High-Pressure Balloon-Assisted Stretching of the Coracohumeral Ligament to Determine the Optimal Stretching Positions: A Cadaveric Study

Abstract

Background: The coracohumeral ligament (CHL) is a thick capsular structure and markedly thickened when affected by adhesive capsulitis. Therapeutic stretching is the most commonly applied treatment for adhesive capsulitis, but optimal stretching postures for maximal therapeutic effects on the CHL have not been fully investigated. Objective: To investigate the most effective stretching direction for the CHL by measuring the stretching intensity in 5 different directions and to determine whether the stretching intervention resulted in loosening of the ligament by comparing the changes of CHL tightness before and after stretching. Design: Biomechanical cadaver study. Setting: Academic institution cadaver laboratory. Participants: Nine fresh frozen cadaveric shoulders. Methods: A high-pressure balloon catheter inserted under the CHL and intraballoon pressure was measured, to evaluate CHL tightness without ligament damage as well as to augment and monitor stretching intensity. To find the optimal stretching direction, the glenohumeral joint was stretched from the neutral position into 5 directions sequentially under pressure-monitoring: flexion, extension [EX], external rotation [ER], EX+ER, and EX+ER+adduction [AD] directions. Main Outcome Measurements: CHL tightness was determined by a surrogate parameter, the additional pressure created by the overlying CHL. The pressure increase (Delta P-str) by a specific directional stretch was considered as the stretching intensity. Results: Delta P-str by the 5 directions were mean (standard deviation) values of 0.03 +/- 0.07 atm, 0.87 +/- 1.31 atm, 1.13 +/- 1.36 atm, 1.49 +/- 1.32 atm, and 2.10 +/- 1.70 atm, respectively, revealing the highest Delta P-str by the EX+ER+AD stretch (P < .05). The balloon pressure by the overlying CHL was decreased from 0.45 +/- 0.35 atm to 0.18 +/- 0.14 atm (P = .012) before and after the stretching manipulation. Conclusions: EX+ER+AD of the glenohumeral joint resulted in the greatest increase in balloon pressure, implying that it could be the most effective stretching direction. A series of stretching manipulations assisted with an underlying pressure balloon were capable of decreasing CHL tightness. With further development and modification, high-pressure balloon-assisted stretching can be a potential therapeutic option to release tight CHL, including the advantage of augmenting and monitoring stretching intensity. Level of Evidence: II