Methods Within 518 individuals with knee OA considered from the ArGon study (Klussmann et al., 2010), the condition of the knee cartilage was documented graphically. In this visualisation, the knee surface was divided into 48 quadrants so that the localisation of cartilage damage in individuals with different exposure and occupations could be compared.
Results The most frequent damage was in the centre of the medial femur condyle and in the medial surface of the tibia plateau. In subgroup analysis compared to subjects without malalignment of the knee, the prevalence of damaged cartilage increased significantly on the medial femur condyle and the medial surface of the tibia plateau in the group with genu varum and in contrast on the lateral femur condyle and the lateral surface of the tibia plateau in the group with genu valgum. Further comparisons (e.g obesity vs. normal weight, floor layers vs. office workers) determined only low or not significant differences between the prevalence of damage in the single quadrants.
Discussion Besides malalignment of the knee, the actual analyses do not suggest the existence of exposure-specific or occupation-specific patterns of cartilage damage in the knee joint. However, frequent changes in professional activities during working life and partially low numbers of individuals in specific professional groups might restrict occupation-specific statements.
References Klussmann A, Gebhardt H, Nübling M, et al.: Individual and occupational risk factors for knee osteoarthritis: results of a case-control study in Germany. Arthritis Research & Therapy 2010, 12:R88.