Morphometric Study of the Human Lumbar Spine for Operation–Workspace Specifications

Abstract

The anatomy of the lumbar vertebrae of 55 patients was measured by use of data provided by computed tomography. On the basis of these measurements, the location of puncture points and the orientation of the surgical instruments for pedicle, vertebral body, and disc entry points were calculated for open as well as percutaneous surgery. Normal anatomic variations of the lumbar spine were investigated to define the workspace for several spinal procedures and to define the workspace of a robot designed to guide the physician during those procedures. Several comprehensive studies of vertebrae dimensions have been conducted in the past, but they lack several dimensions that are needed to determine the exact location of the entry point and orientation of the tool, in particular when a computerized guidance system is used. Fifty-five spinal columns (L1-L5, total 250 vertebrae) were measured by computed tomography. These data provide geometric relations that determine entry points and tool orientations for different spinal interventions. The workspace for spinal operations was defined on the basis of anatomic data taken from computed tomography scans. The data included 15 measurements for each vertebra that defined its shape. The processed data provided puncture points for several spinal procedures in both open and percutaneous surgery. This study provides additional information on vertebral structure needed to calculate accurately the entry point and tool orientation in various spinal procedures. These statistical data are also valuable for model and implant designs and for workspace specifications for a robot-assisted surgery system.