Morphometric study of the human lumbar spine for operation-workspace specifications

Study Design. The anatomy of the lumbar vertebrae of 55 patients was measur ed by use of data provided by computed tomography. On the basis of these me asurements, the location of puncture points and the orientation of the surg ical instruments for pedicle, vertebral body, and disc entry points were ca lculated for open as well as percutaneous surgery. Objective. Normal anatomic variations of the lumbar spine were investigated to define the workspace for several spinal procedures and to define the wo rkspace of a robot designed to guide the physician during those procedures. Summary of Background. Several comprehensive studies of vertebrae dimension s have been conducted in the past, but they lack several dimensions that ar e needed to determine the exact location of the entry point and orientation of the tool, in particular when a computerized guidance system is used. Methods. Fifty-five spinal columns (L1-L5, total 250 vertebrae) were measur ed by computed tomography. These data provide geometric relations that dete rmine entry points and tool orientations for different spinal interventions . Results. The workspace for spinal operations was defined on the basis of an atomic data taken from computed tomography scans. The data included 15 meas urements for each vertebra that defined its shape. The processed data provi ded puncture points for several spinal procedures in both open and percutan eous surgery. Conclusions. This study provides additional information on vertebral struct ure needed to calculate accurately the entry point and tool orientation in various spinal procedures. These statistical data are also valuable for mod el and implant designs and for workspace specifications for a robot-assiste d surgery system.