Paper #17 - Remplissage of an off-track hill-sachs lesion is necessary to restore biomechanical glenohumeral joint stability in a bipolar bone loss model

Abstract

Purpose: To validate the “glenoid track” concept in a cadaveric bipolar bone loss model and to test whether “on-track” and “off-track” lesions can be adequately stabilized with Bankart or remplissage repair techniques. Methods: Eight fresh-frozen cadaver shoulders were tested in a custom shoulder rig with passive axial rotation and then progressive translational loading (10-40N). The injury conditions included glenoid bone loss of 15% with “on-track” (15%) and “off-track” (30%) Hill-Sachs lesions. Repair conditions included Hill-Sachs remplissage and/or Bankart repair. Engagement of bipolar lesions was noted, and glenohumeral joint stiffness was calculated from force-displacement measurements. Results: As seen in Table 1, for on-track lesions, engagement was rare and stability was adequately restored with Bankart repair only. For off-track lesions, engagement was routine and the addition of Hill-Sachs remplissage was necessary to restore biomechanical stability. As seen in Figure 1, injury conditions had much lower stiffness than the intact shoulder. Stiffness after off-track HS remplissage was much larger than that of the intact shoulder, injury conditions, and Bankart repair only conditions. Bankart repair of the on-track HS injury condition improved stiffness to near intact, while addition of on-track HS remplissage increased stiffness over Bankart repair alone at 90°. Conclusions: The glenoid track concept is supported by this model of two Hill-Sachs lesions with 15% glenoid bone loss. Our results support the paradigm of Bankart repair for on-track lesions and Bankart plus remplissage for off-track lesions. Remplissage of on-track lesions might be considered for increased stability in high-risk patients. Level of Evidence: Biomechanical study. Table 1Force at 60 or 90° causing engagement of the Hill-Sachs lesions with the glenoid. – indicates no engagement. Bold indicates that a given repair affected the engagement of the experimental condition to the left Figure 1Glenohumeral joint stiffness calculated from the translation of the humeral head with applied loads from 10-40 N at two rotation positions for the various injury and repair conditions of the shoulder. View Large Image Figure Viewer Download Hi-res image