Changed cervical kinematics after fusion surgery.

Purpose: Analyzing and comparing the range of motion and movement pattern of subjects who underwent an anterior cervical fusion using trabecular metal with control subjects.

Methods: Three-dimensional kinematics of planar active axial rotation and active lateral bending of 50 experimental and 41 control subjects were registered by means of an electromagnetic tracking system.

Results: Comparing the experimental group with the control group reveals that the range of the main motion component differs significantly (p < 0.01) during the active axial rotation and lateral bending movement. During active axial rotation, the coupled lateral bending motion component also differs between both groups. The root mean square value of the jerkiness (derivative of the acceleration) and de deviation from the 6-polynomial smoothed function of the main as well as the coupled motion component express the qualitative aspects of kinematics and are significantly different between the experimental and the control group for both movements (p < 0.05).

Conclusions: Subjects who have an anterior cervical fusion with trabecular metal show significant quantitative as well as qualitative differences in cervical kinematics during active axial rotation and lateral bending compared to control subjects.