Imaging of osteomyelitis and musculoskeletal soft tissue infections:: current concepts

Osteomyelitis is an inflammatory disease of bone, usually caused by bacterial infection, which most commonly affects the lower extremities. Infection occurs either via haematogenous spread, or contiguous spread (including open trauma and orthopaedic procedures). Staphylococcus aureus is the most common infecting organism. It most commonly affects children and susceptible adults. Diagnosis is made by clinical presentation supported by inflammatory markers, tissue sampling for microbiological analysis and relevant imaging including X-rays and MRI. Subacute osteomyelitis is characterized by the presence of Brodie's abscess, whilst chronic osteomyelitis usually involves the characteristic features of sequestrum, involucrum and cloaca. Treatment is multidisciplinary, involving Microbiology, Orthopaedics, Plastics and Vascular (when appropriate). It can be conservative, medical (antibiotics), or surgical, depending on the acuity and severity of infection, in addition to host factors (Cierny & Mader classification). Surgical management consists of: radical debridement of infected bone and soft tissues, removal of metalwork (where relevant), obliteration of dead space, adequate soft tissue coverage, and adequate vascular supply to the affected region. Reconstruction options include bone transport and Masquelet ‘induced membrane’ techniques for large bone defects. Amputation should not be discounted in appropriate cases.

La osteomielitis es la infección y la destrucción del tejido óseo por microorganismos. El agente causal más frecuente es Staphylococcus aureus, pero muchos otros agentes infecciosos están implicados. El diagnóstico microbiológico es fundamental para su óptimo manejo, pues es crucial que el tratamiento sea específicamente dirigido contra el microorganismo responsable. En niños predomina la adquisición por vía hematógena, mientras que en adultos es más frecuente porque la inoculación directa de los microorganismos en el tejido óseo es bien por fractura o tras una cirugía. Las osteomielitis agudas suelen responder a tratamiento antibiótico, pero en las formas crónicas existen dos elementos patogénicos, el secuestro óseo y el biofilm, que en la mayoría de los casos obliga a realizar un tratamiento quirúrgico y a prolongar el tratamiento antibiótico; aun así, no siempre es posible la curación. Recientemente, diversos estudios han demostrado que ciclos menos prolongados de antibióticos tienen la misma eficacia que los clásicamente recomendados.

Osteomyelitis is the infection and destruction of bone tissue by microorganisms. The most common causative agent is Staphylococcus aureus, but many other infectious agents are involved. Microbiological diagnosis is fundamental for its optimal management, as it is crucial for treatment to be specifically target the microorganism responsible. In children, hematogenous acquisition is predominant whereas in adults, direct inoculation of microorganisms in the bone tissue occurs due to fractures or surgery. Acute osteomyelitis tends to respond to antibiotic treatment, but in chronic forms, there are two pathogenic elements: bony sequestrum and biofilm, which in the majority of cases make surgical treatment and prolonging antibiotic treatment necessary; even still, a cure is not always possible. Recently, various studies have demonstrated that less lengthy cycles of antibiotics have the same efficacy as classically recommended cycles.

This chapter presents the characteristics of osteomyelitis in diabetes-induced Charcot neuroarthropathy. The risk factors contributing to osteomyelitis are discussed. The pathogenesis of osteomyelitis is reviewed along with the usual pathogens related to bone infections. The readers find in this chapter a section dedicated to skin ulceration as frequent cause of osteomyelitis in patients with diabetes and Charcot neuroarthropathy. The differences between osteomyelitis and noninfectious changes of Charcot neuroarthropathy are elucidated in this chapter. The author emphasizes on the importance of Mr-diffusion weighted imaging as an efficient modality to diagnose osteomyelitis in diabetic patients with Charcot neuroarthropathy. Examples of osteomyelitis in several locations at the ankle-foot unit are provided with illustrative Mr images.

Magnetic resonance imaging (MRI) findings of acute osteomyelitis vary from non-specific bone marrow edema to more reliable signs such as bone destruction, periosteal reaction, and sequestrum. In some cases, imaging features could overlap with other conditions such as trauma and bone tumors. Intra and extramedullary fat globules are a helpful MRI marker for osteomyelitis, as shown in the following case report. We report the MRI findings of a 15-year-old young man with distal femur osteomyelitis, associated with intra and extramedullary fat globules.We present the MRI features of the case and emphasize the importance of noting additional signs of osteomyelitis to make a precise diagnosis.

The purpose of this case report is to describe the presentation of a patient with osteomyelitis of the thumb.

A 21-year-old man presented with painful, red, and edematous thumb pain over the anterior and posterior surface for a duration of 4 days. The patient reported no trauma or recent operation. The patient was treated conservatively for capsulitis. The patient’s symptoms worsened within 2 days, and he was referred for additional imaging consisting of a bone scan. The bone scan showed increased uptake, resulting in a change of diagnosis to suspected osteomyelitis. The patient was referred to a medical doctor for care that consisted of antibiotics and physiotherapy.

Despite treatment, the patient had some mild permanent damage to the range of motion of the joint and soft tissue volume loss.

This case demonstrates the importance of considering osteomyelitis as a differential diagnosis. Amputation was avoided for this patient because of the early recognition and referral.