Multilevel guided growth for hip and knee varus secondary to chondrodysplasia.

BACKGROUND: Young children with chondrodysplasia may develop multilevel varus deformities that compromise comfort and gait. The classic treatment of performing corrective, staged osteotomies, at each level of deformity, is a daunting prospect that is fraught with potential complications. To avoid this scenario, we have adopted single-event, multilevel surgery, using guided growth to simultaneously address bilateral varus deformities of the knee and hip, with good results.

METHODS: Three cousins with Schmid-type metaphyseal dysplasia, presented for treatment of progressive varus deformities. In lieu of osteotomies, we used simultaneous guided growth of the proximal and distal lateral femora and proximal lateral tibiae, while ignoring the distal tibial deformity. The pan-genu 8-plates served to neutralize the mechanical axis while preserving a horizontal knee. The rationale for applying the trochanteric 8-plate was to stabilize the proximal femoral chondroepiphysis, hoping to postpone or avert intertrochanteric osteotomy. The average age at surgery was 28 months, with a range of 19 to 33 months, and follow-up has ranged from 28 to 59 months (average 48 mo). The pan-genu 8-plates were removed after an average of 12 months, leaving the trochanteric implants in situ, pending further growth.

RESULTS: Neutralization of the mechanical axis resolved lateral knee thrust and intoeing. As the femur is effectively adducted by knee realignment, the greater trochanteric impingement on the ilium is alleviated. Lateral tethering of the trochanteric apophysis served to increase the femoral neck-shaft angle, improving the abductor lever arm. Each patient experienced complete resolution of the fatigue hip pain and Trendelenburg gait. As knee alignment was restored, the ankle varus resolved spontaneously, requiring no direct treatment. The clinical improvement was reflected in trending of the radiographic angles and axes toward normal.

CONCLUSIONS: These children have benefited from outpatient guided growth, rather than the anticipated osteotomies, to correct multilevel varus deformities. Our goal is to exclusively use guided growth, repeatedly as needed, to avoid osteotomies altogether. Annual follow-up until skeletal maturity is planned.

LEVEL OF EVIDENCE: Level IV-retrospective case series.