Measurement Methods for Humeral Retroversion Using Two-Dimensional Computed Tomography Scans: Which Is Most Concordant with the Standard Method?

BACKGROUND: Humeral retroversion is variable among individuals, and there are several measurement methods. This study was conducted to compare the concordance and reliability between the standard method and 5 other measurement methods on two-dimensional (2D) computed tomography (CT) scans. METHODS: CT scans from 21 patients who underwent shoulder arthroplasty (19 women and 2 men; mean age, 70.1 years [range, 42 to 81 years]) were analyzed. The elbow transepicondylar axis was used as a distal reference. Proximal reference points included the central humeral head axis (standard method), the axis of the humeral center to 9 mm posterior to the posterior margin of the bicipital groove (method 1), the central axis of the bicipital groove -30° (method 2), the base axis of the triangular shaped metaphysis +2.5° (method 3), the distal humeral head central axis +2.4° (method 4), and contralateral humeral head retroversion (method 5). Measurements were conducted independently by two orthopedic surgeons. CONCLUSIONS: Humeral version measurement using the posterior margin of the bicipital groove (method 1) would be most concordant with the standard method even though all 5 methods showed excellent agreements.