Abstract
Objective: Current imaging methods used to examine patients with subacromial impingement syndrome (SIS) are limited by their semi-quantitative nature and their capability of capturing dynamic movements. This study aimed to develop a quantitative analytic model to assess subacromial motions using dynamic ultrasound and to examine their reliability and potential influencing factors. Method: We included 48 healthy volunteers and examined their subacromial motions with dynamic ultrasound imaging. The parameters were the minimal vertical acromiohumeral distance, rotation radius, and degrees of the humeral head. The generalized estimating equation (GEE) was used to investigate the impact of different shoulder laterality, postures, and motion phases on the outcome. Result: Using the data of the minimal vertical acromiohumeral distance, the intra-rater and inter-rater reliabilities (intra-class correlation coefficient) were determined as 0.94 and 0.88, respectively. In the GEE analysis, a decrease in the minimal vertical acromiohumeral distance was associated with the abduction phase and full-can posture, with a beta coefficient of −0.02 cm [95% confidence interval (CI), −0.03 to −0.01] and −0.07 cm (95% CI, −0.11 to −0.02), respectively. The abduction phase led to a decrease in the radius of humeral rotation and an increase in the angle of humeral rotation, with a beta coefficient of −1.28 cm (95% CI, −2.16 to −0.40) and 6.60° (95% CI, 3.54–9.67), respectively. A significant negative correlation was observed between the rotation angle and radius of the humeral head and between the rotation angle and the minimal vertical acromiohumeral distance. Conclusion: Quantitative analysis of dynamic ultrasound imaging enables the delineation of subacromial motion with good reliability. The vertical acromiohumeral distance is the lowest in the abduction phase and full-can posture, and the rotation angle of the humeral head has the potential to serve as a new parameter for the evaluation of SIS.
Highlights
Subaromial impingement syndrome (SIS) is the most common cause of shoulder pain, with a reported prevalence of 48% in a survey of 35,150 patients with shoulder complaints (van der Windt et al, 1995)
As the present study was the first attempt to validate the methodology of subacromial reciprocal movement quantification, we included only participants without any shoulder symptoms who visited the department of physical medicine and rehabilitation
Reliability was examined using the data of the minimal vertical acromiohumeral distance because the other parameters were estimated by the function for circle fitting
Summary
Subaromial impingement syndrome (SIS) is the most common cause of shoulder pain, with a reported prevalence of 48% in a survey of 35,150 patients with shoulder complaints (van der Windt et al, 1995). The incidence of SIS is high among athletes with repetitive overhead activities of the arm, such as volleyball players and swimmers (Lo et al, 1990). Various physical tests have been applied for the diagnosis of SIS, such as the painful arc, Neer’s impingement, and Hawkins-Kennedy tests, but their sensitivity and specificity are mostly unsatisfactory (Chang K.-V. et al, 2020). Owing to the limitations of physical examinations, several imaging methods have been developed to better assess SIS. The two imaging tools mentioned above are not widely used for the evaluation of SIS, considering their accessibility, cost-effectiveness, portability, and capability of dynamic assessment
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