| 1. |
- Brånemark, Rickard, 1960, et al.
(author)
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Biomechanical characterization of osseointegration: an experimental in vivo investigation in the beagle dog.
- 1998
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In: Journal of orthopaedic research : official publication of the Orthopaedic Research Society. - : Wiley. - 0736-0266. ; 16:1, s. 61-9
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Journal article (peer-reviewed)abstract
- This study reports the results of torsion tests, pull-out tests, and lateral loading tests on osseointegrated commercially pure titanium fixtures. The tests were performed in vivo on six beagle dogs. Three fixtures, each with a diameter of 3.7 mm, were installed bilaterally in the tibia of each animal. The mean maximal pull-out load was 1.55 kN (n = 4), the mean maximal lateral transverse load was 0.21 kN (n = 2), the mean maximal lateral axial load was 0.18 kN (n = 2), the mean breakpoint torque was 0.31 Nm (n = 3), and the mean maximal torque was 0.43 Nm (n = 3). The torsion test revealed an almost immediate plastic deformation of the interface between the implant and bone; this indicates that although the contact between the bone and the implant is close, there is no strong bond, at least not in shear. The major transfer of load from the implant to the surrounding bone tissue must therefore depend on the design of the implant. A histological evaluation with measurements of the amount of bone in contact with the fixtures was performed. By the use of the histological and mechanical data, it is possible to estimate shear stresses in bone tissue (pull-out test) and in the interface (torque test). The mean maximal shear stress in bone tissue in the pull-out tests was 100 MPa (n = 4); the mean shear stress in the interface was 4.3 MPa (n = 3) in the torsion tests at the breakpoint torque and was 6.0 MPa (n = 3) at the maximal torque. It was also possible to estimate the shear modulus of elasticity in the pull-out and torque tests. The mean shear modulus in pull-out was 119 MPa (n = 4), and the mean apparent shear modulus in torsion was 9 kPa (n = 3) for an assumed interface thickness of 100 nm and was 86 kPa (n = 3) for an assumed interface thickness of 1,000 nm.
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| 2. |
- Brånemark, Rickard, 1960, et al.
(author)
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Osseointegration and rigid fixation.
- 1992
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In: Rigid fixation of the craniomaxillofacoas skeleton. eds Yaremchuk MJ, Gruss JS, Manson PN.. - : Butterworts-Heinemann Publ. ; , s. 275-279
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Book chapter (other academic/artistic)
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| 3. |
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| 4. |
- Jacobs, R, et al.
(author)
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Evaluation of the psychophysical detection threshold level for vibrotactile and pressure stimulation of prosthetic limbs using bone anchorage or soft tissue support.
- 2000
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In: Prosthetics and orthotics international. - 0309-3646. ; 24:2, s. 133-42
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Journal article (peer-reviewed)abstract
- In the present study the psychophysical detection threshold levels mechanical stimulation of 32 prosthetic limbs were determined. Prosthetic limbs were anchored to the bone by means of an implant (n=17) or supported by a socket enclosing the amputation stump (n=15). Detection threshold levels were assessed for pressure and vibratory stimulation of the prosthesis and the limb at the contralateral side (control). Following vibratory stimulation, thresholds were increased on an average 20% for socket prostheses. but approached those of the control for bone-anchored prostheses. For pressure stimulation, thresholds were increased up to 60% for socket prostheses and 40% for bone-anchored prostheses compared to the control. While bone-anchored prostheses yielded significantly lower threshold levels than socket prostheses, there was no significant difference between both treatments regarding pressure stimulation. Results were applicable to both upper and lower limb amputees. It could be concluded that detection thresholds for pressure and especially vibratory stimulation of prosthetic limbs were generally higher than for control limbs. The outcome was related to the prosthetic limb design with bone-anchored prostheses yielding better perception than socket prostheses.
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| 5. |
- Olsson, Rickard, 1959-, et al.
(author)
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Production of osseointegrating (bone bonding) surfaces on titanium screws by laser melt disruption
- 2018
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In: Journal of Laser Applications. - Melville, NY : Laser Institute of America. - 1042-346X .- 1938-1387. ; 30:4
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Journal article (peer-reviewed)abstract
- Several techniques can be used to modify implant surfaces in order to accelerate bone growth around titanium implants. One method is to generate a surface structure which stimulates bone growth and remodeling. This paper describes and explains a nonablative method for producing osseointegrating (structural and functional bone bonding) surfaces on titanium implants using laser processing. The focus is especially on surface texturing of dental implant screws, where the ability of a Nd:YAG laser to generate "splashy" surfaces covered in resolidified microscale droplets coated with nanoscale surface oxides is assessed. The surfaces produced were analyzed by a scanning electron microscope and energy dispersive x-ray spectroscopy. It is concluded that laser processing using Q-pulsed Nd:YAG lasers can generate surfaces which match the demands set by clinical experience. One important characteristic of the surfaces discussed here is that they involve overhanging features which are suitable for trapping red blood cells and which cannot be created by mechanical or chemical roughening techniques. © 2018 Laser Institute of America.
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| 6. |
- Benca, E., et al.
(author)
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Patient-Specific Guides for Accurate and Precise Positioning of Osseointegrated Implants in Transfemoral Amputations: A Proof-of-Concept In Vitro Study
- 2023
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In: Medicina-Lithuania. - : MDPI AG. - 1010-660X. ; 59:3
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Journal article (peer-reviewed)abstract
- Background and Objectives: The treatment of transfemoral amputees using osseointegrated implants for prosthetic anchorage requires accurate implant positioning when using threaded bone-anchoring implants due to the curvature of the femur and the risk of cortical penetration in misaligned implants. This study investigated the accuracy and precision in implant positioning using additively manufactured case-specific positioning guides. Materials and Methods: The geometry and density distribution of twenty anatomic specimens of human femora were assessed in quantitative computed tomography (QCT) scanning. The imaging series were used to create digital 3D specimen models, preoperatively plan the optimal implant position and manufacture specimen-specific positioning guides. Following the surgical bone preparation and insertion of the fixture (threaded bone-anchoring element) (OPRA; Integrum AB, Molndal, Sweden), a second QCT imaging series and 3D model design were conducted to assess the operatively achieved implant position. The 3D models were registered and the deviations of the intraoperatively achieved implant position from the preoperatively planned implant position were analyzed as follows. The achieved, compared to the planned implant position, was presented as resulting mean hip abduction or adduction (A/A) and extension or flexion (E/F) and mean implant axis offset in medial or lateral (M/L) and anterior or posterior (A/P) direction measured at the most distal implant axis point. Results: The achieved implant position deviated from the preoperative plan by 0.33 +/- 0.33 degrees (A/A) and 0.68 +/- 0.66 degrees (E/F) and 0.62 +/- 0.55 mm (M/L) and 0.68 +/- 0.56 mm (A/P), respectively. Conclusions: Using case-specific guides, it was feasible to achieve not only accurate but also precise positioning of the implants compared to the preoperative plan. Thus, their design and application in the clinical routine should be considered, especially in absence of viable alternatives.
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| 7. |
- Benca, E., et al.
(author)
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Thermal Effects during Bone Preparation and Insertion of Osseointegrated Transfemoral Implants
- 2021
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In: Sensors. - : MDPI AG. - 1424-8220. ; 21:18
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Journal article (peer-reviewed)abstract
- Background: The preparation of bone for the insertion of an osseointegrated transfemoral implant and the insertion process are performed at very low speeds in order to avoid thermal damages to bone tissue which may potentially jeopardize implant stability. The aim of this study was to quantify the temperature increase in the femur at different sites and insertion depths, relative to the final implant position during the stepwise implantation procedure. Methods: The procedure for installation of the osseointegrated implant was performed on 24 femoral specimens. In one specimen of each pair, the surgery was performed at the clinically practiced speed, while the speed was doubled in the contralateral specimen. Six 0.075 mm K fine gauge thermocouples (RS Components, Sorby, UK) were inserted into the specimen at a distance of 0.5 mm from the final implant surface, and six were inserted at a distance of 1.0 mm. Results: Drilling caused a temperature increase of <2.5 degrees C and was not statistically significantly different for most drill sizes (0.002 < p < 0.845). The mean increase in temperature during thread tapping and implant insertion was <5.0 degrees C, whereas the speed had an effect on the temperature increase during thread tapping. Conclusions: Drilling is the most time-consuming part of the surgery. Doubling the clinically practiced speed did not generate more heat during this step, suggesting the speed and thus the time- and cost-effectiveness of the procedure could be increased. The frequent withdrawal of the instruments and removal of the bone chips is beneficial to prevent temperature peaks, especially during thread tapping.
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| 8. |
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Berlin, Örjan, 1948, et al.
(author)
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OPRA Study: Preliminary 5 years results.
- 2015
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In: 6th international conference advances in orthopaedic osseointegration, Las Vegas, NV, USA 26-27 march..
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Conference paper (other academic/artistic)
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| 13. |
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| 14. |
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| 15. |
- Boström, Pontus, 1982, et al.
(author)
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The SNARE protein SNAP23 and the SNARE-interacting protein Munc18c in human skeletal muscle are implicated in insulin resistance/type 2 diabetes.
- 2010
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In: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 59:8, s. 1870-8
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Our previous studies suggest that the SNARE protein synaptosomal-associated protein of 23 kDa (SNAP23) is involved in the link between increased lipid levels and insulin resistance in cardiomyocytes. The objective was to determine whether SNAP23 may also be involved in the known association between lipid accumulation in skeletal muscle and insulin resistance/type 2 diabetes in humans, as well as to identify a potential regulator of SNAP23. RESEARCH DESIGN AND METHODS: We analyzed skeletal muscle biopsies from patients with type 2 diabetes and healthy, insulin-sensitive control subjects for expression (mRNA and protein) and intracellular localization (subcellular fractionation and immunohistochemistry) of SNAP23, and for expression of proteins known to interact with SNARE proteins. Insulin resistance was determined by a euglycemic hyperinsulinemic clamp. Potential mechanisms for regulation of SNAP23 were also investigated in the skeletal muscle cell line L6. RESULTS: We showed increased SNAP23 levels in skeletal muscle from patients with type 2 diabetes compared with that from lean control subjects. Moreover, SNAP23 was redistributed from the plasma membrane to the microsomal/cytosolic compartment in the patients with the type 2 diabetes. Expression of the SNARE-interacting protein Munc18c was higher in skeletal muscle from patients with type 2 diabetes. Studies in L6 cells showed that Munc18c promoted the expression of SNAP23. CONCLUSIONS: We have translated our previous in vitro results into humans by showing that there is a change in the distribution of SNAP23 to the interior of the cell in skeletal muscle from patients with type 2 diabetes. We also showed that Munc18c is a potential regulator of SNAP23.
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| 16. |
- Brånemark, Rickard, 1960, et al.
(author)
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A novel osseointegrated percutaneous prosthetic system for the treatment of patients with transfemoral amputation: A prospective study of 51 patients.
- 2014
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In: The bone & joint journal. - 2049-4408. ; 96:1, s. 106-13
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Journal article (peer-reviewed)abstract
- Patients with transfemoral amputation (TFA) often experience problems related to the use of socket-suspended prostheses. The clinical development of osseointegrated percutaneous prostheses for patients with a TFA started in 1990, based on the long-term successful results of osseointegrated dental implants. Between1999 and 2007, 51 patients with 55 TFAs were consecutively enrolled in a prospective, single-centre non-randomised study and followed for two years. The indication for amputation was trauma in 33 patients (65%) and tumour in 12 (24%). A two-stage surgical procedure was used to introduce a percutaneous implant to which an external amputation prosthesis was attached. The assessment of outcome included the use of two self-report questionnaires, the Questionnaire for Persons with a Transfemoral Amputation (Q-TFA) and the Short-Form (SF)-36. The cumulative survival at two years' follow-up was 92%. The Q-TFA showed improved prosthetic use, mobility, global situation and fewer problems (all p < 0.001). The physical function SF-36 scores were also improved (p < 0.001). Superficial infection was the most frequent complication, occurring 41 times in 28 patients (rate of infection 54.9%). Most were treated effectively with oral antibiotics. The implant was removed in four patients because of loosening (three aseptic, one infection). Osseointegrated percutaneous implants constitute a novel form of treatment for patients with TFA. The high cumulative survival rate at two years (92%) combined with enhanced prosthetic use and mobility, fewer problems and improved quality of life, supports the 'revolutionary change' that patients with TFA have reported following treatment with osseointegrated percutaneous prostheses. Cite this article: Bone Joint J 2014;96-B:106-13.
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| 17. |
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| 18. |
- Brånemark, Rickard, 1960, et al.
(author)
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An in-vivo method for biomechanical characterization of bone-anchored implants.
- 1998
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In: Medical engineering & physics. - 1350-4533. ; 20:3, s. 216-9
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Journal article (peer-reviewed)abstract
- Experimental equipment for in-vivo registrations of pull-out load vs displacement, applied torque vs angle of rotation, and lateral load vs lateral displacement has been developed. The set-up is designed for testing three implants inserted in a row and osseointegrated in, for instance, the proximal tibia of the beagle dog. The details of the set-up are described and considerations of the stress distributions are reported.
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| 19. |
- Brånemark, Rickard, 1960, et al.
(author)
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Biomechanical and morphological studies on osseointegration in immunological arthritis in rabbits.
- 1997
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In: Scandinavian journal of plastic and reconstructive surgery and hand surgery / Nordisk plastikkirurgisk forening [and] Nordisk klubb for handkirurgi. - 0284-4311. ; 31:3, s. 185-95
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Journal article (peer-reviewed)abstract
- The biomechanics and morphology of the interface between bone tissue and threaded, commercially pure titanium implants were studied i an experimental model of monoarticular arthritis in New Zealand white rabbits (n = 8). Two of the eight rabbits died before evaluation. Immunisation with bovine serum albumin (BSA) and repeated intra-articular injections with BSA in one knee joint elicited an immune response and clinical signs of inflammation. The opposite joint was injected with saline. Three implants were inserted intra-articularly in the lateral femoral condyle in each joint. After a period of six weeks the stability of two of the three implants was evaluated by pull-out and torsion tests using a standardised biomechanical model. The rabbits were killed by perfusion fixation, and the implants and surrounding tissue were retrieved en bloc for histological analysis. The amount of bone, the degree of bone apposition, and the biomechanical evaluation showed that the absolute mechanical capacity of anchorage was not significantly reduced on the arthritic side compared with the control knees. These results indicate that it might be possible to obtain osseointegration in juxta-articular bone despite local joint inflammation.
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| 20. |
- Brånemark, Rickard, 1960, et al.
(author)
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Biomechanical characterization of osseointegration during healing: an experimental in vivo study in the rat.
- 1997
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In: Biomaterials. - 0142-9612. ; 18:14, s. 969-78
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Journal article (peer-reviewed)abstract
- This study reports torsion tests and pull-out tests on osseointegrated commercially pure titanium fixtures. The tests were performed in vivo on a total of 26 rats. Three fixtures with a diameter of 2.0 mm were installed bilaterally in the proximal tibia in each animal. The mechanical testing was performed immediately after installation, after 2, 4, 8 and 16 weeks of unloaded healing. The torsional strength started to increase after 4 weeks of unloaded healing and there was a significant increase with time during the initial 16 weeks. The pull-out load increased rapidly during the first 4 weeks; thereafter, a moderate increase occurred during the following 12 weeks. A histological evaluation was performed after 0, 4, 8 and 16 weeks. There were significant (P < 0.01) correlations between torque and percentage of bone in contact with the fixture, and between pull-out load and the bone thickness around the fixture (P < 0.001). Estimations of shear stresses and shear moduli in the bone tissue (pull-out test) and at the interface (torque test) indicated that the increase in bone volume around the implant substantially improved the mechanical capacity.
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| 21. |
- Brånemark, Rickard, 1960
(author)
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Biomechanics and Osseointegration.
- 1991
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In: Osseointegration in skeletal reconstruction and joint replacement. eds. Brånemark P-I, Rydevik B, Skalak R. Aruba: The Institute for Applied Biotechnology.. ; , s. 159-160
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Book chapter (peer-reviewed)
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| 22. |
- Brånemark, Rickard, 1960, et al.
(author)
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Bone response to laser-induced micro- and nano-size titanium surface features.
- 2011
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In: Nanomedicine : nanotechnology, biology, and medicine. - : Elsevier BV. - 1549-9642 .- 1549-9634.
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Journal article (peer-reviewed)abstract
- The present study explored whether laser-induced, site-specific implant surface modifications with micro- and nano-scale topography were able to promote bone formation. The aim was to evaluate the biomechanical and histological response to partly laser-modified titanium implants compared with machined implants. After an early 8-week healing period in rabbit tibia and femur, a 250% increase in removal torque was demonstrated for the partly laser-modified surface. Further, different fracture mechanisms were demonstrated for the two surfaces. Histologically, significantly more bone was found in direct contact with the laser-modified surface for the implants in the tibia sites, while a similar amount of bone tissue was observed in contact with the implant in the femoral sites. In conclusion, an improved bone-implant interface anchorage was promoted by an increase in micro- and nano-scale implant surface topography and surface oxide induced by topological laser treatment.
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| 23. |
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| 24. |
- Brånemark, Rickard, 1960
(author)
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Direct skeletal fixation of limbs.
- 2015
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In: Prosthetic rehabilitation following war injury. London, UK 25 September 2015..
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Conference paper (other academic/artistic)
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| 25. |
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