Using fast Fourier transform and polynomial fitting on dorsal foot kinematics data to identify simulated ankle sprain motion from common sporting motions

Ankle sprain is very common in sports, and a commonly suggested aetiology is the delayed peroneal muscle reaction time. Recent studies showed successful attempts to deliver electrical stimulation to the peroneal muscles externally to initiate contraction before it could react, however, the success relies on a workable method to detect ankle sprain injury in time. This study presented a fast Fourier transform and polynomial fitting method with dorsal foot kinematics data for quick ankle sprain detection. Five males performed 100 simulated ankle sprain and 250 common sporting motion trials. Eight gyrometers recorded the 3D angular velocities at 500Hz. Data were trimmed with a 0.11s window size, the suggested duration of pre-injury phase in ankle sprain, and were transformed from time to frequency domain by fast Fourier transform and fitted with a 5th order polynomial. First order coefficients from polynomial fitting on frequency space were obtained. The method achieved a 97.0% sensitivity and 91.4% specificity in identifying simulated sprains, vertical jump-landing, cutting, stepping-down, running and walking motions, with vertical jump-landing excluded due to its relatively low specificity (67.3%). The method can be used to detect ankle sprain in sports with mainly floor movements and minimal vertical jump-landing motion.</div

An individually moulded insole with 5-mm medial arch support reduces peak impact and loading at the heel after a one-hour treadmill run

Background: Foot pain experienced by long-distance runners could be relieved by functional insoles which aim at evenly distributing the plantar pressure. Research question: We hypothesised that an individually moulded insole with medial arch support would reduce the impact and loading under the heel and metatarsal regions. Methods: Twelve male recreational runners ran on a treadmill at 10 km/h for 1 hour with flat insoles and medial arch supported insoles. A pressure insole system (Novel Pedar, Germany) was used to obtain the peak pressure, peak force, time normalised pressure-time integrals, and the percentage of the total force-time integrals under 10 regions. Results: Medial arch supported insoles reduced the peak force under the heel (medial: -15.3%, p = 0.001; lateral: -19.2%, p = 0.037) during the initial run, and reduced peak pressure under the heel (medial: -13.3%, p = 0.005; lateral: -9.9%, p = 0.006), and peak force under the medial heel (-17.8%, p = 0.006) after the run. The percentage of the total force-time integrals under the heel was reduced (medial: -23.8%, p = 0.004; lateral: -13.6%, p = 0.022) after the run. No significant difference was found under the metatarsal regions. There is shift of load from the metatarsal regions to the medial mid-foot as indicated by the change of the percentage of total force-time integrals. Significance: Medial arch supported insoles were effective in reducing the impact and loading under the heel region in prolonged running on a treadmill. Level of evidence: Controlled laboratory study, Level

Screening for laterally deviated plantar pressure during stance using the Cumberland ankle instability tool and anthropometric measures

This study developed a method that predicts laterally deviated plantar pressure during stance by lower limb anthropometrics and self-reported ability to stop an ankle which has started to roll over. Thirty-two males ran on a treadmill for 2 minutes at 11km/h. Foot pressure data were collected by a pressure insole system for classifying the participants as medial or lateral strikers. Cumberland Ankle Instability Tool score, Tegner Activity Scale score, foot arch height, active and passive ankle and knee range of motion, bi-malleolar width, foot length, foot width and calf circumference were measured. Binary logistic regressions were performed to produce a model which estimated if an individual showed laterally deviated foot pressure during stance. The model utilised the score of Cumberland Ankle Instability Tool Question 8, active and passive knee joint external rotation, height, body mass and bimalleolar width (explained variance of 47.3%, p = 0.037), producing a sensitivity of 71.4% and a specificity of 54.5%. A validation trial on another 15 runners reported a 73.3% accuracy in prediction if they are medial or lateral strikes

Using a single uniaxial gyroscope to detect lateral ankle sprain hazard

Lateral ankle sprain is very common in sports. Recently, there was a wearable assistive technology that stimulates the peroneal muscles to prevent this injury, but it requires a monitoring system to detect injury hazards and actuate the protection. This study presents the feasibility of a uniaxial gyroscope to monitor the peak ankle inversion velocity during common sporting motion and simulated ankle sprain motion. Ten males performed walking, running, 45-deg cutting, vertical jump-landing, stepping-down from a block, 5 kinds of simulated ankle sprain motion on sprain simulators, and a manual ankle-twisting motion in a biomechanics laboratory. The peak ankle inversion velocity was collected by an optical motion analysis system at 120 Hz. Besides, a uniaxial gyroscope was attached to the heel to collect the peak twisting velocity at 500 Hz. Pearson test showed a strong or high positive correlation between the two parameters. Independent t-test showed no difference between the two parameters in all testing motions except the manual ankle-twisting test which the value was 82% of that from the optical motion capture system and both values are above the threshold, 300 deg/s. We concluded the method is applicable to detect the hazard of lateral ankle sprain injury.</div

An inverted ankle joint orientation at foot strike could incite ankle inversion sprain: Comparison between injury and non-injured cutting motions of a tennis player

Ankle sprain is very common in sports. Research on its prevention is as important as on its treatment as recommended in the 2016 consensus statement of the International Ankle Consortium. Successful prevention depends on the understanding of its mechanism, which has been presented with quantities in some recent case reports. Inciting event was suggested to be an inverted ankle joint at foot strike, however, is still lacking evidence from comparison with non-injury trials. This study investigated the ankle joint orientation at foot strike in successful non-injury cases and compared them with a previously analysed ankle sprain injury case. Two injury-free cutting motions with similar movement approach to a previously analysed ankle sprain injury performed by the same athlete were collected from an online search and were trimmed from 0.05 second before until 0.30 second after the foot strike. The video sequences were then processed by video editing software and then analysed by a model-based image-matching motion analysis technique. Ankle joint orientation at foot strike and the profiles were presented in inversion, plantarflexion and rotation planes, for both the previously analysed injury case and the two non-injury cases. The ankle joint orientation at foot strike was 0-1 degree inverted and 10-21 degree dorsiflexed in the two non-injury cases, compared to 14-degree inverted and 16-degree plantarflexed in the previously analysed injury case. From the case comparison, it can be observed that an inverted ankle joint orientation at foot strike in an inciting event of ankle inversion sprain