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What is osteomyelitis?
Nelaton is thought to be the first one to use the term osteomyelitis to describe an infection of bone and marrow in 1844.
Infection of the cortex alone without marrow involvement is more appropriately described as "Osteitis".
Infection of the periosteum alone should be called "periostitis."
What are the common pathogens seen in osteomyelitis?
Many studies have shown that Streptococcus species and Staphyloccus aureus were common pathogens in osteomyelitis.
Anaerobes are not common, but when isolated are often gram-positive with Peptostreptococcus species most common.
Bacteroides species are the most common gram-negative anaerobic organism in osteomyelitis.
What is the etiology of pedal osteomyelitis?
While neuropathic ulceration is the most common condition that can lead to pedal osteomyelitis, puncture wounds can easily lead to ostemyelitis if not treated properly.
Hematogenous osteomyelitis is seen in children but is very rare in adults.
Open fractures and bony-surgery can predispose to osteomyelitis.
What is the classification of Osteomyelitis?
There are 2: 

1. Ciemy-Mader- developed to describe long bone osteomyelitis. It needs to be modified to describe pedal osteomyelitis. The system is based on the anatomy of the bone and the physiological status of the host.

2. Waldvogel- an etiologic system.

* Both systems can be used concurrently to effectively describe osteomyelitis and to develop treatment guidelines.
Antibiotic therapy for osteomyelitis?
Because infection in patients with diabetes is usually poly-microbial, an empiric broad-spectrum antibiotic should be started then adjusted based on results of wound and bone cultures. IV antibiotics are generally more efficacious than oral antibiotics. The duration of antibiotic course is not clear. Most clinicians follow a six-week course, but may vary between 4 and 12 weeks.
What needs to be examined when evaluating diabetic patients with osteomyelitis?
Examination of patients with possibe osteomyelitis should not be deviated ffrom any other type of physical examination. 

1. Careful hx of ulcer. Even in the case of severe infection, many of these patients will not relate any contitutional symptoms. 
2. Past medical and surgical hx, allergy, current medication can help determine the appropriate treatment.
3. Vital signs even though they might not mount fever in response to their infection
4. A finger stick to determine blood glucose shows clue to infection
5. A complete physical exam
6. Ulcer and surrounding soft tissue need to be evaluated. Any exposed bone is highly suggestive of osteomyelitis. The presence of sinus tract that can lead a metal probe to the underlying bone is also highly suggestive of osteomyelitis.
7. Kidney function needs to be evaluated to start the antimicrobial therapy properly. Blood cultures are not always necessary but needed if the patient appears septic,
8. Radiographic examination can provide detail of structural deformity.
Role of Bone scan in diagnosis of osteomyelitis?
The three-phase bone scan is highly sensitive but has a poor specificity; however, newer techniques under investigation have been shown to improve the sensitivity and specificity of the scan to over 90%.
The difficulty encountered is that some procedures require drawing blood and re-introducing it into the patient. Some patients may not tolerate the radioactive-labeled material.
Role of MRI in diagnosis of osteomyelitis?
The advantage of MRI is that it is non-invasive but some patients may have claustrophobia and not able to undergo the procedure. MRI is becoming cheaper as technology advances and the sensitivity and specificity of the procedure has been reported to be close to 100% in some institutions.
Other diagnosis modalities for osteomyelitis?
Probing to bone appears to be the most cost-effective method to make the diagnosis of osteomyelitis. This method has been shown to have a good sensitivity and specificity.
A recent un published study from the same intitution shows sensitivity and specificity comparable to those of Magentic Resonance Imaging and Bone scan. Ultrasound method is being evaluated for making diagnosis of osteomyelitis.
Invasive diagnosis of osteomyelitis?
The gold standard for making the diagnosis of osteomyelitis is bone biopsy. Bone culture from the biopsy can easily be contaminated yielding false results, but this should not affect the anti-mictobial therapy because the organism that infected the soft tissue and the bone should be similar. If surgery is performed to remove the osteomyelitic bone, the specimen should always be sent to pathology for examination.
Treatment for osteomyelitis?
Medical management should not be different from those provided to ulcer. Optimal management requires multidisciplinary approach. Medical conditions such as hyperglycemia, nephropathy, or cardiac insufficiency need to be addressed while treating the osteomyelitis.
Antimicrobial therapy will help control and treat sepsis.
The wound and any exposed bones needs to be debrided aggressively.
The ulcerated area needs to be offloaded using the methods the provider is most experienced with.
The wound bed should be kept clean and moist using appropriate wound care products.
Any deficient circulation to the ulcer area needs to be restored for the ulcer and the bone to have a chance to heal.
Surgical removal of the bone followed by delayed secondary closure has been shown by many authors to be the most effective method to treat osteomyelitis.
In some cases a skin graft, advancement flap, rotation flap, or free tissue transfer may be required to cover a large defect caused by the infected ulcer osteomyelitis.
What is sequestration?
It is a segment of dead, devascularized bone due to Haversian and Volkman canal and osteocyte destruction. The process is highly suggestive of osteomyelitis. Diabetic neuropathic arthropothy may have similar presentation.
What is involucrum?
As the infection progresses, the periosteum is elevated by purulent material. The new bone formation under the periosteum is called involucrum. This is also suggestive of osteomyelitis.
What is Cloaca?
Cloaca is the formation seen at the bone-periosteal interface to extrude sequestmm and other necrotic products from the infected bone.
How does peripheral vascular disease affect osteomyelitis?
If not treated, the disease will prolong hospitalization and may even lead to unnecessary amputation. It must be recognized and treated.
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