History of ankle sprain affect the star excursion balance test among youth football players.

BACKGROUND: The relationship between the results of the Star Excursion Balance Test (SEBT) and lateral ankle sprain (LAS) among youth football players was investigated. METHODS: The dominant leg and history of LASs were asked from 33 male youth football players. The SEBT in the anterior, posterolateral, and posteromedial directions were measured for both limbs. The relationship between the history of LAS and reach difference over 4 cm between the dominant and nondominant legs in each direction was statistically analyzed. RESULTS: The number of players with the history of LAS, whose dominant/nondominant reach difference was over 4 cm in the anterior direction, was significantly higher to that in players without a history of LAS in both the dominant (94% vs. 63%, p = 0.02) and nondominant (100% vs. 25%, p = 0.02) legs. CONCLUSION: Youth football players with a history of LAS showed reach deficit in the anterior direction in the SEBT.

Gait classification of knee osteoarthritis patients using shoe-embedded internal measurement units sensor.

BACKGROUND: Knee osteoarthritis negatively affects the gait of patients, especially that of elderly people. However, the assessment of wearable sensors in knee osteoarthritis patients has been under-researched. During clinical assessments, patients may change their gait patterns under the placebo effect, whereas wearable sensors can be used in any environment. METHODS: Sixty patients with knee osteoarthritis and 20 control subjects were included in the study. Wearing shoes with an IMU sensor embedded in the insoles, the participants were required to walk along a walkway. The sensor data were collected during the gait. To discriminate between healthy and knee osteoarthritis patients and to classify different subgroups of knee osteoarthritis patients (patients scheduled for surgery vs. patients not scheduled for surgery; bilateral knee osteoarthritis diagnosis vs. unilateral knee osteoarthritis diagnosis), we used a machine learning approach called the support vector machine. A total of 88 features were extracted and used for classification. FINDINGS: The patients vs. healthy participants were classified with 71% accuracy, 85% sensitivity, and 56% specificity. The "patients scheduled for surgery" vs. "patients not scheduled for surgery" were classified with 83% accuracy, 83% sensitivity, and 81% specificity. The bilateral knee osteoarthritis diagnosis vs. unilateral knee osteoarthritis diagnosis was classified with 81% accuracy, 75% sensitivity, and 79% specificity. INTERPRETATION: Gait analysis using wearable sensors and machine learning can discriminate between healthy and knee osteoarthritis patients and classify different subgroups with reasonable accuracy, sensitivity, and specificity. The proposed approach requires no complex gait factors and is not limited to controlled laboratory settings.

Differences in kinematic parameters during gait between the patients with knee osteoarthritis and healthy controls using an insole with a single inertial measurement unit: A case-control study.

BACKGROUND: An inertial measurement unit is small and lightweight, allowing patient measurements without physical constraints. This study aimed to determine the differences in kinematic parameters during gait using an insole with a single inertial measurement unit in healthy controls and on both sides in patients with knee osteoarthritis. METHODS: Twenty patients with knee osteoarthritis and 13 age-matched controls were included in this study. The participants walked at a self-selected speed and foot kinematics were measured during gait using an insole with a single inertial measurement unit. The right side of the healthy controls and both the affected and contralateral sides of patients with KOA were analyzed separately. FINDINGS: The foot extension angular velocity at toe-off was significantly reduced on the affected side than on the contralateral side (P < 0.001) and in healthy controls (P < 0.001). During the swing phase, foot posterior-anterior acceleration was significantly lower on the affected side than on the healthy controls (P = 0.005). Furthermore, despite a decrease in walking speed, foot superior-inferior acceleration at initial contact in patients was significantly lower on the contralateral side than in healthy controls (P = 0.0167), but not on the affected side (P = 0.344). INTERPRETATION: An insole with a single inertial measurement unit can detect differences in foot kinematics during gait between healthy controls and patients with knee osteoarthritis. Our findings indicate that patients with knee osteoarthritis exhibit dysfunction of push-off at toe-off and shock absorption at initial contact on the affected side.

Prevalence of disabled throwing shoulder and its shoulder function among youth football goalkeepers.

Aim: Although the football goalkeepers are overhead athletes, no studies have reported the prevalence of disabled throwing shoulder (DTS) and the shoulder function. Thus, this study aimed to investigate the prevalence of DTS among youth football goalkeepers and to determine the relationship among their shoulder functions. Methods: Youth football goalkeepers, who participated in a pre-participation medical examination were included in the study. The questionnaire was handed out before the examination to determine the players' age, dominant hand, and shoulder pain history. If the player had a history of shoulder pain during ball throwing motion in the past, they were defined as goalkeepers with DTS. Physical examination of scapular positioning, scapular retraction and rotator cuff muscle strength, and ultrasonographic evaluation were performed. Results: Six goalkeepers (16%) had a history of DTS among the 38 male youth football goalkeepers. The presence of scapular malpositioning, limitation of scapular retraction, and decrease in rotator cuff strength was significantly higher in goalkeepers with DTS than in those without DTS (p = 0.03, p < 0.001, p < 0.001, respectively). Three goalkeepers with DTS revealed ultrasonographic findings. Conclusion: The prevalence of DTS among youth football goalkeepers was 16%. All these players had scapular malpositioning and limitation of scapular retraction. Scapular malpositioning and limitation of scapular retraction may be related to the DTS in youth football goalkeepers. Level of evidence: Level IV.

Three-dimensional GRF and CoP Estimation during Stair and Slope Ascent/Descent with Wearable IMUs and Foot Pressure Sensors.

Wearable systems for gait analysis in daily living have been recently developed. Previous studies have demonstrated the significant potential of these systems; however, most of them focused on the level-walking condition, which is a limited portion of daily activities. To provide a new contribution to the gait analysis field, we have developed the first models for estimating three-dimensional (3D) ground reaction force (GRF) and center of pressure (CoP) during stair and slope ascent/descent with wearable sensors. Our system comprises light weight inertial measurement units (IMUs) and foot pressure sensors. We modeled the correlation between the measurements obtained with the wearable sensors and the ground truth of GRF/CoP from force plates, on the basis of linear regression models. Twenty healthy subjects completed a collection of ascent/descent tasks on stairs or slopes. We tested our models using cross-validation to evaluate the estimation accuracy in terms of the root mean square error (RMSE), the normalized RMSE (NRMSE), and the Pearson's correlation coefficient between the estimated GRF/CoP and those obtained from force plates. The experimental results showed practical estimation accuracy was obtained for GRF (RMSE ≤ 44.94 N) and CoP (RMSE ≤19.43 mm). Our system promises to contribute to clinical and sports medicine research by serving as a novel tool for assessing stair and slope ascent/descent outside laboratory environments.

Influence of thoracic posture on scapulothoracic and glenohumeral motions during eccentric shoulder external rotation.

BACKGROUND: Throwing injuries to the shoulder joint often occur during shoulder external rotation. An appropriate combination of thoracic, scapular, and humeral motion during throwing is important to prevent such injuries, but it is unclear how thoracic posture contributes to shoulder motion during throwing. RESEARCH QUESTION: The purpose of this study, therefore, was to clarify the influence of thoracic posture on scapulothoracic and glenohumeral motion during shoulder external rotation. METHODS: Eccentric external rotation at 90° of shoulder abduction in thoracic flexion and extension postures was performed by 15 asymptomatic participants. Three-dimensional scapulothoracic and glenohumeral movements were measured with an electromagnetic tracking device at 75°, 80°, 85°, and maximum shoulder external rotation. The thoracic angle and maximum shoulder external rotation in absolute coordination were measured with a three-dimensional motion capture system. RESULTS: The results showed that scapular posterior tilting and external rotation in the thoracic extension posture were significantly greater than those in the flexion posture (p < 0.05). Glenohumeral horizontal extension was significantly less in the thoracic extension posture than in the flexion posture (p < 0.05), whereas maximum shoulder external rotation was significantly greater (p < 0.01). Thus, thoracic extension increased scapulothoracic posterior tilting and external rotation and reduced glenohumeral horizontal extension during shoulder external rotation, as well as increasing maximum shoulder external rotation. SIGNIFICANCE: These findings suggest that thoracic extension may contribute to reduction of mechanical demand in the glenohumeral joint during throwing, potentially reducing shoulder injuries.