Assessment of the LED phototherapy on femoral bone defects of ovariectomized rats: a Raman spectral study

Osteoporosis is a disease characterized by the reduction of bone mineral density. LED wavelengths seem to have similar photo-stimulating effects to laser light. The aim of this study was to assess the Raman shifts: ∼960 (phosphate hydroxyapatite), ∼1,070 (carbonate hydroxyapatite), and ∼1,454 cm−1 (lipids and proteins) on bone defects of ovariectomized rats treated or not with LED phototherapy (LED-PT). Thirty female rats were divided into four groups (Basal, OVX, OVX+Clot, and OVX+Clot+LED), then subdivided into two subgroups (15 and 30 days after surgery). Osteoporosis induction by ovariectomy (OVX) was performed in all groups, except for the normal basal group. Following development of osteoporosis, one surgical bone defect (5 mm2) was created on the femur of each animal. Defects were irradiated with LED light (λ = 850 ± 10 nm, P = 150 mW, CW, Ф = 0.5 cm2, 20.4 J/cm2 per session, t = 128 s, 163.2 J/cm2 per treatment) at 48 h interval during 2 weeks. Raman measurements were taken at the surface of the defects 30 days after surgery. Significant difference between groups Basal, OVX+Clot, and OVX+Clot+LED for the peaks at ∼960 (p ≤ 0.001; 15 and 30 days), ∼1,070 (p ≤ 0.001; 15 and 30 days), and ∼1,450 cm−1 (p = 0.002; 15 days; p = 0.004; 30 days) were detected. In addition, statistical differences were obtained between groups OVX, OVX+Clot, and OVX+Clot+LED for these same peaks at all time points (p ≤ 0.001). At 15 and 30 days, there were statistical differences between groups OVX+Clot and OVX+Clot+LED for the peaks at ∼960 (p ≤ 0.001), ∼1,070 (p ≤ 0.001; p = 0.003), and ∼1,450 cm−1 (p ≤ 0.001; p = 0.002). The results of this study are indicative that infrared LED-PT improved the deposition of HA on bone defects of ovariectomized rats.