Objectives-(a) To determine the topographical variations in cartilage thickness over the entire surfaces of cadaveric lower limb joints, and (b) to examine the correlations between: cartilage thickness and its site specific modulus; cartilage thickness and donor age, weight, height, and body mass index. Methods-The cartilage thickness of 11 sets of cadaveric human joints each comprising an ankle, knee, and hip was measured using a needle probe technique. Statistical analysis was used to compare the cartilage thickness of the diVerent lower limb joints and the diVerences in cartilage thickness over the surface of individual joints. It was further examined whether cartilage had a correlation with its stiVness, and any of the details of the specimen donors such as age, weight, height, and body mass index. Results-The mean cartilage thickness of the knee was significantly greater than that of the ankle and hip (p<0.001) in all 11 sets of joints, while the cartilage thickness of the hip was significantly greater than that of the ankle in 10 sets of joints (p<0.001). The mass of specimen donors was found to correlate with the mean cartilage thickness of all three lower limb joints. A correlation was also found between the height of donors and the mean cartilage thickness of the knee and hip joints, while only in the ankle joint was a correlation found between the mean cartilage thickness and the body mass index of the specimen donors. A further correlation was found between cartilage thickness and its modulus; the thinner the cartilage, the higher the modulus. Conclusions-The thickness of articular cartilage seems to be related to the congruance of a joint; thin cartilage is found in congruent joints such as the ankle, whereas thick cartilage is found in incongruent joints such as the knee. The correlations in this study imply that the larger and heavier was a donor the thicker was the cartilage in the lower limb joints. The data further suggest the presence of an inverse relation between the mean cartilage thickness and mean compressive modulus in each of the joints examined.

Background: Articular cartilage is a viscoelastic material, but its exact behaviour under the full range of physiological loading frequencies is unknown. The objective of this study was to measure the viscoelastic properties of bovine articular cartilage at loading frequencies of up to 92 Hz.

The topographical variations in the cartilage instantaneous compressive modulus over the surfaces of the lower limb joints were matched by differences in the stresses occurring in different areas of each joint. The results of the present study corroborate previous findings and show that the site-specific stresses and corresponding values of the instantaneous cartilage compressive modulus over the surfaces of lower limb joints were correlated (r = 0.82 at P < 0.01), thus adding credence to the conditioning hypothesis of cartilage by prevalent stress.

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Background: Polyurethane (PU) foam is widely used as a model for cancellous bone. The higher density foams are used as standard biomechanical test materials, but none of the low density PU foams are universally accepted as models for osteoporotic (OP) bone. The aim of this study was to determine whether low density PU foam might be suitable for mimicking human OP cancellous bone.