Factors associated with shoulder function following ultrasound-guided hydrodilatation in patients with frozen shoulder: a prospective observational study

Background: Existing research on the influence of symptom duration on the outcomes of ultrasound-guided shoulder hydrodilatation for frozen shoulder remains limited. This prospective analytical study aims to investigate the associations between symptom duration and other potential factors and shoulder function following ultrasound-guided shoulder hydrodilatation.Methods: This study was conducted at the Department of Rehabilitation Medicine, King Chulalongkorn Memorial Hospital, and involved patients with frozen shoulder who underwent ultrasound-guided shoulder hydrodilatation. Using convenience sampling, 72 participants were recruited, and 36 were classified into the early hydrodilatation group and 36 into the late hydrodilatation group. Outcome measures were the Oxford Shoulder Score (OSS), visual analog scale (VAS), and shoulder range of motion (ROM), which were assessed both before and 6 weeks after the hydrodilatation procedure.Results: Duration of symptoms, age, sex, history of diabetes mellitus, physiotherapy, and baseline shoulder ROM did not exhibit any association with OSS changes. However, a high VAS score at baseline was associated significantly with improved shoulder function following ultrasound- guided shoulder hydrodilatation (P=0.006).Conclusions: There was no association between the duration of symptoms and enhanced shoulder function after ultrasound-guided shoulder hydrodilatation in short-term assessments. Patients with higher baseline shoulder pain severity tended to experience greater improvements in shoulder function compared to those with milder pain levels.Level of evidence: III.