Emerging Insights In Diagnosing And Treating Osteomyelitis
Is the probe to bone test losing its gold standard luster? Will nuclear medicine imaging reinvent the diagnostic approach to osteomyelitis? Can antibiotic beads have an impact in treatment? Offering insights from the literature as well as their own clinical experience, these authors answer those questions and many more.
One of the greatest threats to the population of patients with diabetes is osteomyelitis, which may ultimately lead to amputation and limb loss. As podiatric physicians, we spend a large portion of our time in the prevention and management of such infections.
Accurate diagnosis and early intervention of osteomyelitis is imperative due to the complex and lengthy nature of current treatment regimens.1 Advances in diagnostic modalities and treatment options will hopefully modify the standard of care to maximize successful patient outcomes and prevent the recurrence of infection.
Osteomyelitis is a disease characterized by bone infection leading to inflammation and bone destruction in the presence of necrosis and new bone formation.2 Vasodilation in the acute inflammatory phase of osteomyelitis accelerates the breakdown of bone, resulting in bone necrosis caused by developing tissue pressure. Bone necrosis subsequently causes the development of abscesses, cloacae and sequestra, which various imaging modalities can commonly detect.2 Nevertheless, the presence of comorbidities that mask obvious signs of infection or limit diagnostic modalities makes the diagnosis of osteomyelitis challenging in all patients.
Research has overwhelmingly proven that patients suffering from diabetes have at least a 10-fold greater risk of being hospitalized for bone and soft tissue infection in the lower extremity.3 Over the span of two decades, osteomyelitis affects the lower extremity more than any other site in the human body.4 Yet the diagnosis and treatment still prove to be problematic given the lack of a single imaging modality or treatment plan to correctly diagnose or cure osteomyelitis in all cases.5
Wound history including initial presentation of pedal ulcers, examination of dermatological changes and wound exploration are mandatory for every foot ulcer.6 The typical human response to bacterial invasion and infection involves erythema (vasodilation), edema (increased vessel permeability) and pain (nerve impingement from expanding tissue).7 However, the clinical presentation of infection can often be misleading in the presence of diabetes mellitus, peripheral vascular disease or Charcot neuroarthropathy, all of which compromise local and systemic reactions to infection.7
Questioning The ‘Gold Standard’ Of Osteomyelitis Diagnosis
The clinical diagnosis of bone infection has long weighed heavily in favor of the probe to bone test as an indicator for osteomyelitis. Multiple studies have concluded that palpating or probing to bone through a pedal ulcer is both highly sensitive (66 percent) and specific (85 percent) for osteomyelitis.8 Lavery and colleagues in 2007 suggested using the probe to bone test as a negative predictor of osteomyelitis.9 They determined that diabetic wounds that did not probe to bone in the presence of pedal ulcers were negative for osteomyelitis 98 percent of the time.