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- Arndt, A, et al.
(författare)
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An in vitro comparison of bone deformation measured with surface and staple mounted strain gauges
- 1999
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Ingår i: JOURNAL OF BIOMECHANICS. - : ELSEVIER SCI LTD. - 0021-9290. ; 32:12, s. 1359-1363
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Chicken tibiae were chosen as a model for human second metatarsals. Local surface bone deformation in a 4-point bending configuration was measured in vitro by both strain gauge instrumented staples and strain gauges bonded to the bone's cortical surface.
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- Arndt, A, et al.
(författare)
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Ankle and subtalar kinematics measured with intracortical pins during the stance phase of walking
- 2004
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Ingår i: Foot & ankle international. - : SAGE Publications. - 1071-1007 .- 1944-7876. ; 25:5, s. 357-364
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Tidskriftsartikel (refereegranskat)abstract
- The absence of external landmarks on the talus has rendered the description of ankle and subtalar joint kinematics difficult. Abnormal motion at these joints has, however, been implied in the etiology of an array of lower extremity overuse injuries. Methods: Intracortical pins were inserted under local anesthesia in the tibia, talus, and calcaneus with external marker clusters traced by a video motion analysis system. Kinematic data were collected during walking trials on a flat surface for three subjects. Gait pattern was monitored by comparison of ground reaction force curves during stance phase with and without the pins inserted. Results: Results were presented in terms of helical axis orientation for both joints and the component rotations about these axes. Large intersubject differences were seen in both ankle and subtalar joint helical axis orientation. Maximum rotations over the complete stance phase for the ankle and subtalar joints respectively were: eversion/inversion, 6.3° and 8.3°; dorsiflexion/plantarflexion, 18.7° and 3.7°; and abduction/adduction, 5.0° and 6.1°. Conclusions: The majority of ankle eversion/inversion occurred at the subtalar joint; however, the ankle component cannot be ignored. Abduction/adduction range of motion at the subtalar joint was surprisingly high, indicating that this component motion during walking is not purely attributable to the ankle joint. Future research should include greater subject numbers in order to present more universally applicable results. Clinical Relevance: The in vivo kinematics of the talus during weightbearing activity are poorly understood. The description of this motion may assist in the structuring of clinical rehabilitation and in the design and insertion of ankle joint prostheses.
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- Ekenman, I, et al.
(författare)
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A study of intrinsic factors in patients with stress fractures of the tibia
- 1996
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Ingår i: Foot & ankle international. - : SAGE Publications. - 1071-1007 .- 1944-7876. ; 17:8, s. 477-482
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to study intrinsic factors in 29 consecutive patients with well-documented unilateral stress fractures of the tibia. Anthropometry, range of motion, isokinetic plantar flexor muscle performance, and gait pattern were analyzed. The uninjured leg served as the control. A reference group of 30 uninjured subjects was compared regarding gait pattern. Anterior stress fractures of the tibia (N = 10) were localized in the push-off/ landing leg in 9/10 athletes, but were similarly distributed between legs in posteromedial injuries (N = 19). Ten (30%) of the stress fracture subjects had bilateral high foot arches, similar to those found in the reference group. There were no other systematic differences in anthropometry, range of motion, gait pattern, or isokinetic plantar flexor muscle peak torque and endurance between injured and uninjured legs. No other differences were found between anterior and posteromedial stress fractures. We conclude that anterior stress fractures of the tibia occur mainly in the push-off/landing leg in athletes. Within the limitations of our protocol, no registered intrinsic factor was found to be directly associated with the occurrence of a stress fracture of the tibia.
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- Ekenman, I, et al.
(författare)
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Local bone deformation at two predominant sites for stress fractures of the tibia: an in vivo study
- 1998
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Ingår i: Foot & ankle international. - : SAGE Publications. - 1071-1007 .- 1944-7876. ; 19:7, s. 479-484
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Tidskriftsartikel (refereegranskat)abstract
- Local bone deformation was registered at two predominant injury sites for tibial stress fractures in a healthy female volunteer. Two instrumented strain gauge staples were inserted under local anesthesia to the anterior middiaphysis (AM) and to the posteromedial part of the distal tibia (PD). Calibration and reliability of the instrumented staple system have previously been demonstrated in vitro. Concomitant ground reaction forces were registered with a Kistler force plate. Studying peak values, it was shown that during a voluntary 30-cm forward jump, PD deformation was greater during forefoot landing (2700–4200 microstrain) than during a heel strike landing (1200–1900 microstrain) and also compared with the concomitant AM deformation under both above testing conditions (1300–1900 microstrain). The stance phase during walking resulted in PD deformation of 950 microstrain, whereas the concomitant AM deformation was 334 microstrain. The greatest AM deformation (mean, 2128 microstrain) was registered during ground contact after a voluntary vertical drop from a height of 45 cm, concomitant with a PD deformation of 436 microstrain. These data are the first to show different local deformations at various sites of the tibia in vivo. The PD deformation was larger than previously noted from other parts of the tibia, whereas the middiaphysis data are consistent with other reports. The results may support the clinical assumption of different etiologies for stress fractures at these predominant sites.
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- Westblad, P, et al.
(författare)
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Differences in ankle-joint complex motion during the stance phase of walking as measured by superficial and bone-anchored markers
- 2002
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Ingår i: Foot & ankle international. - : SAGE Publications. - 1071-1007 .- 1944-7876. ; 23:9, s. 856-863
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Tidskriftsartikel (refereegranskat)abstract
- Bones of the ankle-joint complex are difficult to represent with superficial markers and an invasive approach is required to quantify skin movement artifact. Three-dimensional coordinates during gait were first calculated from sets of three superficial markers located on both the lower leg and heel. Intracortical pins equipped with external marker arrays were subsequently inserted in the tibia, talus and calcaneus for further trials. Tibiocalcaneal and talocalcaneal joint helical axis component rotations were calculated. Intersubject motion patterns were comparable. Root mean square (RMS) differences were chosen to describe discrepancies between temporal intracortical pin and superficial marker curves. Results for the tibiocalcaneal rotations inversion / eversion, plantarflexion / dorsiflexion and abduction / adduction were 2.5°, 1.7° and 2.8° respectively. Inversion / eversion about the talocalcaneal joint showed an RMS difference of 2.1°. A systematic over- or underestimation of superficial relative to bone-anchored markers could not be determined.
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