| 1. |
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| 2. |
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| 3. |
- Alonso-Vazquez, A, et al.
(författare)
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Initial stability of ankle arthrodesis with three-screw fixation. A finite element analysis
- 2004
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Ingår i: Clinical Biomechanics. - : Elsevier BV. - 0268-0033. ; 19:7, s. 751-759
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Compare the initial stability at the fusion site of ankle arthrodesis fixed with two and three screws. Design. Finite element models of ankle arthrodesis were developed from computed tomography images. Two-screw constructs were augmented with a third screw in different orientations and Subjected to loads likely to affect the ankle postoperatively. Background More stable fixation seems to increase the chance of fusion, as it minimises the motion between the tibiotalar interfaces. Methods. Non-linear elastic finite element analyses were performed in external torsion and dorsiflexion. The micromotions at the tibiotalar interface were computed to compare the two- and three-screw fixation in intact and flat-cut arthrodesis. Results. Adding a third screw reduced the micromotions at the fusion site. Inserting the third screw anteriorly predicted lower peak micromotions than inserting the screw posteriorly, except for the intact arthrodesis tested in dorsiflexion. Three-screw intact arthrodesis predicted lower peak micromotions than flat-cut arthrodesis. Conclusions. Better stability was predicted for three-screw ankle arthrodesis. In flat-cut arthrodesis, a third screw inserted anteriorly performed better than a posterior screw. In intact arthrodesis, a posterior screw seemed a better option when flexion stability was the main concern. Even with three-screw fixation, the configuration of the first two-crossed screws may still be important to improve the stability at the fusion site. Relevance The optimal number and placement of screws in ankle arthrodesis has yet to be determined. The differences in stability predicted between various screw configurations and Surface preparation techniques presented here may be the difference between success and failure. (C) 2004 Elsevier Ltd. All rights reserved.
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| 4. |
- Alonso-Vazquez, A, et al.
(författare)
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The effect of bone quality on the stability of ankle arthrodesis. A finite element study
- 2004
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Ingår i: Foot & Ankle International. - 1944-7876. ; 25:11, s. 840-850
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Tidskriftsartikel (refereegranskat)abstract
- Background: Despite uniform operating techniques, lack of fusion still occurs after ankle arthrodesis. Differences in the biological healing potential may be a factor but the mechanical performance of the arthrodesis construct because of varying bone quality also may be important. Internal compression techniques are preferred because of higher union rates, shorter fusion times, and fewer complications. A three-screw configuration has been shown to be more stable than a two-screw configuration, but it is not obvious when it should be used. Methods: Three-dimensional finite element models of intact and flat-cut ankle arthrodeses were built, using two and three screws in different configurations. Poor bone quality was simulated by decreasing Young's modulus of the bone. The constructs were loaded in torsion and dorsiflexion, and micromotions at the fusion site were measured. Results: Bone quality had a marked effect on the stability at the arthrodesis site. Inserting two screws at 30 degrees relative to the longitudinal axis of the tibia in an intact arthrodesis seemed the best option, especially as bone quality worsened. The addition of a third screw increased the stability at the arthrodesis site. Conclusions: Overall, intact joint surfaces and three-screw fixation, with the lateral and medial screws inserted produced the most stable arthrodesis constructs when bone quality was poor. Clinical Relevance. Ankle arthrodeses are technically demanding because of the shape and small size of the talus. Preoperative planning is an absolute necessity to determine placement and number of screws. This study shows that poor bone quality decreases the stability of the arthrodesis constructs, suggesting that an attempt should be made to create the most stable three-screw configuration. Finite element models can be used as an effective preoperative tool for planning screw number and placement.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Bhat, Sumrita, et al.
(författare)
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In Vitro Neo-Cartilage Formation on a Three-Dimensional Composite Polymeric Cryogel Matrix
- 2013
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Ingår i: Macromolecular Bioscience. - : Wiley. - 1616-5195 .- 1616-5187. ; 13:7, s. 827-837
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Tidskriftsartikel (refereegranskat)abstract
- Limited blood supply and the avascular nature of articular cartilage restricts its self repair capacity, frequently leading to osteoarthritis. This work focuses on scaffolds for tissue repair from natural polymers, for example gelatin, chitosan, and agarose in the form of composite. A novel way of fabrication, known as cryogelation, is presented, in which matrices are synthesized at sub-zero temperature. Cell seeded scaffolds incubated under appropriate conditions result in the accumulation of matrix components on the surface of the gel in the form of neo-cartilage. Neo-cartilage exhibits similarity to native cartilage with respect to its physical, mechanical and biochemical properties. Based on the similarities of neo-cartilage to the native cartilage, it can provide a new approach for the treatment of localised joint injuries.
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| 9. |
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| 10. |
- Camire, Christopher, et al.
(författare)
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Material characterization and in vivo behavior of silicon substituted alpha-tricalcium phosphate cement.
- 2006
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 76B:2, s. 424-431
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Tidskriftsartikel (refereegranskat)abstract
- The possibility and biological effects of substituting silicon in a-tricalcium phosphate (alpha-TCP) by way of solid-state reaction have been evaluated. a-TCP powders with varying substitution amounts (1 and 5 mol % Ca2SiO4) were synthesized by reacting mixtures of CaCO3, Ca(2)P(2)O7, and SiO2, at a rate of 4 degrees C(min)(-1) to 1100 degrees C, left to dwell for 2 h and then heated to 1325 degrees C at 4 degrees C(min)(-1) and left to dwell for a period of 4 h. The powders were then rapidly quenched in air. Si incorporation could be verified by X-ray diffraction analysis, indicating an increase of the lattice volume with increasing Si content from 4284.1(8) to 4334(1) angstrom(3) for pure alpha-TCP and alpha-Si5%TCP, respectively. The hydrolysis of milled alpha-SiTCP powders was monitored by isothermal calorimetry, and the compressive strength of set cements was tested. The results showed changes in speed and amount of heat released during reactivity tests and a decrease in mechanical strength (60, 50, and 5 MPa) with increasing Si content. In vitro bioactivity of the set cements after soaking in simulated body fluid for 4 weeks was also tested. The formation of a bonelike apatite layer on the surface of the set cements could be observed and was thickest for 1% Si (20 mu m). These results were in good agreement with the in vivo studies performed, which showed strong evidence that the cement containing 1% silicon doped alpha-TCP enhanced mesenchymal cell differentiation and increased osteoblast activity compared with alpha-TCP. (c) 2005 Wiley Periodicals, Inc.
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| 11. |
- Camire, Christopher, et al.
(författare)
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Production methodology and reactivity of silica substituted a phase tricalcium phosphate
- 2004
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Ingår i: Transactions - 7th World Biomaterials Congress. - 1877040193 ; , s. 1437-1437
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Konferensbidrag (refereegranskat)abstract
- A silica substituted alpha phase tricalcium phosphate was developed by way of solid state reaction. The difference in reactivity of two different production methods using isothermal calorimetry and X- ray diffraction was also recorded. It was suggested that a silica substituted alpha phase tricalcium phosphate can be produced and characterized by way of X-ray measurement. Referencing selected significant peaks for α-TCP, β-TCP and apatite.
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| 12. |
- Camire, Christopher, et al.
(författare)
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Study of particle size dependant reactivity in an alpha-TCP orthophosphate cement
- 2004
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Ingår i: Key Engineering Materials. - 1013-9826. ; 254-256, s. 269-272
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Tidskriftsartikel (refereegranskat)abstract
- Calcium phosphates have been of great interest in the field of medicine for many decades due to their biocompatibility, hardening properties and diverse areas of application. In this study two different alpha phase tricalcium phosphate powders were produced of distinctly different particle size distributions. These two powders were then tested for reactivity and phase evolution. X-ray diffraction was used to characterise the beginning and final products and the exotherm were measured with an isothermal calorimeter. The powders were then viewed relative to their starting properties and differences were drawn. Fine material exhibited a much larger exotherm, which was not directly proportional to the difference in surface area of the particulate. The difference has been attributed to the variant concentrations of nucleation sites assisting the ionic dissolution and precipitation reaction. For proper and ultimately efficient use of this material in the clinic it remains important to fully understand and have control over reactivity. Higher success rates and more reliable fracture fixation will result.
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| 13. |
- Camire, Christopher, et al.
(författare)
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Study of Particle Size Dependant Reactivity in an α-TCP Orthophosphate Cement
- 2004
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Ingår i: Key Engineering Materials. - 1013-9826. ; 254-256, s. 269-272
-
Konferensbidrag (refereegranskat)abstract
- Calcium phosphates have been of great interest in the field of medicine for many decades due to their biocompatibility, hardening properties and diverse areas of application. In this study two different alpha phase tricalcium phosphate powders were produced of distinctly different particle size distributions. These two powders were then tested for reactivity and phase evolution. X-ray diffraction was used to characterise the beginning and final products and the exotherm were measured with an isothermal calorimeter. The powders were then viewed relative to their starting properties and differences were drawn. Fine material exhibited a much larger exotherm, which was not directly proportional to the difference in surface area of the particulate. The difference has been attributed to the variant concentrations of nucleation sites assisting the ionic dissolution and precipitation reaction. For proper and ultimately efficient use of this material in the clinic it remains important to fully understand and have control over reactivity. Higher success rates and more reliable fracture fixation will result.
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| 14. |
- Camire, Christopher, et al.
(författare)
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The effect of crystallinity on strength development of alpha-TCP bone substitutes.
- 2006
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 79B:1, s. 159-165
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Tidskriftsartikel (refereegranskat)abstract
- Alpha phase tricalcium phosphates (alpha-TCP) were produced using a solid-state reaction method and milled for various periods of time. The resulting four materials were alpha-TCPs, ranging in crystalline content. Powders were exposed to X-ray diffraction for material identification as well as for use in crystallinity and purity calculations. Powder particle size was investigated using laser diffraction. Materials were mixed with 2.5% Na2HPO4 solution to initiate the hydration of alpha-TCP to calcium-deficient hydroxyapatite (CDHA). Isothermal calorimetry was performed to observe thermal response of the powders over a period of time. During the reaction process, at various time points up to 216 h, the material was compression tested to observe strength development. Materials proved to be predominantly alpha phase, while amorphous content determined by XRD varied. Reactivity, as measured by isothermal calorimetry, varied with crystallinity of the alpha-TCP powder. Speed of strength development did not change except for the most finely ground powder. In addition, crystal size of the CDHA was changed only in the product formed from the most highly ground material. It is proposed that increasing reactivity of alpha-TCP cements does not result in a corresponding increase in rate of strength development until there is sufficient supersaturation to produce significant crystal nucleation.
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| 15. |
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| 16. |
- Chen, Peilin, et al.
(författare)
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Fabrication of a silver nanoparticle-coated collagen membrane with anti-bacterial and anti-inflammatory activities for guided bone regeneration
- 2018
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Ingår i: Biomedical materials. - 1748-6041. ; 13:6
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Tidskriftsartikel (refereegranskat)abstract
- Alveolar bone loss is a common problem that affects dental implant placement. A barrier between the bone substitute and gingiva that can prevent fibro-tissue ingrowth, bacterial infection and induce bone formation is a key factor in improving the success of alveolar ridge reconstruction. This study aims to develop a bioactive collagen barrier material for guided bone regeneration, that is coupled with anti-bacterial and anti-inflammatory properties. We have evaluated two silver coating methods and found controllable and precise coating achieved by sonication compared with sputtering. The optimized AgNP-coated collagen membrane exhibited excellent anti-bacterial effects against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) with limited cellular toxicity. It also displayed effective anti-inflammatory effects by reducing the expression and release of inflammatory cytokines including IL-6 and TNF-alpha. Additionally, AgNP-coated collagen membranes were able to induce osteogenic differentiation of mesenchymal stem cells that guide bone regeneration. These findings demonstrate the potential application of AgNP-coated collagen membranes to prevent infection after bone graft introduction in alveolar ridge reconstruction.
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| 17. |
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| 18. |
- Dreinhofer, Karsten E, et al.
(författare)
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Multinational survey of osteoporotic fracture management
- 2005
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 1433-2965 .- 0937-941X. ; 16:Suppl. 2, s. 44-53
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Tidskriftsartikel (refereegranskat)abstract
- Osteoporosis is characterized by a decreased bone mass and an increased bone fragility and susceptibility to fracture. Patients with a fragility fracture at any site have an increased risk of sustaining future fractures. Orthopedic surgeons manage most of these fractures and are often the only physician seen by the patient. Mounting evidence that orthopedic surgeons are not well attuned to osteoporosis led the Bone and Joint Decade (BJD) and the International Osteoporosis Foundation (IOF) to survey 3,422 orthopedic surgeons in France, Germany, Italy, Spain, the United Kingdom, and New Zealand. The majority of the respondents in all countries had the opinion that the orthopedic surgeon should identify and initiate the assessment of osteoporosis in patients with fragility fractures. Heterogeneous practice pattern exist in different countries; however, identification and treatment of the osteoporotic patient seems to be insufficient in many areas: half of the orthopedic surgeons surveyed received little or no training in osteoporosis. Only approximately one in four orthopedic surgeons in France, the UK and New Zealand regarded themselves as knowledgeable about treatment modalities. Less than one-fifth of the orthopedic surgeons arranged for a surgically treated patient with a fragility fracture to have a bone mineral density (BMD) test. Twenty percent said that they never refer a patient after a fragility fracture for BMD. Only half of the orthopedic surgeons in southern Europe know about the importance of some external risk factors for hip fractures (cataracts, poor lighting, pathway obstacles, poor balance). In summary, this survey clearly indicates that many orthopedic surgeons still neglect to identify, assess and treat patients with fragility fractures for osteoporosis. More educational opportunities need to be offered to orthopedic surgeons through articles, web-based learning and educational seminars. Development of a simple clinical pathway from evidence-based guidelines is an important step to ensure that optimal care is provided for patients with fragility fractures.
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| 19. |
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| 20. |
- Dunbar, M J, et al.
(författare)
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Appropriate questionnaires for knee arthroplasty. Results of a survey of 3600 patients from The Swedish Knee Arthroplasty Registry
- 2001
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Ingår i: Journal of Bone and Joint Surgery: British Volume. - 2044-5377. ; 83:3, s. 339-344
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish Knee Arthroplasty Registry (SKAR) has recorded knee arthroplasties prospectively in Sweden since 1975. The only outcome measure available to date has been revision status. While questionnaires on health outcome may function as more comprehensive endpoints, it is unclear which are the most appropriate. We tested various outcome questionnaires in order to determine which is the best for patients who have had knee arthroplasty as applied in a cross-sectional, discriminative, postal survey. Four general health questionnaires (NHP, SF-12, SF-36 and SIP) and three disease/site-specific questionnaires (Lequesne, Oxford-12, and WOMAC) were tested on 3600 patients randomly selected from the SKAR. Differences were found between questionnaires in response rate, time required for completion, the need for assistance, the efficiency of completion, the validity of the content and the reliability. The mean overall ranks for each questionnaire were generated. The SF-12 ranked the best for the general health, and the Oxford-12 for the disease/site-specific questionnaires. These two questionnaires could therefore be recommended as the most appropriate for use with a large knee arthroplasty database in a cross-sectional population.
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| 21. |
- Dunbar, Michael J, et al.
(författare)
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Translation and validation of the Oxford-12 item knee score for use in Sweden
- 2000
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 71:3, s. 268-274
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Tidskriftsartikel (refereegranskat)abstract
- The Oxford-12 Item Knee Score is a recently developed and validated patient-completed outcome measure designed specifically for use with knee arthroplasty in the United Kingdom. We have translated this questionnaire into Swedish and tested the validity and reliability of the translated version in a cross-sectional study by a postal survey to 1,200 randomly selected patients from the Swedish Knee Arthroplasty Register. Swedish versions of the WOMAC, Nottingham Health Profile, SF-36, SF-12, and the Sickness Impact Profile were employed in the validation process. We also tested feasibility and patient-burden parameters. The translated version appeared to be linguistically and culturally equivalent to the original version with good validity and reliability. Indirect measures of responsiveness indicated that it is at least as responsive to relevant knee arthroplasty patient states as the previously validated Swedish version of the WOMAC. Application of the translated questionnaire to this population is feasible with minimal imposed patient-burden. The Swedish translation of the Oxford-12 Item Knee Score is a valid and reliable tool for outcome studies on knee arthroplasty patients.
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| 22. |
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| 23. |
- Flivik, Gunnar, et al.
(författare)
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Effects of lamination on the strength of bone cement
- 1997
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 68:1, s. 55-58
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Tidskriftsartikel (refereegranskat)abstract
- To improve cement penetration into the cancellous bone of the acetabulum in hip arthroplasty, sequential cementation of each anchoring hole may be feasible. Since this procedure creates laminations in the cement, we have determined the conditions under which such laminations affect the strength of the cement. Cement bars made at 2, 3 or 4 minutes after the start of cement mixing and with either dry laminations or laminations including blood or saline were tested for tensile strength. Solid unlaminated bars were used as references. Dry and saline laminations made up to 4 minutes after the start of cement mixing did not reduce the strength of the cement. However, there was a time-dependent decrease in cement strength if blood was entrapped in the interface. In such cases, there was a decrease in strength for laminations made at 4 minutes, at 3 minutes this was less pronounced and at 2 minutes no weakening at all was noted. Our findings indicate that a sequential cementation procedure is permissible as regards cement strength, provided it is performed with 2-3 minutes after the start of cement mixing. If the cement area is kept free from blood, the time may be prolonged up to 4 minutes, without the risk of weakening the cement strength.
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| 24. |
- Flivik, Gunnar, et al.
(författare)
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Technetium-99m-nanocolloid scintigraphy in orthopedic infections: a comparison with indium-111-labeled leukocytes
- 1993
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Ingår i: Journal of Nuclear Medicine. - 0161-5505. ; 34:10, s. 1646-1650
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Tidskriftsartikel (refereegranskat)abstract
- Twenty-three patients with clinically suspected acute or chronic osteomyelitis and 21 patients with suspected joint prosthetic infection underwent scintigraphy using both 99mTc-nanocolloid and 111In-labeled leukocytes. The scintigrams of the two tracers were blindly interpreted by three independent observers. Their evaluations showed high correspondence. Patients were classified as having no infection, probable infection or proven infection according to specific criteria which included results of bacteriological cultures and histopathological examinations. For proven and probable infection taken together, the sensitivity with 99mTc-nanocolloid was 94%, the specificity 84% and the accuracy 87%, compared with 75%, 90% and 85% with 111In-labeled leukocytes. We conclude that 99mTc-nanocolloid scintigraphy is at least equivalent with 111In-leucocyte scintigraphy, and its additional advantages are shorter examination time, less complexity and better radiation dosimetry.
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| 25. |
- Forslund, Carina, et al.
(författare)
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Effects of high-intensity focused ultrasound on the intervertebral disc: A potential therapy for disc herniations
- 2006
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Ingår i: Journal of Clinical Ultrasound. - : Wiley. - 0091-2751 .- 1097-0096. ; 34:7, s. 330-338
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Tidskriftsartikel (refereegranskat)abstract
- Purpose. To determine the potential application of high-intensity focused ultrasound for the minimally invasive treatment of herniated intervertebral discs by developing a probe that produces sufficiently high temperature locally to shrink collagen fibers (65-75 degrees C). Materials and Methods. A 5-mm ultrasound probe was produced with a geometric focal length of 15 mm. The probe produced 2.5 W of acoustic power and was operated at a frequency of 4.1 MHz. Measurements of temperature increase were performed in discs from bovine tails. In vivo experiments were performed to assess histologic changes in the disc as well as in nerve root and muscle. Results. Sufficient temperature increase to produce collagen shrinkage was observed close to the focus of the ultrasound. Temperature measurements in vertebral end plates showed a temperature increase of only 4 degrees C after 60-second exposure of the disc. In vivo experiments revealed histologic changes in the disc consistent with collagen shrinkage, with no adverse effects seen in surrounding tissues. Conclusions. The experiments demonstrated the feasibility of high-intensity focused ultrasound in the treatment of contained herniated discs. This technique has several advantages over other thermal treatment modalities. (C) 2006 Wiley Periodicals, Inc.
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| 26. |
- Gupta, Ankur, et al.
(författare)
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Cell factory-derived bioactive molecules with polymeric cryogel scaffold enhance the repair of subchondral cartilage defect in rabbits.
- 2017
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : Hindawi Limited. - 1932-6254. ; 11:6, s. 1689-1700
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Tidskriftsartikel (refereegranskat)abstract
- We have explored the potential of cell factory-derived bioactive molecules, isolated from conditioned media of primary goat chondrocytes, for the repair of subchondral cartilage defects. Enzyme-linked immunosorbent assay (ELISA) confirms the presence of transforming growth factor-β1 in an isolated protein fraction (12.56 ± 1.15 ng/mg protein fraction). These bioactive molecules were used alone or with chitosan-agarose-gelatin cryogel scaffolds, with and without chondrocytes, to check whether combined approaches further enhance cartilage repair. To evaluate this, an in vivo study was conducted on New Zealand rabbits in which a subchondral defect (4.5 mm wide × 4.5 mm deep) was surgically created. Starting after the operation, bioactive molecules were injected at the defect site at regular intervals of 14 days. Histopathological analysis showed that rabbits treated with bioactive molecules alone had cartilage regeneration after 4 weeks. However, rabbits treated with bioactive molecules along with scaffolds, with or without cells, showed cartilage formation after 3 weeks; 6 weeks after surgery, the cartilage regenerated in rabbits treated with either bioactive molecules alone or in combinations showed morphological similarities to native cartilage. No systemic cytotoxicity or inflammatory response was induced by any of the treatments. Further, ELISA was done to determine systemic toxicity, which showed no difference in concentration of tumour necrosis factor-α in blood serum, before or after surgery. In conclusion, intra-articular injection with bioactive molecules alone may be used for the repair of subchondral cartilage defects, and bioactive molecules along with chondrocyte-seeded scaffolds further enhance the repair. Copyright © 2015 John Wiley & Sons, Ltd.
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| 27. |
- Gupta, Ankur, et al.
(författare)
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Evaluation of Three-Dimensional Chitosan-Agarose-Gelatin Cryogel Scaffold for the Repair of Subchondral Cartilage Defects: An In Vivo Study in a Rabbit Model
- 2014
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Ingår i: Tissue Engineering. Part A. - : Mary Ann Liebert Inc. - 1937-335X .- 1937-3341. ; 20:23-24, s. 3101-3111
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the potential of a chitosan-agarose-gelatin (CAG) cryogel scaffold for the repair of subchondral cartilage defects was explored in female New Zealand white rabbits. Custom-made CAG cryogel scaffold was implanted in a surgically created subchondral defect (diameter of 4 mm, depth of 4 mm) in knee joint of rabbit. The repair of the subchondral defect was evaluated at regular time interval by both macroscopic as well as microscopic examinations. The gross evaluation of the scaffold-implanted site showed integration of the scaffold with the surrounding tissue. Scanning electron microscopy and histological staining of the remnants of implanted cryogel scaffold showed infiltration of the host cells. The repair of the subchondral defect along with well-integrated regenerated cartilage was confirmed by the histology analysis of the joint. Results showed significant cartilage regeneration by the fourth week until eighth week after implantation. Immunohistochemical analysis confirmed that regenerated tissue is hyaline cartilage and absence of hypertrophy marker was reported. In addition, the CAG scaffolds did not elicit any adverse immunological rejection as shown by hematological analysis. Enzyme-linked immunosorbent assay did not show any statistically significant change in the concentration of tumor necrosis factor-alpha in the serum, and remained in a nontoxic range. Rabbits with a surgically created defect but no scaffold did not show any cartilage regeneration throughout the experiment of 8 weeks. These results demonstrate that CAG cryogel scaffolds promote repair of an osteochondral defect at a load-bearing site in rabbits.
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| 28. |
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| 29. |
- Horstmann, Peter Frederik, et al.
(författare)
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Composite biomaterial as a carrier for bone-Active substances for metaphyseal tibial bone defect reconstruction in rats
- 2017
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Ingår i: Tissue Engineering - Part A. - : Mary Ann Liebert Inc. - 1937-3341 .- 1937-335X. ; 23:23-24, s. 1403-1412
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Tidskriftsartikel (refereegranskat)abstract
- Restoring lost bone is a major challenge in orthopedic surgery. Currently available treatment strategies have shortcomings, such as risk of infection, nonunion, and excessive resorption. Our primary aim was to study if a commercially available gentamicin-containing composite calcium sulfate/hydroxyapatite biomaterial (GBM) could serve as a carrier for local delivery of bone morphogenic protein-2 (BMP-2) and zoledronic acid (ZA) in a tibia defect model in rats. Empty and allograft-filled defects were used as controls. A 3 × 4-mm metaphyseal bone defect was created in the proximal tibia, and the rats were grouped according to defect filling: (1) Empty, (2) Allograft, (3) GBM, (4) GBM + ZA, and (5) GBM + ZA + BMP-2. In vivo microcomputed tomography (micro-CT) images at 4 weeks showed significantly higher mineralized tissue volume (MV) in the intramedullary defect region and the neocortical/callus region in all GBM-Treated groups. After euthanization at 8 weeks, ex vivo micro-CT showed that addition of ZA (GBM + ZA) and BMP-2 (GBM + ZA + BMP-2) mainly increased the neocortical and callus formation, with the highest MV in the combined ZA and BMP-2-Treated group. Qualitative histological analysis, verifying the increased neocortical/callus thickness and finding of trabecular bone in all GBM-Treated groups, supported that the differences in MV measured with micro-CT in fact represented bone tissue. In conclusion, GBM can serve as a carrier for ZA and BMP-2 leading to increased MV in the neocortex and callus of a metaphyseal bone defect in rats.
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| 30. |
- Huang, Jintian, et al.
(författare)
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A calcium sulphate/hydroxyapatite ceramic biomaterial carrier for local delivery of tobramycin in bone infections : Analysis of rheology, drug release and antimicrobial efficacy
- 2023
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Ingår i: Ceramics International. - 0272-8842. ; 49:21, s. 33725-33734
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Tidskriftsartikel (refereegranskat)abstract
- Local targeted treatment of bone and joint infections using antibiotic-containing carriers is a common practice today. A recently FDA approved biphasic calcium sulphate/hydroxyapatite (CaS/HA) carrier containing gentamicin has been reported to give a sustained drug release, highly effective in eradicating bone infections. We present the first study evaluating the widely used aminoglycoside tobramycin (TOB) incorporated in the CaS/HA material with or without gentamycin (GEN) or vancomycin (VAN) with focus on rheology, drug release and antibacterial efficacy. In-vitro antibiotic release kinetics and biomaterial degradation were established by immersing the composites in phosphate buffered saline. The anti-bacterial effect of antibiotic containing CaS/HA composites as well as antibiotics release fractions were evaluated by Kirby-Bauer disk diffusion against S. aureus. The CaS/HA + GEN + TOB combination delayed setting to over 30 min whereas TOB + VAN slightly prolonged setting time (25 min vs. 15 min) still with good injectability. TOB was released from CaS/HA continuously for 35 days and during this period, the antibiotic loaded biomaterial could show a continuous anti-bacterial efficacy even at the last time point of day-35. After day-35, the pellets used for antibiotic release were taken out from release medium and broken into a paste. CaS/HA + TOB paste showed the largest ZOI (25 mm) against S. aureus ATCC 25923, while CaS/HA + VAN paste had no ZOI and CaS/HA + VAN + TOB paste had a ZOI of 18 mm. At the same time, the ZOI of CaS/HA + TOB against S. aureus P-3 was 14 mm compared to 0 mm in the other two groups. Adding TOB to CaS/HA containing VAN, extended the antimicrobial effect with a longer time and larger zone of inhibition, while no synergistic effect of the co-delivery was observed. Our in-vitro results indicate that CaS/HA could be used as a carrier for TOB as a local targeted delivery system in the treatment of bone infections.
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| 31. |
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| 32. |
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| 33. |
- Johnell, Olof, et al.
(författare)
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Rörelseorganens sjukdomar
- 2005
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Ingår i: En människa i rörelse : forskning om skelett, leder och muskulatur i Region Skåne och Södra sjukvårdsregionen. - 1653-9265. ; 3, s. 10-12
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 34. |
- Kesteris, Uldis, et al.
(författare)
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Contamination of polyethylene cups with polymethyl methacrylate particles: an experimental study
- 2001
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Ingår i: Journal of Arthroplasty. - : Elsevier BV. - 0883-5403. ; 16:7, s. 905-908
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Tidskriftsartikel (refereegranskat)abstract
- The articulating surfaces of 6 ultra-high molecular weight polyethylene cups were exposed to curing polymethyl methacrylate (PMMA) bone-cement and examined with scanning electron microscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Three of the cups were exposed to blood and bone-cement, and the rest were exposed to bone-cement only. After removal of the bone-cement bulk, PMMA particles were found and identified in all 6 cups. The particles were verified by identifying zirconium with energy-dispersive x-ray fluorescence spectroscopy in 5 cups and with LA-ICPMS in 1 cup. The degree of surface contamination was estimated with LA-ICPMS. The number of zirconium-containing particles detected was on average 10 to 20/mm2. PMMA bone-cement left in polyethylene cups during polymerization can contaminate the articulating surface with adherent PMMA particles.
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| 35. |
- Kjellson, Fred, et al.
(författare)
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Bone cement X-ray contrast media: A clinically relevant method of measuring their efficacy.
- 2004
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied Biomaterials. - : Wiley. - 1552-4981 .- 1552-4973. ; 70B:2, s. 354-361
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Tidskriftsartikel (refereegranskat)abstract
- It is important to compare different contrast media used in bone cement according to their ability to attenuate X-rays and thereby produce image contrast between bone cement and its surroundings in clinical applications. The radiopacity of bone cement is often evaluated by making radiographs of cement in air at an X-ray tube voltage of 40 kV. We have developed a method for ranking contrast media in bone cement simulating the clinical situation, by (1) choosing the same X-ray tube voltage as used in clinical work, and (2) using a water phantom to imitate the effects of the patients' soft tissue on the X-ray photons. In clinical work it is desirable to have low radiation dose, but high image contrast. The voltage chosen is a compromise, because both dose and image contrast decrease with higher voltage. Three contrast media (ZrO2, BaSO4, and Iodixanol) have been compared for degree of "image contrast." Comparing 10 wt % contrast media samples at an X-ray tube voltage of 40 kV, ZrO2 produced higher image contrast than the other media. However, at 80 kV, using a water phantom, the results were reversed, ZrO2 produced lower image contrast than both BaSO4 and Iodixanol. We conclude that evaluations of contrast media should be made with voltages and phantoms imitating the clinical application. (C) 2004 Wiley Periodicals, Inc.
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| 36. |
- Kjellson, Fred, et al.
(författare)
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Effect of iodixanol particle size on the mechanical properties of a PMMA based bone cement.
- 2007
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Ingår i: Journal of Materials Science: Materials in Medicine. - : Springer Science and Business Media LLC. - 1573-4838 .- 0957-4530. ; 18, s. 1043-1051
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Tidskriftsartikel (refereegranskat)abstract
- Iodixanol (IDX) is a water soluble opacifier widely used in radiographical examinations of blood vessels and neural tissue, and it has been suggested as a potential contrast media in acrylic bone cement. The effect of the iodixanol particle size on the polymerisation process of the bone cement, the molecular weight, and the quasi-static mechanical properties have been investigated in this article. The investigation was performed using radiolucent Palacos powder mixed with 8 wt% of iodixanol with particle sizes ranging from 3 to 20 mu m MMD, compared with commercial Palacos R (15 wt% ZrO2) as control. Tensile, compressive and flexural tests showed that smaller particles (groups with 3, 4, and 5 mu m particles) resulted in significantly lower mechanical properties than the larger particles (groups with 15, 16, and 20 mu m particles). There was no difference in molecular weight between the groups. The thermographical investigation showed that the IDX cements exhibit substantially lower maximum temperatures than Palacos R, with the 4 mu m IDX group having the lowest maximum temperature. The isothermal and the constant rate differential scanning calorimetry (DSC) did not show any difference in polymerisation heat (Delta H) or glass transition temperature (T-g) between radiolucent cement, or cement containing either IDX, or ZrO2. The findings show that the particle size for a bone cement containing iodixanol should be above 8 mu m MMD.
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| 37. |
- Kjellson, Fred, et al.
(författare)
-
Tensile properties of a bone cement containing non-ionic contrast media
- 2001
-
Ingår i: Journal of Materials Science: Materials in Medicine. - 1573-4838. ; 12:10-12, s. 889-894
-
Tidskriftsartikel (refereegranskat)abstract
- The addition of contrast media such as BaSO4 or ZrO2 to bone cement has adverse effects in joint replacements, including third body wear and particle-induced bone resorption. Ground PMMA containing particles of the non-ionic water-soluble iodine-based X-ray contrast media, iohexol (IHX) and iodixanol (IDX), has, in bone tissue culture, shown less bone resorption than commercial cements. These water-soluble non-ceramic contrast media may change the mechanical properties of acrylic bone cement. The static mechanical properties of bone cement containing either IHX or IDX have been investigated. There was no significant difference in ultimate stress between Palacos R (with 15.0 wt % of ZrO2) and plain cement with 8.0 wt % of IHX or IDX with mass median diameter (MMD) of 15.0 or 16.0 microm, while strain to failure was higher for the latter (p < 0.02). The larger particles (15.0 or 16.0 microm) gave significantly higher (p < 0.001) ultimate tensile strengths and strains to failure than smaller sizes (2.4 or 3.6 microm). Decreasing the amount of IHX from 10.0 wt % to 6.0 wt % gave a higher ultimate tensile strength (p < 0.001) and strain to failure (p < 0.02). Scanning electron microscopy (SEM) showed the smaller contrast media particles attached to the surface of the polymer beads, which may prevent areas of the acrylate bead surface from participating in the polymerization. In conclusion, the mechanical properties of bone cement were influenced by the size and amount of contrast medium particles. By choosing the appropriate amount and size of particles of water-soluble non-ionic contrast media the mechanical properties of the new radio-opaque bone cement can be optimized, thus reaching and surpassing given regulatory standards.
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| 38. |
- Kjellson, Fred, et al.
(författare)
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Water uptake and release from iodine-containing bone cement.
- 2004
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Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1552-4965 .- 0021-9304 .- 1097-4636. ; 71:2, s. 292-298
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Tidskriftsartikel (refereegranskat)abstract
- Water uptake and release characteristics of PMMA cement containing the water-soluble contrast media iohexol or iodixanol have been investigated. The water uptake study revealed that iohexol had the highest uptake of water (3.7%) and that iodixanol had an uptake close to that of Palacos(R) R (2.3% and 1.9%). The curves obtained showed the materials to follow classic diffusion theory, with an initial linearity with respect to t(1/2) making it possible to calculate the diffusion coefficients. This showed iohexol to have the lowest diffusion coefficient, Palacos(R) R the highest, and iodixanol close to that of Palacos(R) R. The release study showed that more iohexol than iodixanol was released from the bone cement; the long-term release was above 25 mug/ml, for iohexol compared to slightly above 10 mug/mL for iodixanol. A muCT investigation showed that the risk of developing an observable radiolucent zone is negligible. (C) 2004 Wiley Periodicals, Inc.
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| 39. |
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| 40. |
- Knutson, Kaj, et al.
(författare)
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The Swedish knee arthroplasty register. A nation-wide study of 30,003 knees 1976-1992
- 1994
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470 .- 1745-3674. ; 65:4, s. 375-386
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Tidskriftsartikel (refereegranskat)abstract
- 1976 through 1992, 30,003 primary knee arthroplasties and their revisions have been recorded in a nation-wide Swedish study. We report on the structure of the register, demographic data and survivorship. We found that operations for osteoarthrosis (OA) counted for the increase in number of arthroplasties in contrast to rheumatoid arthritis (RA), where the number had slightly declined. For primary operations, the total knee prostheses have practically eliminated other types in RA and are steadily gaining popularity in OA at the expense of the unicompartmental prostheses. Total knee replacements showed gradually improving survival even in unchanged designs while the unicompartmental prostheses don't, partly because of newly introduced inferior designs. We also found that failed unicompartmental prostheses were best replaced with a tricompartmental prosthesis and that a total revision was to be preferred when a tricompartmental tibial component failed. The risk of the most devastating complications, e.g., infection, leading to extraction of the prosthesis or arthrodesis has decreased considerably also in the last years.
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| 41. |
- Kok, Joeri, et al.
(författare)
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Augmenting a dynamic hip screw with a calcium sulfate/hydroxyapatite biomaterial
- 2021
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Ingår i: Medical Engineering and Physics. - : Elsevier BV. - 1350-4533. ; 92, s. 102-109
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Tidskriftsartikel (refereegranskat)abstract
- Internal fixation failure in hip fractures can lead to reoperation. Calcium sulfate/hydroxyapatite (CaS/HA) is a biomaterial that can be used for augmenting fracture fixation. We aimed to determine whether an injection of 2 ml CaS/HA increases the fixation of a dynamic hip screw inserted in synthetic and human trabecular bone. The study consists of two parts: 1) synthetic bone blocks (n = 74), with three subgroups: empty (cannulated screw, no injection), cannulated, and fenestrated; and 2) osteoporotic human femoral heads (n = 29), with the same subgroups. The heads were imaged using µCT. Bone volume fraction, insertion angle, and head diameter were measured. Pullout tests were performed and peak force, stiffness, and work were measured. The fenestrated group showed increases in pullout strength compared to no injection in the synthetic blocks. The cannulated group showed a higher pullout strength in low-density blocks. In the femoral heads, the variation was larger and there were no significant differences between groups. The bone volume fraction correlated with the peak force and work, and the insertion angle correlated with the stiffness. CaS/HA can improve the fixation of a dynamic hip screw. For clinical use, spreading of the material around the threads of the screw must be ensured.
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| 42. |
- Kok, Joeri, et al.
(författare)
-
Fracture behavior of a composite of bone and calcium sulfate/hydroxyapatite
- 2022
-
Ingår i: Journal of the Mechanical Behavior of Biomedical Materials. - : Elsevier BV. - 1751-6161. ; 130
-
Tidskriftsartikel (refereegranskat)abstract
- Calcium sulfate/hydroxyapatite (CaS/HA) biomaterials have been investigated for use in several orthopedic applications. However, the mechanical interactions between the composite of CaS/HA and bone at the microscale are still unknown. The aim of this study was to determine if and how augmentation with CaS/HA alters the fracture behavior of bone. Eleven cylinders of trabecular bone were drilled from human femoral heads and cleaned from bone marrow. Among them, five cylinders were injected with CaS/HA to generate composite specimens, while the others were kept intact. One extra specimen of pure CaS/HA was prepared. All specimens were compressed in situ using synchrotron X-ray tomography and imaged at ∼2% strain intervals. Structural properties were calculated from the images in unloaded state and mechanical properties were determined from the load-curves. CaS/HA alone displayed the highest peak force and stiffness and the lowest strain at fracture. All composite specimens had a higher peak force than the pure bone specimens and the composite specimens had higher toughness than the pure CaS/HA specimen. Furthermore, the fracture behavior was analyzed further to characterize the local deformations. The pure bone specimens presented damage in multiple trabeculae and the CaS/HA specimen displayed sharp transition in strains, with low strain in one load step and large cracks in the next. The composite specimens deformed uniformly, with the CaS/HA preventing tissue damage and the bone preventing cracks in the CaS/HA from propagating through the specimen. In conclusion, using tomography with in situ loading, it was possible to show how CaS/HA can help prevent bone tissue damage before global failure.
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| 43. |
- Kok, Joeri, et al.
(författare)
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Fracture strength of the proximal femur injected with a calcium sulfate/hydroxyapatite bone substitute
- 2019
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Ingår i: Clinical Biomechanics. - : Elsevier BV. - 0268-0033. ; 63, s. 172-178
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Tidskriftsartikel (refereegranskat)abstract
- Background: Available interventions for preventing fragility hip fractures show limited efficacy. Injection of a biomaterial as bone substitute could increase the fracture strength of the hip. This study aimed to show the feasibility of injecting a calcium sulfate/hydroxyapatite based biomaterial in the femoral neck and to calculate the consequent change in strength using the finite element method. Methods: Five patients were injected with 10 ml calcium sulfate/hydroxyapatite in their femoral neck. Quantitative CT scans were taken before and after injection. Five additional patients with fragility hip fractures were also scanned and the images from the non-fractured contralateral sides were used. Finite element models were created for all proximal femora with and without injection and the models were tested under stance and sideways fall loading until fracture. The change in fracture strength caused by the injection was calculated. Additionally, perturbations in volume, location, and stiffness of the injected material were created to investigate their contribution to the fracture strength increase. Findings: The 10 ml injection succeeded in all patients. Baseline simulations showed theoretical fracture strength increases of 0–9%. Volume increase, change in location and increase in stiffness of the material led to increases in fracture strength of 1–27%, −8-26% and 0–17%, respectively. Altering the location of the injection to a more lateral position and increasing the stiffness of the material led to increases in fracture strength of up to 42%. Interpretation: This study shows that an injection of calcium sulfate/hydroxyapatite is feasible and can theoretically increase the hip's fracture strength.
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| 44. |
- Lazarinis, Stergios, et al.
(författare)
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Consensus document on prosthetic joint infections
- 2013
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Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 84:6, s. 507-508
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 45. |
- Lewold, Stefan, et al.
(författare)
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Oxford meniscal bearing knee versus the Marmor knee in unicompartmental arthroplasty for arthrosis. A Swedish multicenter survival study
- 1995
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Ingår i: Journal of Arthroplasty. - 0883-5403. ; 10:6, s. 722-731
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Tidskriftsartikel (refereegranskat)abstract
- In the Swedish Knee Arthroplasty Study, all 699 Oxford meniscal bearing cemented unicompartmental prostheses (Biomet, Bridgend, UK) were identified and analyzed regarding failure pattern and compared with all Marmor prostheses (Smith & Nephew Richards, Orthez, France) and with a time-, age-, and sex-matched subset of Marmor prostheses using survival statistics expressed as cumulative revision rates. After 1 year there was already a higher rate, and after 6 years the rate of the Oxford group was more than twice that of the Marmor group. There were 50 revisions in the Oxford group: dislocating meniscus in 16, loosening of the femoral component in 6, tibial component in 4, both components in 4, contralateral arthrosis in 10, infection in 4, and technical failure with instability, pain, and/or impingement of the meniscal bearing anterior in the femoral condyle in 6. It is still unclear if the design with the sliding menisci will, in the long turn, reduce wear and loosening, thereby compensating for the initially inferior results. It is recommended that until this question is clarified, the Oxford knee should be used on a limited scale for long-term comparative studies only.
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| 46. |
- Lewold, Stefan, et al.
(författare)
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Revision of unicompartmental knee arthroplasty: outcome in 1,135 cases from the Swedish Knee Arthroplasty study
- 1998
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 69:5, s. 469-474
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Tidskriftsartikel (refereegranskat)abstract
- From 1975 through 1995, 45,025 knee arthroplasties were recorded in the prospective Swedish Knee Arthroplasty study. By the end of 1995, 1,135 of 14,772 primary unicompartmental knee arthroplasties (UKA) for localized, mainly medial arthrosis had been revised. The Marmor/Richards and St. Georg sledge/Endo-Link prostheses were used in 65%. Mean age at revision was 72 (71) years. 232 revisions were performed as an exchange UKA (partial in 97) and 750 as a total knee arthroplasty (TKA). 153 were revised by other modes. In medial UKA, the indication for revision was component loosening in 45% and joint degeneration in 25% and in lateral UKA, the corresponding figures were 31% and 35%, respectively. In 94 cases, unicompartmental components were added to the initially untreated compartment, in 14 with partial exchange of a component. The CRRR was estimated using survival statistics. After only 5 years, the risk of having a second revision was more than three times higher for failed UKAs revised to a new UKA (cumulative rerevision rate (CRRR 26%) than for those revised to a TKA (CRRR 7%). This difference remained, even if those revised before 1985, when modern operating technique was introduced, were excluded (CRRR 31% and 5%, respectively). UKA is a safe primary procedure, when performed with well-designed components and modern surgical technique. It gives documented good patient satisfaction, range of motion, pain relief and relatively few serious complications. However, once failed, the knee should be revised to a TKA. This applies to most modes of failure. Not even joint degeneration of the unoperated compartment can be safely treated by adding contralateral components; CRRR after this procedure was 17%, while it was 7% when converted to a TKA.
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| 47. |
- Lidgren, Lars, et al.
(författare)
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Acrylic bone cements: clinical developments and current status: Scandinavia.
- 2005
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Ingår i: Orthopedic Clinics of North America. - : Elsevier BV. - 0030-5898. ; 36:1, s. 55-55
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Tidskriftsartikel (refereegranskat)abstract
- This article focuses on bone cement, the cementing technique used, and their influence on aseptic loosening and infection of acrylic and joint implants in Scandinavia.
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| 48. |
- Lidgren, Lars
(författare)
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Bone and Joint Decade update
- 2001
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Ingår i: European Orthopaedics. Bulletin of EFORT. - 1356-2509. ; :14, s. 8-8
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Tidskriftsartikel (refereegranskat)
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| 49. |
- Lidgren, Lars
(författare)
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Bone Substitutes
- 2002
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Ingår i: Karger Gazette. - 0451-4475. ; :65
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Tidskriftsartikel (refereegranskat)
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| 50. |
- Lidgren, Lars
(författare)
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Chronic inflammation, joint replacement and malignant lymphoma.
- 2008
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Ingår i: Journal of Bone and Joint Surgery: British Volume. - 2044-5377. ; 90:1, s. 7-10
-
Tidskriftsartikel (refereegranskat)abstract
- This paper considers the increased risk of the development of lymphoma in patients with chronic inflammatory disease who undergo metal-on-metal arthroplasty.
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