Adikrishna A, Hong H, Deslivia M F, Zhu B, Tan J, Jeon I-H
Department of Orthopaedics Surgery, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Republic of Korea.
Department of HCI and Robotics, University of Science and Technology, Daejon, Republic of Korea; Center of Robotics, Korea Institute of Science and Technology, Seoul, Republic of Korea.
Orthop Traumatol Surg Res. 2017 Apr;103(2):159-163. doi: 10.1016/j.otsr.2016.11.015. Epub 2017 Jan 8.
Restoration of native head-shaft angle (HSA) is critical for treatment of proximal humerus fracture. However, HSA has not been properly investigated according to the humeral rotation. This study was designed to analyze the relationship between the humeral rotation and the HSA at 1° increments, and clarify its serial changing pattern according to the humeral rotation.
The angulation of HSA would be undervalued when the humerus is being rotated externally and it would be overvalued when it is being rotated internally.
Eight dried cadaveric normal humeri were CT scanned. They were analyzed using computer-aided design with a standardized neutral position. HSA was the angle between the humeral shaft axis (SA) and the humeral head axis (HA). SA and HA were the best-fit lines through center of all the best-fitting circles in every cross section along the humeral shaft and within the humeral head, respectively. Each 3D model was rotated 30° internally and 45° externally relatives to the SA at 1° increments with the camera was fixed at antero-posterior view of neutral position. Angulation of HSA in every rotational degree was documented as ratio relatives to the angulation of HSA in neutral position.
The average HSA at neutral position was 133±1.93°. HSA was underestimated by 8±1.9% and it was overestimated by 20±5.1% at the maximum external rotation (ER) and internal rotation (IR), respectively. HSA was underestimated by 1% in every 5.8° of ER and overestimated by 1% in every 1.5° of IR. Rotational misalignments within 10° of IR and 18° of ER could be tolerated (P>.05).
HSA was underestimated at ER and was overestimated at IR. This information could be useful for surgeons in restoring the native HSA for treatment of proximal humerus fracture.
Basic research study.
恢复正常的头干角（HSA）对于肱骨近端骨折的治疗至关重要。然而，尚未根据肱骨旋转对头干角进行恰当的研究。本研究旨在分析肱骨旋转与头干角之间以1°增量变化的关系，并阐明其随肱骨旋转的连续变化模式。
当肱骨外旋时，头干角的角度会被低估；而当肱骨内旋时，头干角的角度会被高估。
对8具干燥的尸体正常肱骨进行CT扫描。使用计算机辅助设计在标准化中立位对其进行分析。头干角是肱骨干轴线（SA）与肱骨头轴线（HA）之间的角度。SA和HA分别是沿着肱骨干的每个横截面以及肱骨头内所有最佳拟合圆的中心的最佳拟合线。将每个三维模型相对于SA分别进行30°内旋和45°外旋，每次旋转1°，相机固定在中立位的前后视图。记录每个旋转角度下头干角的角度，并将其表示为相对于中立位头干角角度的比例。
中立位时头干角的平均角度为133±1.93°。在最大外旋（ER）和内旋（IR）时，头干角分别被低估8±1.9%和高估20±5.1%。每外旋5.8°头干角被低估1%，每内旋1.5°头干角被高估1%。内旋10°和外旋18°以内的旋转错位可被接受（P>.05）。
外旋时头干角被低估，内旋时头干角被高估。该信息对于外科医生在治疗肱骨近端骨折时恢复正常头干角可能有用。
基础研究。
