The Effects of Age and Migration Severity on Surgical Success After Guided Growth for Hip Displacement in Cerebral Palsy: A Preliminary Report

BACKGROUND: Hip displacement in cerebral palsy (CP) is common, with incidence linked to ambulatory status. In the past, children 6 years of age or younger were treated with adductor releases alone, but a high failure rate was reported. Proximal femoral guided growth (PFGG) has had modest improvements in hip migration (∼10%) for older children (6 y of age or older). The purpose of this study was to evaluate the effects of age and preoperative migration percentage (MP) severity on treatment success for young children (6 y of age or younger) with CP.

METHODS: Children with CP 6 years of age or younger, all Gross Motor Function Classification System (GMFCS) levels and motor types, undergoing PFGG ±adductor tenotomies, were identified. Children were stratified by age (younger than 4, 4 to 6 y), motor type, and preoperative MP. The primary outcome was the MP. A successful outcome was defined as a ∆MP ≥10% (definitive improvement) or ∆MP <5% (no progression) at final follow-up. Changes in MP and differences in success rates between age groups were determined.

RESULTS: Forty-four patients (78 hips) were included; follow-up was 1.9 (range: 0.8 to 4) years (22 [50%] ≥2 years follow-up). Concurrent adductor tenotomies were performed in 33 hips. All GMFCS levels showed improvement (GMFCS I-III: MP 37% to 29%, P=0.007, GMFCS IV to V: MP 43% to 37%, P<0.001). Greater MP improvements were seen for hips with preoperative MP ≥40% and for patients <4 vs 4 to 6 years old [41% to 28% (P<0.001) vs. 37% to 37% (P=0.44), respectively]. Definitive improvement was seen in younger children (younger 4 vs. 4 to 6 y: 62% vs. 13%, respectively; P=0.003), and both age groups had high success with no progression (100% vs. 81%, respectively; P=0.07).

CONCLUSIONS: PFGG was associated with improved hip migration for patients 4 years of age or younger, with high rates of success (no progression) for both age groups. Greater MP improvement was seen with MP ≥40%, possibly secondary to concomitant femoral neck shortening. Although PFGG offers a promising minimally invasive treatment for younger children with CP, further studies with longer follow-up duration, increased sample size, and comparison to an adductor-only group are necessary to determine its true efficacy.

LEVEL OF EVIDENCE: Level III.