Growth modulation with a medial malleolar screw for ankle valgus deformity

BACKGROUND AND PURPOSE Growth modulation with a medial malleolar screw is used to correct ankle valgus deformity in children with a wide spectrum of underlying etiologies. It is unclear whether the etiology of the deformity affects the angular correction rate with this procedure. PATIENTS AND METHODS 79 children (20 girls) with ankle valgus deformity had growth modulation by a medial malleolar screw (125 ankles). To be included, patients had to have undergone screw removal at the time of skeletal maturity or deformity correction, or a minimum follow-up of 18 months, and consistent radiographs preoperatively and at the time of screw removal and/or follow-up. The patients were assigned to 1 of 7 groups according to their underlying diagnoses. The lateral distal tibial angle (LDTA) was analyzed preoperatively, at screw removal, and at follow-up. RESULTS Mean age at operation was 11.7 (7.4-16.5) years. The average lateral distal tibial angle normalized from 80° (67-85) preoperatively to 89° (73-97) at screw removal. The screws were removed after an average time of 18 (6-46) months, according to an average rate of correction of 0.65° (0.1-2.2) per month. No significant differences in the correction rate per month were found between the groups (p = 0.3). INTERPRETATION Growth modulation with a medial malleolar screw is effective for the treatment of ankle valgus deformity in patients with a wide spectrum of underlying diagnoses. The individual etiology of the ankle valgus does not appear to affect the correction rate after growth modulation. Thus, the optimal timing of growth modulation mainly depends on the remaining individual growth and on the extent of the deformity.