In Vitro Effects of 3 Common Arthroscopic Instruments on Articular Cartilage

Purpose: The purpose of this study was to compare chondroplasty performed with an ExoJet high-pressure fluid-driven burr (Mitek, Norwood, MA), a mechanical shaver, and a bipolar radiofrequency (RF) wand on articular cartilage–covered condyles taken from sheep cadavers that were induced to have an osteoarthritic-like condition, and corresponding healthy control tissue. Type of Study: Experimental designed animal cadaveric, biochemical, and histologic study. Methods: Sheep condyles were used as a source of articular cartilage. Femurs were extracted approximately 1 hour postmortem and a transverse section of the condyles was made. Half of the samples were treated to induce an osteoarthritic-like condition. The condyles were then subjected to chondroplasty performed with the ExoJet high-pressure fluid-driven burr, a mechanical shaver, and a bipolar RF wand under sterile saline solution by an experienced orthopaedic surgeon. Twenty cross-sections from each condyle were examined by confocal microscopy to measure smoothness and depth of tissue damage to the articular cartilage caused by each of the 3 instruments. Results: The ExoJet high-pressure fluid-driven burr and the bipolar RF wand left a smoother surface on the articular cartilage compared with the mechanical shaver. Additionally, the ExoJet fluid-burr caused slightly less tissue damage to the cartilage than the bipolar RF wand, both of which were less damaging than the shaver. Conclusions: Orthopaedists have multiple choices for surgical instruments used on cartilage. However, the effect on the integrity of the cartilage left remaining at the knee was previously unknown. Based on this study, a fluid-burr appears to leave the cartilage with a smaller zone of injury than does the RF wand or shaver. It also leaves the cartilage surface smoother than the shaver. During surgical procedures, minimizing cartilage breakdown and smooth remaining surfaces are desired because they minimize the vulnerable tissue to further destruction. A fluid burr leaves cartilage with less injury and with a smoother surface than do more traditional surgical instruments. Clinical Relevance: This information should help surgeons in their selection of currently available surgical instruments and should aid engineers in the design of future instruments that function to modify articular cartilage.