title: High power, low frequency ultrasound: meniscal tissue interaction and ablation characteristics.
abstract: This study evaluates high power low frequency ultrasound transmitted via a flat vibrating probe tip as an alternative technology for meniscal debridement in the bovine knee. An experimental force controlled testing rig was constructed using a 20 kHz ultrasonic probe suspended vertically from a load cell. Effect of variation in amplitude of distal tip displacement (242-494 μm peak-peak) settings and force (2.5-4.5 N) on tissue removal rate (TRR) and penetration rate (PR) for 52 bovine meniscus samples was analyzed. Temperature elevation in residual meniscus was measured by embedded thermocouples and histologic analysis. As amplitude or force increases, there is a linear increase in TRR (Mean: 0.9 to 11.2 mg/s) and PR (Mean: 0.08 to 0.73 mm/s). Maximum mean temperatures of 84.6°C and 52.3°C were recorded in residual tissue at 2 mm and 4 mm from the ultrasound probe-tissue interface. There is an inverse relationship between both amplitude and force, and temperature elevation, with higher settings resulting in less thermal damage.
authors.affiliation: Department of Trauma and Orthopaedic Surgery, Royal College of Surgeons in Ireland, Cappagh National Orthopaedic Hospital, Dublin, Ireland.
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: O'Daly
authors.forename: Edmund
authors.initials: E
authors.lastname: Morris
authors.forename: Graham P
authors.initials: GP
authors.lastname: Gavin
authors.forename: Conor
authors.initials: C
authors.lastname: O'Keane
authors.forename: John M
authors.initials: JM
authors.lastname: O'Byrne
authors.forename: Garrett B
authors.initials: GB
authors.lastname: McGuinness
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology* / Q000528:radiation effects; D002417:Cattle; D004307:Dose-Response Relationship, Radiation; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D066298:In Vitro Techniques; D008592:Menisci, Tibial / Q000033:anatomy & histology / Q000503:physiopathology* / Q000601:surgery*; D011829:Radiation Dosage