Instrumented minimally invasive spinal-transforaminal lumbar interbody fusion (MIS-TLIF): Minimum 5-year follow-up with clinical and radiologic outcomes

Objective: To determine the clinical and radiologic outcomes of the long-term results of instrumented minimally invasive spinaltransforaminal lumbar interbody fusion (MIS-TLIF) in unstable, single-level, low-grade, isthmic spondylolisthesis (IS) or degenerative spondylosis (DS) including degenerative spondylolisthesis, foraminal stenosis with central stenosis, degenerative disk disease, and recurrent disk herniation. Summary of Background Data: MIS-TLIF is a common surgical procedure to treat lumbar spondylolisthesis. However, there are no studies that have documented the long-term results of MISTLIF. Methods: Forty-four patients who had undergone instrumented MIS-TLIF between July 2003 and January 2005 were retrospectively reviewed. The visual analog scale, Oswestry Disability Index, patient satisfaction rate, and the patient's return-to-work status were used to assess clinical and functional outcomes. Radiologic follow-up were carried out in patients to check for adjacent segmental degeneration (ASD). The plain radiographs, computed tomography and magnetic resonance imaging, were used in all patients in last follow-up period. Results: The mean visual analog scale scores for back and leg pain decreased from 5.8 and 7 to 3.5 and 3.7, respectively, in the DS group (n=19) and from 6.8 and 6.9 to 1.8 and 2.0, respectively, in the IS group (n=25) (P<0.001). The mean Oswestry Disability Index scores improved from 61.7% to 21.5% in the DS group and from 53.9% to 16% in the IS group (P<0.001). Patient satisfaction rate was 80% and 81% in the DS and IS groups, respectively. Evidence of fusion was observed radiologically in 24 (96%) and 19 (100%) of the patients in the IS and the DS group, respectively, giving an overall fusion rate of 97.7% (43/44). The final ASD rate, observed using radiography, was 68.4% (13/19) in the DS and 40% (10/25) in the IS group. However, 15.8% (3/19) in the DS and 4% (1/25) in the IS group had symptoms associated with ASD. Conclusions: The long-term clinical and radiologic outcomes after instrumented MIS-TLIF in patients with unstable singlelevel spine are favorable.