Tomoya Takabayashi, Mutsuaki Edama, Erika Yokoyama, Takuma Inai, Yuta Tokunaga and Masayoshi Kubo
Objective: Backward stair descent has attracted attention from the viewpoint of injury prevention. Previous studies have shown that knee extension moment is lower during the backward stair descent than during the forward stair descent. However, it remains unclear whether the bone-on-bone force at the tibiofemoral joint differs between the two stair descent methods. The purpose of this study was to estimate bone-on-bone forces at the tibiofemoral joint during forward and backward stair descent.
Methods: Six healthy young men participated in this study. The stair descents were performed in the forward and backward direction using a step-by-step pattern. The muscle tensions of the lower limbs were estimated based on the net joint moments and information provided by the electromyography. The bone-on-bone forces at the tibiofemoral joint were calculated based on the estimated muscle tensions and geometry of limbs.
Results: While the knee extension moments were significantly lower during backward stair descent than forward stair descent, the estimated bone-on-bone forces at the tibiofemoral joint in two different descending methods showed no significant difference. The quadriceps femoris tension during backward stair descent was significantly lower than that during forward stair descent.
Conclusions: The bone-on-bone forces reflect mechanical load to the articular surface. Thus, the results of this study suggested that the load of tibiofemoral articular surface remains unchanged between the forward and backward stair descent. However, backward stair descent might be a relevant method for reduction of quadriceps femoris tensions.