Introduction
The aim of this study was to use model-based image matching method (MBIM) to study ankle inversion sprain injury mechanism from basketball cases. MBIM can be used to understand the injury mechanism quantitatively by analyzing the three-dimensional human motion [1].
Methods
An ankle inversion sprain injury occurred in a televised basketball match was found from the internet. The videos were transformed into uncompressed AVI image sequence by using Adobe Premiere Pro (CS4, Adobe Systems Inc, San Jose, California). Then the image sequences were synchronized and rendered into 1-Hz video sequences by Adobe After-Effects (CS4, Adobe Systems Inc). 3-dimension animation software Poser 4 and Poser Pro Pack (Curious Labs Inc, Santa Cruz, California) were used to perform the matching part. Virtual environment was built according to the real dimensions of a basketball court and it was manually matched to the background for each frame in every single camera view. The skeleton model from Zygote Media Group Inc. (Provo, Utah) was used to match with the athlete. The segment dimensions were adjusted according to the subject’s height. The skeleton matching started with the hip, thigh, shank segment and then distally matched the foot and toe segments frame by frame. The ankle time histories were input into Microsoft Excel (Microsoft Office, Microsoft, US) to calculate the velocity-related information.
Results
The peak inversion in this case lies within the range (48°-142°) obtained in previous studies [1]. Different from previous studies [1], plantarflexion is found at the time of peak ankle inversion during the injuring motion.
Table 1
Peak value of the ankle angles and velocities (inversion, internal rotation and plantarflexion) were shown in the table below. The lowest row indicates the duration of the ankle sprain injury.
Max. Inversion angle (deg) | 110 |
Max. Inversion velocity (deg/sec) | 2916. |
Time of peak inversion (sec) | 0.24 |
Max. Internal rotation angle (deg) | 56 |
Max. Internal rotation velocity (deg/sec) | 551 |
Time of peak internal rotation (sec) | 0.52 |
Max. Plantarflexion angle (deg) | 32 |
Max. Plantarflexion velocity (deg/sec) | 580 |
Time of peak plantarflexion (sec) | 0.40 |
Whole duration (sec) | 0.52s |
Conclusion
The analysis of basketball ankle inversion ligamentous sprain case was done and compared with previous studies. Since no basketball cases have been analyzed before, so more basketball cases should be analyzed by MBIM in order to understand the real injury mechanism.
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