Introduction and Objective

One of the clinical problems in the animals is bone fracture and trauma, due to closely connection between skeletal and neuromuscular system and important role of skeletal system in movement. According to recovery problems in skeletal system, more research about bone healing is necessary. Due to this importance, in this study role of polycaprolactone composite mixed with hydroxyapatite were evaluated. According to our findings, appropriate approach to these lesions can be determined.

Method

In this study, 12 adult male New Zealand white rabbits, weighing 2.5 to 3 kg and about 6 months of age were used. They were NPO for 4 hours before experiment. They were divided into 2 groups of experiment: E1, using composite O = hydroxyapatite (HAP) and E2, using composite contained hydroxyapatite mix with polycaprolactone S = MW 2000, having 6 rabbits in each group. Acepromazine maleate (2%) was used 0.5 mg/kg bw intramuscularly as premedication and anesthesia was induced intramuscularly by using 35 mg/kg bw ketamine hydrochloride with combination of xylazine hydrochloride 5 mg/kg bw. After securing in the dorsal position of each rabbit, the medical surface of right stifle joint was shaved and prepared aseptically for operation. Skin incision given on the inner surface of medial condyle and after separation of connective tissue and fascia, a hole in size 4 mm in diameter was made in all rabbits' femoral condyle. The composite O were inserted in each hole in the experiment E1 and the composite S3 were used in the experiment E2. Rabbits in each of two experimental groups were hospitalized for 1 and 3 months and sampling and further study were accomplished later.

Results and Conclusions

Comparison of clinical signs in the E1 and E2 groups indicated that they had similar physical activity and same degree of lameness during observation in period of 90 days. On the gross examination E1 and E2 showed pale yellow smooth callus which had smoother surface rather than the condition without use of any composite for bone healing.

In the E1, after 1 month histopathological observation indicated diffuse new bone formation and the composite had completely disappeared, but after 3 months high quantity of new bone formation with active osteocytes had been formed and had filled the canal. In the E2, after 1 month histopathological observation indicated the filling of the space between the composite and the canal with connective tissue and no new bone tissue formation observed, but after 3 months in the site of defect new bone tissue had been formed and the composite had completely disappeared. Result of compressive strength (Table 1) and elastic modulus (Table 2) shows that use of S composite in the E2 group had better improvement of biomechanical specifications of bone tissue rather than O composite in the E1.

Table 1

1 - Mega pascal

Table 2