Geometrical analysis for assessing torsional alignment of humerus

Abstract

Background: Compared to other types of surgeries, minimally invasive surgeries (MISs) of humeral shaft fractures are associated with less radial nerve injury, less soft tissue injury and higher union rate. However, malrotation often occurs in MISs when closed reduction methods are used. This study aims to define specific palpable landmarks to help surgeons determine the correct torsional angle and reduce the incidence of malrotation. Methods: Twenty-eight normal humeral computed tomography scans were retrieved from our image database. One line was drawn through the vertices of the intertubercular sulcus of the humeral head in the coronal view, and another line was drawn through the longest axis between the medial and lateral condyles in the coronal view. The angle between these two lines was measured at least 3 times for each scan. Results: The profile of the intertubercular sulcus tangent line of the humeral head and the axis of the distal humerus was identified as the most accurate method for assessing the precision of torsion during MIS for humeral shaft fractures. The transepicondylar axis line is more internally rotated than the intertubercular sulcus tangent line. The mean angle was measured to be 41.1 degrees. Conclusions: The axis of the distal humeral condyles is internally rotated by approximately 41.1 degrees compared with the intertubercular sulcus tangent line of the humeral head. Minimally invasive surgeries can be performed by using these palpable landmarks. The torsional deformities can be reduced with the proper angle adjustment without the need for fluoroscopy. It can also be used to treat unstable comminuted humeral fractures. Level of evidence: Retrospective Study, Diagnostic study, Level III.

A new circle method for measuring humeral torsion on MRI-scans less sensitive to Hill-Sachs lesions

“…To find a normal value of the HTA, we were reviewing the literature ( Table 1 ). Of the 17 reviewed publications with sufficient number of measurements (number of shoulders and means) the combined means were calculated of measurements in CT-images [5] , [7] , [22] , [23] , [24] , [30] , [36] , in radiographs [6] , [19] , [28] and by ultrasonic scans [8] , [13] , [18] , [23] , [38] , [39] , [40] . The combined mean HTAs were 29° ± 25° (mean ± SD, n = 993), 27° ± 16° (n = 1673) and 36° ± 24° (n = 705), respectively.…”

“…If in such a position the humeral retrotorsion is diminished, the threshold for a spontaneous dislocation of the shoulder may be lowered, i.e., subluxation may occur earlier at lower degrees of abduction and/or external rotation [1] . Reviewing 40 methodologically defined studies published in the last 108 years [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] , [40] we found greatly varying methods and results. Most reports have investigated between 3 and 250 individuals, only one study has investigated 410 persons ( Table 1 ).…”

Ultrasonographic Measurement of Torsional Side Difference in Proximal Humerus Fractures and Humeral Shaft Fractures: Theoretical Background with Technical Notes for Clinical Implementation

“…The determination of the proximal joint axis proves to be particularly problematic, since clear landmarks for the determination of this axis are lacking in the region of the proximal humerus [ 34 ]. For the determination of the proximal joint axis [ 3 , 28 , 35 , 36 ] and the distal joint axis [ 3 , 28 ], different points of orientation are sometimes chosen in the literature, which is why the position of the two axes may differ slightly in various publications. As a result, torsion angles using different measurement methods, and sometimes even using the same measurement methods, can have very different values and cannot be directly compared with each other ( Table 2 ).…”