(E-176) Development of a shear wave tensiometer for investigating Achilles tendinopathy in dancers

Introduction:: Achilles tendinopathy is a common injury in classical ballet caused by overuse and repeated stress in the Achilles tendon. However, the scientific literature lacks quantitative data relating Achilles stress in dancers to their tendinopathy. Techniques including ultrasound elastography and magnetic resonance elastography measure tendon shear wave speed, which is directly related to tendon stress, but they cannot acquire measurements while a subject is dancing. The goal of this study is to develop a reliable wearable device that measures the shear wave speed throughout a dance routine with the long-term goal of providing quantitative stress data for dancers suffering from Achilles tendinopathy.


Materials and Methods:: The tensiometer introduces shear waves into the tendon using an electromagnetic actuator operating at 50 Hz. Two accelerometers, placed 1 cm apart on the skin over the tendon, measure the time delay between the arrival of shear waves, which is used to compute shear wave speed. To identify the optimal device placement (which allows for a clear signal while accounting for the placement of pointe shoe ribbons), the accelerometers and electromagnetic actuator were placed in 8 different locations along the tendon (see Figure 1). In addition, the accelerometers were tested above and below the actuator for each location. Multiple stationary measurements were performed in sitting, standing and tensed positions. The subject then performed heel raises that tense the tendon to analyze the change in wave speed with time.


Results, Conclusions, and Discussions:: Results

The best placement for the shear wave tensiometer was in the location where the dancers attach their pointe shoes with ribbons. A secondary location approximately 3.5 cm above the ribbons also allowed for reliable results. Figure 2 shows the shear wave speed measured in the Achilles tendon during heel raises at the best placement location. The tensiometer produced shear wave speeds that agree with previously published data.

Conclusion

The shear wave tensiometer we have developed produces reliable shear wave speed measurements in the Achilles tendon. Next steps include making the device mobile with a portable actuation and data acquisition system that could fit in a small backpack. This will enable acquisition of shear wave measurements while allowing dancers to spin, jump, and move with minimal interference to their routine.


Acknowledgements (Optional): :

References (Optional): :