Concomitant calcaneo-cuboid-cuneiform osteotomies and the modified Kidner procedure for severe flatfoot associated with symptomatic accessory navicular in children and adolescents

BACKGROUND Accessory navicular can become symptomatic in childhood, and in some cases, the condition is associated with progressive flattening of the longitudinal arch. Moreover, some severe, rigid flatfoot deformities are associated with an accessory navicular. We investigated the results of concomitant calcaneo-cuboid-cuneiform osteotomies (triple C) and the modified Kidner procedure for severe flatfoot associated with a symptomatic accessory navicular in children and adolescents. METHODS Twenty-one feet of 13 patients (nine boys, four girls; mean age 12.7 years) with severe flatfoot associated with a symptomatic accessory navicular who were treated with concomitant triple C and the modified Kidner procedure were evaluated based on clinical and radiographic examinations preoperatively and at a mean follow-up of 22.4 months (range, 12-36 months). We measured 12 variables on the anteroposterior (AP) and lateral weight-bearing radiographs, and we used the American College of Foot and Ankle Surgeons (ACFAS) score for clinical assessment. RESULTS We found significant improvements (p < 0.001) in eight of the 12 radiographic measurements: the AP talo-first metatarsal (MTT) angle, AP talo-navicular coverage angle, AP talo-calcaneal angle, lateral talo-first MTT angle, calcaneal pitch, lateral talo-calcaneal angle, lateral talo-horizontal angle, and naviculo-cuboid overlap. Average ACFAS scores were significantly improved at the time of the last follow-up (p < 0.001). The only complication was overcorrection of the hindfoot in one patient. CONCLUSIONS Concomitant triple C and the modified Kidner procedure result in favorable radiographic and clinical outcomes in the treatment of severe flatfoot associated with a symptomatic accessory navicular in children and adolescents.