A Novel Arthroscopic Curette Microphone for Cartilage Defect Preparation in Joint Preservation Surgery: Proof-of-Concept and Tissue-Specific Debridement Audio Features

ObjectiveDuring open chondral defect preparation, audible debridement sound changes mark the transition from deep cartilage to the calcified cartilage layer. We developed a novel curette microphone to characterize these audio feature differences during arthroscopic defect preparation.DesignA piezoelectric curette microphone was used to transmit and record debridement sound from 12 defect preparations (6 deep cartilage, 6 CCL) using human osteochondral allograft remnants. Live audio from the device was used to stop each debridement at the intended level, which was verified histologically. Spectrograms and power-spectral density plots were used to describe the audible transition from deep cartilage to CCL. We compared 22 audio features describing loudness, frequency, and complexity between the two tissue levels.ResultsCurette strokes against the deep cartilage were louder, higher frequency, and more acoustically complex than strokes against the CCL (p < 0.001). Cartilage debridement generated acoustically complex frequency bands above 2.5 kHz that diminished upon reaching the CCL. Debridement of the CCL produced a simpler audio profile that was predominant below 350 Hz.ConclusionThe novel curette microphone presented here transmits high-fidelity debridement audio that can be used to accurately distinguish tissue depth based on the distinct audio profiles of the deep cartilage and CCL.