In this month’s Pathology Spotlight we take a look at Osteomyelitis.
This specimen is one of the best known in Surgeons’ Hall Museums, where it is featured in its own display case. It is a tibia bone from an Edinburgh-born sailor called Charles Anderson. In 1814, aged 17 years, Anderson was sailing in the Baltic when he fell from a mast onto the deck and fractured his tibia. He arrived back in Edinburgh in 1815 and his tibia had swelled at the top and developed a hole, or sinus, from which abundant pus and fluid flowed; admitted to hospital, he refused amputation. As the swelling increased in size and the discharge became difficult to manage he fitted a wood and tow plug into the main sinus. Every day he removed the plug and let the discharge flow out, often half a litre in volume, before returning the plug to its position. Despite the chronic infection and the gradual enlargement of the cavity he was able to walk and only permitted amputation in 1831.
The image shows a tibia that is normal in its lower half but the top is distended into a large cavity which was infected and filled with pus; the plug from which the pus was vented is clearly visible towards the bottom of the cavity on the right side. Chronic osteomyelitis, or infection of the bone, is one of the oldest recorded diseases and was a severe problem in the pre-antibiotic days. Louis Pasteur, the ‘Father of Microbiology’ correctly implicated the bacterium Staphylococcus aureus in the condition. When bacteria gain access to bone, probably due to breaching of the skin when Anderson fell from the mast, they can grow there. Despite the fact that they activate a defensive inflammatory response, with formation of pus, the bacteria are not killed. Instead they continue to grow at the site of the infection, stimulating a protracted, chronic inflammatory response. Over time the presence of chronic inflammation results in destruction of bone at the site of the infection along with abnormal patterns of bone growth producing, for example, the large distended pus-filled cavity seen in this case. Modern therapy for osteomyelitis includes drainage, removal of dead bone and wound protection and closure if possible. Culture of the causative microbe allows rational choice of an effective antibiotic.