Minimally Invasive Decompression for Degenerative Lumbar Conditions

Presented at SMISS Annual Forum 2014
By Reginald Q. Knight MD, MHA
With Scott Grainger BS, RN,

Disclosures: Reginald Knight MD, MHA B; Stryker Spine, Vertebral Technology Inc, Vertera Spine. C; Stryker Spine, Vertebral Technology Inc, Vertera Spine. D; Vertebral Technology Inc, Vertera Spine, Gerstner Medical. Scott Grainger BS, RN None,

Introduction:
Degenerative conditions of lumbar spine producing symptoms of mechanical back pain, radiculopathy and neurogenic claudication impact a growing segment of our society. Many patients are elderly with multiple comorbidites and reluctant to undergo surgery. Failing adequate functional improvement via non-operative means surgical decompression using minimally invasive techniques may become a viable option.

Aims/Objectives:
Assess our experience treating lumbar spinal stenosis in a diffuse population to evaluate functional outcomes as they relate to prior surgery, diabetes, smoking and age.

Methods:
From January 2010 to present a surgical registry developed at our institution produced a consecutive cohort of 104 patients enrolled via IRB sanctioned parameters. MIS techique included use of 16mm - 18mm tubular retractor and microscope. Data colleced from serial chart review include perioperative demographics and functional outcome (Oswestry, VASB, VASL, Patient Health Questionaire - 9 [PHQ-9]) preop, 1, 4, 10, and 24 months. Statistics were analyzed using Student T-test with significance at p< 0.05.

Results:
Our cohort had a mean age of 69.9 years (21 - 89). 73 were Medicare beneficaries. There were 65 male and 39 female patients. 25 patients had prior surgery at the index level, 27 were diabetic requiring medication, 13 were smokers. Perioperative demographics: mean levels decompressed 1.7 (1- 4), op time 116.7 minutes (28 - 325), estimated blood loss 39.3 cc (5 - 250), fluoroscopy time 20.8 sec (3 - 235) and LOS 0.6 days (0 - 11) [64 outpatient, 34 one day]. 102/104 (98%) patients were dischage home. 4/104 (3.8%) patients were readmitted without reoperation. Complications (events related to change in expected ORT or LOS): intraoperative 1/104 (0.9%) - dural tear, postoperative 3/104 (2.8%) - 2 urniary retentions, 1 superficial wound infection. Patient functional outcome noted significant improvement in all parameters (VASB, VASL, ODI, PHQ-9). Comparison within groups demonstrated no significant functional outcome difference related to Medicare status, sex, single vs multiple levels, prior surgery or presence of diabetes. Smokers presented with increased back pain and PHQ-9 related to non-smokers. Multilevel cases were associated with increased intraoperative demographics. Patients requiring bilateral decompression (defined as contralateral foraminotomy via unilateral approach) presented with lower VASB, ODI and PHQ-9.

Conclusions:
Spinal decompression, including multilevel procedures and those requiring bilateral decompression via unilateral approach, for lumbar degenerative conditions via minimally invasive technique should be expected to improve patient function with minimal periopeative morbidity. Prior surgery and history of diabetes did not negatively impact outcomes in this cohort.