Up to one-third of children with CP have hip instability, with an increasing incidence associated with GMFCS level. Traditional surgical management for hip migration in patients with CP, includes hip reconstruction involving soft tissue releases, femoral and pelvic osteotomies. These procedures are associated with significant perioperative morbidity and long recovery times. In younger children, an adductor/psoas tenotomy can be considered as an alternative to hip reconstruction. However, the failure rate (defined as progression of migration to > 50% or the need for secondary bony surgery) is high with 34-74 % of patients requiring additional surgery. Recent reports have shown that guided growth can also be used to influence growth at the level of the hip by performing a temporary medial hemi-epifysiodesis of the proximal femur. A screw placed over the medial side of the proximal femoral epiphysis, can induce a tethering effect resulting in progressive varus of the proximal femur. Before this promising new technique can be widely implemented, a well-designed and adequately powered trial comparing the effect of soft tissue release alone with soft tissue releases and proximal femur guided growth to prevent progressive hip migration in CP patients is warranted.
The study we are conducting is a multicenter, randomized controlled trial. All centers involved in the care for children with CP in the Netherlands will participate in this study. We aim to include 84 children with spastic CP, GMFCS level IV and V, aged 2 to 8 years with an abduction ≤40 degrees, a migration percentage of 30-50% and a head shaft angle > 145 degrees. Participants will be randomized with a 1:1 allocation to either the intervention group; bilateral adductor/psoas tenotomies and guided growth of the proximal femur or the control group; adductor/psoas tenotomies only.
The primary outcome measure is treatment success, defined as: no need for secondary surgery to prevent or treat hip migration, or progression of hip migration to >50% during the planned 5-year follow-up.
Secondary outcomes will be changes in proximal femur morphology with regard to head shaft angle, hip migration percentage and other radiographic parameters, change in range of motion (ROM) and differences in patient reported outcome measures (PROMs), in both treatment arms. In a subgroup of patients 3D femoral head shape changes will be analyzed using advanced modeling techniques.
Should hemi-epiphysiodesis of the proximal femur indeed prove to be effective in preventing progressive hip migration, serious complaints and the need for major hip surgery can be prevented with a relatively simple and low-impact intervention. Therefore, the study results can have a significant impact for a large number of vulnerable CP patients, by reducing treatment morbidity and improving quality of life.