear and angular parameters of the spinal vertebra was conducted by computerized tomographic scans and comparison with previous studies in literature.

Detailed knowledge of the spinal vertebral morphometry is important for proper instrumentation. The morphologic measurements vary among races. Morphometric studies have been conducted in white populations. This study aims to suggest dimensions for anterior and posterior spinal implants and to improve the instrumentation techniques.

The vertebral pedicles, bodies and intervertebral disc spaces of the subaxial cervical, thoracic and lumbar spine were studied in 48 healthy individuals by computerized tomographic scan methods. The following parameters were studied: pedicle length, pedicle width, transverse pedicle angle (TPA), sagittal pedicle angle, anterior corpus height, posterior corpus height, anterior disc height, middle disc height and posterior disc height.

Our results were slightly different compared to previous studies. Individual differences were found in the same subgroups. The transverse pedicle diameter was largest at L5 (14.95 mm) and smallest at C3 (5.1 mm). The pedicle was longest at L5 (19.9 mm) and shortest at T10 (15.7).The TPA was largest at C3 (47.6 degrees ) and smallest at T6 (11.3 degrees ). The vertebral body was largest at L5 (34.9 mm) and smallest at C3 and C5 (15.6 mm). The vertebral body width was largest at L5 (46.6 mm) and smallest at C4 (22 mm). The intervertebral disc space height was largest at L2-3 (10 mm) and smallest at T1-2 (2.85 mm). There were no significant differences between the left and right sides.

In our morphometric study of the spinal vertebrae, we found differences compared to a number of previous morphometric studies performed mainly on a white population. Also, we documented the individual morphometric differences of the same parameters in the same subgroups. These results emphasize the importance of preoperative computed tomography and conventional radiography of each patient in planning a surgical procedure and selecting the appropriate size of the instruments, thus avoiding possible postoperative complication related to implants.