Kinematic effects of two therapeutic interventions for glenohumeral joint instability: A preliminary feasibility trial.

PURPOSE: Multidirectional instability (MDI) of the glenohumeral joint involves excessive humeral translations with symptoms such as pain or apprehension. As MDI is typically managed through therapeutic exercise, this feasibility study examined the practicality of comparing targeted stabilization and general-strengthening interventions on glenohumeral kinematics and patient-reported outcomes.

SCOPE: Twenty competitive swimmers with MDI were randomized to a targeted rehabilitation group (MDI-EX) or a general shoulder exercise group (GSE). Participants completed 16 exercise sessions over eight weeks. Glenohumeral kinematics were captured with dynamic biplane radiography. The change in humeral position, instantaneous helical axis dispersion, and contact path length during arm activity were examined. Western Ontario Shoulder Instability (WOSI) scores collected before, after, and eight weeks after intervention were evaluated. There were no significant kinematic differences between groups (p = 0.07-0.99; effect sizes: 0.02-0.41). WOSI scores improved significantly after the intervention and at eight weeks (p < 0.01). Consistent kinematic changes and moderate effect sizes support the feasibility of larger studies.

CONCLUSION

This study demonstrates that measuring kinematic and patient-reported outcomes in MDI is feasible in a research setting, with early findings supporting further evaluation of targeted rehabilitation in larger cohorts.