The Effect of Different Wavelength of Low Power Laser on Fracture Healing

Kim, Myung Ho; Yoo, Moon Jib; Park, Hee Gon; Rhee, Chung Ku; Meng, Ye; Kim, Young Jae; Hwang, Sung Su

Abstract

PURPOSE: The purpose of this study is to evaluate the effect of different wave length of low power laser on early fracture healing.
METHODS
AND MATERIALS: Nine week old female English Hartley guinea pigs were used for this experiment. Sixty guinea pigs were divided into three groups, and then right femur was fractured and fixed with an intramedullary nail. The frequency of 632 nm and 830 nm semi-conductor laser machines were used. Finally, 46 guinea pigs were survived (including 14 cases in control group, 16 cases in 632 nm group and 16 cases in 830 nm group). Guinea pigs were sacrificed at 3 and 6 weeks separately. The gross, radiologic and histologic findings were assessed by the Modified Zorlu Scoring System. The statistical evaluation was done by repetitive measured ANOVA test.
RESULTS
In the gross findings and radiologic findings, both of 632 nm and 830 nm radiation groups showed a greater amount of callus formation at postoperative 3 weeks with statistical significance (P<0.01) compared to the control group. Quantity of callus formation in 830 nm group was larger than that in 632 nm group although there was no significant difference (P>0.05). The result of histological findings showed that an increase of osteoblastic proliferation in two radiation groups was greater than that in the control group at 3 and 6 weeks (P<0.01). Enhancement of osteoblastic proliferation was greater in 830 nm group compared to in 632 nm group at 3 weeks (P<0.05). The comparison between the experimental groups for wave length of 632 nm and 830 nm at 6 weeks showed significant difference (P<0.05).
CONCLUSION
In this study, it became known that applying 632 nm and 830 nm wavelength laser to the fracture site accelerate bony union, and 830 nm wavelength laser showed earlier bony union than 630 nm wavelength laser.