Accuracy of the glenohumeral subluxation index in nonpathologic shoulders

作者：Jacxsens Matthijs; Van Tongel Alexander; Willemot Laurent B; Mueller Andreas M; Valderrabano Victor; De Wilde Lieven^*

来源：Journal of Shoulder and Elbow Surgery, 2015, 24(4): 541-546.

DOI：10.1016/j.jse.2014.07.021

• 3D evaluation
• 3D CT scan
• 3D reconstruction
• glenohumeral subluxation
• humeral subluxation index
• subluxation index

Background: Correction of posterior humeral subluxation, measured by the humeral subluxation index (HSI) according to Walch, is necessary in total shoulder arthroplasty to prevent early loosening. The 3-dimensional (3D) measurement of the shoulder is becoming well accepted and common practice as it overcomes positional errors to which 2-dimensional (2D) glenohumeral measurements are prone. The first objective was to describe the HSI in a nonpathologic population with the 2D HSI according to Walch and a newly described 3D HSI method. The second objective was to compare both measuring methods with each other.
Methods: In 151 nonpathologic shoulders, the 2D HSI was measured on the midaxial computed tomography scan cut of the scapula. The 3D HSI, based on the native glenoid plane, was defined as X+R/2R 100%, in which X is the projection of the center of the humeral head to the anteroposterior axis of the glenoid fossa and R is the radius of the humeral head. Both measuring methods were compared with each other. Correlation was determined. Interobserver and intraobserver reliability of the 3D HSI was measured.
Results: The mean 3D HSI (51.5% +/- 2.7%) was significantly (P < .001) more posterior than the mean 2D HSI (48.7% +/- 5.2%), with a mean difference of 2.9% +/- 5.6%. No correlation was found between the 2D and 3D HSI. The interobserver and intraobserver reliability was excellent.
Conclusion: The 2D HSI seems to underestimate the humeral subluxation compared with a 3D reliable equivalent.

• 出版日期2015-4