Gradual correction of proximal tibia deformity for Blount disease in adolescent and young adults

Abstract

Purpose: Management of Blount disease in adolescents and young adults is complex and associated with high risk of morbidities. Gradual correction with external fixator can minimize soft tissue injury and allow subsequent adjustment in degree of correction. This study investigates the surgical outcome and complication rate of gradual correction of neglected Blount disease through single-level extra-articular corticotomy. Methods: Patients treated for Blount disease using external fixator from 2002 to 2016 were recruited for the study. We used Ilizarov and Taylor Spatial Frame (TSF) external fixator to perform simultaneous correction of all the metaphyseal deformities without elevating the tibia plateau. Surgical outcome was evaluated using mechanical axis deviation (MAD), tibial femoral angle (TFA), and femoral condyle tibial shaft angle (FCTSA). Results: A total of 22 patients with 32 tibias have been recruited for the study. The mean MAD improved from 95 ± 51.4 mm to 9.0 ± 37.7 mm (medial to midpoint of the knee), mean TFA improved from 31 ± 15° varus to 2 ± 14° valgus, and mean FCTSA improved from 53 ± 14° to 86 ± 14°. Mean duration of frame application is 9.4 months. Two patients developed pathological fractures over the distracted bones, one developed delayed consolidation and other developed overcorrection. Conclusions: Correction of Blount disease can be achieved by gradual correction using Ilizarov or TSF external fixator with low risk of soft tissue complication. Longer duration of frame application should be considered to reduce the risk of pathological fracture or subsequent deformation of the corrected bone.