Precise preparation of cartilage defects is technically critical in joint preservation surgery. Whether employing microfracture or advanced methodologies such as matrix induced autologous chondrocyte implantation (MACI), controlled-depth debridement is key to clinical success, with penetration beyond the calcified layer leading to risk of subchondral fracture whereas inadequate debridement leaves behind a sub-optimal base with residual pathologic tissue. To date, techniques to assist level of debridement remain informal, with surgeons employing experience and often attempting to describe audio feedback with distinct sound and pitch changes assisting with debridement when training others. The purpose of this study was to characterize the audiometric properties of chondral defect debridement by cartilage surgery specialists to inform technique and depth of curettage.
Audiometric recordings of cartilage defect preparation with a ringed curette at the time of surgical arthrotomy were obtained for formal analysis, to be correlated to the time at which the calcified layer had been satisfactorily debrided according to the operating surgeon. Digital audio analysis was employed to determine peak sound intensity (decibels, dB) of individual curette strokes as well as stroke spectrography to analyze frequency profile from 0 to 22,000 hertz (Hz). Analysis was performed comparing the curette strokes prior to and immediately following satisfactory cartilage debridement by the surgeon in order to characterize tone and volume intensity profile changes.
Peak curette stroke volume intensity was on average 6.0±1.4 dB or 4-fold higher immediately prior to debridement completion as compared to after satisfactory preparation (p<0.01). In addition, stroke pitch changed substantially, with a sharp drop off in frequencies above 2400 Hz observed following satisfactory defect debridement (p<0.01).
Cartilage surgeons can be assisted by both a substantial decrease in heard curette volume intensity and lower curette pitch when achieving satisfactory calcified layer debridement. This may serve as an additional technical aid during cartilage restoration procedures.