The radiocapitellar line (RCL) has been widely used to diagnose elbow dislocation. However, there are limitations to the RCL, with the cartilaginous portion of bone making interpretation of radiographs difficult. The study aims to show that the radiocoronoid line, which connects two points on the medial aspect of the radius, proximal to the radial tuberosity, is more suited to diagnose elbow dislocations in the anterior-posterior projection. This study also observes factors affecting accuracy of the radiocapitellar line. The radiographs of 50 normal and 17 laterally dislocated elbows were obtained. An unbiased independent reviewer drew the radiocoronoid and radiocapitellar line (RCL). Four other blinded independent reviewers drew the RCL and the radiocoronoid line for 20 radiographs and repeated the process a week later. The accuracy of the RCL was assessed using distance away from bisection point of capitellum, and ratio (distance from the point where line crosses capitellum to lateral aspect of capitellum over the total width of capitellum). The relationship of the radio-coronoid line and the lateral aspect of coronoid fossa was assessed, with dislocation being the line lateral to it and normal being medial to or on it. The radiocoronoid line had a higher accuracy (95.5%) compared to RCL (32.8%), higher specificity (94%) compared to RCL (10%) as well as higher positive predictive value (85%) compared to RCL (27.4%). There was no intra- or inter-observer variability for the radio-coronoid line. Skeletal age statistically predicted the ratio for the male population (P < 0.05), however, the independent variables did not statistically predict the dependent variables for the female and total population. The radiocoronoid line serves as an additional method to assess radiocapitellar joint lateral dislocation. It is more accurate and reliable than the radiocapitellar line in the anterior-posterior projection. Sex and skeletal age also influence the accuracy of the radiocapitellar line with the radiocapitellar line nearing the bisection point as skeletal age in males increases.

桡骨头线（RCL）已广泛用于诊断肘关节脱位。然而，RCL 存在局限性，骨骼的软骨部分使得 X 光片的解读变得困难。该研究旨在表明，连接桡骨内侧、桡骨结节近端的两个点的放射冠线更适合在前后投影中诊断肘关节脱位。这项研究还观察了影响放射线小头线准确性的因素。获得了 50 个正常肘部和 17 个横向脱位肘部的 X 光片。一位公正的独立评审员绘制了放射性冠状动脉和放射性小头线（RCL）。另外四名盲法独立评审员绘制了 20 张 X 光片的 RCL 和放射性冠状线，并在一周后重复了该过程。使用距小头平分点的距离和比率（从线穿过小头的点到小头横向的距离除以小头总宽度）来评估 RCL 的准确性。评估放射冠突线和冠突窝外侧的关系，脱位是其外侧的线，正常的是其内侧或上方的线。与 RCL (32.8%) 相比，放射性冠状线具有更高的准确性 (95.5%)，与 RCL (10%) 相比，其特异性 (94%) 更高，与 RCL (27.4%) 相比，其阳性预测值 (85%) 更高。放射冠突线没有观察者内或观察者间的变异性。骨龄统计预测了男性人口的比例（P < 0.05），但是，自变量并没有统计预测女性和总人口的因变量。放射性冠状线作为评估放射性小头关节侧向脱位的附加方法。它比前后位投影中的桡骨头线更准确、更可靠。性别和骨骼年龄也会影响放射小头线的准确性，随着男性骨骼年龄的增加，放射小头线接近平分点。