Mesenchymal Stem Cell Allograft In One And Two Level ACDF's: A Matched Cohort Analysis

Presented at SMISS Annual Forum 2014
By Kern Singh MD
With Branko Skovrlj MD, Sheeraz Qureshi MD, MBA, Alejandro Marquez-Lara MD, Islam Elboghdady , Abbas Naqvi BS, Khaled Aboushaala MD, Steven McAnany MD, Nomaan Ashraf MD, Samuel Overley 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 Branko Skovrlj MD None, Sheeraz Qureshi MD, MBA A; Cervical Spine Research Society. B; Zimmer-Biomet, Stryker Spiner, Globus Medical, Inc. D; Avaz Surgical. F; RTI, Zimmer-Biomet, Stryker Spine, Alejandro Marquez-Lara MD None, Islam Elboghdady None, Abbas Naqvi BS None, Khaled Aboushaala MD None, Steven McAnany MD None, Nomaan Ashraf MD None, Samuel Overley MD None,

Introduction:
Live mesenchymal stem cell (MSC)-containing allogenic bone grafts have recently gained popularity and currently account for 17% of all bone grafts and bone graft substitutes utilized in spinal surgery. Potential advantages include long-term cell proliferation, self-renewal capabilities, and multi-potent differentiation. Currently, little is known about their clinical success when used in anterior cervical discectomy and fusion (ACDF).

Aims/Objectives:
To assess the fusion rate in ACDF using MSC allograft.

Methods:
A consecutive series of 57 patients (85 cervical levels) who underwent a one- or two- level ACDF procedure between 2010 and 2012 were retrospectively analyzed. All fusion constructs comprised of an interbody allograft, an anterior plate. and Osteocel® (NuVasive, San Diego, CA, USA). These patients were matched with regards to diagnosis, number of fusion levels, smoking status, and comorbidity burden to a control group of 57 patients (85 cervical levels). The fusion construct in the control group included a structural interbody bone allograft (Vertigraft (DePuy, Raynham, MA, USA)) and anterior plating without other graft enhancers. The six-month arthrodesis rates were assessed with thin-slice computerized tomography (CT) scan. Patients with pseudarthrosis at six-months were reassessed at 1 year with flexion-extension x-rays and CT scan. Statistical analysis was performed with independent sample T tests for continuous variables and Chi-square analysis for categorical data. Clinical and radiographic evidence of arthrodesis were compared between cohorts with <0.05 denoting statistical significance.

Results:
Of the 57 cases in both cohorts, 29 (50.9%) were single-level and 28 (49.1%) were two-level ACDFs. There were no significant differences in patient age (47.3±10.2 vs 46.6±9.0 years, p=0.71), gender, comorbidity burden (CCI: 1.95±1.48 vs 2.42±1.31, p=0.71) or body mass index (28.0±7.5 vs 28.4±5.4 Kg/m2, p=0.79) . At the one-year follow up, 50/57 (87.7%) patients in the Osteocel® cohort demonstrated a solid fusion compared to 54/57 (94.7%) in the control group (p=0.19). Seven (12.3%) patients in the Osteocel® cohort were reported as having a failed fusion at one-year. Four (7.0%) of these patients were symptomatic and underwent revision surgery with a posterior cervical fusion, while three patients (5.3%) were asymptomatic and did not require a secondary intervention. The three patients (5.3%) in the control cohort all required revision surgery.

Conclusions:
This is the firststudy to analyze a matched cohort assessing the one-year arthrodesis rates associated with a non-structural MSC allograft in ACDF procedures. Although not statistically significant, patients treated with MSC allografts demonstrated lower fusion rates compared to a matched non-MSC cohort.