Two basic components of the radiographically measured knee osteoarthritis (KOA), joint space width (JSW) and size of osteophytes (OPH), were studied in order to characterize early stage of KOA and to reveal additional aspects of grading it. The study was conducted in 161 individuals (100 women and 61 men, 34{54 years old). A linear mixed and a generalized linear models were used to identify risk factors for JSW and OPH. Accounting for intra- and inter-knee correlations in these models is novel for knee studies. We obtained that at the early stage of KOA, JSW is more constitutionrelated, while the appearance of OPH more disease-related. The e®ect of gender on JSW was su±ciently large to establish di®erent de¯nitions of KOA for genders. In this case attention should be paid to the medial compartment as the narrower one. Our ¯ndings also suggested that the height of women could be taken into account when grading KOA, and that the imbalance between knee and thigh circumferences refers to the presence of OPH.