Osteomyelitis 02: History & Physical exam

Welcome back to the Osteo series – Whereas part one focused mainly on etiology, part 2 delves into making the diagnosis with a good history and physical. I should really say that your history and physical helps increase your index of suspicion – since osteo can be quite elusive especially in the early stages.

Harkening back to part one, it is important to remember that initially osteo is a localized disease. Since 90% of cases are unifocal you’d be right to assume that localized pain is a predominant symptom. That pain will manifest in limp in the older child, pelvic pain if it involves the hips and back pain in vertebral osteo. Really, any location can be involved. But overall limp is the number one functional limitation in cases of osteo due to the lower extremity predominance.

Pseudoparalysis – a situation where a child will not move the limb due to pain is more common in infants and younger children. In 70-80% of kids the fever is above 38.5 C. Once pus breaks through the cortex you will see localized redness and swelling. If the nidus of infection is near a joint capsule then the child will present with limitation of range of motion as well as increased pain. It is important to note that this generally occurs more frequently in children under the age of 3 and in especially those less than 1 since the cortex is thinner and less able to resist the pressure of the inflammation and exudate.

See how nondescript the redness and swelling is in this child’s leg with osteo

When trying to isolate the location of pain in the skittish child some experts recommend percussing adjacent parts of potentially involved bones. Finally, the most challenging patient population is certainly the infant – as their only initial symptom may be irritability. Thus, your index of suspicion must be high and your instructions to parents complete – especially when it comes to follow up if osteo is lower on your differential initially.

In part 3, which is coming soon, we’ll discuss labs.