Ultrasound-guided percutaneous rotator interval approach for simulated adhesiolysis: A proof-of-concept feasibility and anatomical safety study

Background Several key structures involved in frozen shoulder are located in the anterior shoulder capsule. While ultrasound-guided corticosteroid injections and capsular hydrodilatation have demonstrated favorable outcomes through an anterior approach, percutaneous interventions aimed at mechanical adhesion release remain insufficiently investigated. This study evaluated the feasibility and anatomical safety of an ultrasound-guided simulated percutaneous adhesiolysis of the rotator interval in a cadaveric model. Methods The procedure was performed in a single non-pathological Thiel-embalmed shoulder from a 73-year-old male body donor. Under ultrasound guidance, a 14 G intravenous catheter was advanced from an anterior cutaneous entry point into the glenohumeral joint through the superior aspect of the subscapular recess. After removal of the needle, a 1.5-mm blunt stylet was introduced through the catheter and redirected into the plane between the intra-articular long head of the biceps tendon and the overlying rotator interval capsule. Controlled proximal–distal and medial–lateral sweeping movements were performed to simulate mechanical adhesiolysis. Subsequent anatomical dissection was used to confirm the instrument path and identify any gross injury to adjacent structures. Results The catheter and stylet could be positioned within the intended anatomical plane under ultrasound guidance and sweeping movements were feasible in both proximal–distal and medial–lateral directions, until soft resistance was encountered at surrounding anatomical boundaries. Anatomical dissection confirmed accurate capsular entry and intra-articular instrument placement. No macroscopic injury to the long head of the biceps tendon, rotator cuff tendons, or humeral head cartilage was identified. The extent of tissue mobilization was not objectively quantified due to the absence of pathological adhesions in the specimen. Conclusions Ultrasound-guided simulated rotator interval adhesiolysis using a 14 G catheter was anatomically safe and feasible in a cadaveric model. Future clinical trials in frozen shoulder patients are warranted to confirm the efficacy of this ultra-minimally invasive approach.