Predictive Value for Femoral Head Sphericity From Early Radiographic Signs in Surgery for Developmental Dysplasia of the Hip Chia-Hsieh Chang, MD,* Wen-E Yang, MD,* Hsuan-Kai Kao, MD,* Chun-Hsiung Shih, MD,w and Ken N. Kuo, MDzy Background: Avascular necrosis after treatment for late devel- opmental dysplasia of the hip can result in deformity of the femoral head and long-term morbidity. This study aims to analyze the clinical and radiographic factors that are associated with femoral head deformity in the early stage of avascular necrosis. Methods: Thirty patients with unilateral developmental dyspla- sia of the hip treated by the same operation before 3 years of age and who developed early signs of avascular necrosis, were studied. Avascular necrosis was diagnosed by either broadening of the femoral neck, fragmentation of the capital epiphysis, or the presence of a metaphyseal growth disturbance line in the first postoperative year. After 10-year follow-up, the hips were classified into spherical head or deformed head by irregularity <2 mm or more to analyze the associated factors. Results: Sixteen hips had spherical femoral heads and the other 14 hips had deformed femoral heads. Age, sex, side, Tonnis classification, and preoperative or postoperative acetabular index were not associated with the outcome after avascular necrosis. Among the early signs of avascular necrosis, fragmen- tation of the capital epiphysis was significantly associated with later head deformity. Fragmentation was a sign with high sensitivity (79%) and high specificity (88%) in predicting a deformed head. Broadening of femoral neck had a high sensitivity (93%), but a low specificity (38%) in outcome prediction. Conclusions: Fragmentation and flattening of the femoral epiphysis are the worst radiographic signs indicating subsequent growth disturbance and deformity of the proximal femur. Broadening of the femoral neck exhibited high sensitivity in predicting later deformity, and physicians should be alerted to subsequent epiphyseal fragmentation. A metaphyseal growth disturbance line is a sign of avascular necrosis, but the predictive value is limited. Level of Evidence: Diagnostic level 3. Key Words: developmental dysplasia of the hip, head sphericity, avascular necrosis (J Pediatr Orthop 2011;31:240–245) A vascular necrosis is a disaster after the treatment of developmental dysplasia of the hip (DDH). Cooperman et al 1 reported that 80% of 30 hips had moderate or severe osteoarthritis in a 37-year follow-up of avascular necrosis. 1 As experienced in the Legg-Calve´- Perthes disease, the sphericity of the femoral head was determined to be a significant prognostic factor for early hip degeneration. 2,3 After treatment for DDH, a common cause of femoral head deformity is avascular necrosis 4,5 and sphericity of the femoral head was also found to play a role in early hip degeneration. 6 As hips with avascular necrosis do not always recover to a spherical femoral head, the factors predicting a greater risk of head deformity after avascular necrosis are of clinical significance. Keret and MacEwen 7 reported 90 patients with avascular necrosis and classified them as mild, moderate, and severe. Excellent and good results at skeletal maturity were found in 17 of 29 mild cases (59%), 7 of 17 moderate cases (41%), and 13 of 44 severe cases (30%). The classification of severity did not seem to offer significant value in predicting the outcome after avascular necrosis. In reviewing the patients with unilateral DDH who underwent the same surgical treatment in the hospital of the authors, we found that half of the hips with avascular necrosis had recovered to spherical femoral heads, whereas the other half had proceeded to deformed femoral heads 10 years later. The purpose of our study was to analyze the clinical and radiographic factors that are associated with femoral head deformity in the early stage of avascular necrosis. METHODS Patients In a retrospective review of medical records, we identified 91 patients who underwent 1-stage open Copyright r 2011 by Lippincott Williams & Wilkins From the *Department of Pediatric Orthopedics, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan; wDepart- ment of Orthopedic Surgery, Chung Shan Hospital; zDepartment of Orthopedic Surgery, National Taiwan University Hosptial; and yCollege of Medicine, Taipei Medical University, Taipei, Taiwan. Supported by none. Reprints: Ken N. Kuo, MD, College of Medicine, Taipei Medical University, 250 Wu Hsing Street, Taipei 110, Taiwan. E-mail: kennank@aol.com. ORIGINAL ARTICLE 240 | www.pedorthopaedics.com J Pediatr Orthop  Volume 31, Number 3, April/May 2011