Effect of intra-articular pressurization associated with arthroscopy on the immature physis: Investigation in an animal model

Background: Despite the increased use of arthroscopy in pediatric orthopaedics, there is a paucity of data regarding the potential long-term effects of this procedure on the immature physis. The purpose of this study was to test the hypothesis that elevated intra-articular pressures used during arthroscopic surgery do not result in growth disturbances or morphologic alterations in the epiphyseal plate. Methods: Twenty-seven 6-week-old skeletally immature New Zealand white rabbits were divided into experimental (n≤21) and control groups (n≤6). In the experimental group, a hydraulic pump was used to pressurize 1 randomly assigned knee joint per rabbit to intra-articular pressures of 120 mm Hg for 2 hours. In the control group, rabbits received a sham intervention. All rabbits were killed at 6 months of age (skeletal maturity), and their tissues were evaluated grossly, radiographically, and histologically. Data collection included gross measurements (femur and tibia lengths, evaluation of varus/valgus angulation, and knee joint range of motion) and histologic analyses to determine whether morphologic changes were present in the articular cartilage or physis. Confidence intervals were used to test for statistical equivalence. Results: The pressurized and control groups had statistically equivalent gross measurements. No significant articular cartilage or physeal lesions were identified in histologic sections or radiographic studies. Conclusion: This study provided no evidence that arthroscopic pressurization of the knee joint to 120 mm Hg for 2 hours significantly affected physeal growth in a skeletally immature rabbit model. Clinicial Relevance: This study provides the first direct evidence that arthroscopic pressurization of immature joints has no clinically significant adverse long-term effects. Therefore, novel uses of arthroscopy in pediatric patients should be explored without undue concern with regard to premature physeal closure.