Orthopedic Emergencies

Published on 26/03/2015 by admin

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Last modified 26/03/2015

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Chapter 47 Orthopedic Emergencies

Fred A. Fow, MD

1 Describe the presentation of osteomyelitis.

Fever, pain, and decreased use of the involved extremity are common manifestations of osteomyelitis. There may be accompanying signs of systemic illness, such as anorexia, malaise, and vomiting. Infants may exhibit decreased feeding, irritability, or listlessness. Pain may be manifested in neonates as pseudoparalysis. Examination findings include focal swelling, warmth, tenderness, and erythema, often metaphyseal in location. Neonates and younger children are more prone than older patients to present with secondary joint involvement. Proximal humerus and proximal femur infections involve the joint as a result of their intracapsular location. When there is limited soft tissue involvement tenderness may be out of proportion to the soft tissue findings. A patient may present with symptoms of severe illness, including signs of generalized sepsis and shock.

Other diagnoses to consider in the patient with suspected osteomyelitis include cellulitis, pyomyositis, necrotizing fasciitis, septic arthritis, toxic synovitis, thrombophlebitis, trauma, rheumatologic diseases, Ewing’s sarcoma, osteosarcoma, and leukemia.

Frank G, Mahoney HM, Eppes SC: Musculoskeletal infections in children. Pediatr Clin North Am 52:1083–1106, 2005.

Gutierrez KM: Bone and joint infections. In Long SS, Pickering LK, Prober CG (eds): Principles and Practice of Pediatric Infectious Disease, 2nd ed. Philadelphia, Churchill Livingstone, 2003, pp 467–474.

2 How are most cases of osteomyelitis acquired? Direct inoculation? Hematogenous spread? Contiguous spread?

The most common source for osteomyelitis is hematogenous spread. Direct inoculation into the bone is less common, as is local invasion from a contiguous infection.

Kaplan SL: Osteomyelitis in children. Infect Dis Clin North Am 19:787–797, 2005.

3 What laboratory tests are helpful in the diagnosis of osteomyelitis?

Reasonable screening laboratory tests to obtain in suspected cases of osteomyelitis include complete blood count (CBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). ESR and CRP are more sensitive indicators than white blood cell (WBC) count. ESR is elevated in up to 90% of cases of hematogenously acquired osteomyelitis. CRP is elevated in up to 98% of cases. Blood cultures should be obtained and are positive in 50–80% of cases of hematogenously acquired osteomyelitis. The highest yield for isolating a causative organism is achieved when bone aspirate, joint aspirate, and blood are collected for culture. With the exception of patients who are clinically unstable, these cultures should be obtained before initiation of parenteral antibiotics.

Look for emerging literature on the usefulness of polymerase chain reaction in identifying infections secondary to Bartonella henselae and Kingella kingae.

4 What imaging studies are indicated when osteomyelitis is suspected?

Plain radiography is a reasonable initial imaging choice in the emergency department (ED) evaluation of a patient with suspected osteomyelitis. This may rule out fracture, tumor, or other concerns. Its usefulness is limited, however, because bony changes (lytic lesions, periosteal elevation, and periosteal new bone formation) may not appear until 10–20 days after symptoms begin. Changes to adjacent soft tissues (deep soft tissue swelling and loss of normal tissue planes) may occur much earlier, as early as several days after symptoms begin.

Technetium 99 bone scanning is more sensitive in the early diagnosis of osteomyelitis than plain radiography, with reported sensitivities of 80–100%. However, results of bone scanning can be normal in up to 20% of cases in the first few days of illness. Its specificity in differentiating osteomyelitis from other differential diagnostic considerations (malignancy, soft tissue cellulitis, septic arthritis, trauma, fracture, and infarction) is also limited.

Magnetic resonance imaging (MRI) (Fig. 47-1) appears to be the imaging study of choice for evaluating the patient with suspected osteomyelitis. Sensitivity ranges from 92% to 100%. MRI helps differentiate osteomyelitis from cellulitis and demonstrate myositis or pyomyositis contiguous to the site of bone involvement. As with bone scanning, malignancy, fracture, and infarction can appear similar to osteomyelitis on MRI.