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Primary total hip arthroplasty after infection.

Only a few of the more than 200,000 total hip arthroplasties performed annually in the United States are done after an infection of the hip joint or the proximal aspect of the femur.

Although some infections produce severe early destruction of the hip joint, most patients, if treated promptly, regain good hip function and do not present again until much later in life, when secondary degenerative changes have occurred1. It is therefore necessary to be aware of the possibility of a previous infection and to inquire about it specifically.

The first recurrence of bone infection may be delayed for many decades. Gallie2 reported a case of femoral osteomyelitis in a ten-year-old girl that did not recur until after nearly eighty years. The risk that a previous infection of the hip region poses to a hip prosthesis is multifactorial. The type of infection (osteomyelitis or septic arthritis), the level of activity of the infection (active or quiescent), the time since the infection (recent or historical), the organism (pyogenic, tuberculous, or fungal), and the reconstruction technique all contribute to the outcome.

### Osteomyelitis

Ever since Staphylococcus aureus was first isolated from osteomyelitis by Pasteur3 in the late nineteenth century, it has remained the predominant infecting organism, implicated in approximately 90% of infections where an organism is isolated (range, 88% [140 of 159] to 95% [392 of 411])4,5. The infecting organisms in the remaining cases are largely Staphylococcus epidermidis and streptococci.

More recently, there has been a shift in the prevalence of certain causative organisms, with fewer infections caused by Staphylococcus aureus . There has also been a significant increase (from eight of sixty-five cases to eight of nineteen cases; p < 0.001) in the proportion of cases that are subacute and that have a greater tendency …