ABSTRACT
OBJETIVO: Avaliar, mecânica e histologicamente, a aplicação do laser terapêutico de baixa potência, no processo reparativo de lesões provocadas por impacto em músculos gastrocnêmios de ratas. MÉTODOS: 45 ratas Wistar foram divididas em três grupos (n=15/grupo): C (controle, sem lesão), LM (lesão muscular) e LM-L (lesão muscular e laserterapia). A lesão muscular experimental foi produzida pela queda de uma carga de 250 g, de uma altura de 30cm, diretamente sobre o músculo. Os animais do grupo LM-L foram submetidos à aplicação de laser 960nm, 2J/cm², durante três dias, duas aplicações por dia, no local da lesão. Foi realizado ensaio mecânico na máquina universal de ensaio Emic®. RESULTADOS: As médias dos valores de força máxima foram: (35,70 ± 2,69) N no grupo C, (31,77 ± 2,59) N no grupo LM e (34,36 ± 3,63) N no grupo LM-L, com diferença estatística significativa nos grupos C e LM (p < 0,05). As médias dos valores de rigidez relativa foram (3,75 ± 0,98) N/mm no grupo C, (3,84 ± 0,32) N/mm no grupo LM e (4,43 ± 0,68) N/mm no grupo LM-L, sem diferença estatística (p > 0,05). A análise histológica evidenciou presença de vasos sanguíneos no grupo LM-L e hematomas em processo de reparação. CONCLUSÃO: A laserterapia influencia de forma positiva no processo de regeneração da lesão muscular.
OBJETIVE: To evaluate, by means of biomechanical and histological analysis, the effect of low-level laser therapy on the gastrocnemius of rats subjected to muscle lesion by impact. METHODS: 45 female Wistar rats, weighing 250g, were divided into 3 groups (n=15/group): C (control), ML (animals submitted to muscle lesion) and ML-L (animals submitted to muscle lesion and laser therapy). The animals from groups ML and ML-L were subjected to an experimental muscle lesion by means of an impact of a 250g load, released from a height of 30 cm, directly on the gastrocnemius. The animals from group ML-L were submitted to a treatment with a 960 Nm laser, 2 J/cm², for 3 days, twice a day. RESULTS: The mechanical tests were performed on the Universal Testing Machine. The average values of maximum force were: 35.70 (± 2.69) N in group C, 31.77 (± 2.59) N in group ML and 34.36 (± 3.63) N in group ML-L, with a statistically significant difference between groups C and ML (p < 0.05). The average values of stiffness were: 3.75 (± 0.98) N/mm in group C, 3.84 (± 0.32) N/mm in group ML and 4.43 (± 0.68) N/mm in group ML-L, with no statistically significant differences (p>0.05). Histological analysis showed a presence of blood vessels in group ML-L and a hematoma in the healing stage. CONCLUSION: Treatment with low-level laser had a positive effect in the healing process of muscle injury.
Subject(s)
Animals , Rats , Low-Level Light Therapy , Muscle, Skeletal/anatomy & histology , Muscle, Skeletal/injuries , Rats, WistarABSTRACT
An experimental study of the influence of the therapeutic ultrasound on the regeneration of the sciatic nerve submitted to a controlled crush injury was carried out in rats. Twenty female Wistar rats weighing 250 g on average were used and divided into two groups of 10 animals each, respectively, submitted to: (1) crush injury followed by ultrasound irradiation and (2) crush injury only. Under general anaesthesia the sciatic nerve was exposed on the right thigh and crushed with a device especially developed and built for this purpose, with a 15,000g constant load for 10 min, affecting a 5mm-long segment of the nerve proximal to its bifurcation. Pulsed ultrasound irradiation (1:5, 1 MHz, 0.4 W/cm(2), 2 min duration) was started the day after the operation and repeated for 10 consecutive days. The sciatic functional index (SFI) was evaluated at weekly intervals up to the third week, when the animal was killed for histologic and nerve fiber density studies of the sciatic nerve carried out on the lesion site and on the segments immediately proximal and distal to it. The SFI progressively improved for both treated and untreated nerves but in a more marked and significant way for the treated nerves (73 and 55%, respectively). Nerve fiber density did no return to normal in either case but was significantly higher in the treated nerves, with predominance of small diameter thin myelin sheath fibers typical of nerve regeneration in the treated nerves, as opposed to large diameter thin myelin sheath fibers in the untreated nerves. The authors conclude that low intensity therapeutic ultrasound enhances nerve regeneration, as demonstrated with significance on the 21st postoperative day.