Assessment of glenoid inclination on routine clinical radiographs and computed tomography examinations of the shoulder

Abstract

BACKGROUND: Accurate assessment of glenoid inclination is of interest for a variety of conditions and procedures. The purpose of this study was to develop an accurate and reproducible measurement for glenoid inclination on standardized anterior-posterior (AP) radiographs and on computed tomography (CT) images. MATERIALS AND METHODS: Three consistently identifiable angles were defined: Angle by line AB connecting the superior and inferior glenoid tubercle (glenoid fossa) and the line identifying the scapular spine; angle by line AB and the floor of the supraspinatus fossa; angle by line AB and the lateral margin of the scapula. Experimental study: these 3 angles were measured in function of the scapular position to test their resistance to rotation. Conventional AP radiographs and CT scans were acquired in extension/flexion and internal/external rotation in a range up to ±40°. Clinical study: the inter-rater reliability of all angles was assessed on AP radiographs and CT scans of 60 patients (30 with proximal humeral fractures, 30 with osteoarthritis) by 2 independent observers. RESULTS: The experimental study showed that angle and have a resistance to rotation of up to ±20°. The deviation from neutral position was not more than ±10°. The results for the inter-rater reliability analyzed by Bland-Altman plots for the angle fracture group were (mean ± standard deviation) -0.1 ± 4.2 for radiographs and -0.3 ± 3.3 for CT scans; and for the osteoarthritis group were -1.2 ± 3.8 for radiographs and -3.0 ± 3.6 for CT scans. CONCLUSION: Angle is the most reproducible measurement for glenoid inclination on conventional AP radiographs, providing a resistance to positional variability of the scapula and a good inter-rater reliability.

Measurements of three-dimensional glenoid erosion when planning the prosthetic replacement of osteoarthritic shoulders

“…1 The inclination angle was calculated here only to make comparisons with other similar studies and our measured inclination was consistent with reported values for normal scapulae. 18,20,25,30 In our OA scapulae, the inclination decreased, especially in group C. Instead of using the version V and orientation O proposed here, the 3D orientation of the glenoid could be characterised by the inclination and another angle measured in the plane perpendicular to the scapula. The radius of the fitted sphere was in the same range as the reported values, 21,22,35,36 as was the RMSE.…”

“…Our scapular axis does not pass through the glenoid centre, but follows the supraspinatus groove, as already proposed. 30 It is nearly parallel to the usual transverse scapular axis passing from the medial point of the scapula and the glenoid centre.…”

Distribution of bone and tissue morphological properties related to subacromial space geometry in a young, healthy male population

“…Technique: ratio of the glenoid-acromion distance to the glenohumeral distance. Specifically, the distance between the glenoid axis and the most lateral aspect of the acromion divided by the distance between the glenoid axis and the most lateral aspect of the humerus [2,25] Glenoid inclination (radiographic) View: anterior-posterior Technique: intersection between the glenoid axis and a line drawn along the floor of the supraspinatus fossa [22] Minimum subacromial space width (radiographic and ultrasonic)…”

“…Lastly, while all injury classification ranges were based on available data, the glenoid inclination classification may slightly diverge from those in the literature due to the variation in measurement technique. The measurement method in this research was one established recently by Maurer et al [22] that was shown to reliably measure inclination on radiographs. Thus, the injury classification of approximately 90°b y Hughes et al [17] was modified to 95°to include the difference in measurement technique.…”

“…Bone characteristics such as increased acromial anterior slope, lateral acromial angulation angle, reduced acromial tilt and an increased lateral acromion to humerus ratio (acromion index) have all been associated with SAIS and/or rotator cuff pathology [1-3, 5, 9, 12, 18, 21, 25, 29, 31-33, 38]. Additionally, an increased glenoid inclination angle has been associated with both increased superior migration of the humeral head and rotator cuff tear prevalence [11,17,19,22,37]. While these abnormal morphological features have been generally identified in an elderly population, leading researchers to hypothesize mechanistic origins to their development, variability in morphological features also exists in younger populations, suggesting possible genetic origins that would predispose individuals to SAIS [24,34].…”