Osteomyelitis

Osteomyelitis is an infection of the bone that occurs most frequently in the lower extremities.  Most commonly, it develops after severe local trauma with an associated open fracture.  The adjacent soft tissue structures are injured together with the bone, and can form a poorly vascularized and scarred tissue bed.  Simple debridement and antibiotic therapy are often unsuccessful in treating lower extremity osteomyelitis.  As a result, patients frequently present after multiple failed treatments and with resistant or polymicrobial bacterial infection.  

Successful treatment for chronic osteomyelitis in this setting requires:

• Effective debridement

• Antibiotic therapy and

• Vascularized soft tissue coverage - preferably with a muscle flap

Stability of the bone must aslo be restored if infection or trauma has led to bone loss and or non-union. 

Preoperative Evaluation

Like any lower extremity injury a thorough history and physical examination is obligatory before developing the most appropriate treatment regimen.  The following are critical elements:

• Neurological evaluation - lack of sensation on the plantar aspect of the foot may point to nerve injury or neuropathy and preclude reconstruction.

• Skeletal examination - the requirement for concurrent orthopedic treatment or the need for secondary bone reconstruction after coverage may affect the choice and timing of flap coverage.

• Vascular assessment - the presence of injury to the vascular inflow to the foot will often dictate the choice of flap if microvascular transplantation is indicated.

Clinical Example

This case demonstrates a patient with a chronic osteomyelitis of 20 years duration. The patient had multiple surgical procedures and treatments with antibiotics, but continued to have a draining sinus in the lower leg.  In the area adjacent to the draining sinus, soft tissue swelling and signs of chronic infection and previous surgical treatment can be seen.

X-rays revealed the presence of chronic osteomyelitis in the tibia.  Areas of radiolucency are present at the base of the wound that are compatible with erosion of bone due to infection.  Although the bone is stable with no evidence of fracture or non-union, the extent and chronic nature of the infection may have required debridement that would weaken or destabilize the tibia.

A debridement was performed to remove the bulk of the surrounding inflammatory tissue and infected bone. This left a defect of soft tissue and a raw surface of tibia.  Enough bone was still present to provide lower extremity stability.  Some scarring was left behind to minimize the size of the open wound and to reduce post-operative discomfort.  The bulk of the unstable and thin scar would be excised at the flap procedure.  This is usually staged several days after the debridement in order that bacterial cultures can be finalized.

A latissimus muscle flap was used to fill the defect in the tibia and resurface the area of scar tissue that was removed.  The latissimus muscle has a long vascular leash and could reach proximal to the point where the patient's anterior tibial artery showed evidence of injury.

The patient is seen at the summit of Baboquivari peak in southern Arizona roughly 8 months after surgery. There has been no evidence of recurrence of osteomyelitis for 4 years and the patient is pain free.