| 1. |
- Ericson, Mats O, et al.
(författare)
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Tibiofemoral joint forces during ergometer cycling.
- 1986
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Ingår i: American Journal of Sports Medicine. - : SAGE Publications. - 0363-5465 .- 1552-3365. ; 14:4, s. 285-90
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Tidskriftsartikel (refereegranskat)abstract
- Six healthy subjects pedaled on a weight-braked bicycle ergometer at different workloads, pedaling rates, saddle heights, and pedal foot positions. The subjects were filmed with a cine-film camera and pedal reaction forces were recorded from a force transducer mounted on the left pedal. Net knee moments were calculated using a dynamic model, and the tibiofemoral shear and compressive force magnitudes were calculated using a biomechanical model of the knee. During cycling at 120 W, 60 rpm, midsaddle height, and anterior pedal foot position, the mean peak tibiofemoral compressive force was 812 N [1.2 times body weight (BW)]. The maximum anteriorly directed tibiofemoral shear force was found to be low (37 N). The compressive and shear forces were significantly increased by an increased ergometer workload. The pedaling rate had no influence on the tibiofemoral force magnitudes. The stress on the ACL was low and could be further decreased by use of the anterior foot position instead of the posterior.
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| 2. |
- Nisell, R, et al.
(författare)
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Tibiofemoral joint forces during isokinetic knee extension.
- 1989
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Ingår i: American Journal of Sports Medicine. - : SAGE Publications. - 0363-5465 .- 1552-3365. ; 17:1, s. 49-54
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Tidskriftsartikel (refereegranskat)abstract
- Using a Cybex II, eight healthy male subjects performed isokinetic knee extensions at two different speeds (30 and 180 deg/sec) and two different positions of the resistance pad (proximal and distal). A sagittal plane, biomechanical model was used for calculating the magnitude of the tibiofemoral joint compressive and shear forces. The magnitude of isokinetic knee extending moments was found to be significantly lower with the resistance pad placed proximally on the leg instead of distally. The tibiofemoral compressive force was of the same magnitude as the patellar tendon force, with a maximum of 6300 N or close to 9 times body weight (BW). The tibiofemoral shear force changed direction from being negative (tibia tends to move posteriorly in relation to femur) to a positive magnitude of about 700 N or close to 1 BW, indicating that high forces arise in the ACL when the knee is extended more than 60 degrees. The anteriorly directed shear force was lowered considerably by locating the resistance pad to a proximal position on the leg. This model may be used when it is desirable to control stress on the ACL, e.g., in the rehabilitative period after ACL repairs or reconstructions.
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