13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- rats, collected in three separate occurrences once every 12 weeks. Due to the biological nature of the material, variations in the results are substantial, even between samples that have undergone identical treatments. Assessing the effectiveness of “A” and “B” on the fracture healing of rat bones is important, as it supplies information on the viability of using such treatments for humans. Sprague Dawley rats were used because of their similarity to humans in reaction to diseases. This report provides the mechanical properties of the bones for each treatment. If a treatment is successful in providing the bone with feasible parameters, it can then be further investigated for potential human use. Although, this report is only a small step towards the process it helps to determine and document the outcomes, difficulties and considerations when using the treatments considered. 2. Methodology 2.1. Sample procurement To acquire the data for the study, 12 female Sprague-Dawley rats were raised in identical environmental conditions (diet, temperature and humidity). The rats were randomly divided into 4 groups, to which were applied a specific medical treatment according to the weight of the animal. This study is divided into three phases, where each phase consists of 4 rats. The phases follow each other chronologically in 3-month intervals. The samples are thus harvested every 3 months. A rat provides two bone samples: its left and right femur, which is then prepared and conserved for biomechanical testing. The rats undergo a surgical procedure at approximately 6 months of age. The average age of a Sprague Dawley rat is around 2.5-3.5 years [6], at 6 months the animals have reached maturity. At the end of the 12-week treatment period, each rat was sacrificed for bone extraction. The samples of this study have been separated into four different groups: normal fracture, control group, “A” treatment and “B” treatment (Table 1). Table 1. Sample group characterization Sample Group Description Label Group Name Normal fracture with physiological serum F+S Normal fracture Subtraction osteotomy with physiological serum OS+S Control group Subtraction osteotomy with “B” treatment OS+B “B” treatment Subtraction osteotomy with “A” treatment OS+A “A” treatment The physiological serum acts as a placebo for the normal fracture and control group, whilst providing the animals with the required nutrients. The operation procedure was the same for the OS+S, OS+A and OS+B sample groups. The surgical procedure and theoretical bone healing progression has been summarized in the sketch of Figure 1. The operation of F+S samples was similar except that there was no bone subtraction and thus no gap, as it is a simple fracture. In the operation, the rat’s skin was incised and a 2 mm section from the centre of the femur was removed, (subtraction osteotomy). Once the gap was created a stainless steel screw (2mm x 24mm) was inserted in the lower extremity of the right femur to maintain the gap. To verify that the callus was developing correctly, the animals were monitored taking x-rays of the right femurs (Figure 2: 7 days after the operation, 6 weeks after start the treatment and 12 weeks prior to the slaughter). The pictures were analized to measure the gap size (in mm) and evolution throughout the treatment. In order to conduct the biomechanical tests on the bones, they were removed from the rats by surgical procedure carried out by medical personnel. The extracted bones were conserved to avoid their deterioration through drying, in a saline solution (HBSS) at 4ºC until they were tested.
RkJQdWJsaXNoZXIy MjM0NDE=