In recent literature, the potential of guided growth of the proximal femur to modify hip growth in patients with cerebral palsy has been shown. Using medial hemi-epiphysiodesis of the proximal femur (TMH-PF) morphology of hips at risk of symptomatic (sub)luxation in cerebral palsy (CP) can be changed, aiming to reduce further hip migration and the need for more invasive surgical treatment modalities. Further research is necessary to assess if the results of TMH-PF in combination with adductor tenotomies are significantly better than the results of the current standard of care; adductor tenotomies alone. The investigators objective is to determine whether guided growth of the proximal femur decreases the risk of further hip migration and need for further surgery in cerebral palsy patients.