Progressive Genu Valgum Secondary to a Fibrous Tether at the Distal Aspect of the Femur. A Case Report

Bilateral angular deformity of the lower extremity in children is common, and it is often due to benign physiological conditions in which the deformity corrects with growth1,2. However, unilateral angular deformity is rare and usually involves an abnormal condition such as Blount disease, fibrous dysplasia, Ollier disease, dyschondrosteosis, neurofibromatosis, a growth disturbance resulting from a physeal injury or infection, or even a rare condition described as tibia vara caused by focal fibrocartilaginous dysplasia2. To our knowledge, only five children with unilateral angular deformity of the distal end of the femur secondary to a focal fibrous tether have been described in the literature, and only two of them had a valgus deformity1,3. We describe a boy who had a progressive genu valgum secondary to a tether of fibrous tissue, confirmed by histological examination, at the distal end of the femur. A twenty-seven-month-old boy was referred to us for evaluation of a valgus deformity of the distal aspect of the right femur. The mother had first noted the deformity when the child was twelve months old. At that time, the tibiofemoral angle measured 18 degrees radiographically. When the boy was eighteen months old, the tibiofemoral angle was 24 degrees (Fig. 1) and a varus osteotomy and a tenotomy of the iliotibial tract was performed by another surgeon. A biopsy of the bone revealed normal findings. The deformity recurred nine months later, with a resultant tibiofemoral angle measuring 40 degrees of valgus radiographically (Fig. 2). Fig. 1: Preoperative radiograph, made when the patient was eighteen months old, …