Why We Still Cannot Answer Clearly If Low-Intensity Pulsed Ultrasound Treatment Can Repair Articular Cartilage?

Ioannis Manousakas

Department of Biomedical Engineering, I-Shou University, Taiwan

Dr. Ioannis Manousakas, Department of Biomedical Engineering, I-Shou University, Taiwan.

Keywords: Low Intensity Pulsed Ultrasound; Articular Cartilage; Treatment Protocol

Abstract

Five years ago a question was raised. Is it possible for Low-intensity pulsed ultrasound treatment (LIPUS) to repair articular cartilage? A daily 20-minute treatment for 3 months was given to surgically created cartilage defects of 5mm in diameter on the right side distal femoral condyle of rabbits. The ultrasonic device used was an Exogen low-intensity pulsed ultrasound device (Smith & Nephew Inc, Memphis, TN, USA) which provided a peak intensity of 30mW/cm² at a frequency of 1.5MHz. After treatment, the cartilage defects of the LIPUS-treated group were covered by proliferative tissue, where the non-treated were not. The study concluded that there was no significant therapeutic effect.
In a recent similar type study, the treatment was for 10 min per day for 14 days at 1W/cm² at a frequency of 1MHz (the ultrasonic device was not disclosed). This study suggested that LIPUS has therapeutic potential for the treatment of mandibular condylar cartilage defects of 2mm in diameter. In [12], normal and osteoarthritis chondrocytes in culture dishes were treated with 3MHz ultrasound for 6 days, 20 min per day at intensities of 20, 30, 40 and 50mW/cm². In [1], a frequency of 1MHz, with an intensity of 0.1 W/cm² was used on human osteoarthritic knee showed no significant difference in the treatment effect. In [4] 1MHz with a peak intensity of 1W/cm² at a 20% duty cycle was applied for cartilage repair in humans. In this study it is mentioned that there is limited understanding about the important factors that may influence the effects of the treatment, such as dose, intensity, mode, or application techniques.

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