A Novel Approach to Investigate Running Kinematics in Achilles Tendinopathy Patients Using Inertial Sensors

Abstract

Mid-portion Achilles tendinopathy (AT) is a common injury in runners. Overloading the tendon results in pain, swelling and impaired running performance. Recovery involves rest and a gradual build up. Determining whether patients can resume training is difficult and currently rather qualitative. To provide quantitative data to the physician to assist clinical decision- making, we studied the between leg differences in running kinematics for AT patients using inertial sensors in the clinical setting. PURPOSE:To investigate lower limb kinematics in AT patients during 5 minute treadmill running in the clinic, using inertial magnetic measurement units (IMUs). METHODS:4 runners diagnosed with mild unilateral AT (4M , 48.8 ± 7.5 yrs, 188.8 ± 11.2 cm, 82.5 ± 11.1 kg) performed a 5 min. treadmill run in the sports medicine clinic, as part of a larger study, with 8 IMU’s at the feet, tibia, upper legs, sacrum and sternum. Ankle and knee angles were determined at initial contact (IC) and mid stance (MS). Additional parameters that were calculated were the vertical lower leg angle at IC (VLL), peak tibial impact (PTA), peak sacral impact (PSA), push-off power (POP) (lin. velocity at toe off, TO) and internal rotation (IR) of the tibia (at TO). Parameters were determined for the injured and non-injured leg at 1-min. intervals. An independent Mann-Whitney U-test was used to test for differences within patients between the injured and non-injured leg. RESULTS: Table 1 CONCLUSIONS:The injured leg of these AT patients showed significantly different running kinematics. AT strongly affected ankle mechanics, possibly as a compensatory strategy, indicating non-full recovery of the patients. The use of IMUs to determine the recovery of AT patients quantitatively is promising. Using IMUs there is no need for 3d optical motion capture systems or an instrumented treadmill to quantify running kinematics. Future research should follow up on these measurements to identify fully recovered patients.Table 1: Mean values ± standard deviation of the selected outcome parameters. Statistical differences was tested for using an independent Mann-Whitney-U-test.