| 11. |
- Nilsson, Malin K, et al.
(författare)
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Factors influencing the compressive strength of an injectable calcium sulfate-hydroxyapatite cement.
- 2003
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Ingår i: Journal of Materials Science: Materials in Medicine. - 1573-4838. ; 14:5, s. 399-404
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Tidskriftsartikel (refereegranskat)abstract
- A biphasic injectable bone substitute, suitable for filling bone defects, that sets in the body, based on calcium sulfate and hydroxyapatite (HA), is presented. For applications in bone defects the compressive strength is important to assure support of the defect site during loading when the patient is weight bearing. To control the strength, the influence of four different factors; the liquid-to-powder (L/P) ratio, the HA particle morphology, the HA content and the amount of accelerator, were investigated. alpha-Calcium sulfate hemihydrate (CSH) and four different HA powders (three sintered and one spray-dried) were used. All differed in size and morphology. CSH and each HA powder were mixed together with distilled water to form the bone substitute. An accelerator, in form of calcium sulfate dihydrate, was added to the powder phase to obtain an adequate setting time. Cylindrical specimens were compression tested. A lower L/P-ratio gave stronger cement, but was more difficult to inject. The shape and the morphology of the HA particles influenced the strength, and reducing the amount of HA increased the strength. The amount of accelerator (calcium sulfate dihydrate) had no influence. (C) 2003 Kluwer Academic Publishers.
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| 12. |
- Tägil, Magnus, et al.
(författare)
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No augmentation of morselized and impacted bone graft by OP-1 in a weight-bearing model.
- 2003
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 74:6, s. 742-748
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Impacted morselized bone allograft is thought to be remodeled to a great extent. We have previously shown that load-bearing increases the remodeling of impacted morselized bone allografts in a rabbit knee prosthesis model. Bone Morphogenic Proteins (BMPs) also stimulate bone formation and bone allograft remodeling. In this study, our aim was to determine whether it was possible to increase further the remodeling of impacted morselized bone allografts by combining load-bearing with a BMP. Experiment: A solution of Osteogenic Protein-1 (OP-1, also called BMP-7) was added to freeze-dried bone allograft chips before impaction grafting in our rabbit knee prosthesis model. 23 skeletally mature rabbits received an uncemented tibial knee prosthetic component inserted into a bed of impacted morselized bone allograft. 12 rabbits were given OP-1-treated allograft (50 µg OP-1 per gram allograft), and 11 rabbits vehicle-treated allograft. Each rabbit received mean 0.53 g graft. The rabbits were killed after 3 or 6 weeks and the grafted region was examined by histomorphometric assessment of the volume fraction of newly formed bone and remaining graft. Results and interpretation: We found that OP-1 did not increase the bone density (graft plus new bone) to any substantial extent. However, we can not exclude that this might be due to a carrier problem, since the OP-1 was added as a solution directly to the dry graft.
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| 13. |
- Wang, Jian-Sheng, et al.
(författare)
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Bone integration of an injectable calcium phosphate based bone substitute
- 2004
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Ingår i: Transactions - 7th World Biomaterials Congress. - 1877040193 ; , s. 276-276
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Konferensbidrag (refereegranskat)abstract
- The bone formation and bone integration in calcium phosphate (CaP) and CaP with 20% calcium sulfate (CaS) were investigated. In the study, six adult, loop-eared rabbits were used and bone harvest chambers were implanted bilaterally in the proximal tibiae. It was found that the front of bone formation follows closely the front of material resorption without interposition of fibrous tissue. The results implied that a mixture of CaP and CaS can be introduced as an injectable bone graft substitute for filling bone defects.
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| 14. |
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| 15. |
- Wang, Jian-Sheng, et al.
(författare)
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Load-bearing increases new bone formation in impacted and morselized allografts
- 2000
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Ingår i: Clinical Orthopaedics and Related Research. - 0009-921X. ; :378, s. 274-281
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Tidskriftsartikel (refereegranskat)abstract
- The effects of mechanical loading on the incorporation of morselized impacted grafts were addressed in this study. Twelve skeletally mature rabbits were surgically treated. Six rabbits received a proximal tibial joint replacement with a tibial tray and a load-bearing 25-mm long stem. The tibia was packed with fresh frozen, morselized, cancellous rabbit bone. No cement was used. In six other rabbits only the stem was inserted, without a tibial tray, leaving the stem and the likewise impacted bone graft mechanically unloaded. The rabbits were euthanized after 6 weeks, and the tibias were sectioned and analyzed by histomorphometric examination. In the loaded specimens the graft was resorbed and replaced by new bone (30% of area of interest) to a larger extent than in the unloaded specimens. Mechanical loading of an impacted, morselized graft surrounding a conical uncemented stem, increased the amount of new bone that replaced the graft. The ability of morselized impacted grafts to allow mechanical stimulation of ingrown tissue appears to be a principal cause for the success of this grafting procedure.
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| 16. |
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