Cath Lab Digest

Given that osteomyelitis in the diabetic foot can lead to complications such as limb loss, ensuring a proper diagnosis and timely treatment is vital. Accordingly, this author surveys the literature to review pertinent classification systems, the merits of different imaging techniques and current thoughts on the debate over conservative therapy versus surgical treatment.

   The worldwide incidence of diabetes has reached nearly epidemic proportions. With this increased incidence, there has been a significant rise in the comorbidities commonly associated with the disease process in patients living with diabetes.

   Diabetic foot ulcerations (DFUs) are a common complication. Researchers have estimated that people with diabetes have as high as a 25 percent lifetime risk of developing a DFU.^1,2 In addition to the development of DFUs, greater than 50 percent of these ulcerations will become infected. This would account for nearly 20 percent of all diabetes-related hospital admissions and therefore a significant portion of healthcare-related costs. This amounted to nearly $11 billion in 2001.^3-9

   In those patients presenting with infected diabetic ulcerations, underlying osteomyelitis is present in as many as 65 percent of patients, and these infected ulcerations present a major risk factor for non-traumatic lower extremity amputation (LEA).¹⁰

   It has been well documented that the consequences of major lower extremity amputation are severe with the estimated five-year survival rate following surgery being less than 50 percent.¹¹ In fact, this data suggests that the mortality rate associated with diabetic LEAs is greater than most cancers.¹¹ It is therefore vital to provide early and effective diagnosis, and management of patients presenting with diabetic ulcerations, especially those presenting with concomitant osteomyelitis, in order to avoid potential limb loss.

A Guide To Classification Systems For Osteomyelitis

   Osteomyelitis can generally be defined as any inflammatory process in bone that is caused by microorganism infection.^12,13 Persistent involvement of the osseous structures, which is often accompanied by clinical signs of inflammation, can yield osseous fragmentation and overall destruction of the skeletal architecture.^14-16

   There have been numerous attempts to classify osteomyelitis and perhaps Waldvogel presented the most recognized classification, in which he classified osteomyelitis according to etiology.¹⁷ This classification system grouped osteomyelitis into one of three clinical categories: hematogenous osteomyelitis, osteomyelitis associated with a contiguous focus and chronic osteomyelitis.

   Hematogenous osteomyelitis most commonly occurs in pediatric patients although this type of osteomyelitis is presenting in increasing numbers of elderly and immunocompromised patients. In this cohort, the bone infection begins with bacteria seeded from the blood. This most commonly occurs in the metaphyseal region of long bones.

   Osteomyelitis associated with a contiguous focus most commonly occurs in patients presenting with lower extremity ulceration and, by extension, those patients with diabetes whom we see most frequently. In this cohort, bacterial inoculation into bone occurs from an external source such as a penetrating traumatic injury with contaminated objects, infection following implant placement or in patients with persistent overlying soft tissue infection. This type of osteomyelitis can affect any age group and is the most commonly observed overall.

   Chronic osteomyelitis can originate from either a hematogenous or contiguous focus, and is often associated with increasing antibiotic resistant microorganisms.¹⁵