Gravity Fluid Flow More Accurately Reflects Joint Fluid Pressure Compared With Commercial Peristaltic Pump Systems in a Cadaveric Model

Purpose: To evaluate intra-articular fluid pressures and joint compliance generated by fluid management systems on cadaveric shoulders and knees under simulated arthroscopic conditions, and to compare joint compliance between knee and shoulder specimens.

Methods: Intra-articular pressures of 5 cadaver shoulders and 5 knees were recorded for 4 arthroscopic pumps (Stryker FloControl, Stryker CrossFlow, Arthrex DualWave, DePuy Mitek FMS Duo) and a gravity feed system. Each specimen was tested 6 times with a pressure transducer for 2 minutes at 0, 25%, and 50% suction. The average pressures were analyzed with 1-way analysis of variance and Tukey's honestly significant difference tests (P < .05).

Results: At all suction levels, all pumps exhibited significantly greater pressure than gravity feed (P = .001 to P < .001). At both 25% and 50% suction, FloControl displayed significantly greater pressures (P 160.44 mm Hg) than the other pumps or gravity feed (P 46.9 mm Hg). CrossFlow had the lowest net percentage error (36.8%, 18.4 mm Hg) when compared with the standard pressure of 50 mm Hg, followed by gravity feed. All pumps had large initial overshoot (ie, P CrossFlow 99.4 mm Hg) followed by settling time, whereas gravity feed did not (P 55.2 mm Hg).

Conclusions: Gravity feed is an accurate, reliable delivery method for arthroscopic fluid with minimal overshoot and lower intra-articular pressure ranges than commercial pump systems. There was no evidence of plastic deformation of the joint capsule, because capsular compliance increased linearly in both knee and shoulder specimens throughout testing within the established safe range of intra-articular pressures.

Clinical Relevance: Arthroscopic flow management systems produce maximal and overshoot pressures that are not seen with gravity flow. Surgeons should understand intra-articular pressure and fluid delivery behavior during shoulder and knee arthroscopy to adapt to the variability and higher maximal pressures when using pump systems. Maintaining appropriate pressure could prevent fluid extravasation and possible neuromuscular dysfunction.