Pediatric Septic Arthritis Surgery
- Author: Thomas R Lewis, MD; Chief Editor: Dennis P Grogan, MD more...
Septic arthritis in infancy and childhood is a true clinical emergency (see image below). Delays in the diagnosis and treatment of septic arthritis can result in disastrous complications, including complete destruction of the articular cartilage and the underlying epiphysis, loss of the adjacent growth plate, and dislocation of the joint. With prompt treatment, the condition may be cured and sequelae avoided.
The clinician must be alert to a diagnosis that can be subtle, particularly in the young child or infant. The clinical presentations of other conditions can closely mimic that of septic arthritis.[1, 2, 3] Pain with passive motion is the most consistent finding in septic arthritis, and the diagnosis must be considered in any joint with this presentation. An aggressive workup is indicated whenever signs and symptoms suggest septic arthritis. This evaluation must include blood cultures and joint aspiration.
Before the advent of antibiotics, the consequences of septic arthritis were usually severe and often fatal. Surgical drainage was the only treatment available. With the development of effective antibiotics, it became possible to cure septic arthritis, but, except in a very few select situations, surgical drainage must still be performed. The most recent change in the prevention and treatment of septic arthritis has occurred with the institution of routine immunizations against Haemophilus influenzae type b.
Occasionally, the clinical signs of septic arthritis are prominent, but the clinician fails to obtain pus by aspiration. Decision-making in these situations should be analogous to that used in the management of an acute abdomen. The risks of an unnecessary arthrotomy are minimal compared with the certainty of permanent joint damage that accompanies a neglected septic arthritis.
The chief concern with septic arthritis in childhood and infancy is the potential for severe complications. The condition must be expeditiously diagnosed and appropriate treatment begun without delay. The diagnosis must be considered whenever painful joint dysfunction is present.
Septic Arthritis vs Transient Synovitis
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 erythrocyte sedimentation rate (ESR) of 40 mm/hr or more, and a serum white blood cell (WBC) count higher than 12,000/µL. 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 septic joint should be considered a closed abscess, and antibiotic treatment alone should not be expected to resolve the infection. 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 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 Staphylococcus 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.
The white blood cell (WBC) count is usually elevated, but it may be within the normal range early in the clinical course. Infants may also have a normal WBC count. A normal WBC count does not rule out septic arthritis.
The erythrocyte sedimentation rate (ESR) is elevated in septic arthritis; it returns to normal levels with resolution of the infection. The initial elevation and the return to normal lag behind the clinical status.
The C-reactive protein (CRP) level is elevated in septic arthritis; it returns to normal with resolution of the infection. The CRP level is a more valuable diagnostic tool and a better indicator of response to treatment than the ESR because it is generally more sensitive and more responsive.
A prospective study by Caird et al investigated predictors, including CRP, and found that a fever higher than 38o C and CRP levels greater than 2.0 mg/dL were strong predictors of septic arthritis. They concluded that the CRP level is a valuable tool with which to assess the presence of septic arthritis but must be used with careful clinical judgment; in their study, 15% of patients with confirmed septic arthritis had CRP levels lower than 2.0 mg/dL.
Blood cultures are frequently positive for the causative organism in septic arthritis and should be obtained. The joint aspirate may not yield a viable culture.
If gonococcal arthritis is suspected, cultures and Gram stain material should be obtained from the cervix in postpubertal girls, from the vagina of prepubertal girls, and from any urethral discharge in a male.
If sexual abuse is suspected—and it should be suspected in any prepubertal child with gonococcal arthritis—obtain additional cultures with samples from the pharynx and rectum. If child abuse is suspected, clinicians have a legal obligation to report the suspicions and to preserve all records and laboratory results as possible future legal evidence.
Lyme titers should be obtained in regions where this disease is endemic. If a rapid test that can provide results within hours is not available, it may be necessary to initially assume that the diagnosis is septic arthritis and treat accordingly.
Obtain radiographs to rule out other conditions in the differential diagnosis, such as trauma or Legg-Calvé-Perthes disease. Radiographs are not helpful in diagnosing acute septic arthritis. Even if the infection developed from an adjacent metaphyseal osteomyelitis, no initial bony findings are likely to be apparent until 7-10 days after onset. Signs of soft-tissue swelling and edematous infiltration into fatty tissue planes may be observed.
Radionuclide scanning is generally not helpful, and it is contraindicated if it delays more appropriate diagnostic or treatment measures. Such scanning may, however, be helpful in locating or ruling out other sites of involvement, particularly in very sick children and in neonates.
Ultrasonography is useful in confirming a joint effusion in a deeply placed joint such as the hip. It can also be used to guide joint aspiration.
Magnetic resonance imaging (MRI) has no role in the initial workup. The use of this expensive and time-consuming modality should be reserved for situations in which simpler measures, such as joint aspiration, fail to provide a diagnosis. In such cases, the diagnosis is probably something other than septic arthritis.
Computed tomography (CT) is indicated in patients with a suspected psoas abscess; in such patients, the clinical signs are suggestive of septic arthritis of the hip but the joint aspiration culture is negative.
Joint aspiration is the single most important diagnostic procedure for establishing the presence of septic arthritis.
Aspirate the joint with a large-bore needle before administering antibiotics. Peripheral joints are readily tapped in a clinic or office setting. Aspirate deep joints, such as the hip, under image-intensifier control or ultrasound guidance and with the patient appropriately sedated or anesthetized. Fluid from joint aspirates from children younger than 3 years should be inoculated directly into blood culture bottles to enhance the isolation of Kingella kingae, a fastidious pathogen increasingly common in this age group.[11, 12]
Of vital importance is ensuring that the joint was penetrated before the aspiration results are declared negative. If no fluid is obtained, perform an arthrogram by injecting contrast material through the needle.
A positive joint aspirate typically yields opaque yellow or white-gray pus. The WBC count is usually in excess of 50,000/µL, with more than 80% neutrophils.
Gram stains of joint aspirates should always be performed. A positive Gram stain is valuable information, being diagnostic for infection; however, false-negative results are common. Although the Gram stain is positive in only a minority of cases of septic arthritis; however, failure to visualize organisms on the Gram stain should never be interpreted as evidence that infection is not present.
If gonococcal arthritis is suspected, obtain the culture in a manner approved by the clinical laboratory for this organism. N gonorrhoeae is a difficult organism to grow, and special handling and special culture media are required to maximize recovery.
If the results from aspiration are consistent with a septic joint, antibiotics must be begun on an empirical basis immediately after the cultures have been obtained.
A disturbing trend associated with acute osteoarticular infections in children is the increasing incidence of community-associated methicillin-resistant S aureus (CA-MRSA).[13, 14] In a 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. It is probable that this trend toward antibiotic resistant pathogens will continue.
Unless the joint is easily accessible to repeated aspirations and the signs are minimal and improving with treatment, formal operative drainage is required. The relevant principles that apply to all surgical infections should be followed. A septic joint should be considered an abscess, and medical treatment alone is inappropriate. Appropriate treatment must be begun without delay; the risks of complications are time dependent.
Open drainage performed in the operating room is unquestionably more effective than percutaneous aspiration. In needle aspiration procedures, encountering heavy fibrin deposits that clearly cannot be removed (even through large-bore needles) is not unusual.
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.
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 study by Thompson et al that aimed to evaluate the safety and efficacy of arthroscopic treatment of septic arthritis in various joints in very young children reported that arthroscopic lavage appears to be a safe, quick, and effective alternative to open arthrotomy.
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 (ESR) or C-reactive protein (CRP) level normalize. No consensus exists regarding the appropriate length of antibiotic treatment. The author’s recommendations (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 represent a middle ground in the controversy.
Follow up with the patient for at least 1 year after operation. 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.
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.
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.
Frank G, Mahoney HM, Eppes SC. Musculoskeletal infections in children. Pediatr Clin North Am. 2005 Aug. 52(4):1083-106, ix. [Medline].
Yagupsky P, Bar-Ziv Y, Howard CB, Dagan R. Epidemiology, etiology, and clinical features of septic arthritis in children younger than 24 months. Arch Pediatr Adolesc Med. 1995 May. 149(5):537-40. [Medline].
Mataika R, Carapetis JR, Kado J, Steer AC. Acute rheumatic fever: an important differential diagnosis of septic arthritis. J Trop Pediatr. 2008 Jun. 54(3):205-7. [Medline].
Peltola H, Kallio MJ, Unkila-Kallio L. Reduced incidence of septic arthritis in children by Haemophilus influenzae type-b vaccination. Implications for treatment. J Bone Joint Surg Br. 1998 May. 80(3):471-3. [Medline].
Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am. 1999 Dec. 81(12):1662-70. [Medline].
Nusem I, McAlister A. Arthroscopic lavage for the treatment of septic arthritis of the hip in children. Acta Orthop Belg. 2012 Dec. 78(6):730-4. [Medline].
Caird MS, Flynn JM, Leung YL, Millman JE, D'Italia JG, Dormans JP. Factors distinguishing septic arthritis from transient synovitis of the hip in children. A prospective study. J Bone Joint Surg Am. 2006 Jun. 88(6):1251-7. [Medline].
Rice PA. Gonococcal arthritis (disseminated gonococcal infection). Infect Dis Clin North Am. 2005 Dec. 19(4):853-61. [Medline].
Willis AA, Widmann RF, Flynn JM, Green DW, Onel KB. Lyme arthritis presenting as acute septic arthritis in children. J Pediatr Orthop. 2003 Jan-Feb. 23(1):114-8. [Medline].
Song J, Letts M, Monson R. Differentiation of psoas muscle abscess from septic arthritis of the hip in children. Clin Orthop Relat Res. 2001 Oct. (391):258-65. [Medline].
Moylett EH, Rossmann SN, Epps HR, Demmler GJ. Importance of Kingella kingae as a pediatric pathogen in the United States. Pediatr Infect Dis J. 2000 Mar. 19(3):263-5. [Medline].
Kehl-Fie TE, Miller SE, St Geme JW 3rd. Kingella kingae expresses type IV pili that mediate adherence to respiratory epithelial and synovial cells. J Bacteriol. 2008 Aug 29. [Medline].
Korakaki E, Aligizakis A, Manoura A, Hatzidaki E, Saitakis E, Anatoliotaki M, et al. Methicillin-resistant Staphylococcus aureus osteomyelitis and septic arthritis in neonates: diagnosis and management. Jpn J Infect Dis. 2007 May. 60(2-3):129-31. [Medline].
Morrison MJ, Herman MJ. Hip septic arthritis and other pediatric musculoskeletal infections in the era of methicillin-resistant Staphylococcus aureus. Instr Course Lect. 2013. 62:405-14. [Medline].
Arnold SR, Elias D, Buckingham SC, Thomas ED, Novais E, Arkader A, et al. Changing patterns of acute hematogenous osteomyelitis and septic arthritis: emergence of community-associated methicillin-resistant Staphylococcus aureus. J Pediatr Orthop. 2006 Nov-Dec. 26(6):703-8. [Medline].
Dodwell ER. Osteomyelitis and septic arthritis in children: current concepts. Curr Opin Pediatr. 2013 Feb. 25(1):58-63. [Medline].
Thompson RM, Gourineni P. Arthroscopic Treatment of Septic Arthritis in Very Young Children. J Pediatr Orthop. 2015 Sep 20. [Medline].