AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Indications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Indications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Septic arthritis in infancy and childhood is a true clinical emergency. 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. Pain with passive motion is the most consistent finding in septic arthritis, and the diagnosis must be considered in any joint with this presentation.

This article focuses on the most common presentations of septic arthritis as it occurs in infancy and childhood. Important variations from these common presentations are seen in septic arthritis in the neonate and with gonococcal arthritis. Discussions of these 2 entities appear in the sections below, as appropriate.

History of the Procedure

Prior to 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; however, 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.

From the 1970s until the development of the vaccine, H influenzae type b was responsible for the majority of joint infections in children aged 1-4 years. Since the institution of this vaccination, joint infections with H influenzae have virtually disappeared in the United States, and Staphylococcus aureus has become the most common joint pathogen in all age groups.

Problem

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.

Frequency

Septic arthritis is relatively common in infancy and childhood, to the extent that all primary care physicians caring for children can expect to encounter this disease. The exact incidence is difficult to estimate, because all series are retrospective and lack denominators. Septic arthritis is known to be about twice as common as osteomyelitis in childhood, and the incidence of joint infection in all age groups peaks in the early years of the first decade of life.

Etiology

In all age groups, the most common infecting organism is Staphylococcus aureus. Other common pathogens include Streptococcus species; Pseudomonas aeruginosa; pneumococci; Neisseria meningitidis (with or without an associated meningitis); Escherichia coli; Klebsiella species; and Enterobacter species. Newborns can acquire Neisseria gonorrhoeae from an infected birth canal. Gonococcal arthritis is more common in sexually active teenagers, and it may be seen in younger children in association with sexual abuse.

A neonate aged 5 weeks or younger is susceptible to infection due to a wide range of organisms that are unlikely pathogens in children with more developed immune systems. S aureus is still the most common pathogen in this age group; group B streptococcus is the next most common pathogen. Gram-negative organisms may be seen in as many as 15% of joint infections affecting neonates in a neonatal intensive care setting. Candida albicans may also be present in these patients, as well as in patients who have received prolonged antibiotic therapy.

In the past, H influenzae was the dominant pathogen causing septic arthritis in children younger than 3 years. A vaccine against this organism was introduced in 1985, and more effective conjugated vaccines against H influenzae are now extensively used in the United States. As a consequence, H influenzae has nearly disappeared as a pathogen of osteoarticular infections in young children.

Kingella kingae is a fastidious aerobic gram-negative microorganism that was first described in 1960. As the incidence of H influenzae has decreased, the incidence of K kingae as a pathogen of osteoarticular infection in children younger than 3 years has dramatically increased. Because it is fastidious, this relatively new organism may be difficult to grow in culture. It is now common enough that its presence must be suspected and investigated in children in this age group.

The incidence of community-associated methicillin-resistant S aureus (MRSA) is increasing in North America. In regions where this trend has been observed, consideration should be given to the inclusion of coverage for MRSA in the empirical coverage for patients with septic arthritis pending culture results.

In about one third of all cases of septic arthritis, identification of the responsible organism may be impossible.

Pathophysiology

Although it is uncommon, a penetrating wound may result in septic arthritis. It also may develop by contiguous spread from an adjacent cellulitis. Most commonly, however, the pathogenesis of septic arthritis is hematogenous. Transient episodic bacteremia is common, even in healthy individuals. It may occur with something as simple as toothbrushing. In almost all cases, the body's defense mechanisms rapidly eliminate the threat; occasionally, bone or joint infection may result.

Hematogenous septic arthritis may develop directly through the synovial blood vessels. Another common route is from an adjacent hematogenous metaphyseal osteomyelitis. Just under the metaphyseal side of the growth plate in a growing child, vascular loops nourish the bone that forms in association with enchondral ossification. Blood flow in these loops is thought to be relatively slow, and this region is somewhat poorly defended by the reticuloendothelial system. These loops form the site of origin for hematogenous osteomyelitis in infancy and childhood.

An abscess forms in the metaphysis in association with localized bone destruction. In the infant (from birth to 18 months), the infection may spread into the epiphysis through blood vessels that cross the cartilaginous physis. From the epiphysis, the infection may then break directly into the adjacent joint, resulting in septic arthritis. This mechanism of spread directly into the epiphysis is unique to infancy.

The blood vessels that cross the physis disappear by age 18 months, and the cartilaginous growth plate becomes a barrier to the spread of infection. In the older child, hematogenous osteomyelitis spreads within the metaphysis until it breaks through the metaphyseal cortex. For most of the long bones, the bone infection breaks either into the subperiosteal space or through the periosteum into the adjacent soft tissues. Joint infection does not result, because the joint capsule is firmly anchored to the epiphysis. In the proximal femur, the proximal humerus, the distal lateral tibia, the distal fibula, and the proximal radius, however, the joint capsules attach to the metaphyses; therefore, in these locations, hematogenous osteomyelitis may decompress directly into the hip, shoulder, ankle, and elbow joints, respectively.

Whatever the mechanism, once bacteria enter the joint, the space effectively becomes a closed abscess. A variety of enzymes capable of degrading articular cartilage are released by leukocytes and by certain bacteria, such as S aureus and some gram-negative organisms. Significant articular damage can occur in as little as 8 hours. Increased pressure within the joint can interrupt the blood supply to the epiphysis, causing bone destruction and loss of the adjacent growth plate. If the infection remains untreated, the ligaments of the capsule will be destroyed and the joint may dislocate. For example, the extreme result in a septic hip would be complete destruction of the femoral head, dislocation of the proximal femur from the acetabulum, and loss of 30% of all future growth of the affected femur.

Neonates are special in that their immune systems still are immature. They are susceptible to a wide range of organisms that are unlikely pathogens in an older individual, and they are less capable of mounting an inflammatory response to infection. Premature infants in the neonatal intensive care unit are particularly at risk. They often are debilitated with other illnesses, and they typically present with multiple ports for bacterial entry. Bone and joint infections in these patients commonly involve multiple sites.

Neisseria gonorrhoeae may cause a distinct syndrome of a disseminated gonococcal infection, with skin lesions, tenosynovitis, and polyarthralgias, rather than frank arthritis. Less commonly, it may cause a suppurative arthritis resembling septic arthritis caused by other bacteria isolated to 1 or 2 joints.

Clinical

A developing septic arthritis is generally accompanied by the onset of fever, malaise, and prominent localizing signs at the affected joint. In the distal extremities, swelling, erythema, and tenderness are prominent; the findings may be less evident with deeper joints, such as the hip. The most consistent sign is pain with passive motion. The patient will generally hold the joint in the position that maximizes intracapsular volume. For the hip, these positions are flexion, abduction, and external rotation (see Image 1). With a septic knee, the joint is most comfortable when moderately flexed. It is not unusual for a young child or infant to appear completely comfortable, so long as the affected joint remains immobile in the position of comfort. Any attempt by the examiner to passively move the joint, however, dramatically reveals the pathology.

Refusal of the child to move the affected joint is called pseudoparalysis. This sign is often mistaken for a neurologic problem. An isolated true paralysis, however, is far less common than a septic arthritis; when it does occur, it is rarely associated with pain with passive motion. The inability of a child to bear weight on a lower extremity or to spontaneously move any joint must be considered a sign of septic arthritis until proven otherwise.

The differential diagnosis of septic arthritis includes noninfectious inflammatory arthritides, including juvenile rheumatoid arthritis (JRA) and acute rheumatic fever. JRA usually presents a more gradual onset, as well as symptoms and signs that are less dramatic. Acute rheumatic fever is often associated with migratory polyarthralgias. Legg-Calvé-Perthes disease may present with pain in the hip with weight bearing, but rarely is the pain as disabling as the pain associated with a true infection.

Lyme disease commonly appears with arthritis, and the clinical presentation may be difficult to distinguish from septic arthritis. With Lyme arthritis, there is generally less pain with joint motion and, when lower extremity joints are affected, ambulation is usually possible; however, in regions where Lyme disease is endemic, this condition should be included in the differential diagnosis.

The clinical presentation of an abscess of the psoas muscle may be indistinguishable from that of septic arthritis of the hip. Atypical features, such as bladder irritability or a femoral nerve neurapraxia, may point toward this rare disorder, but in their absence joint aspiration should be performed. If the aspiration culture is negative, obtain a computed tomography (CT) scan, as this is generally diagnostic for a psoas abscess.

Transient synovitis (also called toxic synovitis) is the most common condition that mimics septic arthritis. Possibly of viral origin, it is a self-limited condition that most commonly involves the juvenile hip. While transient synovitis usually causes less pain with passive joint motion than septic arthritis, it may be clinically indistinguishable from septic arthritis. Patients with transient synovitis are less likely to have fever or elevated C-reactive protein levels, but differentiation from septic arthritis may still require examining the joint aspirate.

Neonates with septic arthritis typically present with a blunted immune response. They may have little or no fever. They may have minimal or no increase in their serum WBC counts. Joint involvement is less obvious in neonates than in other patients because neonates are less active to begin with. Septic arthritis is also more difficult to diagnose in neonates, but making an early diagnosis is more important in these patients. If 1 infected joint is diagnosed in a neonate, look for other sites of bone or joint infection. Consider obtaining a bone scan to assist in this search.

Immunocompromised patients with septic arthritis are also likely to present with a blunted immune response. Symptoms, physical signs, and laboratory parameters may appear deceptively benign. Such patients warrant an increased index of suspicion.

With gonococcal infections, a disseminated infection may, in addition to fever and chills, cause a constellation of clinical signs quite distinct from septic arthritis, including a variety of skin lesions, such as macules, pustules, and bullae; tenosynovitis, most commonly of the dorsum of the wrists and hands; and polyarthralgias. Less commonly, the presentation may be clinically indistinguishable from septic arthritis caused by other organisms. The knee is the most commonly affected joint, but any joint may be involved. If this diagnosis is suspected (for example, in a sexually active teenager), cultures and antigen examinations of all potential mucosal sites of infection should be combined with cultures of joint aspirate and blood. The physician should keep in mind that gonococcal arthritis may be seen in younger patients in association with sexual abuse.

INDICATIONS

Section 3 of 10  

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• Introduction
• Indications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

An aggressive workup is indicated whenever signs and symptoms suggest septic arthritis. This evaluation must include blood cultures and joint aspiration. If the aspirate results are consistent with a septic joint, antibiotics must be begun on an empirical basis immediately after the cultures have been obtained. 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.

WORKUP

Section 4 of 10  

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• Indications
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• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Lab Studies

• White blood cell (WBC) count
• • The 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.
• Erythrocyte sedimentation rate (ESR)
• • The 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.
• C-reactive protein (CRP)
• • The CRP level is elevated in septic arthritis; it returns to normal with resolution of the infection.
  • CRP is a more valuable diagnostic tool and a better indicator of response to treatment than ESR because CRP is generally more sensitive and more responsive. 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.
  • Other cultures and Gram stains may be useful.
  • 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.
  • Gram stains of joint aspirates should always be performed because a positive Gram stain is valuable information. The Gram stain is positive in a minority of the cases of septic arthritis; however, a negative result should never be interpreted as evidence that infection is not present.
  • Fluid from joint aspirates from children younger than 3 years should be inoculated directly into blood culture bottles to enhance the isolation of K kingae, a fastidious pathogen increasingly common in this age group.

• 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.

Imaging Studies

• Plain radiography
• • 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
• • Radionuclide scanning is generally not helpful, and it is contraindicated if it delays more appropriate diagnostic or treatment measures.
  • Scanning may be helpful in locating or ruling out other sites of involvement, particularly in very sick children and in neonates.
• Ultrasonography
• • Ultrasonography is useful in confirming a joint effusion in a deeply placed joint such as the hip.
  • This modality can also be used to guide joint aspiration.
• Magnetic resonance imaging (MRI)
• • 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)
• • A CT scan 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.

Diagnostic Procedures

• Joint aspiration
• • Joint aspiration is the single most important diagnostic procedure.
  • 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.
  • 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 per milliliter, with more than 80% neutrophils.
  • A positive Gram stain is diagnostic for infection, but false-negative results are common. The failure to visualize organisms on the Gram stain does not rule out infection.
  • 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.

TREATMENT

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Medical therapy

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. 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.

Surgical therapy

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.

Postoperative details

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.

Follow-up

Continue antibiotics until the patient's clinical condition and the ESR or CRP 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.

COMPLICATIONS

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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 Images 2-7.

OUTCOME AND PROGNOSIS

Section 7 of 10  

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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.

FUTURE AND CONTROVERSIES

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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.¹ 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^oC and CRP levels >2.0 mg/dL were strong predictors of septic arthritis.² 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 2004.³ It is probable that this trend toward antibiotic resistant pathogens will continue.  

MULTIMEDIA

Section 9 of 10  

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• Future and Controversies
• Multimedia
• References

Media file 1:  Emergency room photograph of an infant with septic arthritis of the left hip. The child holds his hip rigidly in the classic position of flexion, abduction, and external rotation, a position that maximizes capsular volume. The patient is relatively comfortable as long as the hip joint remains immobile in this position.
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Media type:  Photo

Media file 2:  This is the first radiograph in a series of 6 (Images 2-7) that document the natural history and complications of an inadequately treated septic arthritis of the left hip. The child is aged 22 months and had been symptomatic for a week before this radiograph was obtained. No bone changes are seen, but the left hip is laterally subluxated.
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Media type:  X-RAY

Media file 3:  Second radiograph in the series of a septic left hip (Images 2-7). Three days after presentation and 10 days after the onset of symptoms, there is still no change in the bone's appearance, but the hip joint is further subluxated.
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Media type:  X-RAY

Media file 4:  Third radiograph in the series of a septic left hip (Images 2-7). Three weeks after presentation, the left hip is dislocated, and new periosteal bone formation is noted. This last finding is characteristic of an associated osteomyelitis of the left femur.
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Media type:  X-RAY

Media file 5:  Fourth radiograph in the series of a septic left hip (Images 2-7). Seven weeks after onset, increased opacity is noted in the central portion of the proximal femoral metaphysis and in the proximal femoral epiphysis. The findings are consistent with avascular necrosis of these structures.
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Media type:  CT

Media file 6:  Fifth radiograph in the series of a septic left hip (Images 2-7). Five months after onset, the femoral head has been completely resorbed, and the femoral shaft has regenerated.
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Media type:  X-RAY

Media file 7:  Sixth radiograph in the series of a septic left hip (Images 2-7). At age 11, or 9 years after onset of the infection, the hip joint and the proximal femoral growth plate are destroyed. A profound limb-length discrepancy is noted, in addition to severely impaired hip function.
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Media type:  X-RAY

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Indications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

1. 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. Dec 1999;81(12):1662-70. [Medline].
2. 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. Jun 2006;88(6):1251-7. [Medline].
3. 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. Nov-Dec 2006;26(6):703-8. [Medline].
4. Frank G, Mahoney HM, Eppes SC. Musculoskeletal infections in children. Pediatr Clin North Am. Aug 2005;52(4):1083-106, ix. [Medline].
5. Moylett EH, Rossmann SN, Epps HR, Demmler GJ. Importance of Kingella kingae as a pediatric pathogen in the United States. Pediatr Infect Dis J. Mar 2000;19(3):263-5. [Medline].
6. Paterson DC. Acute suppurative arthritis in infancy and childhood. J Bone Joint Surg Br. Aug 1970;52(3):474-82. [Medline].
7. 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. May 1998;80(3):471-3. [Medline].
8. Rice PA. Gonococcal arthritis (disseminated gonococcal infection). Infect Dis Clin North Am. Dec 2005;19(4):853-61. [Medline].
9. Song J, Letts M, Monson R. Differentiation of psoas muscle abscess from septic arthritis of the hip in children. Clin Orthop Relat Res. Oct 2001;(391):258-65. [Medline].
10. Willis AA, Widmann RF, Flynn JM, Green DW, Onel KB. Lyme arthritis presenting as acute septic arthritis in children. J Pediatr Orthop. Jan-Feb 2003;23(1):114-8. [Medline].
11. 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. May 1995;149(5):537-40. [Medline].

Article Last Updated: Aug 16, 2007