A study of reproducibility of an original method of CT measurement of the lateralization of the intertubercular groove and humeral retroversion

Abstract

An original method of CT measurement of the lateralization of the humeral intertubercular groove is described based on geometric construction following Thales theorem. A study of intra- and interobserver reproducibility was done of this measurement and humeral retroversion on 32 healthy volunteers. The results show good reproducibility of these measurements. The average value of humeral retroversion was lower than the average values found in the literature: 11.71 degrees on average on the dominant side and 7.03 degrees on average on the non-dominant side with a large spread of values. The reasons for these differences are discussed. The average values of lateralization of the intertubercular groove were 114.97 degrees on the dominant side and 121.9 degrees on the non-dominant side. These CT measurements are important to consider in the pathophysiology of chronic anterior instability of the shoulder.

Correlation between the retroversion of the humeral head and the orientation of the intertubercular sulcus: a CT scan anatomical study

“…In our study, the mean humeral retroversion angle of 12.31°confirms other anatomical studies, which found mean normal values that were quite variable, from 9°to 40° [3,6]. This variation is due to several factors, including the definition of humeral head retroversion, different methods of measurement, ranges of normal values, and accuracy of anatomic landmarks to guide determination of anatomic retroversion.…”

“…Humeral head retroversion is generally defined with respect to the plane of the humeral head articular surface proximally; distally, however, the reference axis has been debated, including the transepicondylar axis [3,4,8], trochlear tangent axis [7,9,14,19] and forearm axis [8,18]. Methods of measurement have included direct anatomic [13,15], radiographic [4,14], ultrasound [10], computed tomography scan [3,8], MRI [6], and computer-assisted methods [5,19,21,22]. Boileau et al [2] showed that the radiographic method overestimated the humeral head retroversion relative to the computer-assisted method.…”

“…Rockwood et al [23] found a mean ITS orientation of 45°. Many authors studied the anatomy of the intertubercular sulcus [19,21,24], and some tried to define the relation with the humeral head retroversion [3,6,12]. Doyle and Burks [6] measured the distance from the biceps groove to a line perpendicular to the midpoint of the humeral articular surface.…”

“…Cassagnaud et al [3] measured the intertubercular sulcus and transepicondylar axis creating the angle of lateralization of the intertubercular sulcus. This method requires choosing four CT sections and superimposing them on a single plane.…”

Determining torsion angle of humerus head using MRI method

“…The authors calculated the average HTA in 32 healthy volunteers (17 females and 15 males between 22 and 44 years of age) as 11.71° on the dominant and 7.03° on the nondominant side. Consequently, they demonstrated that the CT measurement method was repeatable and that such measurements would be useful in shedding light on the pathophysiology of chronic anterior shoulder instability (16).…”