gms | German Medical Science

The evaluation of segmental stability and the decision indicating a spondylodesis are essentially based on indirect radiological signs. Surface measuring procedures are inaccurate because of soft tissue overlay as well as radiological procedures, due to the projection problem. Ultrasonic-supported motion analysis system (Zebris^®) regarding practicability and evidence at anatomical preparations as well as intraoperativ was evaluated.

10 not explanted human corpse spinal columns as well as 10 patients during a lumbar spinal operation were examined. After fixation the device at the spinal process L2-S1 defined flexion and extension of the lumbar spine were made. The precision of the measuring system amounts to 0.1 mm.

A gradual decompression of the spinal canal at level L4/5 (defect model) was performed. At each step of decompression and after dynamic stabilisation (Dynesys^®) and dorsal fusion (ART^®) the measurements were done. Intraoperative the evaluation before and after monosegmental decompression as well as after dorsal fusion have been done..

The measuring procedure permits a reproducibly precise representation to the segmental mobility of the lumbar spine. At the corpse spinal column paradoxes movements in the adjacent segments can be determined apart from the increase of the range of movement (ROM) after gradual decompression. The quantity and quality of the segmental movement as well as the intraoperative applicability are analyzed and discussed.

This system allows a sufficient and precise measurement of the lumbar segmental motion. The decompression of the spinal canal leads to a reduction of stability which could be partly compensated by static and dynamic stabilization procedures. The effects on the movement of the adjacent segments do not show significant changes.