- Slower incorporation due to need to remodel existing Haversion canals- Interstitial lamellae preserved- Provides more structural support- 25% of massive grafts sustain insufficiency fractures
Calcium phosphate grafts
- Osteoconductive - Quick resorption - Examples include: OsteoSet (Wright medical)
see Rank-L and Bone Growth Factors
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Average 4.2 of 33 Ratings
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Which of the following graft materials has the least potential to elicit an immune response?
Fresh irradiated corticocancellous bulk allograft
Fresh frozen fibular strut allograft
Fresh frozen Achilles tendon allograft
Fresh Achilles tendon allograft
Freeze dried cancellous bone chips
Select Answer to see Preferred Response
Of the options listed, freeze dried cancellous allograft has the least potential to elicit an immune response. Remember, all allograft tissue has more of an immune response generating capability than autograft tissue, which has the least of any of these materials.
All allograft materials carry immunogenic properties, which decrease as the material is processed via the various sterilizing, freezing, or drying process(es). As the processing increases, the mechanical characteristics of the graft tends to decrease.
Ahlmann et al. compared the complications associated with harvesting iliac crest bone graft from the anterior crest and posterior crest. They found the rates of both minor complications (p = 0.006) and all complications (p = 0.004) were significantly higher after the anterior harvest procedures than they were after the posterior procedures. They recommend that iliac crest bone graft be harvested posteriorly whenever possible.
Answer 1: Most bone and soft tissue allografts undergo irradiation to remove bacteria or other infectious agents, but this does not prevent an immune response in itself.
Answer 2: Fresh frozen allografts have more immunogenic potential than freeze dried, but less than fresh materials. Fresh allograft is not typically utilized, as the processing of allograft (bone or soft tissue) provides the safety of minimizing infectious disease transmission.
Answer 3: Fresh frozen allografts have more immunogenic potential than freeze dried, but less than fresh materials. Thus fresh Achilles tendon allograft has the highest immunogenicity.
Answer 4: Fresh Achilles tendon allograft will elicit the greatest immunogenic response.
Ahlmann E, Patzakis M, Roidis N, Shepherd L, Holtom P
J Bone Joint Surg Am. 2002 May;84-A(5):716-20. PMID: 12004011 (Link to Abstract)
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Average 3.0 of 12 Ratings
Which of the following is true of both calcium phosphate and calcium sulfate?
They have high resistance to shear forces
They have high resistance to torsional forces
They are contraindicated in spinal fusion
They provide a scaffold for bone progenitor cells
They are not biocompatible with stainless steel orthopedic implants
Calcium phosphate and sulfate materials are biocompatible materials that are widely used in orthopedic surgery. They have low tensile and shear stress properties. They serve as osteoconductive void-fillers that prevent the in-growth of soft tissue and provide a suitable environment for bone healing.
Khan et al reviewed the key features of optimal bone graft substitutes. They concluded that one of three essential elements are needed: (1) osteoinductive factors, (2) osteoconductive capabilities and (3) osteogenic stem cells.
Legros reviewed calcium-based bone substitutes, describing their origins, compositions and physical forms. He highlighted their ability to promote cellular function and reviewed the three-dimensional geometry which allows them to bond to BMPs and become osteoinductive agents.
Bucholz reviewed synthetic bone grafts in depth. Synthetic porous substitutes have numerous advantages over autografts and allografts including their unlimited supply, easy sterilization, and storage. The relative advantages and disadvantages of ceramic implants as well as the indications and clinical experience of several of the synthetic bone grafts is reviewed.
Answer 1: Both have low resistance to shear forces.
Answer 2: Both have low resistance to torsional forces.
Answer 3: Both are used in spinal fusion.
Answer 5: Both are used with stainless steel and titanium implants as they are highly biocompatible.
Khan SN, Tomin E, Lane JM.
Orthop Clin North Am. 2000 Jul;31(3):389-98. PMID: 10882465 (Link to Abstract)
Clin Orthop Relat Res. 2002 Feb;(395):81-98. PMID: 11937868 (Link to Abstract)
Clin Orthop Relat Res. 2002 Feb;(395):44-52. PMID: 11937865 (Link to Abstract)
Average 3.0 of 19 Ratings
A 20-year-old male is involved in motor vehicle collision and sustains a depressed tibial plateau fracture. When performing surgery, if calcium sulfate is used as the primary bone substitute void filler, an increase in which of the following outcomes may be expected as compared to autograft?
Increased complications due to serous drainage
Improved clinical outcomes as shown by more rapid time to healing
Improved clinical outcomes as shown by SF-36 scores
Increased complications due to autoimmune reactions and graft rejection
Equivalent complication rates and clinical outcomes
Calcium sulfate bone graft substitute has demonstrated an increased rate of serous drainage at the surgical site. Evidence examining the use of calcium sulfate in the treatment of bone nonunions revealed a significant failure rate, suggesting that this material, used in isolation, is not optimal to promote union in that setting.
Beuerlein and Mckee reviewed the literature, showing that calcium sulfate is an effective void filler in metaphyseal defects after impacted fracture reduction (calcaneus, tibial plateau) or simple bone cysts. However, they report that calcium sulfate is associated with serous wound drainage especially when used at subcutaneous sites and in amounts greater than 20ml.
Ziran et al present a series of 41 patients undergoing bone grafting for atrophic/avascular nonunions with adjunctive calcium sulfate-demineralized bone matrix (Allomatrix). Of the 41 patients, 13 (32%) had drainage that necessitated surgical procedures and 14 (34%) developed a deep infection.
Beuerlein MJ, McKee MD.
J Orthop Trauma. 2010 Mar;24 Suppl 1:S46-51. PMID: 20182236 (Link to Abstract)
Ziran BH, Smith WR, Morgan SJ.
J Trauma. 2007 Dec;63(6):1324-8. PMID: 18212656 (Link to Abstract)
Average 3.0 of 21 Ratings
Which of the following osteoconductive bone graft substitutes resorbs faster than the rate at which bone growth occurs?
Collagen-based matrix with hydroxyapatitie coating
Calcium sulfate has a compressive strength similar to cancellous bone but resorbs quickly.
The review article by Hak discusses that calcium sulfate resorbs faster than bone growth occurs and is resorbed in 4-12 weeks. Tricalcium phospate, coralline hydroxyapatite, and collagen-based matrices with hydroxyapatite coating have compressive strengths similar to cancellous bone and can take 6 months to 10 years to fully resorb. Calcium phosphate has a compressive strength 4-10 times greater than cancellous bone and resorption takes approximately 1 year.
The article by Frankenburg et al reports the results of 70 dogs undergoing an osteotomy with subsequent allograft or calcium phosphate filling and were then sacrificed at interval times over a 4-month period. The osteotomies filled with allograft reached approximately 100% of the strength of the control tibiae by four weeks, whereas the tibiae that had been treated with cement reached their maximum load to failure by eight weeks. Tha authors found trends (no statistical signficance) showing stiffness, displacement at maximum load, and energy to failure was greater with the allograft but conclude that calcium phosphate is well tolerated and may be useful in difficult fractures.
J Am Acad Orthop Surg. 2007 Sep;15(9):525-36. PMID: 17761609 (Link to Abstract)
Frankenburg EP, Goldstein SA, Bauer TW, Harris SA, Poser RD.
J Bone Joint Surg Am. 1998 Aug;80(8):1112-24. PMID: 9730120 (Link to Abstract)
Average 3.0 of 18 Ratings
You are planning surgery on a 54-year-old female with the tibial plateau fracture seen in figures A and B. After reduction of the joint surface you plan to fill the void with a bone-graft substitute to prevent joint collapse. Which of the following bone-graft substitutes disappears most quickly in vivo?
Synthetic calcium sulfate and tri-phosphate mixture
Calcium sulfate disappears in vivo quickly, usually within 4-12 weeks. Calcium phosphate and coraline hydroxyapatite are resorbed slowly, somewhere between 1-10 years, depending on the manufacturer. Synthetics that combine calcium sulfate and phosphate resorb quicker than calcium phosphate but slower than calcium sulfate. Collagen-based matrices show quick resorption of the collegen but slow resorption of their hydroxyapatite coating. Walsh et al. examined the in vivo response of calcium sulfate pellets alone or in combination with autogenous bone graft in a sheep model. They found excellent bone formation in defects filled with calcium sulfate pellets. Immunostaining for various cytokines (BMP-2, BMP-7, PDGF, or TGF-beta) showed elevated levels in the newly formed bone. They proposed that the local environment acidity was responsible for breakdown of the calcium sulfate. Watson evaluated 8 patients with comminuted tibial metaphyseal fractures treated with an injectable calcium sulfate. They found that bone regrowth was observed in all patients and the bone substitute almost completely resorbed by 3 months. Bucholz reviewed the biochemical, biomechanical, and longevity characteristics of the common bone substitutes.
Walsh WR, Morberg P, Yu Y, Yang JL, Haggard W, Sheath PC, Svehla M, Bruce WJ.
Clin Orthop Relat Res. 2003 Jan;(406):228-36. PMID: 12579023 (Link to Abstract)
Orthopedics. 2004 Jan;27(1 Suppl):s103-7. PMID: 14763538 (Link to Abstract)
Average 3.0 of 11 Ratings
Which of the following bone graft substitutes has the fastest resorption characteristics?
Cortical iliac crest autograft
Of the three bone graft substitutes listed (calcium sulfate, tricalcium phosphate, and hydroxyapatite), calcium sulfate has the fastest resorption characteristics. Fibular allograft and cortical iliac crest autograft are not considered bone graft substitutes.
Calcium sulfate, tricalcium phosphate, and hydroxyapatite are all "osteoconductive" bone graft substitutes, meaning that these implants provide a surface and structure that facilitates the attachment, migration, proliferation, differentiation and survival of osteogenic stem and progenitor cells. Each has different chemical, macro- and microstructural properties. Calcium sulfate (plaster of Paris) is a low-molecular weight soluble compound that must be implanted adjacent to viable periosteum to work. It is reabsorbed by a process of dissolution over a period of 5-7 weeks.
Jamali, et al., found that calcium sulphate was completely reabsorbed by 6 weeks. Tricalcium phosphate has compressive strength similar to cancellous bone, but is brittle and weak under tension and shear. It undergoes reabsorbtion via dissolution and fragmentation over 6-18 months; unfortunately less bone volume is produced than tricalcium phosphate absorbed. For this reason, it is used clinically as an adjunct with other less absorbable substitutes.
Moore et al discuss that hydroxyapatite forms the principle mineral content of bone. Synthetically, it is available in ceramic and non-ceramic forms as porous or solid, blocks or granules. HA has good compressive strength, but is weak in tension and shear and brittle making it fracture-prone in shock loading. Ceramic HA preparations are resistant to absorption in vivo, which occurs at 1-2% per year. Non-ceramic HA is more readily absorbed.
Jamali A, Hilpert A, Debes J, Afshar P, Rahban S, Holmes R.
Calcif Tissue Int. 2002 Aug;71(2):172-8. Epub 2002 Jun 5. PMID: 12200649 (Link to Abstract)
Moore WR, Graves SE, Bain GI.
ANZ J Surg. 2001 Jun;71(6):354-61. PMID: 11409021 (Link to Abstract)
Average 2.0 of 11 Ratings
Iliac crest cancellous bone graft can be harvested from either the anterior or posterior aspect of the pelvis. When comparing these two locations, harvesting from the anterior iliac crest has which of the following?
Less severe postoperative pain at the surgical site
Decreased postoperative gait abnormalities
Increased complication rates as compared to posterior harvesting
Decreased postoperative pain duration
Increased cancellous bone graft density
Autologous bone is used to help promote bone healing in fractures and to provide structural support for reconstructive surgery, and can be harvested from the iliac crest, femur, or other areas. The results of autologous bone grafting are more predictable than the use of xenografts, cadaveric allografts, or synthetic bone substitutes because autologous bone grafts provide osteoinductive and osteoconductive properties, are not immunogenic, and are usually well incorporated into the graft site.
Arrington et al reviewed 414 consecutive iliac crest harvest procedures and reported a 10% rate of minor complications and 5.8% of major complications (deep infection, nerve injuries, herniation, fractures, hematomas). They note that with proper surgical technique, the incidence of the complications can be minimized.
Ahlmann et al compared the morbidity related to the harvest of anterior iliac crest bone graft with that related to the harvest of posterior iliac crest bone graft and to determine differences in functional outcome. The rates of both minor complications (p = 0.006) and all complications (p = 0.004) were significantly higher after the anterior harvest procedures than they were after the posterior procedures. The postoperative pain at the donor site was significantly more severe (p = 0.0016) and of significantly greater duration (p = 0.0017) after the anterior harvests.
Arrington ED, Smith WJ, Chambers HG, Bucknell AL, Davino NA.
Clin Orthop Relat Res. 1996 Aug;(329):300-9. PMID: 8769465 (Link to Abstract)
What is the approximate risk of transmission of HIV in fresh-frozen allograft bone?
1 in 10,000,000
1 in 1,000,000
1 in 100,000
1 in 50,000
1 in 10,000
Hepatitis C & B, HIV, TB, and other bacterial infections have been recognized as important transmissible diseases in tissue and organ transplants. Retrospective studies, beginning in 1992, have demonstrated the ability of bone allografts from donors infected with these pathogens to seroconvert recipients and ultimately transmit the disease.
The risk of viral transmission associated with blood properly screened for Hepatitis C is 1 in 100,000. Risk of transmission in Hepatitis B is 1 in 63,000, HIV is between 1 in 650,000 to 1 in 1,000,000 for blood transmission and allograft transmission rates are estimated by the blood transmission rates.
In a current concepts review, Tomford reviews the current literature regarding disease transmission in musculoskeletal allografts. Currently two cases of HIV transmission have been documented in the United States. Current molecular biological efforts towards identification of potential infectious agents in allografts have shown promise in the early identification and prevention of disease transmission.
Instr Course Lect. 2000;49:615-9. PMID: 10829217 (Link to Abstract)
J Bone Joint Surg Am. 1995 Nov;77(11):1742-54. PMID: 7593087 (Link to Abstract)
Average 2.0 of 24 Ratings
Which of the following bone graft material contains live mesenchymal osteoblastic precursor cells?
Fresh-frozen allograft bone
Recombinant bone morphogenic protein
Demineralized bone matrix
Autologous iliac crest marrow aspirate
Calcium phosphate putty
Demineralized bone matrix is obtained from allograft bone using a process of acid extraction which yields a product containing much of the collagen and non-collagenous protein components of bone including BMP.
Demineralized bone matrix contains collagen, BMP, TGF-beta, residual Ca, but NOT mesenchymal precursor cells. Live precursor cells are removed from allograft during processing. Calcium phosphate cement does not contain living cells. The only bone graft material that contain these live precursor cells are those containing autologous marrow-fresh autograft or bone marrow aspirate (answer 4).
Average 3.0 of 15 Ratings
Which of the following groups correctly identifies serologic tests that are required by the American Association of Tissue Banks (AATB) for musculoskeletal tissue allografts?
Cytomegalovirus, Hepatitis A, Hepatitis B, Hepatitis C, HIV, Syphillis
Cytomegalovirus, Hepatitis A, Hepatitis B, Hepatitis C, HIV
Hepatitis A, Hepatitis B, Hepatitis C, HIV, Syphillis
Hepatitis B, Hepatitis C, HIV, Syphillis
Hepatitis B, Hepatitis C, HIV
The American Association of Tissue Banks performs screening testing on all allografts in addition to screening patients medical history. Specific tests include: HIV, HBV, HCV, HTLV-I/II, and Syphilis (see www.aatb.org for more info on screening process).
Neither Cytomegalovirus (CMV) nor Hepatitis A is routinely tested for in the American Association of Tissue Banks for musculoskeletal tissue.
Average 1.0 of 55 Ratings
You are considering using a frozen allograft distal femoral condyle in your reconstruction of a massive giant-cell tumor of the knee. In counseling your patient regarding the risks of allografts, you explain that 5 years after transplantation, what percentage of donor chondrocytes will be present and viable in the allograft?
greater than 50%
None, by 5 years the allograft cartilage will be completely acellular
By 5 years, the allograft cartilage will be completely acellular, so there will be no residual donor chondrocytes.
Enneking et al. conducted both radiographic and histologic studies of sixteen massive retrieved human allografts four to sixty-five months after implantation. Analysis of the articular cartilage revealed no evidence that any chondrocytes had survived, even when the graft had been cryoprotected before it was preserved by freezing.
Enneking WF, Mindell ER.
J Bone Joint Surg Am. 1991 Sep;73(8):1123-42. PMID: 1890115 (Link to Abstract)
Average 2.0 of 20 Ratings
Which of the following substances is most osteoinductive?
Xenograft collagen sheet
An ideal bone-graft substitute must provide scaffolding for osteoconduction as well as progenitor cells and growth factors for osteoinduction. Furthermore, the bone graft must be able to integrate with the host. Autogenous bone graft contains osteoblasts, endosteal osteoprogenitor cells capable of synthesizing new bone, and a structural matrix that acts as a scaffold, making it the gold standard for bone grafting. BMP-2 is a commonly utilized adjunct for grafting, and is inherently osteoinductive.
The referenced article by Buckwalter et al is a review on the biology of bone grafting which nicely defines the various osteoinductive and osteoconductive properties of the various bone graft options.
Buckwalter JA, Glimcher MJ, Cooper RR, Recker R.
Instr Course Lect. 1996;45:371-86. PMID: 8727757 (Link to Abstract)
Buckwalter JA, Glimcher MJ, Cooper RR, Recker R.
Instr Course Lect. 1996;45:387-99. PMID: 8727758 (Link to Abstract)
Orthobiologics: Steven Steinlauf, MD(CSFA #2, 2017)
This is a video of the RIA device for a femoral bone graft harvest. This was do...