[Stress on the knee joint by knee bending as prearthrosis]

Purpose of our study was to prove from the orthopaedic point of view whether or not osteoarthrosis of the knee joint may be regarded as an occupational disease under certain physical loads.

A review and meta-analysis of occupational medicine literature was undertaken, which was reported as a scientific background for the planned occupational disease study "gonarthrose" in Germany.

There exist only four relevant epidemiological studies, showing a correlation between osteoarthrosis of the knee joint and knee flexion under conditions of physiological stress. None of them proves that knee flexion causes osteoarthrosis. It may be only concluded with some restriction that occupations involving extensive kneeling or squatting influence the progress and course of osteoarthrosis of the knee--together with other pathogenetic and aetiological factors.

It cannot be concluded from occupational studies that kneeling and squatting or similar physical strains during work cause osteoarthrosis of the tibio-femural or patello-femoral joint. On the basis of methodical epidemiological and biomechanical considerations a causative correlation as described before cannot be expected. Nevertheless, in the occupational literature one can find some circumstantial evidence which may show whether mechanical functional stress influences the course of knee arthropathy (such as early patella osteophytes, osteoarthrosis of ankle joints) or not (early tibio-femural osteoarthrosis, lack of osteophytes in the elderly).