Figure 3

Schematic showing an intervertebral disc space in the coronal plane, depicting the change in disc space wedge angle due to a surgical compressive force, F. In this schematic, the surgically cleared disc space is initially wedged in the same sense as the overall spinal Cobb angle (positive wedge angle, α). As a result of the surgically applied compressive force (and depending on the stiffness of the spinal tissues), the disc space may remain positively wedged (reduced value of α, not shown), may become negative (concave wedge angle) or close the disc space entirely, resulting in endplate to endplate contact.