Osteomyelitis in Emergency Medicine 

Updated: Apr 12, 2019
Author: Randall W King, MD, FACEP; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD 

Overview

Background

Osteomyelitis is an acute or chronic inflammatory process of the bone and its structures secondary to infection with pyogenic organisms.

Pathophysiology

Osteomyelitis may be localized or it may spread through the periosteum, cortex, marrow, and cancellous tissue. The bacterial pathogen varies on the basis of the patient's age and the mechanism of infection.

The following are the 2 primary categories of acute osteomyelitis: hematogenous osteomyelitis and direct or contiguous inoculation osteomyelitis.

Hematogenous osteomyelitis is an infection caused by bacterial seeding from the blood. Acute hematogenous osteomyelitis is characterized by an acute infection of the bone caused by the seeding of the bacteria within the bone from a remote source. This condition primarily occurs in children. The most common site is the rapidly growing and highly vascular metaphysis of growing bones. The apparent slowing or sludging of blood flow as the vessels make sharp angles at the distal metaphysis predisposes the vessels to thrombosis and the bone itself to localized necrosis and bacterial seeding.

Vertebral osteomyelitis at any age is most often a secondary complication of a remote infection with hematogenous seeding. In approximately one half of vertebral osteomyelitis cases, a source can be identified such as urinary tract or skin, and approximately one third may be diagnosed with endocarditis.[1] Acute hematogenous osteomyelitis, despite its name, may have a slow clinical development and insidious onset.

Direct or contiguous inoculation osteomyelitis is caused by direct contact of the tissue and bacteria during trauma or surgery. Direct inoculation (contiguous-focus) osteomyelitis is an infection in the bone secondary to the inoculation of organisms from direct trauma, spread from a contiguous focus of infection, or sepsis after a surgical procedure. Clinical manifestations of direct inoculation osteomyelitis are more localized than those of hematogenous osteomyelitis and tend to involve multiple organisms.

Additional categories include chronic osteomyelitis and osteomyelitis secondary to peripheral vascular disease. Chronic osteomyelitis persists or recurs, regardless of its initial cause and/or mechanism and despite aggressive intervention. Although listed as an etiology, peripheral vascular disease is actually a predisposing factor rather than a true cause of infection.

Disease states known to predispose patients to osteomyelitis include diabetes mellitus,[2] sickle cell disease, acquired immune deficiency syndrome (AIDS), intravenous (IV) drug abuse, alcoholism, chronic steroid use, immunosuppression, and chronic joint disease. In addition, the presence of a prosthetic orthopedic device is an independent risk factor, as is any recent orthopedic surgery or open fracture.

For the radiologic perspective, see Osteomyelitis, Acute Pyogenic and Osteomyelitis, Chronic.

Epidemiology

Frequency

United States

The overall prevalence is 1 case per 5,000 children. Neonatal prevalence is approximately 1 case per 1,000. The annual incidence in patients with sickle cell anemia is approximately 0.36%. The prevalence of osteomyelitis after foot puncture (as is seen in the image below) may be as high as 16% (30-40% in patients with diabetes). The incidence of vertebral osteomyelitis is approximately 2.4 cases per 100,000 population.[1]

Osteomyelitis of diabetic foot. Photography by Dav Osteomyelitis of diabetic foot. Photography by David Effron MD, FACEP.

International

The overall incidence is higher in developing countries.

Mortality/Morbidity

Morbidity can be significant and can include localized spread of infection to associated soft tissues or joints; evolution to chronic infection, with pain and disability; amputation of the involved extremity; generalized infection; or sepsis. As many as 10-15% of patients with vertebral osteomyelitis develop neurologic findings or frank spinal-cord compression. As many as 30% of pediatric patients with long-bone osteomyelitis may develop deep venous thrombosis (DVT). The development of DVT may also be a marker for disseminated infection.[3, 4] Vascular complications appear to be more common with community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) than was previously recognized.[5]

Mortality rates are low, unless associated sepsis or an underlying serious medical condition is present.

Race

No increased incidence of osteomyelitis is noted based on race.

Sex

Males are at increased relative risk, which increases through childhood, peaking in adolescence and falling to a low ratio in adults.[6]

Age

In general, osteomyelitis has a bimodal age distribution. Acute hematogenous osteomyelitis is primarily a disease in children. Direct trauma and contiguous focus osteomyelitis are more common among adults and adolescents than in children. Vertebral osteomyelitis is more common in persons older than 45 years.

Prognosis

The prognosis for osteomyelitis varies but is markedly improved with timely diagnosis and aggressive therapeutic intervention.

 

Presentation

History

Hematogenous osteomyelitis usually presents with a slow insidious progression of symptoms. Direct osteomyelitis generally is more localized, with prominent signs and symptoms. General symptoms of osteomyelitis are dicussed below.

The following are general symptoms of hematogenous long-bone osteomyelitis:

  • Abrupt onset of high fever (fever is present in only 50% of neonates with osteomyelitis)

  • Fatigue

  • Irritability

  • Malaise

  • Restriction of movement (pseudoparalysis of limb in neonates)

  • Local edema, erythema, and tenderness

The following are general symptoms of hematogenous vertebral osteomyelitis:

  • Insidious onset

  • History of an acute bacteremic episode

  • May be associated with contiguous vascular insufficiency

  • Local edema, erythema, and tenderness

  • Failure of a young child to sit up normally[7]

The following are general symptoms of chronic osteomyelitis:

  • Nonhealing ulcer

  • Sinus tract drainage

  • Chronic fatigue

  • Malaise

Physical

Findings at physical examination may include the following:

  • Fever (present in only 50% of neonates)

  • Edema

  • Warmth

  • Fluctuance

  • Tenderness to palpation

  • Reduction in the use of the extremity (eg, reluctance to ambulate, if the lower extremity is involved or pseudoparalysis of limb in neonates)

  • Failure of a young child to sit up normally

  • Sinus tract drainage (usually a late finding or one that occurs with chronic infection)

Causes

Note that responsible pathogens may be isolated in only 35%-40% of infections.

Causes of acute hematogenous osteomyelitis are as follows (note increasing reports of other pathogens in bone and joint infections including community-associated methicillin-resistant Staphylococcus aureus [MRSA],[8] Kingella kingae,[9] and others):

  • Newborns (younger than 4 mo): Saureus, Enterobacter species, and group A and B Streptococcus species

  • Children (aged 4 mo to 4 y): S aureus, group A Streptococcus species, Haemophilus influenzae, and Enterobacter species

  • Children, adolescents (aged 4 y to adult): S aureus (80%), group A Streptococcus species, H influenzae, and Enterobacter species

  • Adults: S aureus and occasionally Enterobacter or Streptococcus species

  • Tuberculosis (TB): TB has been a historical cause of hematogenous osteomyelitis and should be considered in patients with a history of TB risk or impaired immune status

Causes of direct osteomyelitis are as follows:

  • General -S aureus, Enterobacter species, and Pseudomonas species

  • Puncture wound through an athletic shoe -S aureus and Pseudomonas species

  • Sickle cell disease -S aureus and Salmonellae species

Also see Medscape's Infectious Diseases Resource Center.

Complications

Complications of osteomyelitis may include the following:

  • Bone abscess

  • Paravertebral/epidural abscess

  • Bacteremia

  • Fracture

  • Loosening of the prosthetic implant

  • Overlying soft-tissue cellulitis

  • Draining soft-tissue sinus tracts

 

DDx

 

Workup

Approach Considerations

The studies below are indicated in patients with osteomyelitis.

The Infectious Diseases Society of America (IDSA) issued new guidelines on vertebral osteomyelitis in 2015.[10, 11]

Laboratory Studies

The studies below are indicated in patients with osteomyelitis.

CBC count

The WBC count may be elevated, but it is frequently normal.

A leftward shift is common with increased polymorphonuclear leukocyte counts.

C-reactive protein

The C-reactive protein level is usually elevated and nonspecific; this study may be more useful than the erythrocyte sedimentation rate (ESR) because it reveals elevation earlier.

ESR/CRP

The ESR is usually elevated (90%); however, this finding is clinically nonspecific.

CRP and ESR have limited roles in the setting of chronic osteomyelitis and are often normal.

Elevated ESR and CRP may suggest vertebral osteomyelitis.[10, 11]

Procalcitonin

Procalcitonin elevation: This can potentially be useful in diagnosis because it is relatively specific; however, it lacks sensitivity.[12]

Culture

Superficial wound or sinus tract cultures often do not correlate with the bacteria that is causing osteomyelitis and have limited use. Blood culture results are positive in approximately 50% of patients with hematogenous osteomyelitis. However, a positive blood culture may preclude the need for further invasive procedures to isolate the organism. Bone cultures from biopsy or aspiration have a diagnostic yield of approximately 77% across all studies.[1]

Imaging Studies

Radiography

Radiographic evidence of acute osteomyelitis is first suggested by overlying soft-tissue edema at 3-5 days after infection. Examples of radiographic evidence of osteomyelitis are presented in the images below.

Osteomyelitis of the elbow. Photography by David E Osteomyelitis of the elbow. Photography by David Effron MD, FACEP.
Osteomyelitis of index finger metacarpal head seco Osteomyelitis of index finger metacarpal head secondary to clenched fist injury. Photography by David Effron MD, FACEP.
Osteomyelitis of the great toe. Photography by Dav Osteomyelitis of the great toe. Photography by David Effron MD, FACEP.
Osteomyelitis of T10 secondary to streptococcal di Osteomyelitis of T10 secondary to streptococcal disease. Photography by David Effron MD, FACEP.
Osteomyelitis. Radiography of diabetic foot showin Osteomyelitis. Radiography of diabetic foot showing osteomyelitis with gas. Photography by David Effron MD, FACEP.

Bony changes are not evident for 14-21 days and initially manifest as periosteal elevation followed by cortical or medullary lucencies. By 28 days, 90% of patients demonstrate some abnormality.

Approximately 40-50% focal bone loss is necessary to cause detectable lucency on plain films.

In patients in whom TB is of concern, chest radiography may demonstrate lesions characteristic of TB.

Plain radiographs of the spine are not sensitive for early diagnosis of vertebral osteomyelitis.[10, 11]

MRI

The MRI is effective in the early detection and surgical localization of osteomyelitis.[13, 14]

Studies have shown its superiority compared with plain radiography, CT, and radionuclide scanning and is considered to be the imaging of choice.

Sensitivity ranges from 90-100%.

Patients with elevated ESR and CRP levels should undergo MRI to distinguish infection from disc herniation or other structural cause of back pain.[10, 11]

Positron emission tomographic scanning

Positron emission tomographic (PET) scanning has accuracy similar to MRI.

Radionuclide bone scanning

Three phase bone scan, gallium scan and tagged WBC scan are considerations in patients who are unable to have MRI imaging. A three phase bone scan has high sensitivity and specificity in adults with normal findings on radiograph. Specificity is dramatically decreased in the setting of previous surgery or traumatized bone.

In special circumstances, additional information can be obtained from further scanning with leukocytes labeled with gallium 67 and/or indium 111.

CT scanning

CT scans can depict abnormal calcification, ossification, and intracortical abnormalities.

It is not recommended for routine use for diagnosing osteomyelitis but is often the imaging of choice when MRI is not available

Ultrasonography

This simple and inexpensive technique has shown promise, particularly in children with acute osteomyelitis.

Ultrasonography may demonstrate changes as early as 1-2 days after onset of symptoms.

Abnormalities include soft tissue abscess or fluid collection and periosteal elevation.

Ultrasonography allows for ultrasound-guided aspiration.

It does not allow for evaluation of bone cortex.

Procedures

The probe to bone (PTB) test may be a useful rapid adjunct in the evaluation of the diabetic foot. The procedure involves inserting a blunt probe into the suspected ulceration on the plantar surface of the foot. A "click" (solid or gritty end point) indicates a positive finding. Note that location of the ulcer and the performer’s expertise may affect reliability.[15] . A positive PTB test finding in a high-risk patient indicates a high probability of osteomyelitis. A negative PTB test result in a low-risk patient indicates a low probability of osteomyelitis.[16]

 

Treatment

Emergency Department Care

Osteomyelitis rarely requires emergent stabilization or resuscitation. The primary challenge for ED physicians is considering the appropriate diagnosis in the face of subtle signs or symptoms.

Treatment for osteomyelitis involves the following:

  • Initiation of intravenous antibiotics that penetrate bone and joint cavities

  • Referral of the patient to an orthopedist or general surgeon

  • Possible medical infectious disease consultation

Select the appropriate antibiotics using direct culture results in samples from the infected site, whenever possible. Empiric therapy is usually delayed until culture results can be obtained to better target definitive future antibiotic coverage. Empiric therapy is often initiated on the basis of the patient's age and the clinical presentation. Therapy should always include coverage for S aureus and consideration of CA-MRSA. Further surgical management may involve removal of the nidus of infection, implantation of antibiotic beads or pumps, hyperbaric oxygen therapy,[17] or other modalities.

Diagnosis requires 2 of the 4 following criteria:

  • Purulent material on aspiration of affected bone

  • Positive findings of bone tissue or blood culture

  • Localized classic physical findings of bony tenderness, with overlying soft-tissue erythema or edema

  • Positive radiological imaging study

Consultations

Order an orthopedics, general surgery, or infectious disease consultation, as needed. Patients with diabetic foot osteomyelitis are best cared for by a multidisciplinary team.[18]

Prevention

Acute hematogenous osteomyelitis can potentially be avoided by preventing bacterial seeding of bone from a remote site. This involves the appropriate diagnosis and treatment of primary bacterial infections.

Direct inoculation osteomyelitis can best be prevented with appropriate wound management and consideration of prophylactic antibiotic use at the time of injury.

Long-Term Monitoring

Patients with vertebral osteomyelitis whose pain resolves after antibiotic treatment or surgery generally do not require repeat MRI.[10, 11]

 

Medication

Medication Summary

The primary treatment for osteomyelitis is parenteral antibiotics that penetrate bone and joint cavities. Treatment is required for at least 4-6 weeks. After intravenous antibiotics are initiated on an inpatient basis, therapy may be continued with intravenous or oral antibiotics, depending on the type and location of the infection, on an outpatient basis.

Below are recommendations for the initiation of empiric antibiotic treatment based on the age of the patient and mechanism of infection.

With hematogenous osteomyelitis (newborn to adult), the infectious agents include S aureus, Enterobacteriaceae organisms, group A and B Streptococcus species, and H influenzae. Primary treatment is a combination of penicillinase-resistant synthetic penicillin and a third-generation cephalosporin. Alternate therapy is vancomycin or clindamycin and a third-generation cephalosporin, particularly if methicillin-resistant S aureus (MRSA) is considered likely. Linezolid is also used in these circumstances.[19, 20] In addition to these above-mentioned antibacterials, ciprofloxacin and rifampin may be an appropriate combination therapy for adult patients. If evidence of infection with gram-negative bacilli is observed, include a third-generation cephalosporin.

While data on efficacy are limited, additional choices for gram-positive coverage in adults may also include daptomycin, telavancin, or ceftaroline.[21]

In patients with sickle cell anemia and osteomyelitis, the primary bacterial causes are S aureus and Salmonellae species. Thus, the primary choice for treatment is a fluoroquinolone antibiotic (not in children). A third-generation cephalosporin (eg, ceftriaxone) is an alternative choice.

When a nail puncture occurs through an athletic shoe, the infecting agents may include S aureus and Pseudomonas aeruginosa. The primary antibiotics in this scenario include ceftazidime or cefepime. Ciprofloxacin is an alternative treatment.

For patients with osteomyelitis due to trauma, the infecting agents include S aureus, coliform bacilli, and Pseudomonas aeruginosa. Primary antibiotics include nafcillin and ciprofloxacin. Alternatives include vancomycin and a third-generation cephalosporin with antipseudomonal activity.

In patients in whom tuberculosis is of concern as the etiology of a musculoskeletal infection, the choice of antibiotic is generally the same as for pulmonary infection.

Vertebral osteomyelitis

According to 2015 guidelines on vertebral osteomyelitis issued by the IDSA, unless patients are septic or have neurologic compromise, empiric antimicrobial therapy should be withheld until the microbiologic diagnosis is confirmed.[10, 11]

Most patients with S aureus bloodstream infection within the preceding 3 months and compatible spine MRI changes may be treated empirically without disc space aspiration.

Treatment usually includes intravenous antibiotics for 6 weeks based on the results of culture and in vitro susceptibility testing.

Antibiotics

Class Summary

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Nafcillin (Nafcil, Unipen)

Initial therapy for suspected penicillin G–resistant streptococcal or staphylococcal infections. Use parenteral therapy initially in severe infections. Change to oral therapy as condition warrants. Because of thrombophlebitis, particularly in elderly patients, administer parenterally for only the short term (1-2 d). Change to PO route as clinically indicated. Note: Administer in combination with a third-generation cephalosporin to treat osteomyelitis. Do not admix with aminoglycosides for IV administration.

Ceftriaxone (Rocephin)

Third-generation cephalosporin with broad-spectrum gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms; arrests bacterial growth by binding to one or more penicillin-binding proteins. Note: Administer with a penicillinase-resistant synthetic penicillin, when treating osteomyelitis.

Cefazolin (Ancef)

First-generation semisynthetic cephalosporin that arrests bacterial cell wall synthesis, inhibiting bacterial growth; primarily active against skin flora, including S aureus; typically used alone for skin and skin-structure coverage.

Ciprofloxacin (Cipro)

Fluoroquinolone with activity against pseudomonads, streptococci, MRSA, Staphylococcus epidermidis, and most gram-negative organisms, but no activity against anaerobes. Inhibits bacterial DNA synthesis and, consequently, growth. Continue treatment for at least 2 d (typical treatment, 7-14 d) after signs and symptoms disappear.

Ceftazidime (Fortaz, Ceptaz)

Third-generation cephalosporin with broad-spectrum gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms; arrests bacterial growth by binding to one or more penicillin-binding proteins.

Clindamycin (Cleocin)

Lincosamide for the treatment of serious skin and soft-tissue staphylococcal infections; also effective against aerobic and anaerobic streptococci (except enterococci); inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes, arresting RNA-dependent protein synthesis.

Vancomycin (Vancocin)

Potent antibiotic directed against gram-positive organisms and active against Enterococcus species. Useful in the treatment of septicemia and skin structure infections. Indicated for patients who can not receive or have failed to respond to penicillins and cephalosporins or have infections with resistant staphylococci. For abdominal penetrating injuries, it is combined with an agent active against enteric flora and/or anaerobes.

To avoid toxicity, current recommendation is to assay vancomycin trough levels after third dose drawn 0.5 h prior to next dosing. Use creatinine clearance to adjust dose in patients with renal impairment.

Used in conjunction with gentamicin for prophylaxis in penicillin-allergic patients undergoing gastrointestinal or genitourinary procedures.

Linezolid (Zyvox)

Prevents formation of functional 70S initiation complex, which is essential for bacterial translation process. Bacteriostatic against staphylococci.

The FDA warns against the concurrent use of linezolid with serotonergic psychiatric drugs, unless indicated for life-threatening or urgent conditions. Linezolid may increase serotonin CNS levels as a result of MAO-A inhibition, increasing the risk of serotonin syndrome.

Antibiotic, Miscellaneous

Rifampin

For use in combination with at least one other antituberculous drug. Inhibits DNA-dependent bacterial RNA polymerase but not mammalian RNA polymerase. Cross-resistance may occur.

Treat for 6-9 months or until 6 months have elapsed from conversion to sputum culture negativity.

 

Questions & Answers

Overview

What is osteomyelitis?

What is the pathophysiology of osteomyelitis?

What is the prevalence of osteomyelitis in the US?

What is the global prevalence of osteomyelitis?

What are the morbidity and mortality associated with osteomyelitis?

What are the racial predilections of osteomyelitis?

What are the sexual predilections of osteomyelitis?

Which age groups have the highest prevalence of osteomyelitis?

What is the prognosis of osteomyelitis?

Presentation

What are the signs and symptoms of osteomyelitis?

Which physical findings are characteristic of osteomyelitis?

What causes osteomyelitis?

What are the possible complications of osteomyelitis?

DDX

What are the differential diagnoses for Osteomyelitis in Emergency Medicine?

Workup

Which organization has issued guidelines on the diagnosis and treatment of osteomyelitis?

Which findings on CBC count are characteristic of osteomyelitis?

Which findings of C-reactive protein level is characteristic of osteomyelitis?

What is the role of ESR in the workup of osteomyelitis?

What is the role of procalcitonin in the workup of osteomyelitis?

What is the role of blood culture in the workup of osteomyelitis?

What is the role of radiography in the workup of osteomyelitis?

What is the role of MRI in the workup of osteomyelitis?

What is the roe of PET scans in the workup of osteomyelitis?

What is the role of nuclear imaging in the workup of osteomyelitis?

What is the role of CT scanning in the workup of osteomyelitis?

What is the role of ultrasonography in the workup of osteomyelitis?

What is the role of a probe to bone (PTB) test in the workup of osteomyelitis?

Treatment

How is osteomyelitis treated in the emergency department (ED)?

What are the diagnostic criteria for osteomyelitis?

Which specialist consultations are beneficial to patients with osteomyelitis?

How is osteomyelitis prevented?

What is included in the long-term monitoring of osteomyelitis?

Medications

What is the role of medications in the treatment of osteomyelitis?

Which medications in the drug class Antibiotic, Miscellaneous are used in the treatment of Osteomyelitis in Emergency Medicine?

Which medications in the drug class Antibiotics are used in the treatment of Osteomyelitis in Emergency Medicine?