In most developing countries like China, CT and MRI examinations do not have distribution equity. CT is also not recommended for frequent use given the high levels of radiation. However, MRI is not generally performed at every follow-up due to the high cost and technical requirement. Most importantly, the AP view failed to detect the anterior status of the necrotic lesion, which is also found to be significant for collapse progress through MRI ( 8). The AP view of radiograph is more frequently used, but has lower precision than CT and MRI ( 14). The above-mentioned staging systems of FHN predominantly detected disease progression via anteroposterior (AP) view of standard radiograph, CT or MRI. Therefore, collapse of the femoral head has been the main basis for the disease staging systems, such as Ficat ( 10), Steinberg ( 11) and ARCO ( 12), and also for treatment decisions ( 13). Once collapse of the femoral head occurs, patients treated with hip-preservation treatments could have poor prognosis and could require arthroplasty at a very young age ( 4– 6). It mainly occurs in the lateral and anterior parts of the femoral head, and could be detected by radiographs, computerized tomography (CT) and magnetic resonance imaging (MRI) with different indications, such as discontinuous femoral head surface, change of head shape and subchondral fracture ( 8, 9). Collapse of the femoral head has been generally viewed as the turning point of disease progression and also affects the treatment options ( 1, 2). Therefore, hip-preservation treatments are research hotspots, and early diagnosis and prediction of collapse are equally significant ( 7). Due to the high prevalence of FHN in young population, hip arthroplasty is not recommended in most cases because of the high risk of revision surgery ( 3– 6). It is a complementary method to AP view for detecting the collapse in femur head necrosis during the follow-up, which has moderate or substantial inter-observer reliability.įemur head necrosis (FHN) is a debilitating disease that could result in lower limb dysfunction ( 1– 3). The combination of the anteroposterior view and frog lateral view indicated higher reliability than individual views.Ĭonclusion: The frog lateral view radiograph has higher sensitivity and accuracy than anteroposterior view. Using the CT or MRI results of collapse as the gold standard, the frog lateral view indicated higher sensitivity and accuracy than the anteroposterior view (sensitivity: 82.8 vs. Results: A moderate or substantial reliability was indicated in the evaluation of frog lateral view radiograph, whereas the anteroposterior view only showed fair or poor reliability. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of each evaluation method were also calculated. The inter-observer reliability of each view of X-ray for detecting the collapse were analyzed through the weighted Cohen's kappa index. The anteroposterior view and frog lateral view of X-ray standard radiographs, CT and MRI of patients were collected and simultaneously evaluated by three orthopedists to evaluate the condition of collapse according to the unified standard. Methods: We retrospectively included 1001 hips of 620 patients with femur head necrosis. The purpose of this study was to verify the reliability of the frog lateral view radiograph in detecting the collapse of femoral head. 4Department of Joint Diseases, The Third Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, ChinaĪims: The collapse in femur head necrosis is generally detected by CT or MRI which are not primary routine examination at every follow-up in developing countries.3Department of Orthopedics, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.2Department of Orthopedics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.1Laboratory of Orthopaedics and Traumatology, Lingnan Medical Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China.Fan Yang 1,2 † Xiaoqiang Deng 1,3 † Pengfei Xin 1 Zhinan Hong 1,4 Fengxiang Pang 1 Wei He 1,4 Qiushi Wei 1,4 Ziqi Li 1,4 *

Normal hip frogleg xray