Cross-Sectional study with control group, Level II.

The invention of inertial measurement units allowed the construction of sensors suitable for human motion tracking that are more affordable than expensive optical motion capture systems, but there are a few factors influencing their accuracy, such as the calibration methods and the fusion algorithms used to translate sensor readings into angles. The main purpose of this study was to test the accuracy of a single RSQ Motion sensor in comparison to a highly precise industrial robot. The secondary objectives were to test how the type of sensor calibration affects its accuracy and whether the time and magnitude of the tested angle have an impact on the sensor’s accuracy. We performed sensor tests for nine repetitions of nine static angles made by the robot arm in eleven series. The chosen robot movements mimicked shoulder movements in a range of motion test (flexion, abduction, and rotation). The RSQ Motion sensor appeared to be very accurate, with a root-mean-square error below 0.15°. Furthermore, we found a moderate-to-strong correlation between the sensor error and the magnitude of the measured angle but only for the sensor calibrated with the gyroscope and accelerometer readings. Although the high accuracy of the RSQ Motion sensors was demonstrated in this paper, they require further study on human subjects and comparisons to the other devices known as the gold standards in orthopedics.

Background GIRD is a condition resulting in the loss of internal rotation of the glenohumeral joint as compared to the contralateral side. Mechanism of GIRD is caused by repetitive throwing such as a handball throw. Difference between total shoulders range of motion (ROM) more than 25°is considered as GIRD positive sign. Objective To compare glenohumeral rotation motion between dominant and non-dominant shoulder in handball players. Design Cross sectional study. Setting Elite handball division players. Participants The pilot studies included 48 professional handball players of average age 24.0±4.5 years, height 187.1±5.9 cm, weight 91.0±11.6 kg.Interventions All handball players were tested for internal (IR) and external (ER) glenohumeral rotation range of motion. Mean values, minimum, maximum and standard deviation were calculated. Differences between the dominant (D) and non-dominant (ND) shoulder were determined. T-Test for two independent samples was used to analyze differences between D and ND shoulder. Statistical significance was set at P<.05. Main OutcomesROM. Results We obtained:for ER_D 60.63°±13.23°and for ED_ND 58.65°±13.98°, respectively; for IR_D: 92.60°±6.92°and for IR_ND 88.96°±6.99°. Total ROM values were 153.23°±17.79°f or D and 147.60°±18.76°for ND shoulder. Differences between D and ND shoulders was statistically significant only for IR: 3.65°± 4.34°; P=.0118. For ER: 1.98°±4.92°and Total ROM: 5.63°± 7.76°there was no significant differences (P>.05). Conclusions However there are some cases with glenohumeral internal rotation deficit there is more evidence that such a deficit does not exists in handball players. To verify this results further study with grater sample size should be conducted in comparison to other professional overhead athletes.

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