ABSTRACT
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.
Subject(s)
Anthropometry/methods , Cartilage, Articular/anatomy & histology , Cartilage, Articular/diagnostic imaging , Image Processing, Computer-Assisted/methods , Knee Joint , Animals , Anthropometry/instrumentation , Cartilage, Articular/physiology , Feasibility Studies , Finite Element Analysis , Image Processing, Computer-Assisted/instrumentation , Linear Models , Radiography , Reproducibility of Results , Swine , Weight-Bearing/physiologyABSTRACT
Changes in ankle biomechanics lead to altered load transmission through the ankle joint, possibly predisposing it to osteoarthritis. Contributions of the different bands of the deltoid ligament to the contact characteristics in the ankle were examined. Fifteen normal cadaveric lower extremities were axially loaded to 445 N after intra-articular Fuji film placement. Ankles were tested in neutral, 10 degrees dorsiflexion, and 10 degrees plantarflexion. Repeated testing was done following sequential sectioning of the deltoid ligament, and the contact characteristics were analyzed. The greatest significant tibiotalar changes (P < 0.0001) occurred after sectioning of the tibiocalcaneal fibers of the superficial deltoid ligament complex. Contact areas decreased up to 43%, peak pressures increased up to 30%, and centroids moved 4 mm laterally, on average. In contrast, sectioning of the other bands led to insignificant changes in joint contact characteristics. The data indicate that significant changes in contact characteristics occur before radiographic evidence of deltoid ligament damage is evident, and may indicate that greater attention to the medial side of the ankle is indicated to restore normal biomechanics to this joint.
