OBJECTIVETo study differences of multifidus muscle injury between Wiltse intermuscular approach and intramuscular stripping approach in one-level small incision transforaminal lumbar interbody fusion (TLIF) surgery.

METHODSA total of 46 patients with unilateral lumbar degenerative disease underwent small incision TLIF from August 2009 to February 2011 by one group of surgeons at a single institution. The decompression side of all patients adopted intra-muscular stripping approach; for the non-decompression side, 22 patients adopted Wiltse intermuscular approach (group A),and 24 patients adopted intra-muscular striping approach (group B). In group A, there were 13 males and 9 females, ranging in age from 36 to 74 years old,averaged 52.7 +/- 9.2; 1 patient had disease in L3, 4 12 in L4,5 and 9 in L5S1. In group B,there were 11 males and 13 females,ranging in age from 32 tio 72 years old, averaged 51.8 +/- 8.7; two patients had disease in L3,4, 14 in L4,5, and 8 in L5S1. The following data were compared between the 2 groups: surgical time from skin incision to completion of pedicle screw placement, suturation time, blood loss. Clinical effects were evaluated by VAS score pre-operatively, as well as 1, 6 and 12 months post-operatively. At the latest follow-up, all the patients were evaluated by MRI. This enabled the cross-sectional area (CSA) of lean multifidus muscle, and the T2 signal intensity ratio of multifidus to psoas muscle, to be compared at the operative level.

RESULTSThere was no obvious difference in suturation time, but less surgical time from skin incision to completion of pedicle screw placement, less blood loss, less postoperative back pain in Wiltse intermuscular approach group. For the comparison between the two groups or paired comparison between sides in the Wiltse group, the reduction of lean CSA and increase in the multifidus:psoas T2 signal intensity ratio were all significant lower in Wiltse intermuscular approach group or side.

CONCLUSIONThe Wiltse intermuscular approach is an easy way for pedicle screw placement, and caused less paraspinal muscle damage than intra-muscular stripping approach, and had positive effects on less back pain.