Saline Irrigation Mitigates Chondrocyte Viability Changes During Trochleoplasty.

Abstract

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. 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. Controlled laboratory study. 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. 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%; <i>P</i> = .001) and 3Dry (63.2% ± 13.4%; <i>P</i> = .002). Cartilage viabilities for 5Wet (70.5% ± 11.0%; <i>P</i> = .15) and 3Wet (66.1% ± 10.9%; <i>P</i> = .09) were not significantly different from that of the control. No other intergroup differences were seen. Saline irrigation mitigates chondrocyte-induced thermal necrosis when performing trochleoplasty in this cadaveric model. Saline irrigation should be used when performing a trochleoplasty, while offset of the trochleoplasty bur does not have an effect on cartilage viability.