Various materials and techniques used to fill defects, restore structure and strength, provide scaffold for bone ingrowth
Ceramic: inorganic material transformed during process of heating and cooling, often has crystalline structure
Bone graft
Autograft: harvested from patient, contains marrow elements leading to osteogenesis
Allograft: derived from different individual
Xenograft: derived from different species
Onlay graft: placed along surface of bone
Strut graft: spans defect in bone or segment of spine
Vascularized graft: graft with blood supply, usually reestablished through microvascular techniques; fibula most common source, typically autograft
Sources: iliac crest, fibula, rib, mandible
Biologic activity of grafts
Osteoinductive: recruits and then stimulates osteoprogenitor cells and undifferentiated stems cells to form osteoblasts
Osteoconductive: scaffolding for bone ingrowth
Osteogenic: stimulates new bone formation via implanted cells within graft, primarily autograft
Cancellous graft greater potential than cortical graft
Bone Graft
Autograft
Additional morbidity, especially pain, occurs at harvest site (especially iliac crest)
Cortical: provides strength of cortical bone
Often used as onlay graft
Minimal marrow elements, so incorporation requires long period of time
Cancellous: offers no structural support
Provides marrow elements stimulating bone ingrowth and more rapid incorporation
Corticocancellous
Provides structural support of cortical bone, combined with marrow elements with their osteogenic properties
Vascular grafts
Blood supply and marrow offer all elements needed for graft incorporation
Allograft
Only contains mineralized component of bone; lacks marrow elements
Little risk of disease transmission
Frozen or freeze-dried; techniques reduce strength
Higher rate of complications
Nonunion, fracture, infection
Lacks ability to repair following damage
Incorporation requires balance between bone resorption and bone deposition
Bone Morphogenetic Protein
Group of 6 different proteins (BMP-2 through BMP-7) that stimulate formation of bone and cartilage
BMP-7, a.k.a. OP-1 (osteogenic protein-1)
Derived from recombinant DNA techniques
Requires carrier, usually mixed with bone graft or bone graft substitutes
Provides osteoinductive influence
Offers no structural support
Use in spine may be associated with aggressive bone resorption, mimicking infection
→ caution warranted when interpreting images
Ceramics
Majority are calcium phosphate based
Hydroxyapatite forms most common
Mimics structure of calcium within bone
Available in pastes, powder, granular, block forms
Poor mechanical properties
Coralline hydroxyapatite derived from sea coral; others synthetic
Other less commonly used chemical forms: tricalcium phosphate, calcium sulfate
Density similar to or greater than bone
Fills defects, provides scaffolding for new bone
Resorbs over long periods of time as new bone is incorporated: rapid resorption indicates failure of incorporation or tumor recurrence
Biologic activity
Osteointegrative (new bone binds to graft)
Osteoconductive
May be osteoinductive
Inert material, no toxicity
Bioactive glass: brittle, usually combined with another agent, such as PMMA
Demineralized Bone Matrix
Type of allograft
Useful because releases BMP
No structural properties
Often mixed with other bone fillers to introduce its osteoinductive properties
Demineralized, therefore radiolucent; carrier usually has density
Injectable Cements
Useful because of mechanical properties
Structural characteristics mimic bone
Also provide 3D scaffold for bone ingrowth
Polymer based; no biologic activity
Polymethylmethacrylate
Same material used to make acrylic
Supplied as liquid monomer and powder polymer
Monomer: stabilizer, activator
Powder: includes polymerization initiator
When mixed, creates exothermic reaction
Phases of polymerization
Wetting phase: all powder is wet
Dough time: cement pulls away from surface
Setting time: maximum temperature rise
Working time: interval from dough time to setting time
Desirable phase for joint implants
Too thick for injection via cannula for vertebral augmentation
Uses
Fix joint implants to bone, sometimes pedicle screws
Fill defects in bone after curettage for tumor
May be mixed with slow-release antibiotics and placed in infected bone defects
Most frequently following explant of infected implant
Treatment of painful vertebra and sacrum fractures
Low viscosity cements preferred for vertebral augmentation
Function → load sharing
More flexible than cortical bone, less flexible than cancellous
Strength is in compression; fails along lines of shear
No biologic activity
Barium added to ↑ density
Toxicity to user
Vapors permeate contact lenses
Mucous membrane irritation
Contact dermatitis, numbness, paresthesias
Excess monomer may be toxic to patient
Small amounts always exist in tissues
Earlier vertebroplasties had different monomer:powder ratio resulting in ↑ amounts of free monomer; this caused damage to lungs and liver
IMAGING
Imaging Recommendations
Radiographic and CT Findings
MR Findings
PATHOLOGY
Microscopic Features
CLINICAL ISSUES
Natural History & Prognosis
Selected References
Sallent I et al: The few who made it: commercially and clinically successful innovative bone grafts. Front Bioeng Biotechnol. 8:952, 2020
Sohn HS et al: Review of bone graft and bone substitutes with an emphasis on fracture surgeries. Biomater Res. 23:9, 2019
García-Gareta E et al: Osteoinduction of bone grafting materials for bone repair and regeneration. Bone. 81:112-21, 2015
Gupta A et al: Bone graft substitutes for spine fusion: a brief review. World J Orthop. 6(6):449-56, 2015
Hustedt JW et al: The controversy surrounding bone morphogenetic proteins in the spine: a review of current research. Yale J Biol Med. 87(4):549-61, 2014
Beaman FD et al: Imaging characteristics of bone graft materials. Radiographics. 26(2):373-88, 2006
Jelinek JS et al: MR imaging findings in patients with bone-chip allografts. AJR Am J Roentgenol. 155(6):1257-60, 1990
Manaster BJ et al: Pre- and postoperative imaging of vascularized fibular grafts. Radiology. 176(1):161-6, 1990
Kattapuram SV et al: Intercalary bone allografts: radiographic evaluation. Radiology. 170(1 Pt 1):137-41, 1989
Related Anatomy
Loading...
Related Differential Diagnoses
Loading...
References
Tables
Tables
KEY FACTS
Terminology
Imaging
Clinical Issues
TERMINOLOGY
Abbreviations
Bone morphogenetic protein (BMP)
Polymethylmethacrylate (PMMA), a.k.a. bone cement
Definitions
Various materials and techniques used to fill defects, restore structure and strength, provide scaffold for bone ingrowth
Ceramic: inorganic material transformed during process of heating and cooling, often has crystalline structure
Bone graft
Autograft: harvested from patient, contains marrow elements leading to osteogenesis
Allograft: derived from different individual
Xenograft: derived from different species
Onlay graft: placed along surface of bone
Strut graft: spans defect in bone or segment of spine
Vascularized graft: graft with blood supply, usually reestablished through microvascular techniques; fibula most common source, typically autograft
Sources: iliac crest, fibula, rib, mandible
Biologic activity of grafts
Osteoinductive: recruits and then stimulates osteoprogenitor cells and undifferentiated stems cells to form osteoblasts
Osteoconductive: scaffolding for bone ingrowth
Osteogenic: stimulates new bone formation via implanted cells within graft, primarily autograft
Cancellous graft greater potential than cortical graft
Bone Graft
Autograft
Additional morbidity, especially pain, occurs at harvest site (especially iliac crest)
Cortical: provides strength of cortical bone
Often used as onlay graft
Minimal marrow elements, so incorporation requires long period of time
Cancellous: offers no structural support
Provides marrow elements stimulating bone ingrowth and more rapid incorporation
Corticocancellous
Provides structural support of cortical bone, combined with marrow elements with their osteogenic properties
Vascular grafts
Blood supply and marrow offer all elements needed for graft incorporation
Allograft
Only contains mineralized component of bone; lacks marrow elements
Little risk of disease transmission
Frozen or freeze-dried; techniques reduce strength
Higher rate of complications
Nonunion, fracture, infection
Lacks ability to repair following damage
Incorporation requires balance between bone resorption and bone deposition
Bone Morphogenetic Protein
Group of 6 different proteins (BMP-2 through BMP-7) that stimulate formation of bone and cartilage
BMP-7, a.k.a. OP-1 (osteogenic protein-1)
Derived from recombinant DNA techniques
Requires carrier, usually mixed with bone graft or bone graft substitutes
Provides osteoinductive influence
Offers no structural support
Use in spine may be associated with aggressive bone resorption, mimicking infection
→ caution warranted when interpreting images
Ceramics
Majority are calcium phosphate based
Hydroxyapatite forms most common
Mimics structure of calcium within bone
Available in pastes, powder, granular, block forms
Poor mechanical properties
Coralline hydroxyapatite derived from sea coral; others synthetic
Other less commonly used chemical forms: tricalcium phosphate, calcium sulfate
Density similar to or greater than bone
Fills defects, provides scaffolding for new bone
Resorbs over long periods of time as new bone is incorporated: rapid resorption indicates failure of incorporation or tumor recurrence
Biologic activity
Osteointegrative (new bone binds to graft)
Osteoconductive
May be osteoinductive
Inert material, no toxicity
Bioactive glass: brittle, usually combined with another agent, such as PMMA
Demineralized Bone Matrix
Type of allograft
Useful because releases BMP
No structural properties
Often mixed with other bone fillers to introduce its osteoinductive properties
Demineralized, therefore radiolucent; carrier usually has density
Injectable Cements
Useful because of mechanical properties
Structural characteristics mimic bone
Also provide 3D scaffold for bone ingrowth
Polymer based; no biologic activity
Polymethylmethacrylate
Same material used to make acrylic
Supplied as liquid monomer and powder polymer
Monomer: stabilizer, activator
Powder: includes polymerization initiator
When mixed, creates exothermic reaction
Phases of polymerization
Wetting phase: all powder is wet
Dough time: cement pulls away from surface
Setting time: maximum temperature rise
Working time: interval from dough time to setting time
Desirable phase for joint implants
Too thick for injection via cannula for vertebral augmentation
Uses
Fix joint implants to bone, sometimes pedicle screws
Fill defects in bone after curettage for tumor
May be mixed with slow-release antibiotics and placed in infected bone defects
Most frequently following explant of infected implant
Treatment of painful vertebra and sacrum fractures
Low viscosity cements preferred for vertebral augmentation
Function → load sharing
More flexible than cortical bone, less flexible than cancellous
Strength is in compression; fails along lines of shear
No biologic activity
Barium added to ↑ density
Toxicity to user
Vapors permeate contact lenses
Mucous membrane irritation
Contact dermatitis, numbness, paresthesias
Excess monomer may be toxic to patient
Small amounts always exist in tissues
Earlier vertebroplasties had different monomer:powder ratio resulting in ↑ amounts of free monomer; this caused damage to lungs and liver
IMAGING
Imaging Recommendations
Radiographic and CT Findings
MR Findings
PATHOLOGY
Microscopic Features
CLINICAL ISSUES
Natural History & Prognosis
Selected References
Sallent I et al: The few who made it: commercially and clinically successful innovative bone grafts. Front Bioeng Biotechnol. 8:952, 2020
Sohn HS et al: Review of bone graft and bone substitutes with an emphasis on fracture surgeries. Biomater Res. 23:9, 2019
García-Gareta E et al: Osteoinduction of bone grafting materials for bone repair and regeneration. Bone. 81:112-21, 2015
Gupta A et al: Bone graft substitutes for spine fusion: a brief review. World J Orthop. 6(6):449-56, 2015
Hustedt JW et al: The controversy surrounding bone morphogenetic proteins in the spine: a review of current research. Yale J Biol Med. 87(4):549-61, 2014
Beaman FD et al: Imaging characteristics of bone graft materials. Radiographics. 26(2):373-88, 2006
Jelinek JS et al: MR imaging findings in patients with bone-chip allografts. AJR Am J Roentgenol. 155(6):1257-60, 1990
Manaster BJ et al: Pre- and postoperative imaging of vascularized fibular grafts. Radiology. 176(1):161-6, 1990
Kattapuram SV et al: Intercalary bone allografts: radiographic evaluation. Radiology. 170(1 Pt 1):137-41, 1989
STATdx includes over 200,000 searchable images, including x-ray, CT, MR, and ultrasound images. To access all images, please log in or subscribe.