Article Abstract

Three dimensional modeling and parameter analysis of glenohumeral joint: a method to decide the operative treatment of shoulder instability

Authors: Guang-Wen Yu, Young Lae Moon, Xiao-Bing Xiang, Qing-He Ding

Abstract

Backgrounds: Three-dimensional (3D) measurement in computer software has become increasingly popular, which uses 3D visualization instead of traditional two-dimensional (2D) viewing angle by plain X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI). The goal of this study is to introduce the 3D modeling of glenohumeral joint and a method of 3D measurement technique by using computer tool. We hope it can achieve accurate parameters by computer tool and help surgeons to choose the treatment of shoulder instability. Also, the parameters of normal shoulder can help us choose the prosthesis of both total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA).
Methods: Three dimensional measurement and relative parameters of glenoid and humeral head in normal cadaver and one patient’s shoulder were evaluated with software of Mimics and Imageware, in order to choose the treatment of shoulder instability. We used the Chinese Digital Man No. 1 and Woman No. 1 as the normal cadaver and patient’s shoulder as instability modeling, which were collected and made by Southern Medical University in Guangzhou, China. Four shoulders (both shoulders of the Chinese Digital Man No. 1 and Woman No. 1) were collected from DICOM format by CT scans and three dimensional reconstructions were performed in Mimics software.
Results: The parameters of normal glenoid and humeral head were the anteroposterior diameter, supra-inferior diameter, depth and curvature radius of glenoid labrum, and radius of humeral head. The Man No. 1: The left and right shoulder showed 24.66 and 23.70 mm of anteroposterior diameter, 34.70 and 33.43 mm of supra-inferior diameter, 4.05 and 4.01 mm of depth of glenoid labrum, 25.62 and 25.02 mm of curvature radius of glenoid labrum, 22.16 and 22.22 mm of radius of humeral head, respectively. The Woman No. 1: The left and right shoulder showed 20.40 and 19.96 mm of anteroposterior diameter, 29.68 and 29.35 mm of supra-inferior diameter, 2.48 and 2.34 mm of depth of glenoid labrum, 27.92 and 26.47 mm of curvature radius of glenoid labrum, 20.48 and 19.80 mm of radius of humeral head, respectively. In another case we considered a 27-year-old male with a history of shoulder recurrent dislocation in May, 2018. His CT showed he suffered from a bony bankart injury and Hill-sachs lesion. We calculated and measured the parameters of his shoulder by computer software. The length of the lesion is 31.67 mm. The radius of the circle is 11.64 mm given in the software. According to the distance between border-top and border-bottom of bankart lesion that is 21.74 mm, the area of the circle equals 425.2028 mm2 and the area of bone loss equals 118.2855 mm2, for a calculated bone loss of 27.82%. The depth of the lesion is 11.13 mm.
Conclusions: A 3D model can provide a more vivid vision of the glenohumeral joint. We hope that measuring parameters can be performed by using computer software tool, without manual measurement and calculated in minimum error range.