Transforaminal lumbar interbody fusion: unilateral versus bilateral disk removal--an in vivo study.

We conducted a study to quantify the attainable cross-sectional area available for fusion and the mean volume of disk removed with a unilateral transforaminal lumbar interbody fusion (TLIF). Starting with the unilateral approach and completing the procedure with a bilateral approach, we removed the maximal amount of disk material. Postoperative computed tomography (CT) images were used to estimate the cross-sectional area/vertebral endplate available for bone grafting and fusion. Results showed that, using the unilateral approach, we removed 11.8 cm3 (range, 7-25 cm3) of disk material--or more than 69% of the total volume of resected disk. Postoperative CT images confirmed that more than 56% of the endplate cross-sectional area is available for fusion using the unilateral approach. We conclude that unilateral TLIF removes sufficient disk material for achieving a solid and stable arthrodesis while minimizing neural retraction and dural exposure.