Abstract
BACKGROUND: Developmental dysplasia of the hip (DDH) is the most common musculoskeletal disorder in the neonatal period, which is usually screened using ultrasound. Infants diagnosed with Graf II (a, b, c) type DDH generally undergo treatment with the Pavlik harness at 6 weeks of age. The Pavlik harness can affect the quality of life of infants. Swimming therapy has been shown to enhance neuromotor development and muscle coordination in typical infants. For infants with specific motor disorders such as cerebral palsy, it can also reduce joint load through water buoyancy and improve gross motor function. However, this evidence is derived from populations with clinical characteristics different from those of infants with Graf II type DDH. Its role in key rehabilitation areas for DDH infants, such as regulating hip biomechanics and promoting acetabular development, has not been systematically explored. Therefore, the efficacy of swimming therapy in infants with Graf II type DDH remains unclear. This study aims to explore the efficacy of this therapy in infants with Graf II type DDH and investigate whether it can be used as a new or supplementary clinical treatment method. METHODS: This study is a randomized, prospective clinical trial with a sample size of 136, which was calculated based on previous studies with an alpha risk of 0.05, a beta risk of 0.20, and a 15% follow-up loss assumption. Children will be randomly divided into two groups. The control group will receive the Pavlik harness, while the swimming group will receive 2 swimming sessions per week in addition to the Pavlik harness. Follow-up duration ranges from 6 weeks to 6 months after birth. Primary outcomes include changes in hip α angle after 20 weeks of intervention, assessed using weekly ultrasound. Secondary outcomes include β-angle improvement rate, duration of brace use, surgery conversion rate, and the incidence of adverse events. We employ analysis of covariance (ANCOVA) to adjust for baseline differences and intention-to-treat (ITT) principles and handle missing data. Parametric/non-parametric tests will be used based on data normality. DISCUSSION: This study aims to evaluate the effects of swimming intervention on DDH and clarify the safety of swimming therapy. TRIAL REGISTRATION: This study was registered with the Chinese Clinical Trial Registry, registration number: ChiCTR2400088288, registration date: August 15, 2024.