The tibia is a common site for stress fractures, which are believed to develop from microdamage accumulation to repetitive sub-yield strains. There is a need to understand how the tibia is loaded in vivo to understand how stress fractures develop and design exercises to build a more robust bone. Here, we use subject-specific, muscle-driven, finite element simulations of 11 basketball players to calculate strain and strain rate distributions at the midshaft and distal tibia during six activities: walking, sprinting, lateral cut, jumping after landing, changing direction from forward-to-backward sprinting, and changing direction while side shuffling. Maximum compressive strains were at least double maximum tensile microstrains (mu) during the stance phase of all activities. Sprinting and lateral cut had the highest compressive (-2773 +/- 934 mu and -2266 +/- 815 mu, respectively) and tensile (999 +/- 381 mu and 907 +/- 261 mu, respectively) strains. These activities also had the highest strains rates (peak compressive strain rate = 46237 +/- 38217 mu/s and 41510 +/- 17245 mu/s, respectively). Compressive strains principally occurred in the posterior tibia for all activities; however, tensile strain location varied. In particular, activities involving a change in direction increased tensile loads in the anterior tibia. These observations may guide preventative and management strategies for tibial stress fractures. In terms of prevention, the strain distributions suggest individuals should perform activities involving changes in direction during growth to adapt different parts of the tibia and develop a more fatigue resistant bone. In terms of management, the greater strain and strain rates during sprinting than jumping suggests jumping activities may be commenced earlier than full pace running. The greater anterior tensile strains during changes in direction suggest introduction of these types of activities should be delayed during recovery from an anterior tibial stress fractures, which have a high-risk of healing complications.
Tibial bone loads during basketball maneuvers
