Morphological and biochemical comparison of convex and concave articular surfaces from adult subtalar and midtarsal joints.

Convex and concave articular cartilage from adult subtalar and midtarsal joints showed depressions over surface chondrocytes and linear arrays of surface fibres when examined by scanning electron microscopy (SEM). Full-thickness cartilage from concave surfaces contained significantly less collagen than cartilage from convex surfaces (40.8% vs. 47.4%, p less than 0.05). Plano-concave surfaces contained 44.7% collagen. Water and uronic acid content did not differ significantly for the different shapes. A higher collagen content in convex surfaces is consistent with the hypothesis that collagen networks in these surfaces are subjected to higher tensile stress under load than are those in concave ones.