Studies on the effect of posterior cruciate ligament (PCL) injury on muscle performance have demonstrated that the normal PCL accommodates sensory nerve endings with capabilities that provide the central nervous system with information about characteristics of movement and position-related stretches of the PCL. Concerning the effect of PCL injury on performance of the quadriceps and hamstrings, there is disagreement in the literature. If there is an effect in the PCL-deficient knee, it is not as simple as that in the anterior cruciate ligament (ACL)-deficient knee. Electromyographic studies have demonstrated that the gastrocnemius muscle is significantly activated during walking and isokinetic motion in the involved knee, as compared with the uninvolved knee. Results of a gait-analytic study suggested that there are significant differences in gait cycle between PCL-deficient and normal knees. These phenomena might be part of the compensatory mechanism in PCL-deficient knees, but the data on the effect of PCL injury on muscle performance remain insufficient at the present time.
Kazunori Yasuda, Harukazu Tohyama and Masayuki Inoue
Yuta Koshino, Tomoya Ishida, Masanori Yamanaka, Mina Samukawa, Takumi Kobayashi and Harukazu Tohyama
Identifying the foot positions that are vulnerable to lateral ankle sprains is important for injury prevention. The effects of foot position in the transverse plane on ankle biomechanics during landing are unknown.
To examine the effects of toe-in or toe-out positioning on ankle inversion motion and moment during single-leg landing.
Motion analysis laboratory.
18 healthy participants (9 men and 9 women).
Participants performed single-leg landing trials from a 30-cm high box under 3 conditions: natural landing, foot internally rotated (toe-in), and foot externally rotated (toe-out).
Main Outcome Measures:
4 toe-in or toe-out angles were calculated against 4 reference coordinates (laboratory, pelvis, thigh, and shank) in the transverse plane. Ankle inversion angle, angular velocity, and external moment in the 200 ms after initial foot-to-ground contact were compared between the 3 landing conditions.
All toe-in or toe-out angles other than those calculated against the shank were significantly different between each of the 3 landing conditions (P < .001). Ankle inversion angle, angular velocity, and moment were highest during toe-in landings (P < .01), while eversion angle and moment were highest during toe-out landings (P < .001). The effect sizes of these differences were large. Vertical ground reaction forces were not different between the 3 landing conditions (P = .290).
Toe-in or toe-out positioning during single-leg landings impacts on ankle inversion and eversion motion and moment. Athletes could train not to land with the toe-in positioning to prevent lateral ankle sprains.