These results suggest dietary fat, independent of animal weight, results in altered chondrocyte function. Increased dietary fat was associated with changes in rabbit cartilage in vivo and appears to be a risk factor for the development of OA.

Objective To investigate the effects of lubricin gene dosage and cyclic loading on whole joint coefficient of friction (CoF) and articular cartilage surface integrity in mouse knee joints. Methods Joints from mice with two (Prg4+/+), one (Prg4+/−), and no (Prg4−/−) functioning lubricin alleles were subjected to 26 hours of cyclic loading using a custom-built pendulum. CoF values were measured at multiple time points. Contra-lateral control joints were kept unloaded. Following testing, joints were examined for histological evidence of damage and cell viability. Results At baseline, Prg4−/− CoF values were significantly higher than Prg4+/+ and Prg4+/− values (p<0.001). Cyclic loading continuously increased CoF in Prg4−/− joints. In contrast, Prg4+/− and Prg4+/+ joints had no CoF increases during the first 4 hours of loading. After 26 hours of loading, joints from all genotypes had increased CoF values compared to baseline and unloaded controls. Significantly greater increases occurred in Prg4−/− and Prg4+/− joints compared to Prg4+/+ joints. CoF values were not significantly associated with histological evidence of damage or loss of cell viability. Conclusion Mice lacking lubricin have increased baseline CoF values and are not protected from further increases caused by loading. Prg4+/− mice are indistinguishable from Prg4+/+ mice at baseline, but have significantly greater CoF values following 26 hours of loading. Lubricin dosage affects joint properties during loading, and may have clinical implications in patients for whom injury or illness alters lubricin abundance.

No abstract