Six of 6-week-old NZ rabbits underwent ultrasound treatment using a therapeutic dose (0.5 W/cmZ) and other six were treated with a higher dose (2.2 W/cm2) to the lateral aspect of the left knee joint for 20 min per day and a total of six weeks. The right knee joint served as a control. The goal of this study is to see if the therapeutic dose and high dose (approximately 45-fold therapeutic dose) will have toxic effects on the physis. Histological review appeared normal growth plate in the therapeutic group. In the high dosage group three of six cases displayed flattening of the distal femoral epiphysis and wedging of the proximal tibial plateau and indistinct growth plate lines. It is of interest to note that there are opening radiolucent area in the lateral aspect on the femoral metaphysis in five of six cases, where bone resorption has taken place. Histological results showed that there are disordered arrays of the cartilaginous cells in the proliferative zone. The height of the lateral physis in the high dose group is not only greater than that in the therapeutic dose (1083.8 vs. 500.3 pm), but also greater than that in their contralateral control (530.7 pm) ( P < 0.05). This shortterm study demonstrates that high dose ultrasound has profound pathologic effects in growing bone. Therapeutic doses of ultrasound do not have an adverse effect on bone growth in the short-term follow-up.

The back surface image study is a method for providing a quantitative assessment of mild spinal deformity, allowing evaluation of patients by integrated three-dimensional parameters with no reference to radiographs.

In slipped capital femoral epiphysis (SCFE), cannulated screw fixation is a standard procedure. The aim of this study was to investigate the feasibility of a fluoroscopy-supported navigation system for screw fixation in SCFE. Using a fluoroscopy-enhanced navigation system, a cannulated screw fixation was performed in seven hips of four patients. The navigation system showed a high feasibility in instrument visualization and implant placing. The mean x-ray time was 6.2 seconds. Initial experiences are very promising and show advantages of the fluoroscopy-supported navigation. Considerably reduced x-ray exposure for patients and surgeons is possible. In the future, further efforts will be necessary to develop navigation-specific instruments to enhance the precision of screw positioning.