Scapular Kinematic During Arm Elevation in Shoulder Impingement Syndrome Using Motion Analysis System: A Systematic Review and Meta-analysis

Context: With a key role in normal shoulder function, scapular kinematics have been investigated in shoulder impingement syndrome (SIS). Objectives: This systematic review aimed at determining scapular kinematic patterns in patients with SIS compared to in asymptomatic individuals. Data Sources: Databases such as PubMed, Scopus, Web of Science, Ovid, Embase and PEDRO were searched from January 1995 to June 2021. Study Selection: Articles in English published in peer-reviewed journals and using motion analysis systems to compare scapular kinematics between patients with SIS and asymptomatic subjects during arm elevation were included. Data Extraction: A modified Downs and Black checklist was used to assess the risk of bias of the included studies. A random-effects model was employed to perform a meta-analysis. Results: Nine out of 1650 screened abstracts were included for data extraction. Scapular upward rotation significantly decreased during arm elevation in SIS (SMD = -0.13, 95% CI = -0.23 to -0.02) with a low effect size (I 2= 46%). No differences were observed in scapular posterior tilt (SMD = -0.07, 95% CI = -0.18 to 0.03) and external rotation (SMD = 0.02, 95% CI = -0.06 to 0.09) between patients with SIS and asymptomatic subjects. Conclusions: This review revealed that except for scapular upward rotation, scapular movement was generally insignificantly different between the subjects with and without SIS during arm elevation. Between-group differences might have been overlooked as a result of the high risk of bias in the included studies. The high-quality studies addressing confounders are required to provide a definitive conclusion on the relationship between SIS and scapular kinematics.