Journal of Veterinary Medicine and Health
Open Access

Laser is a short termination for (light ampliication by stimulated emission of radiation [1]. Low level laser therapy (LLLT) can be used successfully in repair mandible defect in rabbits, by increase number of cells proliferation and migration of the osteoblst cells, and its activation in bone formation [2]. laser therapy can promote healing of the chronic defect in the tibial bones in rabbits which achieved by radiographic and physical inding [3], other results work of the radiological and histopathological examination of laser exposure on the fractures of the distal third radius in dogs revealed a positive efect on promoting fractures healing [4,5]. In others works result Nazht and his group in 2018 mention the stimulatory efect of LLLT at 850 nm for 5 minutes on the xeno-sheep bony implantation in the femoral fractures in rabbits [6].

Laser applications play an important roles in orthopedic surgery by accelerating fractures healing and promoting repair bone defect, because of its positive efect on osteogensis, ibroblast cells activation, collagen synthesis, osteoblast cells proliferation and activation with osteoid depositions and mineralization with hard bone formation [2,7,8]. LLLT has a positive efect on the inlammatory phase by reducing the inlammatory signs, pain and its analgesic efect, also its positive roles in orthopedics surgery, on bone metabolism during fractures healing [9- 16]. he pathphysiological action of laser as reported by [17] that the photonic energy of laser absorbed by cells mitochondria of the irradiated target which converted to chemical kinetic energy and inally leads to more production of ATP, which is the source of energy in the cell and necessary for cell activations and synthesis of DNA, RNA, and proteins that are important in cellular proliferation.

he aim of the present project is to evaluate the eicacy of the continuous diode laser therapy at 810 ± 10 nm on the repair of induced Tibia chronic defect in rabbits and evaluate this goal by clinical observation, radiological examination and histopathological inding at the end of the experimental period 2 and half months p.o. (One month from laser exposure).

Eight adults local breed rabbits were used to induce 3 mm diaphyseal chronic defect in Tibia. the medial aspect of tibia was prepared by clipping shaving the hair and wash with soap and tap water then disinfected the area with 70% ethyl alcohol, the defect created by electrical drill with dropping isotonic sterile normal saline to prevent thermal necrosis, the operation done under general anesthesia by intramuscular injection of 2% xylazin hydrochloride and 10% ketamine hydrochloride respectively, the defect implanted with stainless steel screw for one and half month p.o. (Figure 1), then the stainless steel screw removed to create bone chronic defect in Tibia (Figures 2A and 2B), the animals daily observed for any abnormalities or complication with intramuscular administration single daily dosage of penicillin streptomycin as broad spectrum antibiotics for 3 days p.o., the experimental animals were divided to two equal group each contained four rabbits, the control group followed for normal healing processing without laser irradiation, while the treatment group at the medial aspect of tibia (Figure 3), exposed for single daily dosage of continuous diode laser at 810 ± 10 nm, 500 Ma for 10 minutes at 72 hours interval for 14th days(Figures 4 and 5). his work done in the surgery department of Veterinary Medicine College/university of Baghdad/Iraq under observation and ethical committee.

Figure 1: Radiographic image shows the stainless steel screw long black arrow, implanted in the Tibia to create the chronic defect.

Figure 2: Tibia model shows macrograph 2a) he stainless steel screw well inserted in tibia macrograph 2b) Remove the stainless steel device to create the chronic defect 3 mm in diameter ater one and half month.

Figure 3: he treatment group exposed to 810±10nm of LLLT for 10 minutes at the created chronic defect on the medial aspect of Tibia.

Figure 4: Laser apparatus

Figure 5: Laser model and properities

The parameters which were used for the evaluation as follows.

1. Daily clinical observation, the physiological behaviors and animal’s gaite, or any complications or abnormalities which may occur at the site of operation.

2. Radiographic inding at the end 1st and 2nd weeks post laser irradiation.

3. Histopathological examination for both macroscopic and microscopic inding at the end of the experimental periods two weeks post laser irradiation (two and half month p.o.).

Clinical observation

he clinical observation were the same in both group, which revealed loss appetite and diicult to move with body depression immediately p.o., then within 24 hours p.o. then animals begin to move and eat with normal physiological activity (urination and defecation) gradually the next day’s p.o., the skin incisions healed satisfactory within 5-7 days p.o. with no complications, the rabbits normally used the limb in bearing the body weight and walking and running from the end of the 1st week until the end of experimental period.

Radiological inding

End of 1st week post laser irradiation: Sclerotic area around the induced chronic defect which is more dense and wide in the treatment group compare with the control group, the defect illed with new bone formation in both group (Figure 6).

Figure 6: One week post laser irradiation. 6a) control group, 6b) treatment group, represents increase radiographic density, sclerotic area around the induced chronic bone defect which appears wide and clear with decrease the defect diameter in the treatment group compare to the control group , turbidity area inside the pore in the both group represent the newly ibrous connective tissue which may be converted to new bone formation.

End of 2nd week post laser irradiation: he radiographic image show increase in density and widening of the sclerotic area with decrease the defect diameter in the treatment group compare with the control group, the defect illed with new bone formation in both group (Figure 7).

Histopathological examination

Figure 7: Two week post laser irradiation, 7a) control group, 7b) treatment group no signiicant changes in the control group, while the treatment group seemed to show more dense area around the induced chronic defect, with decrease the pore diameter.

Macroscopic examination at the end of the experimental period: he macroscopic indings were the same in both groups which revealed formation of ibrous connective tissues that ill and cover the chronic defect (Figures 8A and 8B).

Figure 8: Grossly examination of the tibia defect, 8a) control group, 8b) treatment group, illustrated close the defect with ibrous connective tissue in both group.

Microscopic examination at the end of the experimental period: he control group: a)he transverse section revealed marked congested B.V. With cellular iniltration in fatty marrow, containing various types of inlammatory cells, the host bone contain large size of H.C. With tissues debris with irregular trabecular bone formation with number of osteocytes at the surface (Figure 9). B) he longitudinal section shows ibrous tissues deposition with osteoblast cells and osteoid formation at the margin of the recipient bone and the defect border, the compact bone contain various size of H.C. with lacuna contain osteocytes, with large marrow space illed with necrotic debris bone specula’s and number of osteoblast (Figure 10). he treatment group: he transverse section revealed numerous congested large blood vessels in the fatty marrow tissue, with hemorrhage area and presence of eosonophilic, new trabeclar bone formation, marrow cavity illed with PMNCS, macrophages, plasma cells, the compact bone of the recipient femoral bone contain number of the osteocytes in the lacuna with few haversain canal, the edge of the host bone replaced by thick ibrous connective tissues and callus formation, the newly developed osteoid tissues supported by active osteocytes cells. Fibrous callus formation with newly developed osteoid tissues ill the space between the host bone (Figure 11).

Figure 9: Figure 9. Control group, transverse Histopathological section, Hemopoetic cells( ) in the bone marrow cells, with increase of blood circulation( ) and new bone formation ( )from the endosteum (H and E× 10).

Figure 10: Control group longitudinal histopathological section which revealed new bone formation that converted to lamellar bone formation ( ) with some cavity which not converted to mature bone formation these cavity illed with vascular connective tissues ( ), with new bone formation, profuse osteoblast cells lining the new bone formation ( H & E× 10 ).

Figure 11: Treatment group longitudinal histopathological section which revealed ibroblast cells( ) proliferation with osteoblast cells ( ) and osteoid depositions ( )and marked new blood vessels ( ) ( H & E× 10 ).

The longitudinal section revealed. he marrow tissues showed extension hemorrhage and B.V congestion with iniltration various type of inlammatory cells, new bone formation. Profuse ibrous connective tissues ill the induced gab with active and numerous blood vessels and collagen deposition iniltrated with inlammatory cells mostly poly morphonucleic cells, the new bone formation around the chronic defect characterized by weak elongated trabeclu bone formation containing vascular canal with lat osteoblast cells lining its surface, the blood vessels inside the haversian canal with the osteocytes cells in the lacuna in centrifugal appearances, with many of the empty lacuna (Figure 12).

Figure 12: Treatment group transverse histopatholoigical section which revealed active hemapotic cells in the bone marrow which illed with fat cells ( ) with highly blood vessels ( ) iniltrated with inlammatory cells ( ).(H & E× 10).

The clinical observation were the same in both group and these signs agree with [10,11,14,16] in which they refer to the inlammatory signs that appears immediately ater operation with loss of appetite and diicult to move, which then retained to normal ater 24 hours p.o.

he radiographic inding of the treatment group which exposed to LLLT in the end of the 1st week post irradiation revealed high sclerotic area around the adage of induced chronic defect that later increase in wide and density at the end of 2nd week post irradiation, with signs reduce in the defect diameter compare with the control group at the same time, these events is due to the stimulatory efect of laser on the osteoblast cells activation and proliferation with osteoid formation and mineralization and these activation may due to increase alkaline phosphates enzymes synthesis and release as mentioned by [3,18].

he macroscopic appearance which shows ibrous connective tissues formation illed the defect in both group, with signs of reduce the diameter of the bone defect in treatment group compare with the control group, that is due to laser stimulation, and this note is agree with [8] hat laser application has stimulatory efect on ibroblast cells metabolism and numbers, which may produce profuse of collagen ibers that will later change to mature trabecula bone.

he Histopathlogical indings of the treatment group shown new bone formation in the bone defect which characterized by mature and wide trabecula bone formation with less of the empty space inside, that illed with vascular connective tissues and active osteoblast cells lining the bone surface, in other section the mature new bone formation converted to lamellar bone compare to the control group in which many space of the mature trabecula bone not changed to lamellar bone, these observation is due to osteoblast cells activation and osteon production with calcium and minerals deposition and these agree with [2] that LLLT of 850 nm has a stimulatory efect on the osteoblast cells in bone defect repair in the lower mandible in rabbits while [7] showed that using diod laser of 780 nm faster bone regeneration in mandibles defects of Holtsman rats, than control group.

he positive results of the LLLT on treatment group compare with control group which achieved by histopathological and radiographic inding, is due to the stimulatory efect of LLLT on osteoblast cells activation and proliferation, with production and release ALP enzymes that promote osteoid production and mineralization besides its stimulation on the ibroblast cells and collagen synthesis with osteogensis and these agree with [3,18] in which they refer to the positive efect of LLLT at dosage of 850 nm on the chronic defect in rabbits tibia, which evaluated radiographically and physical analysis.

Laser therapy of continuous diod laser at dosage 810 ± 10 nm can be used in repair induced tibial chronic defect in rabbits.