The Effect On The Paraspinal Muscles By Unilateral Transforaminal Lumbar Interbody Fusion With Paramedian

Objective. To determine whether unilateral transforaminal lumbar interbody fusion (TLIF) using paramedian approach leads to undesirable changes of the paraspinal muscles, compared to the non-operation side.Methods.40patients with degenerative lumbar diseases who were treated by unilateral TLIF were included in this study. Surgeries were performed using paramedian approach by a single surgeon. Single-level TLIF was performed in30cases (L4-L5in17and L5-S1in13), double-level TLIF plus contralateral facet screws was performed in10cases (L3-L4-L5in4and L4-L5-S1in6). The average follow-up period was8months, range from6to18months. The postoperative cross-sectional area the multifidus and the erector spinae were measured on bilateral sides by computed tomography.Results. In L4-L5group (both the superior and the inferior level) and L5-S1(the superior level) group, no significant difference was found in the CSA of multifidus between the operation side and the non-operation side. However, in the inferior level of L5-S1group, the CSA of multifidus was found significantly smaller on the operation side (p<0.05). Furthermore, the decrease was more remarkable in the inferior level of L4-L5-S1group (p<0.05). The CSA of erector spinae did not change significantly in all the groups.Conclusion:Unilateral TLIF using paramedian approach is useful for the preservation of the paraspinal muscles, especially when the level of fusion above S1ventebra.