Glenohumeral elevation-dependent influence of anterior glenohumeral capsular lesions on passive axial humeral rotation

Abstract

The purpose of this study was to assess the effect of standardized anterior glenohumeral capsular lesions on axial humeral rotation in a full arc of glenohumeral elevation. Using a testing apparatus, the range of internal and external humeral rotation was assessed in an arc of glenohumeral elevation in the scapular plane with steps of 15° in six isolated shoulder joint specimens. Cutting of the glenohumeral joint capsule 1 cm laterally from, and parallel to the glenoid rim was performed in seven steps of 1 cm till the anterior capsule was cut. Capsular lesions were made in three ways: from inferior, from superior and from the middle of the capsule. Anterior capsular lesions resulted in significant increase of external humeral rotation. This occurred particularly at 15–60° glenohumeral elevation. Lesions of the inferior part of the capsule mainly increased external rotation at 30–60° glenohumeral elevation, lesions of the superior part mainly in lower elevation angles and lesions of the middle more gradually in the range till 60° of glenohumeral elevation. Cutting of the anterior glenohumeral capsule barely increased passive axial humeral rotation at elevation angles over 60°. Above 60° glenohumeral elevation, tightening of the inferior posterior glenohumeral joint capsule prevented both internal and, increasingly, external humeral rotation. From these observations it is concluded that increased external rotation correlates with progressive anterior capsular lesions, mainly below 60° glenohumeral elevation. To assess anterior glenohumeral capsular lesions in patients, axial humeral rotation tests should probably not exceed 60° glenohumeral elevation, i.e. 90° thoracohumeral elevation.