An investigation of the short-term effect of exercise on the knee joint by means of computer-assisted auscultation

Although a number of authors have reported the various long term effects of both immobilisation and exercise on the knee joint, few have attempted to quantify the process of change by non-invasive in-vivo means. This study explored the usefulness of an innovative application of auscultation as a tool for non-invasive monitoring of degenerative or regenerative processes within the knee. A structured appraisal of five different component modes of activity (static load, kinetic load, static rest, kinetic rest, seated) was carried out to determine their several influences on the dynamics of the knee joint. Each mode of activity was responsible for a distinct alteration to the characteristics of patellar vibration quantified by amplitude, shape and frequency variables. Loading the knee joint alters its tribology such that patellar vibration is more frequent and of greater amplitude (19·23 Hz, 0·.86 ms−2) than is the case following kinetic rest by continous passive motion (CPM) (2·.85Hz, 0·.13 ms−2). Furthermore, effect of static load is so pronounced that it has zero correlation in terms of vibrational amplitude with that of any previous activity. The amplitude caused by CPM, however, is well correlated (R=0·.73), though greatly reduced from that caused by activity immediately prior to CPM which suggests that CPM facilitates recovery of the joint from the effects of previous activity.