The Effects of Helium-Neon Light Therapy on Healing of Partial Osteotomy of the Tibia in Streptozotocin Induced Diabetic Rats

Abstract

Objective: The effect of light therapy (LT) on surgically created partial osteotomy in streptozotocin (STZ)-induced diabetic rats was examined. Background Data: LT has been shown to enhance bone repair in healthy human and animal models. Materials and Methods: Forty male rats were divided into groups 1 to 5. Diabetes was induced in rats of groups 1, 2, and 3 using an intraperitoneal injection of STZ. All diabetic rats were maintained for 30 days after STZ injection. Under general anesthesia and sterile conditions, a partial transversal standardized osteotomy was made in the mid-portion of the right tibia. The defects in groups 2, 3, and 5 were treated using a helium-neon (He–Ne) laser (632.8 nm, 10 mW, circular beam shape). Groups 1 and 4 were diabetic placebo and normal placebo groups, respectively. A dose of 369.4 J/cm² for groups 2 and 5 and a dose of 66.8 J/cm² for group 3 were applied three times a week. Six weeks after surgery, the right tibia was collected. The specimen was subjected to a three-point bending test. Results: LT with 369.4 J/cm² energy density resulted in significantly greater bending stiffness in group 5 (41.8 ± 5.2) than in groups 1 (18.5 ± 4.1), 2 (17.7 ± 1.6), and 3 (11.5 ± 4) (least significant difference (LSD) test, p < 0.01, p < 0.001, and p < 0.001, respectively). LT with 369.4 J/cm² energy density resulted in a significantly higher stress load in group 5 (10 ± 0.4) than in groups 1 (4.9 ± 1.5), 2 (5.7 ± 0.52), and 3 (3.9 ± 1.1) (LSD test, p < 0.01, p < 0.01, p < 0.001, respectively). Conclusion: LT with a He–Ne laser in STZ-induced diabetic rats did not enhance bone repair of a partial transversal standardized osteotomy.