Summary The Stryker InSpace Balloon Implant is a biodegradable subacromial spacer designed for arthroscopic management of massive, irreparable posterosuperior rotator cuff tears (MIRCTs) Composed of a copolymer of poly-L-lactide-co-ε-caprolactone and is intended to resorb within 12 months, being replaced by fibrous tissue Mechanism is to reduce acromiohumeral abutment and subacromial friction, thereby facilitating humeral head depression and gliding during shoulder movement Indications Symptomatic, irreparable posterosuperior MIRCTs in patients ≥ 40 years with an intact subscapularis and failed nonoperative management Best suited for elderly, low-demand patients with preserved active range of motion and minimal to no glenohumeral arthritis Contraindications: severe glenohumeral arthritis deltoid dysfunction neurovascular compromise prior shoulder infection or extensive surgery within the past year Biomechanics and Properties Recreates the subacromial buffer between the humeral head and acromion Reduces superior migration of the humeral head Improves glenohumeral alignment and articulation Enhances early range of motion and functional scores (ASES, WORC, Constant scores) ASES WORC constant scores Biodegradable over 12 months Relevant Anatomy Subacromial space between the acromion and humeral head Glenohumeral joint Rotator cuff tendons supraspinatus infraspinatus teres minor Deltoid muscle integrity is critical for patient selection Imaging Preoperative MRI is used to confirm tear size and tendon involvement subscapularis integrity glenohumeral cartilage status muscle atrophy and fatty infiltration Postoperative MRI at 1 year shows >94% of implants are fully biodegraded implant displacement/deflation seen in some early post-op MRIs (Week 6), but with no associated clinical concerns Surgical Technique Positioning beach chair or lateral decubitus Preparation performed arthroscopically under general anesthesia Procedure perform subacromial arthroscopy and debridement measure from ~1 cm medial to glenoid rim to lateral border of the greater tuberosity choose size per Table 1 small: <40mm → 9–11 cc saline medium: 40–50mm → 14–16 cc large: >50mm → 23–25 cc insert delivery system via lateral portal inflate with sterile saline, deflate slightly to leave final recommended volume lock balloon in place with red safety lock seal using green release lever and withdraw device confirm stability with shoulder maneuvers Time from insertion to release: ~4 minutes Complications Clinical study findings no serious adverse device effects 4/93 required reoperation vs. 3/91 in partial repair arm reoperation rates are low (4.3–5.9%) implant deflation/displacement on MRI not associated with clinical deterioration Potential complications incorrect positioning balloon deflation or rupture infection shoulder stiffness or persistent symptoms biodegradation-related inflammatory response (rare) References Subacromial Balloon Spacer for Massive Irreparable Rotator Cuff Tears. Srikumaran U, Russo R, Familiari F. Arthroscopy : The Journal of Arthroscopic & Related Surgery : Official Publication of the Arthroscopy Association of North America and the International Arthroscopy Association. 2023;39(3):576-577. doi:10.1016/j.arthro.2022.11.011. Subacromial Balloon Spacer for the Massive Irreparable Cuff Tear. Sewpaul Y, Sheean AJ, Rashid MS, Hartzler RU. Current Reviews in Musculoskeletal Medicine. 2024;17(2):47-57. doi:10.1007/s12178-023-09879-3. InSpace Implant Compared With Partial Repair for the Treatment of Full-Thickness Massive Rotator Cuff Tears: A Multicenter, Single-Blinded, Randomized Controlled Trial. Verma N, Srikumaran U, Roden CM, et al. The Journal of Bone and Joint Surgery. American Volume. 2022;104(14):1250-1262. doi:10.2106/JBJS.21.00667.