Eight-Year Natural Course of a Femoral Neck Deformity Secondary to an Osteoid Osteoma Discovered at Fourteen Months of Age: A Case Report.

Abstract

Osteoid osteoma (OO) is a benign bone tumor that is rarely seen in patients before the age of five years1,2. Although localization in the femoral neck is not rare, deformities of the upper extremity of the femur secondary to an OO are uncommon, and there are few descriptions in the literature3. The following report describes the case of an OO of the femoral neck in a young child, complicated by a hip subluxation and coxa magna. One of the fundamental features of this case was the young age of the child, which explains the difficulty and delay in diagnosis. The natural course after isolated treatment of the OO by percutaneous radiofrequency ablation resulted in long-term reversal (eight years of follow-up) of the bone deformity and raises questions regarding the necessity of early surgical correction4. The local Ethics Committee granted approval for presentation of this case. The parents were informed that data concerning the case would be submitted for publication, and they provided consent. A fourteen-month-old child was brought to the emergency department by his parents because of a left-sided limp. The child was grumpy and seemed to be in pain. Physical examination revealed stiffness of the left hip as well as atrophy of the quadriceps muscle. Even though the child was afebrile and blood tests showed no inflammatory syndrome (C-reactive protein, <10 mg/L; fibrinogen, 3.5 g/L; leukocyte count, 15 × 109/L), the first diagnosis we considered was septic hip arthritis. Nevertheless, an attenuated hemophilia was revealed (factor VIII at 35%). Radiographic evaluation of the pelvis (Fig. 1) showed several abnormalities (Reimer migration index of 50% on the left side versus 13% on the right side). The coxa magna was subtle but measurably different from the contralateral side (120%), and an …