Multicenter Trial of Proximal Femoral Guided Growth in Children With CP and Hips at Risk of Dislocation (GGSH-MC)

Guided Growth in Spastic Hip - Multicenter Study (GGSH-MC)

The Guided Growth in Spastic Hip Multicenter Study (GGSH-MC) is a prospective, multicenter, randomized controlled trial that aims to evaluate the mid-term outcomes of Proximal Femoral Guided Growth (PFGG) in children with spastic cerebral palsy (CP) and hips at risk of dislocation (HRD). Hip dislocation is a common and severe complication in children with CP, especially those who are non-ambulatory, with a reported risk of 70-90%.

The trial includes children aged 3 to 8 years with spastic CP and HRD, defined by a migration percentage (MP) between 30% and 60%. Participants will be cluster-randomized by center into two parallel groups:

• Experimental Group: Standard prophylactic treatment for HRD + PFGG
• Control Group: Standard prophylactic treatment for HRD only

PFGG involves insertion of a fully threaded cannulated screw across the lateral cortex and proximal femoral epiphysis under fluoroscopic guidance, with the aim of modulating growth to improve hip containment. All patients will also receive standard soft tissue surgery (adductor and/or psoas tenotomies), as clinically indicated.

Follow-up will include clinical, radiographic, and functional assessments at 3 and 6 weeks, and at 6, 12, 18, and 24 months post-intervention. The study will include a 1-year inclusion period and a 2-year follow-up, concluding in October 2027.

Primary outcome measures include radiographic indicators of hip displacement. Secondary outcomes include functional scores, complication rates, and need for further surgery. A total of 42 participants (21 per group) will provide 80% power to detect significant differences at a 0.05 significance level. Analyses will be performed using intention-to-treat principles, with subgroup and multivariate analyses to explore modifying factors.

Cerebral palsy (CP) is the leading cause of severe physical disability in childhood, with a prevalence of 1.6 per 1,000 live births in developed countries. Spastic CP, affecting 75% of patients, often leads to progressive musculoskeletal deformities due to muscle imbalance, particularly around the hip joint. Hip dysplasia is the second most common deformity, and if untreated, can progress to dislocation, especially in non-ambulatory children (GMFCS IV-V), where risk exceeds 70%.

Hip displacement in CP is attributed to spasticity of the adductors and flexors, growth-related deformities such as coxa valga and acetabular dysplasia, and limited weight-bearing. These changes can impair function, sitting tolerance, hygiene, and quality of life. Current strategies emphasize surveillance and early intervention for hips at risk of dislocation (HRD), including soft tissue surgery. However, recurrence remains high, and reconstructive surgery, while effective, is invasive and associated with significant morbidity.

Proximal Femoral Guided Growth (PFGG) is a minimally invasive technique involving medial hemiepiphysiodesis with a cannulated screw to modulate proximal femoral growth and improve containment. Though early outcomes are promising, prospective multicenter evidence is limited.

This study is a prospective, multicenter, randomized controlled trial using cluster randomization by center to compare PFGG + standard treatment versus standard treatment alone. Children aged 3-8 years with spastic CP and HRD (MP 30-60%) will be included. The primary outcome is radiographic containment. Secondary outcomes include functional scores, pain, complications, and reintervention rates. Follow-up spans 24 months.

All surgeries follow a standardized protocol. Postoperative care includes early mobilization, use of hip abduction wedge, and physical therapy. Sample size is calculated for 80% power to detect a difference in dislocation rates, requiring 42 subjects. Data will be collected using standardized CRFs and managed centrally under SEOP oversight. Adverse events will be systematically recorded.

The study has IRB approval and complies with ISO 14155, GDPR, and the Helsinki Declaration. Funding is provided by the 2023 EPOS Research Grant (€10,000). Results will be published regardless of outcome.

Inclusion Criteria:

• Patients aged 3 to 8 years.
• Diagnosis of predominantly spastic cerebral palsy (CP).
• Any functional level according to the GMFCS.
• Hips at risk of dislocation (HRD), unilateral or bilateral, defined by a migration percentage (MP) between 30% and 60%.

Exclusion Criteria:

• Children with predominantly hypotonic or dystonic types of CP.
• Children with neuromuscular conditions other than CP.
• Children with high surgical/anesthetic risk.
• Documented history of reconstructive or palliative hip surgery.