OBJECTIVETo investigate the clinical results of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) for lumbar spinal stenosis with lumbar instability.

METHODSRetrospective study was done on 42 cases of lumbar spinal stenosis with lumbar instability treated with bilateral decompression via unilateral approach and MIS-TLIF through an expandable tubular retractor from March 2010 to January 2011. There were 18 males and 24 females, and mean age was 61.7 years (rang, 48 - 79 years). The level of surgery was L(3-4) in 4 patients, L(4-5) in 26 patients, and L(5)-S(1) in 12 patients. All patients had symptoms of intermittent claudication. And 24 patients had symptoms of lower extremity pain and numbness in one side, and 18 patients had same symptoms in both legs. Operation time, intra-operative bleeding, postoperative hospital stay and complications were recorded. Visual analogue scale (VAS) scores for low back pain and leg pain were recorded before and after surgery. Oswestry disability index (ODI) scores were also recorded before and after surgery. The Bridwell criterion was used for evaluating the interbody fusion, and the MacNab criterion was used for assessment after surgery.

RESULTSThe mean operative time was 150.4 minutes (range, 120 - 170 minutes), and mean blood loss was 147.1 ml (range, 50 - 400 ml). The hospitalization time after surgery was 5 - 18 d, an average of 8.8 d. All cases were followed-up for 6 - 14 months (average 11 months). VAS score of low back pain before surgery was 7.3 ± 1.0, and were 2.9 ± 0.8 and 2.0 ± 0.8 at three months after surgery and the last follow-up respectively. VAS score of leg pain before surgery was 7.9 ± 0.7, and were 2.0 ± 0.5 and 1.0 ± 0.7 at three months after surgery and the last follow-up respectively. ODI score was 75% ± 6% before surgery, were 16% ± 6% and 12% ± 5% at three months after surgery and the last follow-up respectively. VAS and ODI scores showed statistically significant improvements (t = 3.110 - 56.323, P < 0.01). There were 40 cases were grade I and II, according to the Bridwell criteria. The clinical results were excellent in 16 cases, good in 22 cases and fair in 4 cases to the MacNab criteria at the final follow-up.

CONCLUSIONSMIS-TLIF is an ideal surgical method for single segment lumbar spinal stenosis with lumbar instability, but close attention should be paid to specific patients, surgeons and hospitals.