Cerebral Palsy Hip Interventions Project (CP-HIP) - Statistical Analysis Plan

Cerebral Palsy Hip Interventions Project (CP-HIP) is a randomised clinical trial comparing adductor muscle release (arm: soft tissue release; STR) against early bony reconstructive surgery (arm: varus derotation osteotomy; VDRO) for the management of hip displacement in young children with cerebral palsy. STR is a less invasive procedure than VDRO and is used to delay the requirement for bony surgery in young children as well as being potentially the definitive hip surgical procedure, for some children. However, it may be less effective than early VDRO. The primary outcome is migration percentage (MP), a measurement of hip displacement, at two years post-surgery. However, because the study is testing a more invasive versus a less invasive intervention, several other outcomes are of interest, including post-operative adverse events, pain, and health related quality of life. A health economic evaluation is also planned. CP-HIP planned to recruit 40 participants with early hip displacement (MP>30) and a restricted range of hip abduction, for whom either STR or VDRO would be appropriate, through the Department of Orthopaedics at The Royal Children’s Hospital.