Measurement of articular cartilage thickness in the articulated knee

A radiographic and image analysis method was developed and applied in porcine knees for the measurement of articular cartilage thickness in articulated joints. The feasibility of the approach was assessed by implementing the method for the lateral femoral condyle from harvested limbs. Measurement of the undeformed cartilage thickness with this method was found to have a great degree of precision, with approximately a 1.0% (14 microm) mean variation. Accuracy was also high when compared to an optical method for measuring the true cartilage thickness. An excellent linear correlation (r2>0.99) between the thickness determined optically and that obtained from the radiographic images was demonstrated. No significant differences were found between these two measures of cartilage thickness. This method, which minimizes disturbance to the structures of the knee to maintain its physiologic environment, also has promise to measure the changes in cartilage thickness as the tissue is deformed during joint loading. Information about the undeformed and deformed cartilage thicknesses can be combined with finite element models to examine cartilage behavior from both experimental and theoretical perspectives.