Osteomyelitis


Osteo is a Greek term meaning bone and myelitis is a latin term meaning infection of the bone marrow (or spinal canal).  So, osteomyelitis is a deep bone infection.  This is a serious problem that is often due to having an open wound that is located over a bone.  The open wound allows bacteria into the area and because this environment of a wound is one that bacteria can thrive in, an infection can occur.  

The reason for an open wound over a bone can be from a disease like diabetes or peripheral vascular disease, or it may be from a trauma where a there was significant soft tissue loss. Osteomyelitis can develop acutely over a period of a week to 10 days, or it may develop slowly as the bacteria have had time to grow.

Signs and Symptoms of Osteomyelitis

People with an active osteomyelitis infection describe feeling nauseated and having fever-like symptoms. There is usually tenderness, redness and warmth in the area of the infection and as well as swelling of the area.  If the osteomyelitis is near a joint there may be a loss of motion at that joint. In addition, pain associated with the infection may lead to reluctance to use the extremity.  

When the infection is active there may be drainage from an open area or sinus tract leading to the infected area.  This is less common with chronic or long-term osteomyelitis.

Diagnosis of Osteomyelitis

  Blood tests like erythrocyte sedimentation rate (Sed rate) or C-reactive protein (CRP) are used to determine if there is an active response by the body to some type of infective process. These tests are not specific to osteomyelitis and, if the osteomyelitis is chronic, these tests may be normal.
  An MRI or CT scan may be ordered to see if there is a process occurring in the bone but these are also not specific to osteomyelitis. A CT is preferred for infections within the bone while MRI is more sensitive for joint or soft tissue involvement.
  Cultures of fluid and tissue from a draining sinus or from an open wound can help in determining the organism causing the infection.
  A bone biopsy with cultures is necessary to confirm a diagnosis of osteomyelitis. This is usually done as an open procedure or with CT (CAT) scan guidance.
  A PET/CT may be ordered to determine if there is an infective process, especially if other tests do not confirm a diagnosis. Studies are showing the PET/CT is effective in detecting chronic osteomyelitis.1

Treatment

Osteomyelitis is a serious infection and if not treated aggressively, or if the infection doesn’t respond to treatment it can result in amputation. A combination of surgery and antibiotic therapy is necessary to adequately treat osteomyelitis.  

The goal of surgery is to get rid of any infected bone and tissue, as well as remove any foreign material (orthopedic implants or sutures) that might be present from previous surgery. Once the area has been thoroughly debrided and washout out, the gap created in the bone is filled with some type of antibiotic spacer. Antibiotic impregnated cement beads or pellets are often used as well.  

During the debridement, infected tissue is collected and analyzed so that the organism causing the infection can be identified.  It can take several days for the results to be known but once the type of bacteria is identified an infectious disease specialist can determine the best antibiotic to use to treat the osteomyelitis.  

The antibiotics are most often given intravenously (through an IV) and the full course is at least 6 weeks.   During this time, a patient is followed closely by an infectious disease specialist in order to monitor the response to the antibiotic treatment.  Once the infectious disease specialist and the orthopedic surgeon feel the infection has been managed the reconstructive surgery can take place.

There are a number of options for reconstructive surgery following debridement and antibiotic therapy.  

These include:

  • the use of allograft (bone bank) tissue, 
  • bone and soft tissue transfer (moving bone and muscle from one part of the body to the area), 
  • bone transport (use of external fixators to regrow bone in the area), 
  • use of orthopedic implants

Each patient’s situation is very different so the orthopedic surgeon will discuss the best options with the patient, educating them on recovery time, anticipated function and potential for recurrence of the infection.  
 


References
1. Pineda C, Vargas A, Rodríguez AV. Imaging of osteomyelitis: current concepts. Infect. Dis. Clin. North Am. 2006;20 (4): 789-825