In young rabbits, the effects of an intravenous injection of
Staphylococcus aureus alone, and in combination with a traumatic injury of
the proximal tibial physis, were studied by light and electron microscopy.
Metaphyseal osteomyelitis and radiographic changes were seen within
forty-eight hours after the injury in all rabbits that had a growth-plate
disruption and bacteremia. An intravenous injection of bacteria alone
produced no morphological or microbiological evidence of infection. In the
absence of trauma, normal tibiae were sterile after forty-eight hours.
Foreign-body particles have been shown to accumulate in the fine vessels
that are adjacent to the growth plate, but we found no similar deposition
of bacteria or evidence of phagocytic removal in this area. Phagocytosis of
bacteria by neutrophils did not appear to be impaired in the distal third
of the metaphysis, but a delayed inflammatory response that allowed
proliferation of bacteria and destruction of tissue was observed in the
proximal two-thirds of the metaphysis after trauma.