(The) effects of ultrasound on growing bone in rabbits
the problems which are concerning the bony growth by way of any kinds of procedures and materials has been considered in numerous reports and this study is until controversial in the field of the Orthopedic Surgery.
As a part of this task, some authers reported that the ultrasound may affect the epiphyseal plate on growing bone in experimental study.
But the results are not clearly defined and not identical each other, but the epiphyseal area of growing bone is generally considered a contraindicated site for ultrasonic therapy.
Arden(1957), Bender(1954), Buchtala(1948), De Forest(953) and Maintz(1950) showed that damage occurs to bone cortex and bone marrow with high intensities of ultrasound.
Arden and Maintz showed that increased osteogenesis of bone revealed with low intensities of ultrasound and Arden defined the critical dose as 10 watts/cm**2.
But it is generally accepted that the low intensities of ultrasonic exposure does not effect upon the epiphyses in growing rabbit.
To clarify the ultrasonic exposure upon the growing epiphyses in rabbit, the auther observed the difference in bone length, microscopic appearance, rate and manner of epiphyseal closure between the treated and control leg in 5 different doses of ultrasonic exposure.
A series of 40 rabbits of the same age was treated with 2, 4, 8, 10, 12 watts/cm**2 for five minutes daily, 5 days a week, from age 3 months until X-ray evidence of epiphyseal closure was obtained.
The ultrasonic apparatus which was used is designed for use clinically(Lindquist) with a round head transducer.
the rabbit's hind leg was held in position under water by a strap around the foot in special fixation device and kept the water at a temperature of 36 C with thermostatic heater.
Baseline study of X-ray was taken of both right(treated) and left(control) hind legs before treatment was begun(at age of 3 months) and begining at age of 5 months, weekly X-ray were made until evidence of epiphyseal closure appeared.
when closure of the epiphyses was noted the animal was sacrificed and the lengths of the disarticulated tibiae and humeri was measured.
The tibiae was then split and fixed in formalin, and microscopic slide were made of the decalcified material.
The results of the experiment are as follows.
1. The ultrasound has no significant effect on bone length in growing rabbit by statistical analysis.
2. The ultrasound has no significant effect on the closure time of the epiphyseal plate in 5 different doses.
3. Histological examination of the upper epiphyseal areas of the both tibiae reveals no difference between treated and control group in lower dosage, but in high dosages of ultrasound, there was a slight degree of increased vascularity and scattered foci of mitosis in the treated leg.
4. From this study, the auther concluded that, in the rabbit, ultrasound applied in this dosage and in this manner has no significant effect on bone length, epiphyseal closure time, and microscopic examination.