52 - Minimally Invasive Surgery for Lumbar Spinal Stenosis - Modified Marmo...

#52 Minimally Invasive Surgery for Lumbar Spinal Stenosis - Modified Marmot Operation versus Spinous Process Transverse Cutting Laminectomy

Oral Posters: MIS

Presented by: M. Kawakami


M. Kawakami (1)
S.-I. Nakao (1)
E. Miyamoto (1)
Y. Kinoshita (1)
D. Fukui (2)
T. Matsuoka (1)

(1) Wakayama Medical University Kihoku Hospital, Spine Care Center, Ito Gun, Japan
(2) Wakayama Rosai Hospital, Orthopaedic Surgery, Wakayama, Japan


Introduction: The exposure of the paravertebral muscles (PVM), which results in muscle injury and denervation, may induce failed back. In 2007, Cho et al reported split-spinous process laminotomy and discectomy named Marmot operation, which might preserve the PVM. However, Marmot operation is difficult to decompress lateral spinal canal. If the splitting spinous process is leaned laterally, the spinal canal can be decompressed easily. We have used this procedure, modified Marmot operation for patients with lumbar spinal stenosis (LSS). However, it is still unknown whether more patients with LSS have clinically improvement following preservation of the PVM than those who exposed the PVM. The purpose of this study was to compare clinical outcomes in patients with LSS treated with modified Marmot operation (MM group) with those treated with spinous process transverse cutting laminectomy through a unilateral approach, exposed the PVM and facet joint (control group).

Methods: Inclusion criteria were all symptomatic patients with diagnosed LSS between 2007 and November 2010. Patients with < 3 levels LSS, concomitant conditions, which could compromise outcomes assessment, and instability were excluded. Fifty-two consecutive patients met the inclusion criteria and completed the study consent. Outcome measures were changes of calculated five subscales using Japanese Orthopaedic Association Back Pain Questionnaire (JOABPEQ), which was patients' self assessment system for low back pain, visual analog scale (VAS) of low back pain, leg pain and numbness, and patients' satisfaction. Operation time, blood loss, perioperative complications, Creatine PhosphoKinase (CPK) and C-Reactive Protein (CRP) 7 days after operation and MRI changes of the PVM at the follow up were evaluated. T1 low and T2 high intensity area of the PVM and muscle atrophy were judged as postoperative PVM changes. Fifty-two patients with LSS were randomly allocated into two groups: the MM-group (25 patients) or the control group (27 patients). Patients were evaluated at 1 year postoperatively. A probability level of less than 0.05 was considered significant.

Results: There were no significant differences in preoperative VAS and JOABPEQ subscales in the two groups. All items except psychological disorders of JOABPEQ in both groups were improved at the follow-up. VAS of low back pain, pain-related disorders, gait disturbance and social life disturbance of the JOABPEQ in the MM group were statistically improved, compared with those in the control group. However, there were no significant differences in patients' satisfaction between the two groups. Although there were no differences in operation time, the mean blood loss in the MM group was significantly less than that in the control group (136.6ml, vs. 205ml). Rise in CRP (mg/dL) on postoperative day 7 (1.1 for the MM group and 2.8 for the control) and CPK (IU/L) (67.5 for the MM group and 253 for the control) showed statistically significant difference. Nine patients of the control group showed positive changes of the PVM. There were no perioperative complications in this series.

Conclusions: Clinical outcomes, which were evaluated with JOABPEQ, in patients with LSS treated with modified Marmot operation were superior to those with spinous process transverse cutting laminectomy through a unilateral approach. Splitting spinous processes approach without the exposure of the PVM might result in better clinical outcomes.