Pediatric Septic Arthritis Surgery Treatment & Management

Administer parenteral antibiotics as soon as blood and joint aspirates have been cultured. The choice of antibiotic should be based on the Gram stain results. When the Gram stain fails to show bacteria, the choice should be empirically based on the patient's age and circumstance. Treat children older than 4 years with a penicillinase-resistant penicillin alone. For children 4 years of age or younger who have not been vaccinated against H influenzae type b, add coverage for ampicillin-resistant strains of H influenzae. Treat neonates, patients who are immunocompromised, and older patients suspected of abusing parenteral drugs with an aminoglycoside in addition to a penicillinase-resistant penicillin in order to cover against enteric gram-negative bacilli and Pseudomonas species. Appropriately adjust the choice of antibiotic after culture and sensitivity results are known.

For children younger than 3 years, K kingae must be considered. This organism is susceptible to a wide variety of antibiotics, including ampicillin, first- and third-generation cephalosporins, aminoglycosides, and semisynthetic penicillins.

A third-generation cephalosporin should be the initial treatment for gonococcal arthritis.

In regions where community-associated methicillin-resistant Staphylococcus aureus (MRSA) is common or when an infection with MRSA is otherwise a risk (such as an infection acquired in the hospital), empirical therapy should include coverage for MRSA.^{[10, 11]} Clindamycin and vancomycin are the 2 agents most commonly used for this purpose, but the antibiotic choice should be adjusted depending on the antibiotic susceptibility patterns of local isolates.

Maintain adequate blood levels of a culture-specific antibiotic for at least 3 weeks after the joint has been drained and the patient has responded clinically. ESR and CRP levels are valuable indicators of clinical response. The CRP is generally more sensitive than the ESR, and antibiotics should be continued at least until this measure has normalized. If visiting nurse services are available, responding patients may be discharged to receive home intravenous antibiotic therapy. Switching to oral antibiotics is also acceptable, provided that adequate blood levels of the antibiotic are demonstrated, the patient’s parents are reliable, and the antibiotic does not cause a gastrointestinal disturbance that would interfere with its absorption.

Consider a septic joint to be a closed abscess and do not expect antibiotic treatment alone to resolve the infection. Remember that the risks of complication are time dependent. In addition to administration of medical therapy, the joint must be adequately drained. Patients may be treated with antibiotics and repeated joint aspiration in cases of involvement of an easily accessible peripheral joint; a clinical course shorter than 6 days; and no evidence of an associated osteomyelitis, immune deficiency, or other chronic illness. If the patient's condition fails to improve, open drainage is the next approach. Peripheral joints may be adequately drained with arthroscopy if the technology is available.

Open drainage performed in the operating room is unquestionably more effective than percutaneous aspiration. In such procedures, encountering heavy fibrin deposits that clearly cannot be removed (even through large-bore needles) is not unusual. Open drainage is definitely indicated in the hip and the shoulder and in peripheral joints that do not respond to percutaneous aspiration. Open drainage is indicated in patients who are systemically ill, and it should be given greater consideration when the suspected organism is S aureus or a gram-negative bacterium that produces cartilage-damaging enzymes. Gonococcal arthritis is less likely to rapidly damage a joint, and these infections may be managed with repeated aspirations if the joints involved are peripheral. Open drainage should still be performed in cases of gonococcal arthritis of the hip.

Perform open drainage through an approach that allows adequate visualization of the joint surfaces and thorough irrigation. Anterior approaches are best for the hip and the shoulder. Inspect the joint surfaces for damage, but be aware that early cartilage damage may not be grossly apparent. Leave the capsular incision open, and loosely close the remaining portion of the wound over a drain placed next to the capsule.

Postoperatively, place the joint at rest in a position of comfort. If the preoperative clinical course was short and the joint was promptly drained, manage a hip with simple bed rest, place a postoperative shoulder in a sling, and use a plaster splint for a peripheral joint. As the patient recovers and the symptoms and signs subside, allow the patient to regain mobility as his or her comfort dictates.

If treatment was significantly delayed, however, substantial capsular damage may have occurred. This complication is particularly likely with a neglected septic hip or shoulder. If instability is suspected, immobilize the patient for a longer period. A neglected septic hip with radiographic instability requires a spica cast, and an unstable shoulder requires a sling and swathe.

Continue antibiotics until the patient's clinical condition and the erythrocyte sedimentation rate or C-reactive protein normalize. Follow up with the patient for at least a year after surgery. Further follow-up can be discontinued if joint function has returned to normal and if no radiographic evidence suggests loss of joint space, avascular necrosis of the epiphysis, joint instability, or damage to the growth plate.

For excellent patient education resources, visit eMedicine's Arthritis Center and Bacterial and Viral Infections Center. Also, see eMedicine's patient education article Gonorrhea and Knee Pain.

As indicated earlier, potential complications associated with delay in treatment include irreversible articular damage, growth arrest, and disruption of joint continuity. Complications that can occur in an inadequately treated septic hip are illustrated in the images below.

With early diagnosis and appropriate medical and operative treatment, the prognosis for septic arthritis is excellent. Effective treatment before enzymatic damage to the articular cartilage occurs is vitally important. Loss of blood supply to the epiphysis and irreversible growth-plate damage are consequences that might occur with further delay. With prompt treatment, all complications might be avoided, and normal function and future growth may be preserved. The keys to proper management are a high index of suspicion in any child with painful joint dysfunction and strict adherence to the principles for treatment outlined above.

Of all the conditions that must be considered in the differential diagnosis of septic arthritis, transient synovitis is the most common. Kocher et al identified 4 independent multivariate clinical predictors that may be useful in differentiating septic arthritis from transient synovitis: a history of fever, an inability to bear weight, an ESR of 40 mm/h or more, and a serum WBC count greater than 12,000 per milliliter.^[12] Using these 4 predictors, they found that the incidence of septic arthritis was 0.2% for no predictors, 3.0% for 1, 40.0% for 2, 93.1% for 3, and 99.6% for all 4 predictors.

A more recent prospective study by Caird et al investigated predictors including CRP and found that a fever of >38^o C and CRP levels >2.0 mg/dL were strong predictors of septic arthritis.^[13] They concluded that the CRP level is a valuable tool with which to assess the presence of septic arthritis, but this tool must be used with careful clinical judgment, as 15% of their patients with confirmed septic arthritis had CRP levels below 2.0 mg/dL.

No consensus exists regarding the appropriate length of antibiotic treatment. The recommendations cited here (at least 3 weeks of antibiotics, with the first week delivered parenterally and no discontinuation of treatment until ESR/CRP levels and clinical symptoms normalize) probably represents a middle ground in the controversy.

Septic arthritis of the hip and shoulder commonly arises from hematogenous osteomyelitis of the intra-articular metaphyses of the proximal femur and the proximal humerus, respectively. Some surgeons advocate drilling the metaphyses to ensure that the bone infection is adequately decompressed. The author of this article does not routinely drill metaphyses because the osteomyelitis decompresses spontaneously when it breaks into the joint. This author has never seen a case in which residual osteomyelitis developed after a septic arthritis was appropriately treated without such drilling.

A disturbing trend associated with acute osteoarticular infections in children is the increasing incidence of community-associated methicillin-resistant S aureus (CA-MRSA). In their recently published retrospective study from Memphis, Tennessee, Arnold et al found the percentage of cases of pediatric osteomyelitis, septic arthritis, and osteomyelitis with septic arthritis caused by CA-MRSA rose from 4% to 40% between 2000 and 2004.^[14] It is probable that this trend toward antibiotic resistant pathogens will continue.