Fabeck L G, Farrokh D, Tolley M, Tollet P E, Zekhnini C, Delincé P E
Department of Orthopaedic and Traumatology, CHU Saint-Pierre, Brussels, Belgium.
J Shoulder Elbow Surg. 2001 Nov-Dec;10(6):546-9. doi: 10.1067/mse.2001.119395.
Computed tomography (CT) allows calculation of anatomic and prosthetic humeral head retroversion. The purpose of this study was to demonstrate how the retroversion angle measured by CT scan varied with changes in arm position in the CT scan reference system. A trigonometric analysis shows that the measured retroversion angle decreases when the arm is in extension and increases when it is in flexion, compared with the true retroversion angle determined perioperatively. For the same degree of flexion, or extension, the error of measurement is greater when the initial true retroversion is low. A shoulder prosthesis with 20 degrees of true head retroversion was radiologically scanned with different degrees of flexion, extension, and abduction. The results validate the theoretical analysis. Trigonometric formulas are proposed to correct the retroversion angle measured by CT scan.
计算机断层扫描（CT）能够计算解剖学上的肱骨头后倾角以及假体的肱骨头后倾角。本研究的目的是展示在CT扫描参考系统中，通过CT扫描测量的后倾角如何随手臂位置的变化而变化。三角分析表明，与术中确定的真实后倾角相比，当手臂伸展时测量的后倾角减小，而当手臂屈曲时测量的后倾角增大。对于相同程度的屈曲或伸展，当初始真实后倾角较低时，测量误差更大。对具有20度真实头部后倾角的肩部假体进行了不同程度的屈曲、伸展和外展的放射学扫描。结果验证了理论分析。提出了三角公式来校正通过CT扫描测量的后倾角。
