Topic Editor: Sara Millican, MBBS
Review Date: 12/06/2012
Definition 
Osteomyelitis is a bacterial or fungal infection involving bone and/or bone marrow. It may be acute or chronic, and can result from contiguous or hematogenous spread of infection, or by direct inoculation through an open wound such as a fracture or following surgery.
Description
- Of the various bacterial pathogens that cause infection in osteomyelitis, Staphylococcus aureus is the most common, with other common pathogens dependent on patient demographics, including Streptococcus pyogenes, Pseudomonas aeuroginosa, and in patient's with hemoglobinopathies, Salmonella species. Additional pathogens commonly found in patients with chronic osteomyelitis include Staphylococcus epidermidis, Serratia marcescens, and Escherichia coli
- Classification of osteomyelitis is most commonly based on the Cierny-Mader Staging system, although the Waldvogel system has been historically used:
- Cierny-Mader Staging System: A four stage system (I-IV) classified primarily by portion of bone affected, and secondarily by the presence or absence of systemic or compromising host factors
- Waldvogel Classification System: Based on pathogenesis, and classified as acute or chronic, whether hematogenous (originating from bacteremia) or contiguous (originating from an infection in a nearby tissue), and on the basis of vascular insufficiency
- Diagnosis depends upon combined factors: clinical examination, laboratory tests, bacteriological tests, and radiographic imaging
- Management consists of evaluation of the patient, determination of the stage of osteomyelitis, identification of the causative organism and its susceptibility to antimicrobial therapy, and, if required, debridement, dead-space management, and stabilization of bone
Epidemiology
Incidence/Prevalence
- The majority of cases are posttraumatic (up to 47%), with vascular insufficiency secondary to diabetes and hematogenous seeding making up the majority of other major causes
- Acute hematogenous osteomyelitis (AHO) occurs primarily in children, with 85% cases being in age 17 years. Its prevalence is estimated to be 1/5000 children
- Incidence of osteomyelitis is 0.02% in children 13 years
- Hematogenous osteomyelitis in children typically affects the metaphysis of long bones; in adults, it typically affects the vertebrae, and less commonly, the long bones, pelvis and clavicle
- Contiguous osteomyelitis typically occurs in patients with diabetes mellitus and/or vascular insufficiency
Age- Osteomyelitis can occur in any age group; it is a common infectious condition in the elderly
Gender
- Osteomyelitis affects males more often than females
Risk factors
- Diabetes mellitus
- Foreign-body (e.g. prosthetic implant or other foreign body)
- History of osteomyelitis
- Immune deficiency (e.g., AIDS, granulocyte deficiency, complement deficiency) or immunosuppressive condition (e.g., chemotherapy, transplantation)
- Intravenous drug abusers
- Neuropathy
- Sickle cell disease
- Surgery (recent)
- Trauma (recent)
- Vascular insufficiency
Etiology
- S. aureus is the most common pathogen found in patients with osteomyelitis, however, different organisms prevail among differing patient demographics
- Common causes of Acute hematogenous osteomyelitis (AHO) in infants include S. aureus, Streptococcus agalactiae, and E. coli
- Common causative organisms in children 4 years include S. aureus, Streptococcus pyogenes and Haemophilus influenza. H. influenzae is rare among patients vaccinated with HIB vaccine
- Elderly patients with AHO are most commonly colonized with gram negative rods
- Uncommon pathogens may be identified in immunocompromised patients
- Salmonella species is common in patients with sickle cell disease and other hemoglobinopathies
- P. aeruginosa is found in cases with nail puncture wounds (through a shoe) of the calcaneus, metatarsal and tarsal bones, as well as being a common pathogen found in intravenous drug users
- S. aureus and gram negative enterics are commonly found in chronic osteomyelitis cases of children
- Multiple organisms are isolated in the majority of children presenting with osteomyelitis secondary to trauma or contiguous soft tissue infection
[Outline]
History
- Clinical manifestations of osteomyelitis differ by infection type, organism, anatomic location, and the host
- Although risk factors are often present, the most common included immunocompromise (including diabetes), recent trauma or surgery, or history of acute osteomyelitis
- In adults, nonspecific pain and low-grade fever may be present. Lethargy, chills, swelling, localized erythema or swelling may also be reported
- In children, symptoms and signs may manifest with signs of acute infection such as fever, chills, pain, and local signs of inflammation (swelling, warmth, redness, pain). Symptoms may however be variable and/or non-specific, such as irritability, lethargy, and resistance to moving or using the affected limb
- Subacute and chronic cases are more common in adults. Chronic osteomyelitis typically presents with chronic discharging sinuses and/or chronic bone pain with a history of acute osteomyelitis, or trauma/surgery for treating fracture. A flare up phase may manifest with acute exacerbations of pain, and swelling and redness of the affected area. Muscle wasting and joint contractures may also be present. Cases of Brodie's abscess may present solely with deep boring bone pain
- In cases involving vascular insufficiency, infection is commonly present in the small bones of the feet. It is typical that such patients have negligible pain due to neuropathy
Physical findings on examination
- Findings in acute osteomyelitis may include local signs of inflammation and infection, with tenderness over the affected bone, and reduced range of motion in adjacent joints. Signs of systemic illness such as fever may also be present. Patients with subacute or chronic of osteomyelitis commonly present with erythema and drainage at the affected region. Other characteristic findings include:
- Deformity
- Draining sinus tractsInstability (bony) and local signs of impaired vascularity
- Limited range of movement
- Neuropathy
- Osteomyelitis with vascular insufficiency is typical in patients with neuropathy. The typical findings include diminished pulses and poor capillary refill (common in long standing diabetics)
[Outline]
General treatment items
Acute osteomyelitis
- Management is usually non-operative unless abscess is present or procedures are needed to obtain appropriate cultures. The mainstays of therapy include supportive therapy for pain and/or dehydration, splinting, and antibiotics
- Mainline treatment is culture-directed antibiotic therapy , with superficial/surgical debridement as an adjunct depending on the stage of the disease
- Selection of appropriate antibiotics is based on the results of culture and sensitivity. It is however typical to begin with empiric antibiotic therapy pending culture results
- Empiric antibiotics used will depend on anatomic site, mode of transmission and predisposing factors
- In cases of Acute hematogenous osteomyelitis (AHO) treatment should include a anti-staphylococcal antibiotic such as nafcillin or oxacillin; in suspected MRSA infection, vancomycin or linezolid are generally used as the anti-staphylococcal antibiotic (rarely clindamycin or trimethoprim/sulfamethoxazole). In newborns and older children, consider coverage against gram-negative enteric bacteria, such as third-generation cephalosporin (e.g. ceftazidime, ceftriaxone, etc.).
- 2nd/3rd generation cephalosporins or amoxicillin and clavulanic acid combinations offer good results among children <4 years of age, as they cover Staphylococci, Haemophilus and gram-negative infections
- In patients who are IV drug users and patients with HIV infection, start broad spectrum agents such as newer generation cephalosporins or gentamicin and flucloxacillin combination therapy
- In patients with a hemoglobinopathy, ciprofloxacin plus a third-generation cephalosporin are advised to cover to salmonella and other gram-negative bacteria
- In cases of contiguous osteomyelitis, empiric therapy may not be recommended unless the patient is acutely ill (await cultures)
- Administer analgesics for pain and fluids for dehydration
- Antibiotic therapy should be initiated promptly and continue for 6 weeks
- Regimens will vary depending on location of the infection, and the pathogen. It is common to start with at least 1 -2 weeks of intravenous therapy before changing over to oral therapy
- Antibiotic therapy is typically continued until there is clinical improvement, and inflammatory markers (generally CRP) returns to normal
- Intravenous therapy only is advised for neonates instead of sequential intravenous-oral regimen due to risk of complications
- Principles of surgical intervention include drainage of pus and debridement of necrotic tissue, and when necessary debridement of surrounding soft tissue, with a goal of restoration of blood supply to the infected region
- Surgery may be avoided in the early stages of osteomyelitis, or when a patient is sufficiently immunocompromised or systemically unwell that the risk of surgery outweighs the benefit
- In children, surgical drainage is recommended in cases showing no improvement within 48 hours of antibiotic initiation, or when an abscess or infected joint is present
Chronic osteomyelitis- Chronic cases are usually managed with antibiotics and surgical debridement; surgery is of substantial importance
- Empiric therapy is generally not indicated
- Usually therapy following surgery has traditionally been 6 weeks of parenteral antibiotics followed by 2-3 months of oral therapy. Some studies suggest that 4–6 weeks of treatment may be effective
- Selection of antibiotic depends upon the outcome of marrow currettings/sequestral culture and sensitivity results
- Duration of therapy should be dictated by the patient's clinical status and normalization of inflammatory markers (generally CRP)
- In cases where surgery cannot be performed, suppressive therapy based on culture and sensitivity report should be initiated
Medications indicated with specific doses
- Amoxicillin/clavulanate
- Cefazolin [IM/IV]
- Ceftriaxone [IM/IV]
- Cefotaxime [IM/IV]
- Ciprofloxacin [IV]
- Clindamycin [IM/IV]
- Gentamicin [IM/IV]
- Nafcillin [IV]|
- Oxacillin [IM/IV]
- Sulfamethoxazole/trimethoprim
- Vancomycin
Dietary or Activity restrictions
- Bed rest with immobilization of the infected bone and/or affected joint if symptomatic
- Adequate nutrition and counseling re: smoking cessation to promote wound healing
- Weight-bearing and activity restriction in children with S. aureus osteomyelitis due to risk of pathological fractures
Disposition
Admission criteria
- Admission is advised for acute osteomyelitis cases
- Chronic cases require admission for surgical procedures, debridement, and to obtain bone cultures and histology
Discharge criteria- Resolution of infection determined through clinical findings and inflammatory markers
- Subacute or chronic form of osteomyelitis can be discharged if there are proper arrangements made for outpatient intravenous antibiotics therapy
[Outline]
Prevention
- In diabetic patients, adequate glycemic control and appropriate foot care (to minimize foot trauma) to reduce the risk for developing osteomyelitis
- Antibiotic prophylaxis is recommended in clean bone surgery and treatment of both open and closed fractures
Prognosis
- Outcomes in acute osteomyelitis are favorable if treatment is initiated promptly and adequately
- Outcomes in chronic infections depend largely on the removal of the entire infected and necrotic tissues/bone
- Risk of treatment failure and/or recurrence is highly dependent on both the pathogen and antibiotic regimen. Recurrence with Pseudomonas aeuroginsa is twice that of cases where Staphylococcus aeurus is the causative organism
- Recurrence rate for infection in children is approximately 5%
- Complications can occur in children due to late diagnosis, shorter duration of treatment, and younger age at the time of initial illness
- Incidence of sequelae in neonatal cases of osteomyelitis ranges from 6-50%
- <5% of AHO cases in children become chronic
- Diabetes and peripheral vascular disease adversely affects the prognosis of patients treated on an outpatient basis
Associated conditions
- Decubitus ulcers
- Diabetes mellitus
- Immune deficiency (eg, AIDS, granulocyte deficiency, complement deficiency) or immunosuppression (e.g., chemotherapy or transplantation)
- Neuropathy
- Peripheral vascular disease
- Sickle-cell disease
- Trauma
Pregnancy/Pediatric effects on condition
- Agustsson , et al reported a case of Salmonella osteomyelitis of the iliac bone in a pregnant woman after suffering from febrile gastroenteritis during the first trimester. A 6 week regimen of antibiotics was curative, with no effects on the pregnancy
- Osteomyelitis of pubic symphysis rarely occurs during pregnancy however it can lead to serious complications
- Pediatric cases can impact forming bones with limb length inequalities being a risk
Synonyms/Abbreviations
Abbreviations
- AHO (Acute hematogenous osteomyelitis)
ICD-9-CM
- 730.00 Acute osteomyelitis, site unspecified
- 730.10 Chronic osteomyelitis, site unspecified
- 730.20 Unspecified osteomyelitis, site unspecified
ICD-10-CM
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