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Cement and Bone Fillers
Cheryl A. Petersilge, MD, MBA
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KEY FACTS

  • Terminology

    • Imaging

      • Clinical Issues

        TERMINOLOGY

        • Abbreviations

          • Bone morphogenic protein (BMP)
          • Polymethylmethacrylate (PMMA) bone cement
        • Definitions

          • Purpose: Various 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: Taken from self, 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 > 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 elements offer maximal opportunity by providing all elements needed for graft incorporation
          • Allograft
            • Only contains mineralized component of bone; lacks marrow elements
            • Little risk of disease transmission
            • Frozen, 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 Morphogenic 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
          • 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
        • 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 incorporated: Complete 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 osseous defects
              • Most frequently following explant of infected implant
            • Treatment of painful vertebral and sacral fractures
          • Low viscosity cements preferred for vertebral augmentation
          • Function is to be 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 increase 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 increased 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

                  1. García-Gareta E et al: Osteoinduction of bone grafting materials for bone repair and regeneration. Bone. 81:112-121, 2015
                  2. Gupta A et al: Bone graft substitutes for spine fusion: a brief review. World J Orthop. 6(6):449-56, 2015
                  3. 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
                  4. Beaman FD et al: Imaging characteristics of bone graft materials. Radiographics. 26(2):373-88, 2006
                  5. Jelinek JS et al: MR imaging findings in patients with bone-chip allografts. AJR Am J Roentgenol. 155(6):1257-60, 1990
                  6. Manaster BJ et al: Pre- and postoperative imaging of vascularized fibular grafts. Radiology. 176(1):161-6, 1990
                  7. Kattapuram SV et al: Intercalary bone allografts: radiographic evaluation. Radiology. 170(1 Pt 1):137-41, 1989
                  Related Anatomy
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                  Related Differential Diagnoses
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                  References
                  Tables

                  Tables

                  KEY FACTS

                  • Terminology

                    • Imaging

                      • Clinical Issues

                        TERMINOLOGY

                        • Abbreviations

                          • Bone morphogenic protein (BMP)
                          • Polymethylmethacrylate (PMMA) bone cement
                        • Definitions

                          • Purpose: Various 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: Taken from self, 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 > 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 elements offer maximal opportunity by providing all elements needed for graft incorporation
                          • Allograft
                            • Only contains mineralized component of bone; lacks marrow elements
                            • Little risk of disease transmission
                            • Frozen, 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 Morphogenic 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
                          • 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
                        • 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 incorporated: Complete 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 osseous defects
                              • Most frequently following explant of infected implant
                            • Treatment of painful vertebral and sacral fractures
                          • Low viscosity cements preferred for vertebral augmentation
                          • Function is to be 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 increase 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 increased 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

                                  1. García-Gareta E et al: Osteoinduction of bone grafting materials for bone repair and regeneration. Bone. 81:112-121, 2015
                                  2. Gupta A et al: Bone graft substitutes for spine fusion: a brief review. World J Orthop. 6(6):449-56, 2015
                                  3. 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
                                  4. Beaman FD et al: Imaging characteristics of bone graft materials. Radiographics. 26(2):373-88, 2006
                                  5. Jelinek JS et al: MR imaging findings in patients with bone-chip allografts. AJR Am J Roentgenol. 155(6):1257-60, 1990
                                  6. Manaster BJ et al: Pre- and postoperative imaging of vascularized fibular grafts. Radiology. 176(1):161-6, 1990
                                  7. Kattapuram SV et al: Intercalary bone allografts: radiographic evaluation. Radiology. 170(1 Pt 1):137-41, 1989