Liu Yong, Liang Xiaoju, Sun Jianping, Qu Jining, Qi Bohai, Yang Yating, Jie Qiang
Pediatric Orthopedic Hospital, Honghui Hospital, Xi'an Jiao tong University, Xi'an, 710000, China.
Yan'an University School of Medicine, Yan'an, 716099, China.
BMC Musculoskelet Disord. 2025 Jan 6;26(1):18. doi: 10.1186/s12891-024-08240-0.
Supracondylar humerus fractures (SCHFs) are the most common elbow fractures in children and are typically treated with closed reduction and Kirschner pin fixation. However, varying degrees of residual rotational displacement may remain after closed reduction. Several methods exist to assess rotational displacement, but none account for the effect of elbow rotation on the results. We hypothesize that the accuracy of the primitive rotational calculation formula (PRCF) decreases as elbow rotation increases and propose a modified rotational calculation formula (MRCF). This study aims to investigate the impact of elbow rotation on PRCF and validate the reliability of MRCF.
Mimics software was used to reconstruct the distal humerus in a child and create a transverse SCHF, which was then subjected to X-ray fluoroscopy simulation. Axial rotational displacement was simulated in 5° increments, from 0° to 45°. Internal and external elbow rotations were simulated by adjusting the "LAO" and "RAO" angles. Five physicians measured and calculated displacement using both the primitive and modified rotational calculation formulas.
The PRCF method showed an average error of 17.98° ± 12.31° with a maximum error of 46.46%. Additionally, 13% of measurements had an error under 3°, and 29% had an error under 10°. With MRCF, the mean error for internal rotation was 2.04° ± 1.67°, with a maximum of 6.09%; 68% of cases had an error under 3° and 94% under 5%. For external rotation, the mean error was 2.74° ± 2.66°, with a maximum of 8.29%; 57% of cases had an error under 3° and 98% under 8°. Intraclass correlation coefficients for the five physicians were 0.966 for internal rotation and 0.989 for external rotation.
This study demonstrates that the accuracy of PRCF decreases as elbow rotation increases, supporting our hypothesis. MRCF effectively addresses the limitations of PRCF and provides stable, accurate measurements of rotational displacement even with varying elbow rotations. Accurate assessment of rotational displacement in the horizontal plane is essential to understanding the relationship between residual rotational displacement and SCHF prognosis. MRCF will play a critical role in this process.
肱骨髁上骨折（SCHFs）是儿童最常见的肘部骨折，通常采用闭合复位和克氏针固定治疗。然而，闭合复位后可能会残留不同程度的旋转位移。目前有几种方法可用于评估旋转位移，但均未考虑肘部旋转对结果的影响。我们假设原始旋转计算公式（PRCF）的准确性会随着肘部旋转角度的增加而降低，并提出了一种改良的旋转计算公式（MRCF）。本研究旨在探讨肘部旋转对PRCF的影响，并验证MRCF的可靠性。
使用Mimics软件重建一名儿童的肱骨远端，并创建一个横行的SCHF，然后对其进行X线透视模拟。以5°为增量，从0°到45°模拟轴向旋转位移。通过调整“LAO”和“RAO”角度模拟肘部的内旋和外旋。五位医生使用原始旋转计算公式和改良旋转计算公式测量并计算位移。
PRCF方法的平均误差为17.98°±12.31°，最大误差为46.46%。此外，13%的测量误差在3°以下，29%的测量误差在10°以下。使用MRCF时，内旋的平均误差为2.04°±1.67°，最大为6.09%；68%的病例误差在3°以下，94%的病例误差在5°以下。对于外旋，平均误差为2.74°±2.66°，最大为8.29%；57%的病例误差在3°以下，98%的病例误差在8°以下。五位医生的组内相关系数在内旋时为0.966，在外旋时为0.989。
本研究表明，PRCF的准确性随着肘部旋转角度的增加而降低，支持了我们的假设。MRCF有效地解决了PRCF的局限性，即使肘部旋转角度不同，也能提供稳定、准确的旋转位移测量。准确评估水平面内的旋转位移对于理解残留旋转位移与SCHF预后之间的关系至关重要。MRCF将在这一过程中发挥关键作用。
