Are Minimally Invasive Lumbar Fusion Outcomes Affected By Stenosis? MASTERS-D Subgroup Analysis

Presented at SMISS Annual Forum 2014
By Wolfgang Senker MD
With Paulo Pereira MD, Ulrich Hubbe MD, Neil Manson MD, FRCSC, Kai-Michael Scheufler MD, Jorg Franke MD,

Disclosures: Wolfgang Senker MD C; Medtronic Paulo Pereira MD B; Medtronic, Ulrich Hubbe MD A; Medtronic, B; Medtronic, C; Medtronic, Neil Manson MD, FRCSC A; Unrestricted Research Grant, $85,000/annum, Medtronic Canada. B; Education Fees, Medtronic Canada., Kai-Michael Scheufler MD B; Medtronic, C; Medtronic, Jorg Franke MD A; Medtronic, B; Medtronic, C; Medtronic,

Introduction:
MASTERS-D provided outcome and complication data following minimally invasive lumbar interbody fusion (MILIF) for degenerative lumbar disorders (DLD). Significant and rapid improvement was observed following MILIF with low surgical risk.

Aims/Objectives:
To investigate whether outcomes of MILIF for DLD were different between patients with/without stenosis and between stenosis patients with/without decompression: data from a multicenter 1-year prospective observational study (MASTERSD; NCT01143324). Methods: 252 patients underwent 1- (83%) or 2-level (17%) MILIF (TLIF: 95%; PLIF: 5%) for treatment of leg pain (52.0%), back pain (38.9%) or claudication (9.1%) due to DLD, including spondylolisthesis (52.8%), stenosis (71.4%), and/or disc pathology (93.7%). Time (days) to first ambulation (TFA) and postsurgical recovery (TPSR), VAS back/leg pain and ODI pre-/post-surgery (4 weeks, 12 months) and changes from baseline [all variables: medians and interquartile ranges (IQR), Mann-Whitney U-test] were compared between stenosis (S: N=180)/non-stenosis (NS: N=72) and stenosis+decompression (S+D: N=142)/stenosis+no decompression (S+ND: N=38) patients.

Results:
All groups demonstrated statistically significant improvement in all outcome measures. TFA was similar for all subgroups [S/NS 1.0 (0.5)/1.0 (1.0) p=0.0702; S+D/S+ND 1.0 (0.0)/1.0 (1.0) p=0.9473)]. TPSR was higher for S vs NS [3.0 (2.5)/2.0 (1.0) p=0.0021] and lower for S+D vs S+ND [2.0 (2.0)/4.0 (3.0) p=0.0017)]. At baseline, VAS Leg pain was statistically significantly higher in S vs NS [7.0 (3.0)/5.0 (4.0) p=0.0014] but similar at 4w [2.0 (5.0)/1.0 (4.0) p=0.3805] and at 12m, it was equally low [1.0 (4.0)/1.0 (5.0) p=0.6425] due to a more pronounced drop from baseline in S (4w: 3.9 vs 3.0, p=0.0784; 12m: 5.0 vs 3.0, p=0.0185). ODI improved slightly better (n.s.) in S vs NS and VAS back pain was equal in these groups. VAS leg pain, ODI and VAS back pain pre-/post-surgery as well as changes from baseline were similar in S+D compared to S+ND.

Conclusions:
Stenosis patients need longer times for surgery recovery, suffer from more leg pain at baseline but experience better Leg pain improvement after MILIF so that outcome at 12m is the same than in non-stenosis patients. Decompressed stenosis patients recover sooner from surgery than non-decompressed patients.

Take Home Message:
The MILIF approach to treat DLD proves valid for stenosis and non-stenosis patients. Stenosis patients benefit even more coming from a higher baseline leg pain level. Decompression can improve TPSR, however further investigation is needed applying well defined, standardized decompression methods.