Can ultrasound propagate in the joint space of a human knee?
A large body of evidence supports the principle that the use of low-intensity pulsed ultrasound with a frequency of 1.5 MHz can reduce fracture healing time. It is hypothesized that similar therapeutic benefits may be achieved in damaged articular cartilage. This study looks specifically at a 22-mm circular ultrasound transducer delivering ultrasound with a frequency of 1.5 MHz. A human cadaver knee was imaged using CT, the resulting images were used to help map a number of hydrophone positions in the joint from which measurements were taken. The experimental results suggest that at best there is a 30-mm window in which to place the ultrasound transducer for ultrasound to propagate through the joint space. In terms of a clinical device delivering an I(SATA) of 30 mW cm(-2) to anterior regions of the joint, the I(SATA) in posterior regions will at best be in the region of 10 mW cm(-2). The clinical implications of this are not known and require further investigation.
White
D
D
Medical Physics, University of Leeds, Leeds, United Kingdom. d.m.white@leeds.ac.uk
Evans
J A
JA
Truscott
J G
JG
Chivers
R A
RA
D000368:Aged; D002102:Cadaver; D002358:Cartilage, Articular / Q000502:physiology; D005260:Female; D017102:Fracture Healing / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D014057:Tomography, X-Ray Computed / Q000379:methods; D014159:Transducers; D014464:Ultrasonic Therapy / Q000379:methods; D014465:Ultrasonics