Electric muscle stimulation for treatment of functional shoulder instability

INTERVENTION: In a multicentric prospective randomized controlled trial, we would like to objectively assess a promising new EMS‐based treatment concept which was evaluated at our institution in a prospective pilot trial involving 24 cases with previously unsuccessful conventional physiotherapy treatment of FPSI. Pathology‐targeted physiotherapy is the current standard treatment of FPSI and will serve as the control intervention in the proposed trial. All involved centers as well as independent experts have specified and agreed on a standardized exercise protocol for the control intervention during a Delphi survey. The control intervention will have the same duration, intervals, and instructing physiotherapist (at each center) as the experimental intervention. An optional bi‐directional cross‐over into the other intervention group (experimental or control) is possible after follow‐up examination at the time‐point T2 (3 months after the beginning/6 weeks after the end of the intervention) in the case of subjectively unsatisfying results despite completion of the originally assigned intervention to offer both possibly superior interventions to all participants. Experimental intervention: electrical muscle stimulation based therapy protocol Control intervention: conventional state‐of‐the art physiotherapy protocol Follow‐up per patient: 0 weeks (T0), 6 weeks (T1), 3 months (T2), 6 months (T3), 12 months (T4) Duration of intervention per patient: 6 weeks The strict inclusion and exclusion criteria create a homogeneous group of study participants. After a patient has decided to enter the study and provided written informed consent, he/she will be randomized in one of the two treatment groups (allocation ratio 1:1). A randomization sequence will be generated electronically using Stata (StataCorp LP, Texas USA) separately for each participating center and loaded within an online study data CONDITION: Non‐controllable positional functional posterior shoulder instability (FPSI). ; Musculoskeletal Diseases PRIMARY OUTCOME: Western Ontario Shoulder Instability Index (WOSI) at T2 SECONDARY OUTCOME: ; 1. WOSI at T1, T3, and T4.; At 0 weeks (T0), 6 weeks (T1), 3 months (T2), 6 months (T3), 12 months (T4):; 2. Subjective shoulder value; 3. Impairment of daily activities; 4. Sports impairment; 5. Pain level; 6. Range of motion; 7. Strength; 8. Satisfaction with treatment; ; Assessment of safety: Based on the complication‐free pilot trial, no adverse events are pre‐specified but continuous recording of unexpected adverse events will be executed in both treatment arms.; INCLUSION CRITERIA: 1. Non‐controllable positional functional posterior shoulder instability (FPSI) 2. Aged 13 or over