A Uniquely Formulated Hyperosmolar Irrigation Solution is Associated with Beneficial Effects for Recovery After Arthroscopic Knee and Shoulder Surgeries: A Preclinical Canine Model

Introduction: Hyperosmolar solutions have emerged as a potential adjunct in knee and shoulder arthroscopic procedures, offering benefits such as reduced tissue edema, and enhanced operative efficiency. The purpose of this study was to compare a uniquely formulated “hyperosmolar-plus” solution to hyperosmolar saline and isotonic solutions in knee and shoulder arthroscopic procedures using a preclinical canine model. Methods: Purpose-bred research dogs (N=6) underwent bilateral shoulder (N=12) and knee (N=12) arthroscopic surgeries. Hyperosmolar-plus irrigation fluid (578 mOsm/L) was compared to lactated Ringer’s solution (273 mOsm/L) and hyperosmolar saline (582 mOsm/L). Irrigation fluid was delivered to each joint at 40 mmHg for 2 hours using standard ingress and egress portals. Shoulder and knee girth measurements and ultrasonographic measurements of joint tissues were recorded before and immediately after surgery. Synovial fluid concentrations of selected biomarkers and viable chondrocyte density were evaluated. Articular cartilage, menisci and synovia were harvested for histopathologic evaluation. Differences between groups were determined, with significance set at P<0.05. Hyperosmolar solutions were associated with consistently greater knee and shoulder ROM compared to the Isotonic solution at all time points. Results: Hyperosmolar-plus was associated with significantly (p=0.02) less severe knee fat pad and synovium pathology scores compared to the Isotonic solution. Although the Isotonic solution group had the greatest mean changes in joint girth, periarticular tissue distension, and knee synovium thickness compared with both hyperosmolar solutions, differences were not statistically significant for either joint (p≥0.10). No significant differences among treatment groups were observed in cell viability or synovial fluid biomarkers. Conclusion: Hyperosmolar-plus was associated with lower histopathology severity scores for several knee and shoulder joint tissues compared to Hyperosmolar and Isotonic solutions, although differences were not statistically significant (p≥0.17). These findings suggest that a uniquely formulated hyperosmolar solution supplemented with anti-inflammatory and anti-oxidant components may have beneficial effects on joint health and recovery following common knee and shoulder arthroscopic procedures.