| 41. |
- Ahlqvist, Jan, et al.
(författare)
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Bone demarcation of the temporomandibular joint. Validity of clinical assessment of bone thickness by means of CT.
- 1998
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Ingår i: Acta Radiologica. - 0284-1851 .- 1600-0455. ; 39:6, s. 649-55
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To study the CT depiction of bone demarcations in the temporomandibular joint, using conventional window level and window width; and to evaluate observer performance in estimating bone thickness in these images.MATERIAL AND METHODS: Seven joint specimens were imaged by CT and then cryosectioned. The measurements of bone wall thickness in the images were compared to the true bone thickness at each cutting level. In addition, 4 experienced radiologists estimated the thickness of the bone walls in the images.RESULTS: The relative difference between the CT reproduction and the true bone thickness was small for bone walls thicker than 2 mm. This difference increased with the decrease in bone thickness and the increase in the inclination of the bone wall from the perpendicular to the image plane. Bone walls thinner than 1 mm were reproduced as considerably thicker than their true thickness. This resulted in a clinical overestimation of bone thickness.CONCLUSION: Both the CT representation and the interpretation of bone demarcation in the temporomandibular joint may constitute a problem. Partial volume averaging effects can result in an overestimation of bone dimensions amounting to 200% for thin bones. The central white zone in images of thin bone walls obtained with the parameters described here could serve as an indicator that could help to reduce the risk of overestimating bone thickness.
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| 42. |
- Ahlqvist, Jan, et al.
(författare)
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Sources of radiographic distortion in conventional and computed tomography of the temporal bone.
- 1998
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Ingår i: Dento-Maxillo-Facial Radiology. - 0250-832X .- 1476-542X. ; 27:6, s. 351-7
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To identify those bony regions of the glenoid fossa where, due to the inclination, there is an increased risk of radiographic distortion in conventional and computed tomography (CT).METHODS: The inclination of the roof and posterior wall of the glenoid fossa was determined relative to established imaging planes. Measurements were performed on 50 corrected coronal MR and 50 axial CT images and 200 sagittal cryosections of 50 temporomandibular joints (TMJs). The location of regions with unfavourable bone wall inclination was identified using the condyle as a reference.RESULTS: The inclination of parts of the fossa roof exceeded the limit for reliable depiction in corrected sagittal and coronal planes in 40% and 8% of the joints respectively. The inclination of parts of the posterior wall of the fossa exceeded the limit for reliable depiction in corrected sagittal and in true sagittal planes in 100% and 84% of the joints respectively. In 84% of the joints the inclination exceeded the limit for reliable depiction in the axial plane. For both bone walls the regions with unfavourable inclination were in the medial part of the joint.CONCLUSIONS: The angulation of parts of the roof and posterior wall of the glenoid fossa in relation to established imaging planes makes them highly susceptible to distortion. The oblique coronal projection is well suited for depiction of the roof of the fossa and preferable to a sagittal projection. An oblique axial projection is required for the posterior wall.
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| 43. |
- Aleman, J, et al.
(författare)
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Saving more neonates in hospital : an intervention towards a sustainable reduction in neonatal mortality in a Nicaraguan hospital
- 1998
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Ingår i: Tropical doctor. - 0049-4755 .- 1758-1133. ; 28:2, s. 88-92
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Tidskriftsartikel (refereegranskat)abstract
- A process of change was initiated in a Nicaraguan regional hospital in order to achieve a sustainable reduction of early neonatal mortality. A series of organizational, educational and hygienic measures was introduced, involving all staff in antenatal care, delivery care and neonatal care. Neonatal mortality decreased from 56/1000 live births in 1985 to 11/1000 in 1993. A commission of maternal and child health, a weekly perinatal audit, the active involvement of all staff and dedicated work of key individuals, as well as national policy decisions, are considered important determinants of the process. Keeping neonatal mortality in focus through continuous analysis of care routines, and through external exchange of ideas is important in order to sustain improvements and to decrease further the mortality.
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| 44. |
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| 45. |
- Alfredson, Håkan, et al.
(författare)
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Achilles tendinosis and calf muscle strength : the effect of short-term immobilization after surgical treatment
- 1998
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Ingår i: American Journal of Sports Medicine. - 0363-5465 .- 1552-3365. ; 26:2, s. 166-71
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Tidskriftsartikel (refereegranskat)abstract
- We prospectively studied calf muscle strength in 7 men and 4 women (mean age, 40.9 +/- 10.1 years) who had surgical treatment for chronic Achilles tendinosis. Surgery was followed by immobilization in a weightbearing below-the-knee plaster cast for 2 weeks followed by a stepwise increasing strength training program. Strength measurements (peak torque and total work) were done preoperatively (Week 0) and at 16, 26, and 52 weeks postoperatively. We measured isokinetic concentric plantar flexion strength at 90 and 225 deg/sec and eccentric flexion strength at 90 deg/sec on both the injured and noninjured sides. Preoperatively, concentric and eccentric strength were significantly lower on the injured side at 90 and 225 deg/sec. Postoperatively, concentric peak torque on the injured side decreased significantly between Weeks 0 and 16 and increased significantly between Weeks 26 and 52 at 90 deg/sec but was significantly lower than that on the noninjured side at all periods and at both velocities. The eccentric strength was significantly lower on the injured side at Week 26 but increased significantly until at Week 52 no significant differences between the sides could be demonstrated. It seems, therefore, that the recovery in concentric and eccentric calf muscle strength after surgery for Achilles tendinosis is slow. We saw no obvious advantages in recovery of muscle strength with a short immobilization time (2 weeks) versus a longer (6 weeks) period used in a previous study.
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| 46. |
- Alfredson, Håkan, et al.
(författare)
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Concentric and eccentric shoulder and elbow muscle strength in female volleyball players and non-active females
- 1998
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 8:5 Pt 1, s. 265-270
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Tidskriftsartikel (refereegranskat)abstract
- Maximal isokinetic concentric (60 degrees/s and 180 degrees/s) and eccentric (60 degrees/s) muscle strength of the external and internal rotator muscles of the shoulder and the flexor and extensor muscles of the elbow was measured in a position resembling spiking and serving in volleyball, on 11 non-injured female volleyball players (first division) and 11 non-active females. In the dominant arm, the volleyball players had significantly higher concentric peak torque of the internal and external rotators and elbow extensors at both velocities, and significantly higher eccentric peak torque of the shoulder internal and external rotators and elbow flexors and extensors, than the controls. In the volleyball group, the concentric internal rotation peak torque at 60 degrees/s was significantly higher in the dominant than in the non-dominant arm. The external/internal strength ratio was significantly lower at 60 degrees/s, but not at 180 degrees/s, in the dominant arm. CONCLUSION: The female volleyball players had a higher concentric and eccentric strength in the rotator muscles of the shoulder and in the extensor muscles of the elbow compared to untrained controls in this special test position. There were signs of rotator muscle imbalance at the low test speed, but no signs of weakness of the external rotators, in the dominant arm of the volleyball players.
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| 47. |
- Alfredson, Håkan, et al.
(författare)
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Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis
- 1998
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Ingår i: American Journal of Sports Medicine. - : Sage. - 0363-5465 .- 1552-3365. ; 26:3, s. 360-366
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Tidskriftsartikel (refereegranskat)abstract
- We prospectively studied the effect of heavy-load eccentric calf muscle training in 15 recreational athletes (12 men and 3 women; mean age, 44.3 +/- 7.0 years) who had the diagnosis of chronic Achilles tendinosis (degenerative changes) with a long duration of symptoms despite conventional nonsurgical treatment. Calf muscle strength and the amount of pain during activity (recorded on a visual analog scale) were measured before onset of training and after 12 weeks of eccentric training. At week 0, all patients had Achilles tendon pain not allowing running activity, and there was significantly lower eccentric and concentric calf muscle strength on the injured compared with the noninjured side. After the 12-week training period, all 15 patients were back at their preinjury levels with full running activity. There was a significant decrease in pain during activity, and the calf muscle strength on the injured side had increased significantly and did not differ significantly from that of the noninjured side. A comparison group of 15 recreational athletes with the same diagnosis and a long duration of symptoms had been treated conventionally, i.e., rest, nonsteroidal antiinflammatory drugs, changes of shoes or orthoses, physical therapy, and in all cases also with ordinary training programs. In no case was the conventional treatment successful, and all patients were ultimately treated surgically. Our treatment model with heavy-load eccentric calf muscle training has a very good short-term effect on athletes in their early forties.
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| 48. |
- Alfredson, Håkan, et al.
(författare)
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High thigh muscle strength but not bone mass in young horseback-riding females
- 1998
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Ingår i: Calcified Tissue International. - : Springer. - 0171-967X .- 1432-0827. ; 62:6, s. 497-501
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate whether the type of weight-bearing loading subjected to the skeleton during horseback-riding was associated with differences in bone mass and muscle strength of the thigh, we investigated bone mass and isokinetic muscle strength in 20 female horse riders (age 17.9 +/- 0.6 years) who were riding 7.0 +/- 3.4 hours/week, and 20 nonactive females (age 17.8 +/- 1.1 years). The groups were matched according to age, weight, and height. Areal bone mineral density was measured in total body, head, lumbar spine, right femoral neck, Ward's triangle, and trochanter, the whole dominant and nondominant humerus, and in specific sites in the right femur diaphysis, distal femur, proximal tibia, and tibia diaphysis using dual X-ray absorptiometry. Isokinetic concentric and eccentric peak torque of the quadricep and hamstring muscles were measured using an isokinetic dynamometer. There were no significant differences in bone mass between the horseback riders and nonactives at any site measured. The horse riders were significantly (P < 0.05-0.01) stronger in concentric hamstrings strength at 90 degrees/second and 225 degrees/second and in eccentric quadricep and hamstring strength at 90 degrees/second. Horseback riding in young females is associated with a high muscle strength of the thigh, but not with a high bone mass.
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| 49. |
- Alfredson, Håkan, et al.
(författare)
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Long-term loading and regional bone mass of the arm in female volleyball players
- 1998
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 62:4, s. 303-308
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we compared the bone mineral content (BMC) and bone mineral density (BMD) in the arms of 11 female volleyball players (mean age 22.0 +/- 2.6 years) training for about 8 hours/week, and 11 nonactive females aged 24.6 +/- 3.1 years (mean +/- SD) not participating in regular or organized sport activity. Using dual X-ray absorptiometry (DXA), BMC was measured in the proximal and distal humerus, and BMD in the distal radius. Isokinetic concentric peak torque (highest value attained during 5 or 10 repetitions) of the rotator muscles of the shoulder and flexor and extensor muscles of the elbow were measured using an isokinetic dynamometer. The volleyball players had significantly higher BMC (P < 0.05) at the proximal humerus of the dominant arm compared with the nonactive group, but there were no differences between the groups in BMC of the distal humerus and BMD of the distal radius. In the volleyball players, BMC was significantly higher at the proximal humerus, at the distal humerus, and at the distal radius in the dominant compared with the nondominant arm. In the nonactive group, there were no significant differences in BMC and BMD between the dominant and nondominant arm at any site measured. Except for shoulder internal rotation strength and elbow flexion strength at 90 degrees/second that was higher in the dominant arm in the volleyball players, there were no significant differences in muscle strength of the rotator muscles of the shoulder and flexor and extensor muscles of the elbow between the dominant and nondominant arm in the volleyball players and nonactive controls. In the volleyball players, but not in the nonactive controls, there were several significant relationships between shoulder and elbow strength and BMC at the distal humerus of the dominant and especially the nondominant arm. These results show that young female volleyball players have a higher bone mass in the proximal humerus, distal humerus, and distal radius in the dominant compared with the nondominant arm, and a higher bone mass in the proximal humerus compared with nonactive controls. Muscle strength of the rotator muscles of the shoulder is not related to the higher bone mass in the proximal humerus of the dominant arm. Theoretically, the observed differences in bone mass can be related to the type of loading the skeleton undergoes when playing volleyball.
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| 50. |
- Alfredson, Håkan, et al.
(författare)
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Prolonged progressive calcaneal bone loss despite early weightbearing rehabilitation in patients surgically treated for Achilles tendinosis
- 1998
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Ingår i: Calcified Tissue International. - : Springer. - 0171-967X .- 1432-0827. ; 62:2, s. 166-171
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Tidskriftsartikel (refereegranskat)abstract
- We prospectively evaluated areal bone mineral density (BMD) of the calcaneus and calf-muscle strength (concentric and eccentric plantar flexion peak torque in Nm) in 10 recreational athletes (5 males and 5 females), mean age 40.9 years (range 26-55), who were selected to undergo surgical treatment for chronic Achilles tendinosis localized at the 2-6 cm level. Surgery was followed by immobilization in a plaster cast for 2 weeks, followed by flexibility training and slowly progressing strength training and weight-bearing activity. One patient was excluded after week 0 because of a new injury. Seven patients were back to their preinjury activity at the 26-week control, and eight patients at the 52-week control postoperatively. BMD in the calcaneus and calf-muscle strength on the injured and noninjured side was measured preoperatively (week 0) and postoperatively (weeks 2, 6, 16, 26, and 52). There were no significant differences in BMD between the injured and noninjured side at weeks 0, 2, and 6, but at weeks 16, 26, and 52, BMD was significantly (P < 0.05) lower (11.5%, 18.4%, and 16.4%, respectively) in the calcaneus of the injured side. Concentric and eccentric plantar flexion strength were significantly lower on the injured side preoperatively. Eccentric, but not concentric plantar flexion strength had recovered compared with the noninjured side 1 year postoperatively. Calf-muscle strength was not related to bone mass in the calcaneus. As a comparison, we used a group of 11 recreational athletes (10 males and 1 female), with a mean age of 46.1 years (range 28.9-58.5) who had been surgically treated for chronic Achilles tendinosis at the 2-6 cm level 39.5 +/- 11.8 months ago. In this group, there was no significant difference in BMD of the calcaneus between the injured and noninjured side. It seems that there was a delayed and prolonged calcaneal bone loss despite early weightbearing loading in patients surgically treated for chronic Achilles tendinosis at the 2-6 cm level. Around that time, when the Achilles tendon had healed (4-6 months) and the athletes returned to their sports, the calcaneal bone had a relatively low BMD and might possibly be vulnerable to heavy loadings. There were no signs of recovery 1 year postoperatively, but in a comparison group there were no significant side-to-side differences 39.5 months postoperatively.
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