Comparison between 2D and 3D computed tomography evaluation of glenoid bone defect in unilateral anterior gleno-humeral instability

Purpose. This study evaluated the agreement between\r\n2D and 3D computed tomography (CT) measurements\r\nin identifying the size and type of glenoid-bone defect in\r\nanterior glenohumeral instability.\r\nMaterials and methods. One hundred patients affected by\r\nunilateral anterior glenohumeral instability underwent a\r\nCT of both shoulders. Images were processed with both\r\n2D [multiplanar reconstruction (MPR)] and 3D [volumerendering\r\n(VR)] methods. The area of the missing glenoid\r\nwas calculated in comparison with the healthy glenoid and\r\nexpressed as a percentage. Agreement between the two\r\nmeasurements was assessed according to the Bland-Altman\r\nmethod; a 5% mean difference was considered as clinically\r\nrelevant.\r\nResults. Analysis of agreement between MPR and VR\r\nmeasurements of the percentage of missing glenoid\r\nshowed a mean difference equal to 0.62%±1.96%. Percent\r\nagreement between the two measurements in detecting\r\nthe presence of bone defect was 97% (p<0.0001).\r\nPercent agreement between the two measurements\r\nin discriminating the type of bone defect was 97%\r\n(p<0.0001).\r\nConclusions. Agreement between 2D (MPR) and 3D\r\n(VR) CT measurements to identify the size and type of\r\nglenoid-bone defect in anterior glenohumeral instability\r\nwas so high that the two measurements can be considered\r\ninterchangeable.