The effects of ionizing radiation on the growth plate in rat tibiae.

The deleterious effects of ionizing radiation on the growth plate continue to be cause for concern. This study evaluated the ionizing radiation effects on bone development and growth plate in the tibia of rats. All animals were submitted to ionizing radiation on the left leg. The animals were divided into two groups and euthanized 30 and 60 days after radiation. The tibiae were removed and separated into groups: control 30 days, irradiated 30 days, control 60 days and irradiated 60 days. Animals in each group (n = 7) were used for macroscopic and histological analysis. The irradiated tibiae showed arrested growth, angular deformity and limb length discrepancy when compared with nonirradiated tibiae. There was statistical difference between control and radiation groups in all the parameters analyzed, except in the lateral-medial thickness of the distal epiphysis. Histological analysis showed evident changes in the growth plate, which was thicker in the Groups irradiated for 30 days, and irradiated for 60 days, compared with their respective controls. The growth plate showed wide areas with disorganized zones of chondrocytes and severely reduced calcification zone. It was concluded that ionizing radiation damaged the growth plate, compromised the endochondral ossification process, and resulted in complete arrest of bone development.

Low-level laser on femoral growth plate in rats.

PURPOSE: To determine the influence of low-level laser therapy on femoral growth plate in rats. METHODS: Thirty male Wistar rats aged 40 days were divided into two groups, G1 and G2. In G1 the area of the distal growth plate of the right femur was irradiated at one point using GaAlAs laser 830 nm wavelength, output power of 40 mW, at an energy density of 10 J/cm(2). The irradiation was performed daily for a maximum of 21 days. The same procedure was done in G2, but the probe was turned off. Five animals in each group were euthanized on days 7, 14 and 21 and submitted to histomorphometric analysis. RESULTS: In both groups the growth plate was radiographically visible at all moments from both craniocaudal and mediolateral views. On the 21st day percentage of femoral longitudinal length was higher in G2 than G1 compared to basal value while hypertrophic zone chondrocyte numbers were higher in G1 than G2. Calcified cartilage zone was greater in G1 than in G2 at all evaluation moments. Angiogenesis was higher in G1 than in G2 at 14th and 21st days. CONCLUSION: The low-level laser therapy negatively influenced the distal femoral growth plate.

Low-level laser on femoral growth plate in rats / Laser terapêutico de baixa potência na placa de crescimento de ratos

PURPOSE: To determine the influence of low-level laser therapy on femoral growth plate in rats. METHODS: Thirty male Wistar rats aged 40 days were divided into two groups, G1 and G2. In G1 the area of the distal growth plate of the right femur was irradiated at one point using GaAlAs laser 830 nm wavelength, output power of 40 mW, at an energy density of 10 J/cm². The irradiation was performed daily for a maximum of 21 days. The same procedure was done in G2, but the probe was turned off. Five animals in each group were euthanized on days 7, 14 and 21 and submitted to histomorphometric analysis. RESULTS: In both groups the growth plate was radiographically visible at all moments from both craniocaudal and mediolateral views. On the 21st day percentage of femoral longitudinal length was higher in G2 than G1 compared to basal value while hypertrophic zone chondrocyte numbers were higher in G1 than G2. Calcified cartilage zone was greater in G1 than in G2 at all evaluation moments. Angiogenesis was higher in G1 than in G2 at 14th and 21st days. CONCLUSION: The low-level laser therapy negatively influenced the distal femoral growth plate.

OBJETIVO: Determinar a influência do Laser Terapêutico de Baixa Potência sobre a placa de crescimento de ratos. MÉTODOS: Trinta ratos Wistar machos com 40 dias de idade foram divididos em dois grupos, G1 e G2. O grupo G1 foi submetido à irradiação com laser GaAlAs 830 nm, potência de saída de 40 mW, e densidade de energia de 10 J/cm2. A irradiação foi aplicada diariamente por um período máximo de 21 dias. O mesmo procedimento foi realizado no grupo G2, com a probe desativada. Cinco animais em cada grupo foram sacrificados nos dias 7, 14 e 21 e submetidas à análise histomorfométrica. RESULTADOS: Em ambos os grupos, o disco fisário esteve radiograficamente visível em todos os momentos nas incidências craniocaudal e médio-lateral. No 21º dia a porcentagem de comprimento longitudinal do fêmur foi maior em G1 que em G2 em relação ao valor basal, e o número de condrócitos da zona hipertrófica foi maior em G1 que em G2. A zona de cartilagem calcificada estava maior em G1 em relação a G2 em todos os momentos de avaliação. A angiogênese foi maior em G1 que em G2 nos 14º e 21º dias. CONCLUSÃO: A terapia com laser terapêutico de baixa potência influenciou negativamente o disco fisário distal do fêmur de ratos.

Low-level laser on femoral growth plate in rats / Laser terapêutico de baixa potência na placa de crescimento de ratos

PURPOSE: To determine the influence of low-level laser therapy on femoral growth plate in rats. METHODS: Thirty male Wistar rats aged 40 days were divided into two groups, G1 and G2. In G1 the area of the distal growth plate of the right femur was irradiated at one point using GaAlAs laser 830 nm wavelength, output power of 40 mW, at an energy density of 10 J/cm². The irradiation was performed daily for a maximum of 21 days. The same procedure was done in G2, but the probe was turned off. Five animals in each group were euthanized on days 7, 14 and 21 and submitted to histomorphometric analysis. RESULTS: In both groups the growth plate was radiographically visible at all moments from both craniocaudal and mediolateral views. On the 21st day percentage of femoral longitudinal length was higher in G2 than G1 compared to basal value while hypertrophic zone chondrocyte numbers were higher in G1 than G2. Calcified cartilage zone was greater in G1 than in G2 at all evaluation moments. Angiogenesis was higher in G1 than in G2 at 14th and 21st days. CONCLUSION: The low-level laser therapy negatively influenced the distal femoral growth plate.(AU)

OBJETIVO: Determinar a influência do Laser Terapêutico de Baixa Potência sobre a placa de crescimento de ratos. MÉTODOS: Trinta ratos Wistar machos com 40 dias de idade foram divididos em dois grupos, G1 e G2. O grupo G1 foi submetido à irradiação com laser GaAlAs 830 nm, potência de saída de 40 mW, e densidade de energia de 10 J/cm2. A irradiação foi aplicada diariamente por um período máximo de 21 dias. O mesmo procedimento foi realizado no grupo G2, com a probe desativada. Cinco animais em cada grupo foram sacrificados nos dias 7, 14 e 21 e submetidas à análise histomorfométrica. RESULTADOS: Em ambos os grupos, o disco fisário esteve radiograficamente visível em todos os momentos nas incidências craniocaudal e médio-lateral. No 21º dia a porcentagem de comprimento longitudinal do fêmur foi maior em G1 que em G2 em relação ao valor basal, e o número de condrócitos da zona hipertrófica foi maior em G1 que em G2. A zona de cartilagem calcificada estava maior em G1 em relação a G2 em todos os momentos de avaliação. A angiogênese foi maior em G1 que em G2 nos 14º e 21º dias. CONCLUSÃO: A terapia com laser terapêutico de baixa potência influenciou negativamente o disco fisário distal do fêmur de ratos.(AU)

Effect of GaAlAs laser irradiation on the epiphyseal cartilage of rats.

OBJECTIVE: To study the effect of an 830-nm gallium-aluminum-arsenic (GaAlAs) diode laser at two different energy densities (5 and 15 J/cm(2)) on the epiphyseal cartilage of rats by evaluating bone length and the number of chondrocytes and thickness of each zone of the epiphyseal cartilage. BACKGROUND DATA: Few studies have been conducted on the effects of low-level laser therapy on the epiphyseal cartilage at different irradiation doses. MATERIALS AND METHODS: A total of 30 male Wistar rats with 23 days of age and weighing 90 g on average were randomly divided into 3 groups: control group (CG, no stimulation), G5 group (energy density, 5 J/cm(2)), and G15 group (energy density, 15 J/cm(2)). Laser treatment sessions were administered every other day for a total of 10 sessions. The animals were killed 24 h after the last treatment session. Histological slides of the epiphyseal cartilage were stained with hematoxylin-eosin (HE), photographed with a Zeiss photomicroscope, and subjected to histometric and histological analyses. Statistical analysis was performed using one-way analysis of variance followed by Tukey's post hoc test. All statistical tests were performed at a significance level of 0.05. RESULTS: Histological analysis and x-ray radiographs revealed an increase in thickness of the epiphyseal cartilage and in the number of chondrocytes in the G5 and G15 groups. CONCLUSION: The 830-nm GaAlAs diode laser, within the parameters used in this study, induced changes in the thickness of the epiphyseal cartilage and increased the number of chondrocytes, but this was not sufficient to induce changes in bone length.

Efeito do ultra-som terapêutico contínuo em placas epifisárias de coelhos / Effect of continuous therapeutic ultrasound in rabbit growth plates

Devido aos efeitos terapêuticos, o ultra-som tem se tornado ferramenta indispensável no tratamento fisioterapêutico de alterações causadas por lesões e em diversas doenças, porém seu uso em pacientes pediátricos é controverso por possíveis distúrbios e danos à placa epifisária. O objetivo deste estudo é verificar se o ultra-som contínuo apresenta efeitos de alteração na placa de crescimento da tíbia de coelhas. Oito coelhas da raça Nova Zelândia com dois meses de idade foram submetidas a um tratamento usando ultra-som terapêutico de forma contínua com dose de 1W/cm² na região lateral da articulação do joelho direito por 5min, durante 10 dias com dois dias de intervalo após a 5ª aplicação. A articulação do joelho esquerdo foi utilizada como controle. A análise histológica mostrou uma alteração na espessura da cartilagem epifisária, sendo que no lado tratado o tamanho foi 24,40 por cento maior do que no controle (p < 0,0001), enquanto a análise radiológica não apresentou diferença entre os membros. Conclui-se que o ultra-som terapêutico na forma utilizada produz alterações histológicas significativas na espessura da cartilagem no lado tratado, sugerindo uma aceleração no metabolismo da placa.

The therapeutic efficiency of ultrasound has become an indispensable tool of physical therapy treatment in cases of alteration by lesions and in many kinds of sickness. However, in pediatric cases the use of ultrasound is controversial due to possible disturbance and damage to the growth plate. The aim of this study is to find out if the continuous ultrasound presents alteration effects on the growth plate of female rabbits. Eight New Zealand female rabbits with two months of age were tested. They were treated by continuous therapeutic ultrasound with doses of 1 W/cm² in the lateral region of the right knee joint for five minutes, during 10 days, with an interval of two days after five applications. The left knee joint was used as a control. The histological analysis showed an alteration in the thickness of the growth plate on the treated side 24.40 percent bigger than in the left knee joint of the control (p < 0.0001). On other hand, the radiological analysis did not show any difference between the limbs. The conclusion was that the therapeutic ultrasound produced significant histological alterations in the cartilage thickness on the treated side according to the manner it was used in the experiment. Such fact suggests an acceleration in the growth plate metabolism.

Debido a los efectos terapéuticos, la ultrasonografía se ha convertido en una herramienta indispensable al tratamiento fisioterapéutico de las alteraciones causadas por lesiones y en diversas enfermedades, a pesar de esto su uso en pacientes pediátricos es controversial por los posibles disturbios y daños a la placa epifisaria. El objetivo de este estudio es verificar si la ultrasonografía continua presenta efectos de alteración en la placa de crecimiento de al tibia de conejas. Ocho conejas de la raza Nueva Zelanda con 2 meses de edad fueron sometidas a un tratamiento usando ultrasonografía terapéutica de forma continua con dosis de 1W/cm² en la región lateral de la articulación de la rodilla derecha por 5 min, durante 10 días con 2 días de intervalo después de la 5ª aplicación. La articulación de la rodilla izquierda fue utilizada como control. El análisis histológico reportó una alteración en la espesura del cartílago epifisario, en el lado tratado el tamaño fue de 24,40 por ciento mayor del que en el control (p < 0,0001); mientras que el análisis radiológico no presentó ninguna diferencia entre los miembros. Por tanto, se concluye que la ultrasonografía terapéutica en la forma utilizada produce alteraciones histológicas significativas en la espesura del cartílago en el lado tratado, lo que sugiere una aceleración en el metabolismo de la placa.