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Assessment of bone healing on radiographs is not necessarily objective. A clinical system was developed to quantify the stiffness of healing fractures of the tibia in patients by the echo tracking (ET) method in a manner similar to a three-point bending test. The lower leg was supported. An ultrasound probe was placed on the proximal and distal fragments and a load of 25 N was applied. With a multiple ET system, two probes measured the displacement of five tracking points on each of the proximal and distal fragments of the tibia, thereby detecting the bending of the two fragments generated by the load. ET angle was defined as the sum of the inclinations of the proximal and distal fragments. Patients with tibial fracture treated by a cast or internal fixation were measured over time. In patients with radiographically normal healing, the bending angle decreased exponentially over time. However, in patients with nonunion, the angle remained the same over time. It was demonstrated that the ET method could be clinically applicable to evaluate fracture healing as a versatile, quantitative and noninvasive technique.

Biomechanical experiments were performed on sacroiliac joints of the cadaver pelvis in three different positions to determine changes in stress pattern. The infrared stress analyzing method was used. In the neutral position, principal stress was observed in the middle to upper part of the sacrum, adjacent to the sacroiliac joints, in the central area of the ilium, and in the acetabular region. In the anterior tilting position, the stress on the sacroiliac joints was smaller than in the posterior tilting position, while it was greater in the symphysis pubis area. Further experiments with dial gauges were performed to measure load-displacement value in four cadaver pelves. Vertical loads of up to 100 kg were applied to the fourth lumbar vertebra. At the maximum test loads, displacement of the anterior surface of the first sacral vertebra ranged from 0.18 mm to 0.73 mm in the anterior direction. In conclusion, it is clear that the range of movement in the sacroiliac joints is very small and that this joint plays a significant role in the maintenance of stability in the pelvic girdle.

I measured hip abduction force using a new device of my own design and evaluated the correlation between hip abduction force and electromyographic (EMG) activity of the gluteus medius, gluteus maximus, rectus femoris and adductor longus in 20 normal adults. Hip abduction force showed a maximum value on starting and decreased during abduction of the hip joint. Durability, on the other hand, showed an increase. The attenuation curve was approximated to the exponential function A.e-Kt; A and l/k indicating maximum hip abduction force and durability, respectively. Maximum hip abduction force was about 20 kg and durability was about 160 seconds on starting hip abduction. The regression coefficient between hip abduction force and EMG activity of the gluteus medius, gluteus maximus, rectus femoris and adductor longus was 1.5, 06, 0.6 and 0.2 respectively. From these results, I concluded that although the gluteus medius plays the major role in hip abduction, the rectus femoris and gluteus maximus may act as stabilizers for maintaining the position of hip abduction.

The possibilities of hyperthermia are discussed from the engineering technology standpoint. Microwave equipment yields powerful effects against a superficial tumor. RF capacitive method and annular phased array system (APAS) are typical heating methods against a deep-seated tumor. We have proposed that in the RF capacitive method the diameter of the applicator electrode should be more than 1.5 times the distance between two electrodes. In APAS another exciting method (TE mode) has been proposed. Electric current flows through the short axis of the body by the TE mode excitation. We are developing re-entrant resonant cavity applicators which have the characteristics to heat cylindrical regions of small diameter. We can install an x-ray tube inside the re-entrant electrode. This method is suitable for deep and concentrated heating. We conclude that the recent rapid development of various kinds of hyperthermia apparatus makes it possible to heat more safely and effectively the deep-seated regions of the human body.