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Purpose To evaluate the intra and interobserver reproducibility of a new system that assesses the three-dimensional humero-scapulo-thoracic kinematics using wearable technology in an outpatient setting. To obtain normative data with the system for scapular angular motions in three planes. Methods The SHoW Motion 3D kinematic tracking system is a motion analysis system that uses wireless wearable non-invasive inertial-magnetic sensors to assess the three-dimensional kinematics of the shoulder girdle. The sensors are placed over the skin in the sternum, scapular spine and arm to precisely define angular motions of the humerus and the scapula with three Degrees of Freedom (DOF) for each segment. The system was used to measure the scapular angular motions in three planes (upward/downward rotation, internal/external rotation and anterior/posterior tilt) during two shoulder full-range movements (flexion/extension and abduction/abduction) in both shoulders of 25 healthy volunteers (13 males and 12 females, mean age: 37 [standard deviation 11.1] years). In a first measuring session one examiner made two evaluations alternating with another examiner that made a third evaluation. In a second session, one week apart, the first examiner made a fourth evaluation. A mean curve was computed from the normalized data for each measurement to obtain normative data for scapular angular kinematics. Intra and inter-observer reproducibility was evaluated using Root Mean Square Error Estimation (RMSE) and Coefficients for Multiple Correlations (CMC). Results Both shoulders of the 25 volunteers were evaluated four times. The two hundred resulting kinematic analyses were pooled to get normative values for relations between humeral elevation angles and the three angular movements of the scapula. The system showed at least very good (CMC > 0.90) intra and inter-observer reproducibility for scapular tilt and upward-downward rotations both in flexion and abduction. For scapular internal-external rotation the results were acceptable (CMC > 0.75) but not as good, especially for the abduction movement. RMSE calculations showed consistently good reproducibility with RSME Conclusion The SHoW Motion 3D kinematic tracking system is a quick, reproducible and easy to use system for the assessment of scapular angular kinematics in healthy adults. The data obtained is similar to that obtained with other validated methods. Level of evidence Level II. Clinical relevance The presented system is portable, easy to use and fast. It also has good intra and inter-observer reproducibility, making it a good tool to assess objectively scapular dyskinesis in the clinical setting. The normative data obtained is consistent with previous information available.

Latissimus dorsi tendon transfer is a surgical option for the treatment of massive irreparable posterosuperior rotator cuff tear. Whether a favourable clinical outcome is due to the latissimus dorsi muscle contraction rather than the passive tenodesis effect remains to be confirmed. The purpose of the current case–control study was to evaluate the shoulder kinematics and latissimus dorsi activation after latissimus dorsi tendon transfer. Eighteen patients suffering from irreparable rotator cuff tear that underwent latissimus dorsi tendon transfer and 18 healthy individuals were examined using a 3D kinematic tracking system and electromyography. Active maximal flexion–extension and abduction–adduction of the humerus were measured for the operated and the contralateral shoulder of the patients and the shoulder of healthy individuals to evaluate the range of motion (ROM) and scapulohumeral rhythm. Electromyographic comparison of isometric contraction between the latissimus dorsi of the operated and contralateral shoulder was carried out. After arthroscopic-assisted latissimus dorsi tendon transfer, patients showed comparable flexion and abduction ROM to their asymptomatic contralateral shoulders and to the shoulders of healthy individuals. Significantly higher scapular ROM values were found between the latissimus dorsi tendon transfer side and the shoulders of healthy individuals. While performing external rotation with 0° shoulder abduction, a greater percentage of the electromyographic peak value (p = 0.047) and a higher latissimus dorsi internal/external rotation ratio (p = 0.004) were noted for the transferred muscle in comparison to the contralateral shoulder. Although the arthroscopic-assisted latissimus dorsi tendon transfer failed to normalize scapulothoracic joint movements of patients, a functional latissimus flap and a shoulder ROM similar to the contralateral side or the shoulder of healthy individuals can be expected after this procedure in patients with massive irreparable posterosuperior rotator cuff tear. III.

While the undisturbed Earth&rsquo, s magnetic field represents a fundamental information source for orientation purposes, magnetic distortions have been mostly considered as a source of error. However, when distortions are temporally stable and spatially distinctive, they could provide a unique magnetic landscape that can be used in different applications, from indoor localization to sensor fusion algorithms for attitude estimation. The main purpose of this work, therefore, is to present a method to characterize the 3D magnetic vector in every point of the measurement volume. The possibility of describing the 3D magnetic field map through Thin Plate Splines (TPS) interpolation is investigated and demonstrated. An algorithm for the simultaneous estimation of the parameters related to magnetometer calibration and those describing the magnetic map, is proposed and tested on both simulated and real data. Results demonstrate that an accurate description of the local magnetic field using TPS interpolation is possible. The proposed procedure leads to errors in the estimation of the local magnetic direction with a standard deviation lower than 1 degree. Magnetometer calibration and magnetic field mapping could be integrated into different algorithms, for example to improve attitude estimation in highly distorted environments or as an aid to indoor localization.