The Effects of Low-Level Laser Therapy, 670 nm, on Epiphyseal Growth in Rats

Adriana Regina De Andrade,Rose Meire Costa Brancalhão,Elisangela Lourdes Artifon,José Roberto Leonel Ferreira,Anamaria Meireles,Gladson Ricardo Flor Bertolini

doi:10.1100/2012/231723

Adriana Regina De Andrade, Rose Meire Costa Brancalhão + Show 4 more

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https://doi.org/10.1100/2012/231723

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Abstract

The longitudinal growth of long bones is attributed to epiphyseal growth. However, the effects of low-level laser therapy (LLLT) in such structures has still not been studied extensively in the literature. Therefore, the aim of this study was to evaluate the use of LLLT, 670 nm, at three different doses on the epiphyseal growth of the right tibia of rats. Twenty-one Wistar rats, aged four weeks, were subjected to the application of LLLT, with dosage according to the group (G4: were submitted to the application of 4 J/cm2; G8: were submitted to the application of 8 J/cm2; G16: were submitted to the application of 16 J/cm2). After completion of protocol they were kept until they were 14 weeks of age and then submitted to a radiological examination (evaluation of limb length) and euthanised. The histological analysis of the growth plates (total thickness and hypertrophic and proliferative zones) was then performed. Comparisons were made with the untreated left tibia. No differences were observed in any of the reviews (radiological and histological), when comparing the right sides (treated) to the left (untreated). It was concluded that the treatment with LLLT within the parameters used caused changes neither in areas of the epiphyseal cartilage nor in the final length of limbs.

Highlights

The longitudinal growth of long bones is assigned to a structure called the growth plate, physis [1], epiphyseal growth plate, or epiphyseal plate [2]
The aim of this study is to evaluate the use of level laser therapy (LLLT), 670 nm in three different doses on the tibia growth plate of Wistar rats by histologic analysis and to check for changes in the tibia by means of radiography
Comparing the treated side with the untreated, no significant difference was found in all groups with respect to the total thickness (G4—P = 0.3973; G8—P = 0.7830; G16—P = 0.6888), and the hypertrophic zones (G4—P = 0.5673; G8—P = 0.8717; G16—P = 0.3417) and proliferative zones (G4—P = 0.3121; G8—P = 4161; G16—P = 0.7837) of the epiphysis

Summary

Introduction

The longitudinal growth of long bones is assigned to a structure called the growth plate, physis [1], epiphyseal growth plate, or epiphyseal plate [2]. This can be divided into zones of chondrocytes, separated by various stages of differentiation: resting, proliferative, hypertrophic, and vascular invasion. Proliferative and hypertrophic zones are mainly responsible for bone growth in length [3]. The growth plate in children and teenagers is more fragile than the surrounding structures, which predisposes the possibility of damage to it. Other disorders that can involve the physis are infections and tumors [1], in addition to repetitive stress injuries, which can cause irreversible damage to growing bones [5]

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