Research Article

Changes in Paraspinal Muscles and Facet Joints after Minimally Invasive Posterior Lumbar Interbody Fusion Using the Cortical Bone Trajectory Technique: A Prospective Study

Figure 2

To estimate the volume, the entire ES muscle is considered as a circular table. The areas of the upper and lower segments are A and B, respectively. Using the height h between the upper and lower segments, the volume of the ES is estimated using the formula .