Saline Irrigation Mitigates Chondrocyte Viability Changes During Trochleoplasty

Background: Trochleoplasty aims to correct trochlear dysplasia, an osseous cause of patellar instability. The procedure involves the use of a high-speed bur directly under femoral articular cartilage, which may place chondrocytes at risk of thermal necrosis. Purpose/Hypothesis: The purpose of this study was to investigate the effect of irrigation and offset used during a trochleoplasty procedure on trochlear chondrocyte viability. It was hypothesized that thermal necrosis would be induced by burring and would be mitigated with saline irrigation. Study Design: Controlled laboratory study. Methods: Cadaveric trochlea were obtained and sectioned into 4 quadrants. Trochleoplasty was performed in each quadrant under one of the following randomized conditions: 3-mm offset with saline irrigation (3Wet), 3-mm offset without irrigation (3Dry), 5-mm offset with irrigation (5Wet), or 5-mm offset without irrigation (5Dry). A 3 × 8-mm strip of cartilage was obtained from the center of each quadrant and from an 8-mm control area. Cartilage samples underwent chondrocyte viability staining with calcein-acetoxymethyl and ethidium homodimer-1. Confocal imaging was performed, and viability across treatment and control groups was compared. Results: Eight cadaveric trochlea were obtained from 5 male and 2 female donors (mean age, 26.4 ± 5.6 years). Trochleoplasty was performed at a mean of 25.3 ± 1.3 days from donor death on 5 right and 3 left trochlea. On analysis, control cartilage viability (75.3% ± 12.9%) was greater than those for 5Dry (60.4% ± 9.3%; P = .001) and 3Dry (63.2% ± 13.4%; P = .002). Cartilage viabilities for 5Wet (70.5% ± 11.0%; P = .15) and 3Wet (66.1% ± 10.9%; P = .09) were not significantly different from that of the control. No other intergroup differences were seen. Conclusion: Saline irrigation mitigates chondrocyte-induced thermal necrosis when performing trochleoplasty in this cadaveric model. Clinical Relevance: Saline irrigation should be used when performing a trochleoplasty, while offset of the trochleoplasty bur does not have an effect on cartilage viability.