Does Low-intensity pulsed ultrasound treatment repair articular cartilage injury? A rabbit model study

Shan-Wei Yang,Yen Ting Lin,Po-Chou Chen,Shwu Jen Chang,Shyh Ming Kuo,Chien-Lin Kuo,Ioannis Manousakas

doi:10.1186/1471-2474-15-36

Abstract

BackgroundLow-intensity pulsed ultrasound (LIPUS) regiment has been used to treat fractures with non-union and to promote bone union in general. The effect of LIPUS on articular cartilage metabolism has been characterized. Yet, the effect of LIPUS to repair articular cartilage injury remains unclear in vivo.MethodsWe designed a study to investigate the effect of LIPUS on articular cartilage repairing in a rabbit severe cartilage injury model. Eighteen rabbits were divided into three groups: Sham-operated group, operated group without-LIPUS-treatment, operated group with-LIPUS-treatment (a daily 20-minute treatment for 3 months). Full-thickness cartilage defects were surgically created on the right side distal femoral condyle without intending to penetrate into the subchondral bone, which mimicked severe chondral injury. MR images for experimental joints, morphology grading scale, and histopathological Mankin score were evaluated.ResultsThe preliminary results showed that the operated groups with-LIPUS-treatment and without-LIPUS-treatment had significantly higher Mankin score and morphological grading scale compared with the sham-operated group. However, there was no significant difference between the with-LIPUS-treatment and without-LIPUS-treatment groups. Cartilage defects filled with proliferative tissue were observed in the with-LIPUS-treatment group grossly and under MR images, however which presented less up-take under Alcian blue stain. Furthermore, no new deposition of type II collagen or proliferation of chondrocyte was observed over the cartilage defect after LIPUS treatment.ConclusionLIPUS has no significant therapeutic potential in treating severe articular cartilage injury in our animal study.

Highlights

Low-intensity pulsed ultrasound (LIPUS) regiment has been used to treat fractures with non-union and to promote bone union in general
Three phases of sagittal view MR images of experimental rabbit knees were acquired from Proton density fast spin echo (PDFSE) pulse sequence
Comparing the MR images from the different phases of rabbits in the with-LIPUS-treatment group, there was a boundary between joint fluid and articular cartilage on the pre-surgery and post-LIPUS-treatment knee, while there was not seen on the post-surgery knee (Figure 2)

Summary

Introduction

Low-intensity pulsed ultrasound (LIPUS) regiment has been used to treat fractures with non-union and to promote bone union in general. The better treatments for chondral injury should target the symptoms of the patient and promote biological repair of the destructed articular cartilage tissue. Ultrasound is a form of mechanical energy that can be transmitted into the biological tissue as high frequency acoustical pressure waves. It was used as a diagnostic and therapeutic tool. Low-intensity pulsed ultrasound (LIPUS) is a recommended therapy to treat fractures with non-union and promotes bone union clinically [3,4,5,6,7,8]. Application of highintensity continuous ultrasound generates considerable heat in living tissues, whereas LIPUS (< 100 mW/cm2) has much lower intensity with non-thermogenic and nondestructive actions

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