Vertebral body replacement

Instrumented implant

Severe compression fractures of a vertebral body or a tumour in the region of the spine sometimes require the replacement of a vertebral body by an implant. The loads on such an implant are not well known. In order to measure these loads, the commercially available vertebral body replacement ‘SYNEX’ was modified. It allows the in vivo measurement of three force components and three moments acting on the implant. The 9-channel telemetry transmitter developed in our biomechanics laboratory was placed into the cylinder of the implant together with 6 load sensors and a coil for the inductive power supply. Usually, the spine is in addition stabilized dorsally by an internal spinal fixation device implanted from the back side.


Implant: vertebral body replacement

Coordinate system

The bone-based coordinate system was chosen according to ISO 2631. The x- axis in the median plane points anteriorly, the y-axis in the frontal plane to the left side, and the z-axis cranially.

The forces and moments are presented in the measuring units N and Nm.

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Coordinate system Vertebral body replacement



Table with basic information about those patients who had vertebral body replacements:

Patient Gender Weight [kg] Age at Implantation [years] Indication
WP1 m 66 62 Fracture L1
WP2 m 72 71 Fracture L1
WP3 f 64 69 Fracture L1
WP4 m 60 64 Fracture L1
WP5 m 63 67 Fracture L3