Low temperature and conventional scanning electron microscopic observations of dog femoral condylar cartilage surface after anterior cruciate ligament division.

The left stifle joints of 16 beagle dogs were subjected to surgical division of the anterior cruciate ligament (ACL). The femoral condyles showed surface alterations and damage after 14 days when examined by low temperature (LTSEM) and conventional scanning electron microscopy (SEM). The first change was an increase in the fibrous texture of the articular cartilage surface. Folds and surface roughening were later recognised. After 112 days deformation and disruption gave way to cracking or fracture of the surface layers. Superficial damage was focal in distribution and accompanied by a decrease in the frequency of tertiary elevations. The affected areas of cartilage increased in frequency and size with time and surgery. The observations obtained from LTSEM, in which the tissue remains fully hydrated during examination, may be caused by alterations in water content and a loss of proteoglycan at the surface, together with changes in cell shape and size. Surface cracks may be the en face appearance of histological fibrillation.