457 - Revision Rates Following Minimally Invasive Decompression for Lumbar S...

General Session: MIS-1

Presented by: R. Rampersaud


N. Moayeri(1,2), M.A. Pahuta(3), R. Rampersaud(3)

(1) University of Toronto, Surgery - Neurosurgery, Toronto, ON, Canada
(2) University Medical Center Utrecht, Neurosurgery, Utrecht, Netherlands
(3) University of Toronto, Surgery - Orthopaedics, Toronto, ON, Canada


Object: Minimally invasive decompression (MID) is an effective and safe procedure for lumbar spinal stenosis (LSS). In short-to-moderate term follow-up studies, (i.e. < 4-5 years) reoperation rates have been shown to be lower with similar functional improvement compared to conventional open laminectomy. However, long-term follow-up data is still lacking. The primary objective of this retrospective cohort study was to evaluate reoperation rates and functional outcome in patients with LSS who underwent a MID, stratified for degenerative lumbar spondylolisthesis (DLS).

Methods: All consecutive patients with LSS with and without grade 1 DLS who had undergone MID between 2002 and 2011 were included in this analysis. The same technique was utilized by the senior author for all patients with neurogenic claudication/mechanical radiculopathy (i.e., leg-dominant symptoms that were relieved by postural change and/or rest), no (or tolerable) mechanical back pain, and those with up to a 25% (grade I) spondylolisthesis, and no obvious dynamic instability on imaging. Radiographic dynamic instability was defined as an increase in spondylolisthesis by 4-5 mm or more demonstrated on supine to standing or flexion-extension imaging. Demographic, perioperative, and radiographic data were collected. Reoperation rates defined as any operation on the same or adjacent level were assessed. Revision decompression alone was considered if the aforementioned clinical and radiographic criteria were met, otherwise patient underwent a minimally invasive posterior fusion at revision. Clinical outcome was evaluated using the Oswestry Disability Index and visual analog scale (VAS) scores.

Results: Two-hundred forty-seven patients of whom 47.1% females with a mean overall age of 66 years [20 − 88] at the time of the initial surgery were included. The majority of patients (68.7%) underwent one level decompression, followed by 23.6%, 6.1% and 1.6% for 2, 3 and 4 levels respectively. The most common decompressed level was L4-5 (47.2%), followed by L3-4 (17.5%), L2-3 (2.8%), L5-S1 (1.2%) and a combination of two or more levels (31.3%). Preoperative spondylolisthesis at the level of spinal stenosis was present in 56.9%.
Mean follow-up period was 8.2 years [5.0 −14.9]. The overall reoperation rate was 15.8%. The cumulative reoperation rate in patients with and without spondylolisthesis after 8 years was 8.5% and 6.5% respectively; fusion was required in 4.1% and 2.8% respectively. No significant differences were observed between those with and without DLS (re-decompression only p = 0.954; fusion p = 0.546). The mean time to reoperation in patients with and without spondylolisthesis was 3.9 years [95%CI 1.8 − 6.0] and 2.8 years [95%CI 1.3 − 4.2], respectively for decompression only, and 3.1 years [95%CI 1.0 − 5.3] and 3.1 years [95%CI 1.1 − 5.1], respectively for fusion.
At the 5-years follow-up point, a mean improvement of 19.4% and 19.7% on the Oswestry Disability Index, 3.7 and 4.4 on the VAS leg, and 2.1 and 2.5 on the VAS back was observed compared with the preoperative baseline (p < 0.0001) in patients with and without spondylolisthesis, respectively.

Conclusions: Minimally invasive decompression is an effective and durable procedure for the treatment of LSS with or without stable DLS. Patients' with leg dominant symptoms and radiographically stable grade 1 DLS, do not require a fusion.