What is Osteomyelitis?
Osteomyelitis is an infection of the bone typically caused by bacteria, although other pathogens like fungus may also cause it. It typically occurs when bacteria spreads from another site such as the surrounding muscles and tissues or from a more distant site by being seeded through the blood. It can affect all components of the bone including the marrow and it can be a very challenging condition to treat and a multimodal approach is important.
What happens in Osteomyelitis?
Once a microorganism infects the bone the immune system begins to react to the infection with leukocytes (white blood cells) that try to eradicate the infection. This process typically results in the release of enzymes that breakdown the bone and the infectious debris can plug up the bone's blood supply impairing the healing process. This area of impaired blood supply form 'sequestra' which become the basis of a chronic infection. As the body has a hard time healing these areas it often ends up forming new bone over the infected area. Osteomyelitis is typically categorized as acute (less the one month) or chronic (longer than one month) in duration, and once it is categorized as chronic, adding hyperbaric oxygen becomes an important adjunct to try and eradicate the infection.
What are the symptoms of Osteomyelitis and how to diagnose it?
Osteomyelitis is often non specific in the symptoms it causes and can present as the following:
Redness over the affected area
Pain in the affected area
Fever and feelings of malaise
Inability to walk or weight bare if the affected bone is involved in weight baring
Swelling of lymph nodes that drain the affected area
Diagnosis of osteomyelitis can be challenging as many of the diagnostic features are not specific (meaning they can occur in other disease states). X-rays and CT scans are typically first line tools and can show bone destruction later in the infection, but can often show very little early on. Bone scans (typically 3-phase) can be helpful by showing increased uptake of gallium in the affected area. This technique combined with WBC (white cell) imagining is about 90% accurate for detecting osteomyelitis. MRI's are also effective at picking up early signs of osteomyelitis but again, the findings are not very specific and may also be caused by other pathologies. Orthopedic surgeons may often take a tissue culture from the affected bone if osteomyelitis is suspected.
How is Osteomyelitis treated medically?
Standard treatment for osteomyelitis involves comprehensive washout and debridement of the affected area and the use of appropriate antibiotics. Antibiotics may start as oral, but may have to be switched to intravenous if the oral formulations are not effective. If the infection is not controlled, further surgical techniques may be required including reconstruction, stabilization, resection, and even possibly amputation if the infection is unable to be controlled and causing complications.
How is Osteomyelitis treated with Hyperbaric Oxygen Therapy?
Hyperbaric oxygen is an important adjunct to osteomyelitis and needs to be used in conjunction with appropriate medical (antibiotics) and surgical treatments. It is typically added once an infection is categorized as chronic (longer than one month). Hyperbaric oxygen therapy works to help irradiate the osteomyelitis by several mechanisms. It increases the amount of oxygen available at the infected bone. Oxygen is an important metabolic requirement for the immune system and poor oxygen delivery as occurs in osteomyelitis impairs these pathways. Additionally, the free radicals generated by oxygen during hyperbaric oxygen therapy have an anti-microbial effect (able to eradicate the bacterium). Hyperbaric oxygen therapy also mobilizes progenitor cells (‘stem cells’) through its effect on the hematologic system resulting in angiogenesis (the creation of new blood supplies) which is needed to improve oxygen delivery to the infected bone and accelerate infection recovery.