Osteomyelitis: Keys To Diagnosis And Treatment
Calcium sulfate is another commonly utilized material for the delivery of local antibiotics. Advantages include ease of access, low cost, safety, a low risk of donor site morbidity and an osteoconductive structure. Disadvantages include sterile sinus tracts that develop as the calcium sulfate beads resorb. Calcium sulfate’s utility as a bone graft substitute, especially in subcutaneous areas, is poor secondary to a limited strength and the production of sinus tracts.31 Of note, serum calcium is not elevated in those individuals with implanted calcium sulfate beads.32
Polylactic acid microspheres have yet to undergo study among human controls although orthopedic surgeons have used it as a structural support for years. Researchers have looked at this modality in rabbits as an antibiotic delivery system and the results are promising. Drug elution qualities with polylactic acid microspheres are superior to their PMMA counterparts and MIC is maintained up to four weeks following implantation. One can also see sterile sinus tracts with this material.32
A Few Thoughts About Preventative Care
The single best way to prevent osteomyelitis in the patient with diabetic neuropathy is with appropriate offloading of pressure areas through padding and shoe gear modifications. In addition to these standard protocols, epidermal nerve fiber density testing can allow for the early detection of small-fiber sensory loss in the patient with diabetes, even in those who may not be experiencing clinic symptoms. Early detection of sensory loss can lead to rapid intervention and treatment.
Appropriate treatment with a disease-modifying agent can result in regrowth of nerve fibers, which one can objectively measure through repeated epidermal nerve fiber density testing. When patients receive a disease-modifying agent early in the process of sensory loss, reversal or delay of neuropathy can often occur, thus preventing ulceration, infection and potential limb loss.33
Osteomyelitis remains one of the most important conditions we treat. Preventative care, such as proper shoe gear selection and offloading, remains essential to avoid amputation in our diabetic, vascular-impaired and neuropathic patient populations. Epidermal nerve fiber density testing may have some current and future important benefits in the early diagnosis of neuropathy. A timely diagnosis allows us to begin treatment of the causative factors potentially delaying or preventing the progression of neuropathic symptoms.
Laboratory studies such as ESR and CRP are still useful in evaluating the individual with bone infection. The ESR is reliable for initial evaluation but CRP is better for long-term assessment of the infectious process and response to antibiotics. White blood cell and temperature remain poor indicators of infection among diabetic populations. Radiographic evaluation often lags behind other imaging techniques such as MRI and indium labeled bone scans in the early identification of bone infection. New and emerging imaging modalities such as FDG-PET may allow us more definitive delineation between osteomyelitis and Charcot neuroarthropathy, which continues to remain a diagnostic challenge.
Dr. Hild is a prior resident of the Kaiser Permanente/Cleveland Clinic Foundation in Cleveland.
Dr. Boike is the head of the Podiatry Section in the Foot and Ankle Center of the Orthopaedic and Rheumatology Institute in Cleveland. He is also the Director of the Podiatry Residency Training program at the Cleveland Clinic. Dr. Boike is a Fellow of the American College of Foot and Ankle Surgeons. He presently serves on the Board of Directors of the American Board of Podiatric Surgery.