Cartilage from 14 human osteoarthritic femoral heads was studied in vitro 1, 20, and 30 days after explantation to assess component proteoglycans. Newly synthesized proteoglycans labeled with tritiated-leucine or Na(2)35SO4 and existing, hexuronate-containing proteoglycans were eluted on Sepharose CL-2B (0.5 mol/L sodium acetate, pH 5.8) as four subpopulations with average partition coefficients ranging from 0.05 to 0.9. These subpopulations were comprised of proteoglycans aggregated to hyaluronic acid and principally nonaggregated proteoglycans. Although this distribution was stable to day 20, by day 30, 35SO4-labeled proteoglycan aggregate decreased and smaller proteoglycans increased in amount. With longer culture periods, the proteoglycan subpopulations contained fewer high-density proteoglycans, which were also decreased in size.