Osteomyelitis (pediatrics): Clinical sciences

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Introduction 0:00–0:50

Osteomyelitis refers to bony inflammation caused by an underlying infection. In children, osteomyelitis is usually caused by Staphylococcus aureus, but it can also be caused by other bacterial pathogens, such as Group A Streptococcus.
Children most commonly present with acute hematogenous osteomyelitis, meaning the infection spreads from the blood to the bone.
Osteomyelitis often involves the metaphyseal region of tubular bones like the femur, due to the increased vascularity of the growth plate.
In order to determine appropriate treatment, it’s important to distinguish stable patients from those with a rapidly progressive infection or worsening clinical status.
Now, if a pediatric patient presents with a chief concern suggesting osteomyelitis, you should first perform an ABCDE assessment to determine if the patient is unstable or stable.

Unstable Patient 0:50–1:25

If unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access and start IV fluids.
Begin continuous vital sign monitoring, including pulse oximetry, blood pressure, and heart rate. If needed, provide supplemental oxygen; and start antibiotics if your patient shows signs of sepsis.
Alright, let’s go back to the ABCDE assessment and look at stable patients. First, obtain a focused history and physical examination.

Stable Patient 1:25–4:31

History may include fever, or a recent trauma or infection. The patient or caregivers typically report pain in the affected bone and pseudoparalysis, meaning they are unable to bear weight or have reduced use of the affected extremity.
Also keep in mind that nonverbal or pre-verbal children might only exhibit nonspecific symptoms, such as fussiness, decreased activity, or decreased appetite.
Physical examination typically reveals edema, warmth, and tenderness over the affected bone. At this point, you should suspect osteomyelitis.
Here’s a clinical pearl! In neonates, osteomyelitis often causes septic arthritis of adjacent joints, due to the presence of vascular channels connecting the bone and joint.
When compared to older children, neonates are also more likely to develop multifocal osteomyelitis and septicemia. Neonatal osteomyelitis is commonly caused by group B Streptococcus or E.
coli, due to perinatal exposure to these organisms. Now, once you suspect osteomyelitis, your next step is to obtain labs.
Labs include CBC, CRP, ESR, and blood culture. Also order imaging studies, such as a plain radiograph or possibly MRI.
Okay, let’s move on to lab results! The CBC might reveal increased WBCs, and platelets might be elevated or low.
The CRP and ESR are usually elevated, and the blood culture might be positive, though it often does not grow any pathogens.
Meanwhile, X-rays may reveal no positive findings, but you might detect bony lucencies, periosteal reaction, or soft tissue swelling.
If you ordered an MRI, findings might reveal bone marrow edema, soft tissue swelling, and possibly a rim lining an abscess cavity, referred to as a “penumbra sign.” Here’s a clinical pearl!
Although an X-ray is often ordered during the initial evaluation of osteomyelitis, plain radiographs often do not show clear evidence of osteomyelitis during early stages of infection.
The first noticeable changes of soft tissue swelling and loss of fat planes may not become visible until day 3; and periosteal thickening, focal osteopenia, and osteolytic lesions are only seen after day 10.
Since X-ray findings lag behind the clinical presentation, MRI is the preferred imaging modality if you need additional evidence to support the diagnosis.
Now, based on these findings, you can make a diagnosis of osteomyelitis. Your next step is to assess your patient’s clinical status.
First, let’s look at clinically stable patients with no concern for a rapidly progressive infection. In these patients, your next step is to assess for evidence of an abscess on the X-ray or MRI.

Clinically Stable, Not Rapidly Worsening 4:31–4:45

If you don’t identify an abscess, or if there’s an abscess no more than 2 centimeters in diameter. If this is the case your next step is to obtain an aspirate or bone biopsy for culture and Gram stain.

No Abscess / Abscess ≤ 2 cm 4:45–5:58

Now, here’s a clinical pearl! While it’s ideal to obtain cultures before you administer antibiotics, don’t delay treatment beyond 48 to 72 hours if your patient is stable, and begin antibiotics immediately if your patient is unstable!
Once you’ve obtained cultures, begin empiric parenteral antibiotics that cover Staphylococcus aureus, since this is the most likely pathogen in children.
Also remember to consider local MRSA rates and resistance patterns when selecting an antibiotic. For patients with a low probability of MRSA, administer antistaphylococcal penicillins like oxacillin or nafcillin; or first-generation cephalosporins such as cefazolin.
Patients with a higher probability of MRSA infection can be treated with clindamycin; but if clindamycin resistance is also high, consider vancomycin.
Now, let’s back up and look at patients whose imaging reveals an abscess more than 2 centimeters in diameter. In this case, first obtain a surgical consultation for debridement; and send an aspirate or biopsy specimen for culture and Gram stain.

Abscess >2 cm 5:58–6:23

Then, begin empiric parenteral antibiotics to cover Staphylococcus aureus while waiting for the culture results. Finally, let’s switch gears and discuss patients with a worsening condition.

Sepsis/Rapidly Progressive Infection/Worsening 6:23–6:58

This includes patients who initially presented with sepsis, or show signs of a rapidly progressive infection, or have a worsening clinical status.
In any of these scenarios, immediately begin empiric parenteral antibiotics to cover Staphylococcus aureus. Then, obtain a surgical consultation for debridement; and send an aspirate or biopsy specimen for culture and Gram stain.
Remember: do not delay antibiotic treatment while awaiting surgical debridement! After you’ve initiated treatment, your next step is to assess the culture results as soon as they become available.

Culture Results 6:58–7:57

If the blood culture, aspirate, and bone culture demonstrate no growth, continue empiric antibiotics; however, if any of the cultures demonstrate bacterial growth, tailor the antibiotics to the culture results.
Here’s a high yield fact! While Staphylococcus aureus is the most common cause of osteomyelitis in children, other pathogens can also cause osteomyelitis in specific populations and clinical scenarios.
For instance, children under 5 who attend daycare can develop Kingella kingae osteomyelitis, while puncture wounds to the foot commonly cause Pseudomonas osteomyelitis.
Finally, patients with hemoglobinopathies such as sickle cell anemia, are susceptible to Salmonella osteomyelitis. While your patient is receiving antibiotic treatment, continue to monitor them for improvement.

Monitor 7:57–8:18

Do this by reviewing sequential CRP results, to ensure the levels are declining. Additionally, perform serial clinical examinations to look for reduction in fever and pain as well as improved musculoskeletal function.
Now, if your patient shows no improvement or demonstrates worsening clinical status, and the CRP level remains elevated, your next step is to re-evaluate the antibiotic regimen to determine if the antimicrobial spectrum, dosage, and penetration are adequate to treat the infection.

No improvement 8:18–8:59

Additionally, you may need to obtain a surgical consultation for consideration of surgical intervention. Here’s another clinical pearl!
Be alert for any complications before or during osteomyelitis treatment, such as septic arthritis, pyomyositis, and deep vein thrombosis!
On the other hand, if your patient shows clinical improvement with the current treatment, and CRP levels are declining, the treatment response is adequate.

Improving 8:59–9:15

In this case, consider transitioning to oral antibiotics, and complete the course of treatment. Alright, as a quick recap… When a patient presents with a chief concern suggesting osteomyelitis, obtain a CBC, CRP, ESR, and blood culture, as well as a plain radiograph and possibly an MRI.

Review 9:15–10:28

If the CRP and ESR are elevated and the imaging reveals signs of osteomyelitis, make the diagnosis. Stable patients without evidence of an abscess greater than 2 centimeters should have an aspirate or bone biopsy for culture and gram stain then begin empiric parenteral antibiotics to cover Staphylococcus aureus.
A larger abscess or rapidly progressive infection warrants surgical consultation for debridement in addition to antibiotics.
If cultures are positive, tailor antibiotics to the results. Otherwise, continue empiric antibiotics.
Next, monitor for improvement with serial CRP levels and physical examinations. If there’s no improvement, re-evaluate the antibiotic regimen, and consider surgical consultation.
However, if the patient is improving,