Osteomyelitis is quite often confused with septic arthritis, even though they are different classes of diseases. Osteomyelitis is the disease in which inflammation causes infection in bones which can either come from neighboring tissues or via blood stream. It also occurs when the bone is injured and germs enter into the open wound to cause infections in bone.
On the other hand, septic arthritis is the infection of synovial fluid or joints. It is more common in children than in adults. In this disease, the joints become infected due to the contact with germs that might travel from the bloodstream. The infection can also occur due to injuries or surgeries.
In this article, we will discuss salient features of osteomyelitis and septic arthritis; their similarities and differences and compare them to clear any kind of confusion that might arise between them.
There are different bases to classify osteomyelitis and septic arthritis.
Osteomyelitis is of two types:
- Acute osteomyelitis that appears 2 weeks after the injury showing inflammatory bone change.
- Chronic osteomyelitis appears 6 weeks after the injury or infection and is characterized by tissue death and bone destruction.
Septic arthritis is classified on the basis of the source that causes the infection. That source could be viral bacteria or any other germ or agent. So, the types of septic arthritis could be:
- Bacteria septic arthritis
- Viral septic arthritis
- Fungal septic arthritis.
Both osteomyelitis and septic arthritis are caused by infectious agents like bacteria. Most common causative agent is staphylococcus aureus.
In osteomyelitis the staphylococcus reaches the bone tissues through following:
- Injury: injuries resulting in cuts and wounds might pave the route for the bacteria to reach the wound and cause infection.
- Blood stream: other infections in the body can release bacteria into the bloodstream and from here it can reach the bone tissue.
- Surgery: during surgery there is a great chance for certain bacteria to enter the body because a part of the body is cut open and is in contact with the atmosphere. The instrument used by the surgeon could also be the carrier of bacteria that might invade bone tissue.
Septic arthritis is caused by a variety of causative agents that invade the synovial fluid and cause inflammation and infection it:
- Staphylococcus: it affects skin
- Gonococcus: it comes through sexual contact
- Mycobacterium: it comes from the joint injection and causes septic arthritis
- Streptococci: causes throat infections
- Gram negative bacteria: it comes from the bacteria in GIT e.g., E. coli.
Most of the symptoms of osteomyelitis and septic arthritis are similar apart from the fact that in osteomyelitis they appear in bone; while in septic arthritis, they appear in joints. The main symptoms include:
- Extreme pain in bone or joint
- Swelling of bone or joint.
- Redness and tenderness on the affected area.
- Stiffness and immobility.
- Pus drainage.
- Fatigue, nausea
- Fever and chills
- Rapid heart rate
- Sweating and general feeling of unwellness.
There are different methods for the diagnosis of osteomyelitis and septic arthritis. Osteomyelitis can be diagnosed through:
- Test on bacterial culture: the culture obtained from the damaged tissue is tested and if the bacterial culture test comes positive from the necrosis, osteomyelitis is diagnosed.
- MRI: magnetic resonating images can provide sensitive imaging and show the difference in healthy bone tissue and affected tissue.
Diagnosis of septic arthritis can be done in 3 ways:
- Obtaining synovial fluid and running test on it for the presence of leukocytes (white blood cells) and bacteria
- Blood tests to detect the presence of certain bacteria in the bloodstream.
- Tests on other fluids of the body like urine, spinal fluid to determine the origin of infection.
Osteomyelitis is treated all over the world the same way by the surgical removal of the dead or infected portion of the bone. The pus is drained from the bone, the infected portion is removed and blood flow is restored to the bone. And finally, the limb is amputated.
On the contrary, septic arthritis could be treated with medication. These medicines include antibiotics and anti-inflammatory drugs. The pus is drained from the joint fluid in the synovial cavity and antibiotics injections are given immediately. These treatments typically last two to six weeks with positive results.