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Variability Across Ten Production Lots of a Single Demineralized Bone Matrix Product
Hyun Bae, MD1; Li Zhao, MD, PhD1; Dagny Zhu, BS1; Linda E. Kanim, MA1; Jeffrey C. Wang, MD1; Rick B. Delamarter, MD1
1 Spine Research Foundation, Spine Institute, 1301 20th Street, Suite 400, Santa Monica, CA 90404. E-mail address for D. Zhu: dagny.zhu@gmail.com
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Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. One or more of the authors, or a member of his or her immediate family, received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from commercial entities (Medtronic, Stryker, SeaSpine, Osprey, Biomet, Aesculap, Synthes, Zimmer, and NuVasive).

Investigation performed at the Spine Research Foundation, Spine Institute, Santa Monica, and Surgical Sciences Laboratory, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California

Copyright ©2010 American Society for Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2010 Feb 01;92(2):427-435. doi: 10.2106/JBJS.H.01400
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Demineralized bone matrix is an osteoinductive allograft derived from processed bone that is commonly mixed with autogenous bone in fusion procedures to treat diseases of the spine. An increasing number of demineralized bone matrix-based products are commercially available for spinal fusion procedures, but osteoinductive variability has been found not only across different products but also among production lots from the same demineralized bone matrix formulation. The purpose of this study was to assess the lot-to-lot variability across a single demineralized bone matrix-based product in terms of both extracted bone morphogenetic protein (BMP) concentrations (in vitro) and fusion performance in rats (in vivo). The goal was also to determine whether the in vitro measures could sufficiently and accurately predict the in vivo fusion performance of different demineralized bone matrix-based product lots.


BMP-2 and BMP-7 were extracted from ten production lots of InterGro DBM Putty and quantified with use of ELISA (enzyme-linked immunosorbent assay). A posterolateral lumbar spinal fusion was performed on forty athymic rats with implantation of a demineralized bone matrix-based product. Fusion success was determined at eight weeks with use of radiographs and manual palpation of the segments. Logistic regression was used to determine the predictive abilities of BMPs.


Significant lot-to-lot variability was found in terms of both BMP concentrations (22 to 110 pg of BMP-2 per milligram of product and 44 to 125 pg of BMP-7 per milligram of product) and in vivo rates of fusion (0% to 75%; p < 0.04 for all). BMP-2 and BMP-7 concentrations correlated positively with each other across lots (r = 0.77, p < 0.0001). Most notably, extracted amounts of BMP-2 and BMP-7 each predicted in a dose-dependent manner the in vivo fusion performance in rats (R2 = 0.32, p < 0.01 for BMP-2, and R2 = 0.22, p < 0.009 for BMP-7).


Assays for demineralized bone matrix-extracted BMP-2 and BMP-7 levels may be feasible and sufficient for predicting spinal fusion performance of individual production lots from the same demineralized bone matrix-based product.

Clinical Relevance: 

In order to improve the consistency and efficacy of demineralized bone matrix-mediated fusions in clinical settings, it may be valuable to perform simple terminal screenings for BMP-2 and BMP-7 on demineralized bone matrix-based product lots prior to their commercial distribution.

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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