Mechanical Chondroplasty: Early Metabolic Consequences In Vitro

Purpose: The purpose of this study was to determine the depth of penetration from mechanical chondroplasty and metabolic consequences of this procedure on the remaining articular cartilage. Methods: Mechanical chondroplasty was performed in vitro on a portion of fresh grade I or II articular cartilage from 8 human knee arthroplasty specimens. Treated and control (untreated) explants (approximately 30 mg) were cut from the cartilage. The explants were divided into 2 groups, day 1 and day 4, placed separately in a 48-well plate containing media, and incubated at 37°C for 24 hours. After the 24-hour incubation, the explants were weighed on day 1 and day 4, and explant media were removed and tested for total proteoglycan synthesis and aggrecan synthesis. At time 0, 2 sets (2.6 mm each) of treated and control cartilage slices were cut with a precision saw. One set was stained for confocal laser microscopy via a cytotoxicity stain to determine cell viability. The second set was stained with H&E to determine depth of penetration. Results: The mean depth of penetration was 252.8 ± 78 μm. There was no significant difference (P > .25) between total proteoglycan synthesis for control versus treatment groups on day 1 or 4. Aggrecan synthesis was significantly reduced on day 1 when normalized for tissue weight (P = .019) and double-stranded deoxyribonucleic acid (P = .004). On day 4, no significant difference was detected. Confocal laser microscopy did not show cell death below the zone of treatment. Conclusions: There was no significant metabolic consequence caused by chondroplasty to the remaining articular cartilage, and the zone of injury was limited to the treatment area. Clinical Relevance: Mechanical chondroplasty causes no significant metabolic consequences to articular cartilage under these conditions.