The Effect of Sequentially Increased Polyethylene Constraint on Impingement in Reverse Shoulder Arthroplasty: A Biomechanical Investigation.

Background: The constraint of the polyethylene liner in reverse total shoulder arthroplasty (rTSA) can affect glenohumeral joint stability. However, its influence on glenohumeral range of motion (ROM) remains unclear. Therefore, it was the objective of this study to determine the effect of sequentially increasing polyethylene liner constraint on impingement-free ROM following rTSA.

Coracoacromial ligament integrity influences scapular spine strain after reverse shoulder arthroplasty.

Background: The purpose of this biomechanical study was to examine the effect of coracoacromial (CA) ligament state (intact vs. released) and arm position on acromial and scapular spine strain following reverse total shoulder arthroplasty (rTSA).

Methods: Eight cadaveric shoulders were implanted with a custom rTSA system and tested using an in-vitro shoulder simulator.

An in-vitro biomechanical comparison of annular ligament repair and reconstructions to restore radial head stability in anterior Monteggia fractures.

Background: Persistent or recurrent instability of the radial head (RH) remains a challenge in treating anterior Monteggia fractures despite anatomic restoration of the ulna. RH instability may be caused by the pull of the biceps muscle with rupture of the annular ligament and other soft tissue stabilizers of the proximal radius. Currently, the optimal method to stabilize the proximal radius is unknown.

Reverse shoulder arthroplasty implant design and configuration has a significant effect on conjoint tendon impingement.

Background: Anterior shoulder pain after reverse shoulder arthroplasty (RSA) is not uncommon and may be due to humeral impingement against the conjoint tendon during internal rotation (IR). It is unknown what effect different implant designs and configurations have on conjoint tendon impingement. The purpose of this study was to investigate the influence of several RSA implant design parameters on conjoint tendon impingement during IR.

Superior capsular reconstruction using the long head of biceps tendon: a biomechanical assessment of tenodesis location and angle of fixation.

Background: Massive irreparable rotator cuff tears (MIRCTs) treated with superior capsular reconstruction (SCR) using the long head of the biceps tendon have shown satisfactory early results. Different techniques and positions for biceps tenodesis have been described. This study aimed to evaluate the effect of tenodesis location and glenohumeral fixation angle for graft tensioning on the biomechanics of an SCR using a single-strand biceps technique.