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Osteomyelitis

With osteomyelitis and bone infection there are three different ways that they tend to emerge. Hematogenous dissemination of organisms; the child gets bacteremic, the organisms float around in circulation and lodge in a bone, or lodge in a joint space. Direct inoculation; child kneels on a needle or in the case of bone infection, gets nailed by stepping on a nail. Spread from a contiguous focus; you have an overlying focus of infection.

How do you diagnose osteomyelitis? Well, it can be diagnosed as simply as good common sense and thinking about the disease, a point radiograph and a big needle. The last case of osteomyelitis that I've seen. The kid presented with pain and erythema over his distal fibula. The orthopedist walked into the room, looked at the films and said, "You know, fever for one day, erythema, doesn't want to move his leg, this looks like osteomyelitis." Boom, up to the operating room, little incision one centimeter long, aspiration, gets pus, the child is back in the room.

Osteomyelitis in non-neonates, because that's where you are typically going to see this disease. Most cases result from hematogenous spread, as I've said, and it's usually gram positives. So starting with a gram positive agent is appropriate. Oxacillin and cefuroxime were typically used. A lot of folks still like to use cefuroxime because we used it a lot in the H. flu days.

We quit keeping children chained in hospitals for 4-6 weeks of antibiotics a long, long time ago. By 1980 it was already clear that you could successfully treat children ... they could get a portion of their therapy, at least, using oral antibiotics. Criteria have been suggested by John Nelson and others for when it's appropriate to switch to oral therapy.

There are two specific funny entities in pediatric osteomyelitis that we talk about that the adults typically don't have to worry about so much. One is the so-called tennis shoe osteochondritis. The child steps on a nail, nail goes through shoe taking with it Pseudomonas aeruginosa and implanting it in the soft tissue of the foot. Now the classic way in which this ... this disease is rather different from hematogenous osteomyelitis. Hematogenous osteomyelitis; treatment in general is necessary for four weeks to fully eradicate that focus of infection in the metaphysis. In the case of this disease you have implantation of organisms that tend to just take off in the soft tissue and begin to erode the cartilage.

Discitis. The child is limping or refuses to walk. Anti-staphylococcal therapy is recommended by some but most authors don't see it as necessary. Other organisms besides staph can cause it but in general discitis self-resolves. Really what you need to do is keep the child comfortable. The radiographic findings are decrease in disc space seen in plain films.

Septic arthritis. Remember I started by saying that you get it the same way you get osteomyelitis, in childhood. Hematogenous, delivery of direct implantation, or you get spread into a joint from a contiguous focus. Typical presenting feature is fever, limp, refusal to move the extremity, pain and a limited range of motion, or in the case of the hip you get this classic flexed abducted externally rotated positioning of the hip.

Causes; what's in the differential diagnosis besides bacterial infection in the joint space? Well there are a number of causes of viral arthritis, including varicella, adenovirus, hepatitis, rubella, parvovirus, Ross River fever, O'nyong-nyong fever, and a few others. The table goes on and on in Dr. Cherry's book. It's interesting to realize that during epidemics of Hepatitis B that arthralgia and arthritis are well described, and varicella has been found in joint fluid in the absence of any bacterial infection. Mycobacterial arthritis, TB can certainly get into joint space, fungal arthritis - cocci is a good example - cellulitis overlying a joint could certainly be confused for arthritis.

Organisms; most of these are gram positive. Both staph aureus, group A Streptococci as well as Pneumococci. Overall that comes up in younger children to be about 90% to 95% of disease. H. flu was fairly common before we succeeded in largely eliminating it as a cause. In newborns and adolescents Gonococci need to be considered, and a classic finding in adolescence.

So how do we evaluate these? Radiographs primarily to rule out other causes of pain on movement. Bone scan if needed. If the bone scan is done to try and differentiate with bone disease, osteomyelitis, you will typically see increased uptake in the second phase in the 30 minutes after uptake.

Surgical drainage is essential for the hip and the shoulder, and increased pressure on the joint will compromise the circulation with the possibility of aseptic necrosis developing. The treatment is typically focused on gram positive disease unless there are other specific considerations; because you are looking at an immunocompromised child.