Shoulder Physiological Offset Parameters in Asian Populations-A Magnetic Resonance Imaging Study

Abstract

Background/Objectives: Physical shoulder offset parameters (SOPs) play important roles in the diagnosis and treatment of shoulder diseases. However, there is little research analyzing SOPs in healthy shoulders using cross-sectional MRI images, especially in Asians. Therefore, this study aimed to establish physiological reference values of shoulder parameters for Asian populations. Methods: This was a retrospective imaging study using MRI images of the shoulder joints of 500 patients (mean age: 55.9 ± 14.0 years). We measured the following SOPs of the normal joint: HO, GO, lateral glenoidal humeral offset (LGHO), humeral shaft axis offset (HAO), and cortical offset (CO). In addition, the offset parameters were examined for associations with age, gender, side, and osteoarthritis. Results: The mean HO was 22.9 (±2.4) mm, the mean GO was 62.3 (±6.6) mm, the mean LGHO was 48.9 (±4.2) mm, the mean HAO was 25.2 (±2.8) mm, and the mean CO was 15.7 (±2.7) mm. Male patients exhibited significantly higher values across all SOPs compared to female patients. In addition, there was a significantly lower mean value for HAO in left shoulders (HAO: 24.7± 2.8 mm vs. 25.5 ± 2.8 mm, p = 0.011). There was a negatively significant correlation between age and all SOPs. No significant difference in mean values was noted between shoulders with osteoarthritis and non-osteoarthritis in any SOPs. Conclusions: Significant gender- and age-specific differences were noted for all measured SOPs. In addition, right shoulders did not show higher mean SOP values than left shoulders, except for HAO, suggesting that the contralateral joint is a reliable reference for surgical planning. These findings should be considered in shoulder surgery planning.

Keywords: Asian; MRI; glenoidal offset; humeral offset; shoulder morphology.

Figure 1

HO, LGHO, HAO, and CO measurements were performed in the coronal view of the shoulder joint on MRI scans, while GO was evaluated in the axial view. (a) To assess the HO, the central point of rotation of the humeral head was identified, and the distance from greater tuberosity to this point was measured as the HO. (b) To measure the LGHO, we determined the center point of the glenoid fossa. The distance from greater tuberosity to this point is LGHO. (c) HAO was determined by measuring the distance from the humeral head shaft axis to the medial cortical edge of the humeral head. This was achieved by drawing a horizontal line that intersects the central point of the humeral head. (d) To measure the CO, we used the same horizontal line as for the HAO and identified the axis of the medial cortical bone of the humerus. The CO is defined as the distance from this axis to the medial cortical edge of the humeral head. (e) Measuring the GO requires first identifying the center of rotation of the humeral head in the coronal view. (f) Then, we used measurement software to locate the corresponding point in the axial view. GO was defined as the distance between this point and the neck of the scapula.

Figure 2

Correlation analysis between patients’ age and HO, GO, LGHO, HAO, and CO. The analysis showed a significant correlation (p < 0.001) between patients age and (a) HO (rho = −0.25), (b) GO (rho = −0.20), (c) LGHO (rho = −0.20), (d) HAO (rho = −0.24), and (e) CO (rho = −0.19).