Vibrational analysis of growth hormone modulated healing of a canine radial partial ostectomy

Sixteen adult Beagle dogs had a single partial radial ostectomy providing a 3 mm gap in the middle of the bone. The dogs were divided into 4 groups based on the duration of treatment with growth hormone, somatotropin. Group 0, the control group, received no somatotropin; group 3 received 3 weeks of treatment; group 6 received 6 weeks of treatment and group 12 received 12 weeks of treatment. At the end of the 12 week healing period, the dogs were humanely euthanized. The healing radius and the normal contralateral radius were excised and tested by vibration and three point bending. Vibration testing included impact testing, and the development of a transfer function and frequency response curve. From the response curve, the natural frequency of the first bending mode was determined. Also the percent of damping was calculated. As the ostectomy healed and increased in stability, the natural frequency increased. The natural frequencies were significantly different with respect to the structural integrity and stability of the bones. Also the natural frequencies positively correlated with the results obtained with three point bending. Calculated damping values were not significantly different and were negatively correlated with the bending tests.