Short communicationHow to sprain your ankle – a biomechanical case report of an inversion trauma
Introduction
Lateral ankle sprains rank among the most frequent injuries in sports (Fong et al., 2007). For successful development of preventive measures, it is essential to have a sound understanding of the injury mechanism (Bahr and Krosshaug, 2005). While several methodological approaches are available to study etiological details about sprain occurrences (e.g., athlete interviews or simulation of non-injury situations), one valuable approach is the analysis of the undesired situation in which an athlete is injured during a biomechanical measurement (Krosshaug et al., 2005).
Few case reports of lateral ankle sprains are available containing biomechanical data about ankle joint kinematics and kinetics during the phase of ground contact (Kristianslund et al., 2011, Mok et al., 2011, Fong et al., 2009). The present case report enlarges this current information as additional measurement methods were applied. This report is able to describe the entire lower limb kinematics, the neuromuscular activation profile and the preparatory adjustments during an ankle sprain. Based on this additional knowledge the injury mechanism of lateral ankle sprains may be understood more comprehensively.
Section snippets
Experimental setup
One male soccer player (23 years; 1.83 m; 75 kg) participated in biomechanical measurements in a cross sectional study. He reported no orthopedic problems in the preceding six months; however he stated previous ankle sprains and self-reported functional deficits during sporting activities (FAAM-G sport subscale: 84%; Nauck and Lohrer, 2011). Before participation the subject gave written informed consent according to the local ethics committee. The protocol of the experimental setup required the
Ankle mechanics
The injury trial was characterized by a rapid increase in plantarflexion (up to 50°), in inversion (up to 45°), and in internal rotation (up to 13°) during the first 60 ms of ground contact (Phase 1; see Fig. 1). The peak angular velocities were: 1240°/s for plantarflexion, 1290°/s for inversion, and 580°/s for internal rotation. After a subsequent reduction of plantarflexion and inversion (Phase 2: 60–105 ms) the forefoot served as a pivot point and both the inversion and especially the internal
Preparatory adjustments
This case report adds the following information to current knowledge: the angular excursions of the pelvis, hip and knee joint had already deviated considerably from the non-injury trials before ground contact. First, this observation clearly points towards the hypothesis that etiological conditions of ankle sprains may not be related to the ankle joint complex alone. To fully understand sprain occurrences it seems important to focus research not only on ankle joint biomechanics (i.e., no
Conflict of interest statement
The cross sectional study was supported by the adidas AG (Herzogenaurach, Germany). The authors state that the sponsor had neither an influence on the decision to submit the manuscript nor on the content of the paper.
Acknowledgment
We thank Martin-Scott Löhrer for his help in writing the Bodybuilder script. The SPLINEFIT Matlab (Mathworks Inc., Natick, USA) script of Jonas Lundgren was used to calculate the angular velocities.
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