Adding reciprocal inhibition to conventional physiotherapy for adhesive capsulitis of the shoulder in Bangladesh: a study protocol for a randomised controlled trial evaluating pain, function and range of motion

INTRODUCTION: Adhesive capsulitis (frozen shoulder) is a common condition characterised by pain, stiffness and reduced function. While conventional physiotherapy (typically comprising joint mobilisation, stretching, strengthening and electrotherapy) is widely used, there is limited evidence for the effectiveness of advanced neuromuscular techniques such as the reciprocal inhibition technique (RIT). This study aims to evaluate the impact of incorporating RIT into standard physiotherapy compared with standard physiotherapy alone in individuals with adhesive capsulitis. METHODS AND ANALYSIS: This is a double-blind, randomised controlled trial. 30 adults aged 30-70 years with clinically confirmed adhesive capsulitis will be recruited from a tertiary rehabilitation centre in Dhaka, Bangladesh. Participants will be randomly allocated to receive either RIT combined with conventional physiotherapy or conventional physiotherapy alone, with both groups undergoing 12 treatment sessions over 4 weeks. The primary outcome is pain intensity at 4 weeks post-randomisation, measured by the Numeric Pain Rating Scale. Secondary outcomes include shoulder range of motion (abduction, internal and external rotation, assessed with a universal goniometer), functional ability (Shoulder Pain and Disability Index) and muscle strength (abduction, internal and external rotation, measured by hand-held dynamometry). Blinded assessors will conduct evaluations at baseline and after the intervention. Data will be analysed using intention-to-treat principles. Between-group comparisons will be made using linear mixed models with fixed effects for group, time and group-by-time interaction, and a random intercept for participants to account for repeated measurements. Within-group changes will be estimated from the models. ETHICS AND DISSEMINATION: This trial has received ethical clearance from the Institutional Review Board of the Institute of Physiotherapy, Rehabilitation & Research (approval number BPA-IPRR/IRB/18/02/2025/32). Results will be disseminated through peer-reviewed publications and international conferences in accordance with Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines. By addressing a significant evidence gap, this study may establish RIT as an effective and affordable adjunct to standard physiotherapy for managing adhesive capsulitis. TRIAL REGISTRATION NUMBER: CTRI/2025/06/089288 [Registered on: 23/06/2025].