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- Nyberg, Jan, 1960-, et al.
(författare)
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Single-dose irradiation followed by implant insertion in rat bone : An investigative study to find a critical level for osseointegration
- 2010
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Ingår i: Journal of Osseointegration. - Carimate, Italy : Ariesdue. - 2036-4121. ; 2:2, s. 52-60
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Tidskriftsartikel (refereegranskat)abstract
- Aim: No general consensus exists regarding the ideal time to insert implants in bone after irradiation or how the various irradiation doses influence implant success. This study aims at investigating integration of implants in pre-irradiated rat bone and find a critical level doses that cause disturbed osseointegration.Materials and methods: Single irradiation doses of 2, 5, 10, 20 and 30 Gy were given to one leg of adult rats 3 days prior to insertion of screw-shaped implants whereas the other leg served as a non-irradiated control. The follow up was 5 weeks. Bone implant contact (BIC) and bone area (BA) were measured on undecalcified cut and ground sections in the light microscope. The tissue quality was also examined in the light microscope.Results: Doses of 5 and 10 Gy resulted in 25% higher contact values for the irradiated samples compared to non-irradiated controls. The most impaired integration occurred when doses of 20 Gy were given, revealing a 50% difference between the irradiated (25%) and the non irradiated samples (50%). The bone area demonstrated no major quantitative differences albeit the qualitative observations differed substantially being most pronounced in the 20 and 30 Gy irradiated samples.Conclusions: The osseointegration was substantially impaired after radiation doses of 20 and 30 Gy. Quantitative data alone are insufficient to describe implant integration in situation like this. Qualitative observations are of utmost importance and require great attention. The importance of judging and describing various grades of tissue damage is complicated but necessary. Based on the results obtained in this study, full scale experiments are now ongoing.
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- Nyberg, Lars, et al.
(författare)
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Falls leading to femoral neck fractures in lucid older people
- 1996
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Ingår i: Journal of The American Geriatrics Society. - : Wiley. - 0002-8614 .- 1532-5415. ; 44:2, s. 156-160
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To analyze the mechanisms of falls that result in femoral neck fractures among lucid older people. DESIGN: A cross-sectional study. SETTING: An orthopedic university hospital department. PARTICIPANTS: A consecutive series of 123 lucid patients, 65 years of age or more, who were admitted for femoral neck fractures. MEASUREMENTS: On admission, the subjects were interviewed about fracture accident characteristics, and falling mechanisms were classified. An arterial blood gas sample was taken from each patient soon after admission. Based on data regarding drug consumption and social and medical characteristics, a fall-risk index was calculated for each subject. RESULTS: It was ascertained that 95% of the fractures were caused by falls and < 2% were spontaneous. Most accidents (68%) took place indoors, 47% of the falls were classified as extrinsic, 24% as intrinsic, 7% as nonbipedal, and 22% remained unclassified. Almost all outdoor falls were extrinsic; however, intrinsic falls were as common as extrinsic falls indoors (P < .001). Extrinsic fallers presented a significantly lower fall-risk index score than subjects with fractures caused by intrinsic, nonbipedal, and unclassifiable falls. A large proportion of subjects (24%) wre hypoxemic (pO2 < 8 kPa) on admission, and patients who sustained fractures at night had lower oxygen tension than that of daytime fallers (P = .006). CONCLUSIONS: Accidental falls are the primary cause of femoral neck fractures. Preventive actions should be directed toward intrinsic, as well as extrinsic, risk factors for falls. Hypoxemia might be a risk factor for falls, especially those falls that occur at night.
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- Nyberg, Lars, et al.
(författare)
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The development of a virtual reality system to study tendency of falling among older people
- 2005
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Ingår i: International Journal on Disability and Human Development. - 1565-012X. ; 4:3, s. 239-243
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Tidskriftsartikel (refereegranskat)abstract
- Injuries related to falls are a major threat to the health of older persons. A fall may result not only in an injury but also in a decreased sense of autonomy in the daily life. To be able to prevent such falls, a need to further understand the complex mechanisms involved in balance and walking is needed. Here we present an immersive virtual reality system, in which a person can move around while being subjected to various events, which may influence balance and walking
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- Sondell, Björn, et al.
(författare)
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Altered walking pattern in a virtual environment
- 2005
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Ingår i: Presence - Teleoperators and Virtual Environments. - Cambridge : MIT Press. - 1054-7460 .- 1531-3263. ; 14:2, s. 191-197
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Tidskriftsartikel (refereegranskat)abstract
- Falls and fractures among elderly persons constitute a major health problem. Many falls occur while walking and falls that occur during turning often result in a fracture. Methods aimed at understanding the complex mechanisms involved in walking should therefore assess tested individuals during walks and turns. In order to identify persons at risk and take the correct preventive measures, it is important to find methods that quantify movements as the tested persons are processing multisensory input. In a clinical setting this is sometimes difficult to achieve in a controlled manner, since tests are difficult to set exactly the same from one time to another. Using a virtual environment (VE) and a tracker system, conditions such as light, sound, events, body movements, and room size can be controlled and measured. Tests in VE can therefore be identically reproduced over and over again to evaluate if a person can withstand changing outer demands at any given moment. In order to perform quantitative measures 8 persons (21-74 years) were tested in immersive virtual reality. The VE was a corridor in which expected and unexpected events could be produced. Events studied were doors swinging open in front of the subjects during a walk and a virtual tilting of the environment. Trackers were used for collecting and analyzing the movement data. Our results show that the system was well tolerated among the subjects and that there was a clear tendency that the system could generate fall tendency among the subjects. There was also a difference among the subjects regarding walking strategies when subjected to the various events.
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