Clinical outcome and multifidus muscle changes of transforaminal lumbar interbody fusion

Abstract

Background: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) has shown to have smaller skin incision, decreased muscular dissection, and less retraction of the thecal sac, compared to conventional open approach. However, its effects on long term functional outcome and degenerative changes of paraspinal muscles are still obscure. Materials and Methods: We studied 81 patients treated by one team of surgeons at a single institution. In the two level spinal fusion, 18 patients underwent conventional TLIF (C TLIF) and 20 patients underwent MIS TLIF. In three level spinal fusion, 23 patients were treated with C TLIF and 20 patients were treated with MIS TLIF. Clinical outcomes included mean operative times, volume of blood loss, percentage of early ambulation, visual analog scale (VAS), and oswestry disability index (ODI) were analyzed. The change of multifidus muscle was calculated from magnetic resonance imaging (MRI) taken before and 6-month after the operation. Results: Lesser blood loss was noted in the MIS TLIF group compared to the conventional group in two- or three-level circumferential spinal fusion. Early ambulation (within 3 days after operation) was found in the MIS TLIF groups. Analysis of VAS scores at leg area showed no significant differences in improvement between each group at 18 month follow up. The postoperative ODI score was significantly less in the MIS TLIF groups than in the C TLIF groups after 6 month follow up. In three segment spinal fusion, MIS TLIF minimized multifidus muscle atrophy, when compared with C TLIF. Conclusion: MIS TLIF in three level lumbar fusion not only has a better functional recovery but also ameliorates the degenerative change of multifidus muscle.