In developed countries, the reported incidence of peripheral bone infection is about 2% per year.[2] Surgical care of open or closed fractures may increase this incidence.[2]

A study in the US showed that the overall age- and sex-adjusted annual incidence of osteomyelitis was 21.8 cases per 100,000 person-years between 1969 and 2009. The annual incidence was higher for men than for women and increased with age.[3] During the study period, incidence rates remained stable among children and young adults (<50 years) but almost tripled among older adults, mostly driven by an increase in diabetes-related cases.

Risk factors

Patients may present with an acute exacerbation of a chronic osteomyelitis.

Reactivation of a site of osteomyelitis can occur, particularly in older patients.[2]

Bacteria can enter through an open fracture site or a wound that penetrates down to bone (e.g., stab wound). Soft-tissue stripping may leave devitalised bone and soft tissues that may become infected. Fracture fixation can also become infected. Delays to initial debridement (or inadequate debridement), lack of appropriate antibiotic prophylaxis, or delays in definitive soft-tissue cover are risk factors for subsequent infection. Many patients describe previous fracture fixation wound healing problems in the initial postoperative period.

Because of the high likelihood of bacteraemia during non-sterile self-injection techniques, bone infections can occur in intravenous drug misusers. The commonest pathogen is Staphylococcus aureus but pathogens such as Pseudomonas aeruginosa also occur (classically in the spine and sacroiliac joints).[5]

Foot infections occur frequently in patients with diabetes. Acute infections usually follow minor trauma and dramatically increase the risk of amputation. Chronic infection may be associated with ulceration as a result of changes in foot biomechanics and peripheral neuropathy.[20] See our topic Diabetic foot complications.

With a weakening immune system, the risk of osteomyelitis increases.[2]

Surgical site infections are common following surgery for injuries such as open fractures, bullet wounds, knife wounds, and lacerations.[21]

Contamination of local bones in the operative field during surgery can lead to osteomyelitis, or prosthetic implant infections (which can be non orthopaedic).

  • For example, sternal osteomyelitis is a complication of acute mediastinitis associated with coronary artery bypass surgery and harvesting of the internal mammary artery, which can lead to sternal ischaemia.[22]

Haematogenous osteomyelitis is seen in patients with distant foci of infection, such as those with infected urinary catheters.

Periodontal abscess can result in osteomyelitis of the mandible, which is more susceptible to osteomyelitis than the maxilla because the cortical plates of the mandible are thin and its medullary tissues have relatively poor vascular supply.[23]

Often associated with adult haematogenous osteomyelitis. Because osteomyelitis may mimic a sickle cell crisis in these patients, culture results are important to establish the diagnosis and to determine the pathogen (which is often atypical).

As an autoimmune disease, rheumatoid arthritis increases the risk of osteomyelitis.[2]

As a chronic condition, chronic kidney disease increases the risk of osteomyelitis.

Incidence of osteomyelitis increases in patients who are immunocompromised due to HIV or autoimmune diseases, chemotherapy or immunosuppressive treatment, or drug or alcohol misuse.[2]

May predispose to Kingella kingae infection.[6]

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