Bone Grafts and Substitutes in Fracture Repair – Part 1

What if bones could heal faster and stronger with the help of materials designed in a lab? Is this science fiction or the reality of orthopedic surgery today? Bone graft substitutes are changing fracture repair, spinal fusion, joint reconstruction, dental surgery, and many other surgical applications. Read on to learn more.

Bone regeneration is an amazing natural process; however, some conditions disrupt healing, making natural regeneration insufficient. Conditions such as avascular necrosis, nonunion and malunion fractures, and bone defects caused by trauma or tumors can significantly impair the body’s ability to rebuild healthy bone tissue. When this happens, surgical intervention and bone grafting become essential tools to stimulate regeneration and ensure proper healing. Let’s take a closer look at the world of bone graft substitutes (BGS) by exploring their types, advantages, limitations, and applications in modern fracture repair

What Defines an Ideal Bone Graft?

Osteoinductive – The graft must actively stimulate bone formation through recruitment of cells and molecules to the implant site.
Osteoconductive – The graft’s ability to support growth of new bone, allowing cells to adhere and multiply on the graft’s surface.
Osteogenic – The graft promotes the formation of new bone tissue.
Biocompatible – The graft material must be safe for implantation, minimizing the risk of infection or immune rejection.
Bioresorbable – The graft material should degrade at a controlled rate, as new bone is deposited.
Mechanical Strength & Porosity – The graft should provide adequate structural support while allowing for vascularization and tissue ingrowth, crucial for long-term bone health.
Growth Factor Delivery – The graft should act as a carrier for biological signals which enhance bone repair.
Non-toxic & Safe – The material must be free from antigenic, teratogenic, or carcinogenic effects, ensuring safety for patients (1-3).

Three Main Types of BGS

Autografts: The Patient’s Own Bone

Autografts involve harvesting bone tissue from a patient’s own body and transplanting it to another location to aid bone repair.

Autografts are osteoconductive, osteoinductive, and have osteogenic properties
Autografts contain viable cells and natural growth factors crucial for healing, including bone morphogenetic proteins (BMP), fibroblast growth factors (FGF), vascular endothelial growth factors (VEGF), platelet-derived growth factors (PDGF), and insulin-growth factor 1 (IGF-1).
Autografts can be combined with other biologics such as bone marrow aspirate or platelet-rich plasma to reduce the amount of bone needed for the graft while enriching growth factor delivery (1-4)

Allografts: Donor-Derived Bone Solutions

Allografts involve harvesting bone from a live donor or a cadaver, which is then sterilized and prepared for transplantation. While radiation sterilization removes osteogenic and osteoinductive properties, allografts retain osteoconductivity, providing a scaffold for new bone growth.

Types of Allografts:

Cancellous allografts – Support structural bone repair
Cortical allografts – Provide denser load-bearing support
Demineralized Bone Matrix (DBM) – acid-extracted, removing minerals but preserving collagen and growth factors like BMPs, to support osteoconductive and osteoinductive action (2-4).

Synthetic bone graft substitutes (BGS): Engineered for Consistency and Reliability

Synthetic BGS are osteoconductive, biocompatible, bioresorbable, and structurally designed to mimic natural bone properties. Unlike autografts and allografts – where quality varies based on the donor – synthetic substitutes ensure consistency and reliability while serving as a scaffold for healing.

Osteoconductive – Allow new bone formation on BGS surface
Bioresorbable – Can be tuned to degrade as the bone heals, ensuring seamless integration
Mechanical Strength & Porosity – Support vascularization and tissue ingrowth
Some BGS are Osteoinductive & Osteogenic – Stimulating mesenchymal stem cell (MSC) proliferation

Forms of Synthetic BGS: Synthetic BGS are available in pellets, putty, powders, blocks, moldable, injectable, and 3D- printed bone scaffolds.

Types of Synthetic Biomaterials:

Calcium phosphate ceramics: tricalcium phosphate (TCP), biphasic calcium phosphate (BCP), hydroxyapatite (HA)
Bioactive glass: osteoconductive inorganic metallic oxides provide durability and strength
Calcium sulfate: temporary scaffold biomaterial
Biodegradable polymer biomaterials: polylactides (PLLA, PDLA), collagen, polyglycolide, and polycaprolactone (8)
Carbohydrate polymer-based scaffolds: such as our Osteo-P® BGS with biocompatibility, biodegradability which matches bone repair, and optimal porosity for osteoconductivity (9-11)
Composite biomaterials which blend ceramics and polymers to combine durability, biocompatibility, and improved bioactivity. Some formulations incorporate metals to enhance mechanical strength and promote osteogenesis (2-7)

Conclusion: The Future of Bone Grafting Innovation

Advances in biomaterials and regenerative medicine are reshaping how we approach bone healing and reconstruction. Each fracture and patient is unique, and surgeons now have a toolbox of bone substitute options including autografts, allografts or synthetic BGS that can be personalized and optimized for each situation.

Next-generation solutions like our hyper-crosslinked carbohydrate polymer scaffolds (Osteo-P® BGS) promote greater precision, faster healing, and enhanced patient outcomes. To learn more about our innovation and the future of bone regeneration visit Molecular Matrix, Inc. at www.molecularmatrix.com.

References:

[1] A. Bigham‐Sadegh, A. Oryan, Basic concepts regarding fracture healing and the current options and future directions in managing bone fractures, Int. Wound J. 12 (2015) 238–247. https://doi.org/10.1111/iwj.12231.

[2] C.E. Gillman, A.C. Jayasuriya, FDA-approved bone grafts and bone graft substitute devices in bone regeneration, Mater. Sci. Eng. C 130 (2021) 112466. https://doi.org/10.1016/j.msec.2021.112466.

[3] V.Al. Georgeanu, O. Gingu, I.V. Antoniac, H.O. Manolea, Current Options and Future Perspectives on Bone Graft and Biomaterials Substitutes for Bone Repair, from Clinical Needs to Advanced Biomaterials Research, Appl. Sci. 13 (2023) 8471. https://doi.org/10.3390/app13148471.

[4] J.W. Łuczak, M. Palusińska, D. Matak, D. Pietrzak, P. Nakielski, S. Lewicki, M. Grodzik, Ł. Szymański, The Future of Bone Repair: Emerging Technologies and Biomaterials in Bone Regeneration, Int. J. Mol. Sci. 25 (2024) 12766. https://doi.org/10.3390/ijms252312766.

[5] J.E. Inglis, A.M. Goodwin, S.N. Divi, W.K. Hsu, Advances in Synthetic Grafts in Spinal Fusion Surgery, Int. J. Spine Surg. 17 (2023) S18–S27. https://doi.org/10.14444/8557.

[6] J.R. Perez, D. Kouroupis, D.J. Li, T.M. Best, L. Kaplan, D. Correa, Tissue Engineering and Cell-Based Therapies for Fractures and Bone Defects, Front. Bioeng. Biotechnol. 6 (2018) 105. https://doi.org/10.3389/fbioe.2018.00105.

[7] M.A. Plantz, E.B. Gerlach, W.K. Hsu, Synthetic Bone Graft Materials in Spine Fusion: Current Evidence and Future Trends, Int. J. Spine Surg. 15 (2021) 104–112. https://doi.org/10.14444/8058.

[8] W.R. Moore, S.E. Graves, G.I. Bain, Synthetic Bone Graft Substitutes, ANZ J. Surg. (2001) 354–361.

[9] K.D. Kim, C.A. Batchelder, P. Koleva, A. Ghaffari-Rafi, T. Karnati, D. Goodrich, J. Castillo, C. Lee, In Vivo Performance of a Novel Hyper-Crosslinked Carbohydrate Polymer Bone Graft Substitute for Spinal Fusion, Bioengineering 12 (2025) 243. https://doi.org/10.3390/bioengineering12030243.

[10] P.M. Koleva, J.H. Keefer, A.M. Ayala, I. Lorenzo, C.E. Han, K. Pham, S.E. Ralston, K.D. Kim, C.C. Lee, Hyper-Crosslinked Carbohydrate Polymer for Repair of Critical-Sized Bone Defects, BioResearch Open Access 8 (2019) 111–120. https://doi.org/10.1089/biores.2019.0021.

[11] S. Michael A, L. Charles C, Bridging and Repair of First Metatarsal Fracture with Chronic Pseudoarthrosis Following Multiple Surgical Interventions Using a Minimally Invasive Approach, Open J. Orthop. Rheumatol. 10 (2025) 001–004. https://doi.org/10.17352/ojor.000050.

Bone Grafts and Substitutes in Fracture Repair – Part 1

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