Development with age of human articular cartilage surface structure. A survey by interference microscopy of the lateral femoral condyle.

The weight-bearing surfaces of the lateral femoral condyles taken from twenty normal human cadavers aged 0-47 years have been examined by reflected light interference microscopy (RLIM) and by scanning electron microscope (SEM). The surfaces appeared normal by naked eye examination. The presence of both 200-400 mum diameter secondary undulations and small ovoid 20-45 mum diameter tertiary hollows was confirmed in all specimens using both techniques. Measurements by RLIM showed that the tertiary hollows increase significantly in depth and diameter with increasing age. A further order of quaternary surface irregularities was shown. Small irregular ridges, 130-275 nm deep and 1-4 mum diameter, were found with increasing frequency on specimens obtained from persons aged 21 years. These quaternary irregularities are thought to be due to exposure of superficial fibre bundles after the loss, with age, of surface ground substance.