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In vivo motion of tibiofemoral joint and surface electromyography of thigh muscles during landing
Poster 131, Poster Session 1/Sport. 14:45-15:45, Room 103 & Alley Area
S612
In vivo motion of tibiofemoral joint and surface electromyography of thigh muscles during landing 1
H Ida1, Y Nagano2, T Fukubayashi2 and K Nakazawa3 Kanagawa Institute of Technology; email: [email protected], 2 Waseda University, 3 National Rehabilitation Center for Persons with Disabilities
INTRODUCTION Female athletes have 2-10 times higher chance of anterior cruciate ligament (ACL) injury than male counterparts, and 70-80% of the injury occurs in a non-contact situation. In addition to the intrinsic risk factors of ACL injury, some extrinsic risk factors such as leg motion and muscle activity have been proposed particularly in the difference between females and males [1]. For the prevention and treatment of ACL injury, however, the in vivo knee mechanisms during various landing situations should be assessed in greater detail. Point cluster technique [2], which estimates in vivo tibial motion relative to the femur, is expected to reveal such a detailed mechanism. The purpose of this study was to estimate the mechanism of ACL injury by examining the motion of tibiofemoral joint and electromyography of thigh muscles during four landing tasks. METHODS Eight healthy young women (age = 20.2 ± 2.2 yrs.) participated in this study. The subjects instructed to fall down from a 30-cm high platform and land with their right leg. The motion tasks were land and stop at neutral foot position (LN), land and stop at toe-out foot position (LT), cut to a 45° left direction at neutral foot position (CN) and cut to a 45° left direction at toe-out foot position (CT). A total of 24 reflective markers (10 for thigh, 6 for shank and the others for bone landmark) attached to the right leg were measured at 200 Hz by VICON370 (Oxford Metrics Inc.,
Oxford). The collected motion data were processed with our PCT algorithm to output flexion / extension, abduction / adduction, internal / external rotation and anterior / posterior thrust and these values at the ground contact were statistically examined. Muscle activity was recorded at 1,000 Hz using surface EMG (Delsys Inc., Boston) from knee extensors; rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM) and knee flexors; biceps femoris (BF) and semimembranosus (SM). The RMS values of the obtained EMG data through 100 ms before and 100 ms after the ground contact were also examined. A one-way ANOVA was performed to test the effect of the motion tasks. RESULTS AND DISCUSSION At the ground contact, the adduction of both LT and CT was significantly greater than that of LN and that of CN (Fig. 1b). LT and CT also showed significantly greater values in the external rotation than CN, respectively (Fig. 1c). Meanwhile, there were no significant differences in the values at the ground contact and following peaks (plateaus) of the flexion (Fig. 1a) and anterior thrust (Fig. 1d). Toe-out position generates the specific tibial position, more adducted and externally rotated than the neutral position, at the ground contact, but doesn’t cause forward translation of the tibia. Extensor muscles were strongly activated (Fig. 2), but all the muscles didn’t show any significant differences among the motion tasks in the RMS values for both before and after the ground contact. It was reported that the muscle activity pattern was different between females and males [1], but seemed to be less influenced by the motion tasks. CONCLUSIONS The difference of foot position at the ground contact changes the tibia position during landing and would have critical influences on the following mechanism leading to ACL. REFERENCES 1. Chappell JD, et al. Am J Sports Med, in press. 2. Andriacchi T, et al. J Biomech Eng 120, 743-749, 1998.
Figure 1. Time course pattern of knee flexion / extension (a), abduction / adduction (b), external / internal rotation (c) and anterior / posterior thrust (d). *p < .05. Journal of Biomechanics 40(S2)
Figure 2. EMG pattern of thigh muscles (LN): knee extensor muscles (a) and knee flexor muscles (b). XXI ISB Congress, Poster Sessions, Wednesday 4 July 2007
S612
In vivo motion of tibiofemoral joint and surface electromyography of thigh muscles during landing 1
H Ida1, Y Nagano2, T Fukubayashi2 and K Nakazawa3 Kanagawa Institute of Technology; email: [email protected], 2 Waseda University, 3 National Rehabilitation Center for Persons with Disabilities
INTRODUCTION Female athletes have 2-10 times higher chance of anterior cruciate ligament (ACL) injury than male counterparts, and 70-80% of the injury occurs in a non-contact situation. In addition to the intrinsic risk factors of ACL injury, some extrinsic risk factors such as leg motion and muscle activity have been proposed particularly in the difference between females and males [1]. For the prevention and treatment of ACL injury, however, the in vivo knee mechanisms during various landing situations should be assessed in greater detail. Point cluster technique [2], which estimates in vivo tibial motion relative to the femur, is expected to reveal such a detailed mechanism. The purpose of this study was to estimate the mechanism of ACL injury by examining the motion of tibiofemoral joint and electromyography of thigh muscles during four landing tasks. METHODS Eight healthy young women (age = 20.2 ± 2.2 yrs.) participated in this study. The subjects instructed to fall down from a 30-cm high platform and land with their right leg. The motion tasks were land and stop at neutral foot position (LN), land and stop at toe-out foot position (LT), cut to a 45° left direction at neutral foot position (CN) and cut to a 45° left direction at toe-out foot position (CT). A total of 24 reflective markers (10 for thigh, 6 for shank and the others for bone landmark) attached to the right leg were measured at 200 Hz by VICON370 (Oxford Metrics Inc.,
Oxford). The collected motion data were processed with our PCT algorithm to output flexion / extension, abduction / adduction, internal / external rotation and anterior / posterior thrust and these values at the ground contact were statistically examined. Muscle activity was recorded at 1,000 Hz using surface EMG (Delsys Inc., Boston) from knee extensors; rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM) and knee flexors; biceps femoris (BF) and semimembranosus (SM). The RMS values of the obtained EMG data through 100 ms before and 100 ms after the ground contact were also examined. A one-way ANOVA was performed to test the effect of the motion tasks. RESULTS AND DISCUSSION At the ground contact, the adduction of both LT and CT was significantly greater than that of LN and that of CN (Fig. 1b). LT and CT also showed significantly greater values in the external rotation than CN, respectively (Fig. 1c). Meanwhile, there were no significant differences in the values at the ground contact and following peaks (plateaus) of the flexion (Fig. 1a) and anterior thrust (Fig. 1d). Toe-out position generates the specific tibial position, more adducted and externally rotated than the neutral position, at the ground contact, but doesn’t cause forward translation of the tibia. Extensor muscles were strongly activated (Fig. 2), but all the muscles didn’t show any significant differences among the motion tasks in the RMS values for both before and after the ground contact. It was reported that the muscle activity pattern was different between females and males [1], but seemed to be less influenced by the motion tasks. CONCLUSIONS The difference of foot position at the ground contact changes the tibia position during landing and would have critical influences on the following mechanism leading to ACL. REFERENCES 1. Chappell JD, et al. Am J Sports Med, in press. 2. Andriacchi T, et al. J Biomech Eng 120, 743-749, 1998.
Figure 1. Time course pattern of knee flexion / extension (a), abduction / adduction (b), external / internal rotation (c) and anterior / posterior thrust (d). *p < .05. Journal of Biomechanics 40(S2)
Figure 2. EMG pattern of thigh muscles (LN): knee extensor muscles (a) and knee flexor muscles (b). XXI ISB Congress, Poster Sessions, Wednesday 4 July 2007