The role of instrumental diagnostic methods in the staging of Sudeck's disease.

Forty patients with Sudeck's atrophy were assessed in order to evaluate the diagnostic accuracy of x-ray, scintigraphy and telethermography in staging the 3 phases of the disease. The dynamic and early static phases of scintigraphy were the most sensitive and specific instrumental tests for detecting the early stage, whereas telethermography was fairly sensitive but not very specific. Radiographic examination was not sensitive in detecting slight changes in bone density, but it was the most reliable index for recognizing the transition to stage II of the disease. Moreover, it was possible to confirm that the late static phase of scintigraphy is the index which is best related to bone metabolism.

[The action of loads on bone tissue]. / L'azione dei carichi sul tessuto osseo.

This paper analyses the effect of mechanical loading on bone remodelling under both physiological and pathological conditions. The sensitivity and the type of the biological response of bone to the changes in mechanical loading are conditioned by several factors: individual race and age, pattern of stress, systemic and local metabolic conditions, etc. Therefore, bone remodelling following mechanical stress is not only a simple repair process, but a complex mechanism of functional adaptation which is controlled by the strain magnitude of bone structure rather than the extent of the stress. Results show that the skeletal changes induced by mechanical stress involve not only the structural properties but also the material characteristics of bone. For example, the size of hydroxyapatite crystals increases under load. These findings allow us to hypothesize that mechanical stress could directly modify the mineral component of bone. Hydroxyapatite appears to be a highly dynamic structure, able to change its crystallinity in relation to external stimuli. It is thus conceivable that hydroxyapatite crystals gather and arient themselves along bone and improve their crystallinity not only under the influence of biological mechanisms, but also as a reaction to mechanical stimuli.

Growth-plate cartilage metabolic response to mechanical stress.

An in vitro study assessing the metabolic response of growth-plate cartilage explants to mechanical stress was performed. Cultured explants were exposed to two types of stress: (a) single high-compressive force (SHC), and (b) multiple intermittent low-compressive force (MILC). Proliferative activity and matrix synthesis were determined with liquid scintillation counting after explants were labeled with [3H]thymidine and [35S]-sulfate. Our in vitro findings suggest that too high a force, even acting for a short time, may result in permanent injury of growth plate cartilage. Hence, we hypothesized that there might be an unknown pathogenetic mechanism of Salter's fifth-type epiphyseal injury. We report the results of our study.