Minimally Invasive Lumbar Laminectomy - The Surgical Learning Curve

Presented at SMISS Annual Forum 2014
By Kern Singh MD
With Sreeharsha V. Nandyala BA, Alejandro Marquez-Lara MD, Islam Elboghdady , Eric Sundberg MD, Abbas Naqvi BS, Hamid Hassanzadeh MD, Anton Jorgensen MD,

Disclosures: Kern Singh MD A; CSRS Resident Grant. B; DePuy, Zimmer, Stryker, CSRS, ISASS, AAOS, SRS, Vertebral Column - ISASS. D; Avaz Surgical, LLC, Vital 5, LLC. F; Zimmer, Stryker, Pioneer, Lippincott Williams & Wilkins, Th Sreeharsha Nandyala BA None, Alejandro Marquez-Lara MD None, Islam Elboghdady None, Eric Sundberg MD None, Abbas Naqvi BS None, Hamid Hassanzadeh MD None, Anton Jorgensen MD None,

Introduction:
There is anecdotal evidence that minimally invasive (MIS) spinal procedures carry an inherently difficult learning curve. Few studies have characterized the surgeon’s learning curve for MIS lumbar laminectomy and have correlated the postoperative complications and outcomes as a function of the surgeon’s experience.

Aims/Objectives:
To characterize the surgical learning curve and outcomes associated with a primary 1 and 2 level minimally invasive (MIS) lumbar laminectomy.

Methods:
A retrospective review of the first 85 patients who underwent a primary 1 and 2 level lumbar laminectomy by a single surgeon for degenerative spinal pathology from 2009-2013 was performed. The initial 42 patients were compared to the second 43 patients in terms of patient demographics, Charlson Comorbidity Index (CCI), intraoperative parameters, perioperative outcomes, visual analogue scores (VAS), and postoperative complications. Statistical analysis was performed with independent sample T tests for continuous variables and Chi-square analysis for categorical data. An alpha level of <0.05 denoted statistical significance.

Results:
Patients in the initial group were older and demonstrated a greater comorbidity burden. The preoperative VAS scores did not significantly differ between the study cohorts. The initial group incurred a greater mean procedural time (61.4±20.5 vs 49.1±21.7, p<0.05), estimated blood loss (EBL) (47.7±13.0 vs 39.6±12.5), and hospitalization (35.5±30.3 vs 20.2±19.8). There was a slightly increased rate of complications and revision/reoperations in the first group that did not reach statistical significance. There were no significant differences in the postoperative 6-month VAS scores.

Conclusions:
In this surgical learning curve analysis of MIS lumbar laminectomies, continued surgical experience was associated with a reduced mean operative time, EBL and hospitalization. Regardless of surgeon experience, all patients demonstrated similar improvements in clinical outcomes. These finding suggest that MIS lumbar laminectomy, while technically challenging, can initially be performed safely without prior experience and that surgical experience improves intraoperative variables.