Geometrical dimensions of the lower lumbar vertebrae - analysis of data from digitised CT images

Abstract

IntroductionAccurate and comprehensive anthropometric data for the lumbar spine vertebrae, a frequent site for implantation surgery, are incomplete at present. Information on the precise dimensions of the lower lumbar vertebrae is, however, essential, for the rational design and development of spinal implants and instrumentation such as pedicle screws and, in particular, with the evolution towards robotic surgery. Previous studies have depended on direct measurements from plain X-ray films [9,12,13,23], or from computed tomographic (CT) scans [8,11,26,34,36]. A few reports have involved the analysis of cadaveric specimens [1,7,24,27,29]. The value of the data has depended on the number of samples and the accuracy of Abstract The precise dimensions of the lumbar vertebrae and discs are critical for the production of appropriate spinal implants. Unfortunately, existing databases of vertebral and intervertebral dimensions are limited either in accuracy, study population or parameters recorded. The objective of this study is to provide a large and accurate database of lumbar spinal characteristics from 126 digitised computed tomographic (CT) images, reviewed using the Picture Archiving Communication System (PACS) coupled with its internal measuring instrumentation. These CT images were obtained from patients with low back pain attending the spinal clinic at the Hammersmith Hospitals NHS Trust. Measurements of various aspects of vertebral dimensions and geometry were recorded, including vertebral and intervertebral disc height. The results from this study indicated that the depth and width of the vertebral endplate increased from the third to the fifth lumbar vertebra. Anterior vertebral height remained the same from the third to the fifth vertebra, but the posterior vertebral height decreased. Mean disc height in the lower lumbar segments was 11.6 ± 1.8 mm for the L3/4 disc, 11.3 ± 2.1 mm for the L4/5, and 10.7 ± 2.1 mm for the L5/S1 level. The average circumference of the lower endplate of the fourth lumbar vertebra was 141 mm and the average surface area was 1492 mm 2 . An increasing pedicle width from a mean of 9.6 ± 2.2 mm at L3 through to 16.2 ± 2.8 mm at L5 was noted. A comprehensive database of vertebral and intervertebral dimensions was generated from 378 lumbar vertebrae from 126 patients measured with a precise digital technique. These results are invaluable in establishing an anthropometric model of the human lumbar spine, and provide useful data for anatomical research. In addition this is important information for the scientific planning of spinal surgery and for the design of spinal implants.

Footprint mismatch in total cervical disc arthroplasty

“…A recent study showed that currently available lumbar disc prostheses are much smaller than lumbar endplates regarding anteroposterior and mediolateral diameter [17]. From a biomechanical point of view, an implant with the largest possible surface area appears best to avoid subsidence into the vertebral body, as the circumference would provide a brace for the strongest areas in the periphery [18]. Inadequate endplate design can equally contribute to subsidence as a result of extremely concentrated stress [2].…”

The lumbar spine in Neanderthals shows natural kyphosis

“…However, the morphological reconstruction of the disc space in fossils is difficult due to the intrinsic variation in this region and the lack of preservation. Measurements of the intervertebral height of the modern spine revealed a remarkable range of variation, suggesting that disk height is highly variable and therefore difficult to predict [18]. To our knowledge no data are available on Neanderthal disc space/ inter-vertebral height.…”

Disc height reduction in adjacent segments and clinical outcome 10 years after lumbar 360° fusion

“…Adjacent segments have been studied using different techniques [radiography, computed tomography (CT), magnetic resonance imaging (MRI)] [6,20,29,38]. Disc height has been described as indicator of disc degeneration and regeneration [26,31].…”