Intra-Articular Pressures of the Shoulder and Stifle During Arthroscopy

Introduction: Arthroscopy reduces morbidity and has superior sensitivity and specificity when compared with arthrotomy. The risks of arthroscopy include fluid extravasation and capsular plastic deformation. The yield point of a human joint capsule without rupture is 170 mm Hg, a pressure demonstrated during stifle arthroscopy. This study investigated the joint pressure (IAP) upon saline distention and the differences in pump pressures and IAP in both the canine shoulder and stifle.

Materials and Methods: This study used fresh canine cadavers. A 3.0 mm arthroscope was used and IAP was measured with an 18G needle connected to an anaesthetic invasive blood pressure monitor. Readings were obtained (1) unadulterated joint (2) 10 mL saline injection (3) every minute thereafter. After two readings the pressure was increased by 10 mm Hg between 30 and 100 mm Hg. The pressure was decreased to 80, 50, and 30 mm Hg. While decreasing, stifle joint IAPs were measured at 130° and 90°.

Results: Saline distention IAPs in the stifle were lower than in the shoulder joint with one exception. All fluid pump setting pressures were significantly lower than the measured IAP (p ≤ 0.0001) by approximately 20 mm Hg. Pressure variability was smaller for shoulders than stifles. Standard deviation increased with increased pressures in the stifle.

Discussion/Conclusion: Saline distention of the joint should be done with minimal fluid. Pump pressures can be expected to exceed IAP by a significant amount. At lower pump pressures the difference between pump pressures and IAP is smaller than at higher pump pressures. Increased pump pressure did not improve visibility.

Acknowledgment

North Carolina State University College of Veterinary Medicine startup funds were used for purchases of materials.

Publication History

Article published online:
15 July 2025