A 2-year-old boy is brought to the ED by his mother for persistent fevers. The mother says her child has been having high fevers of 102-103 for the past 4-5 days. He was seen at another hospital earlier in the course and was told it was likely a viral syndrome. He does have sick contacts at school and has been noted to have a slight cough and congestion. She became concerned when the fevers persisted and has noticed he appears to be limping at times favoring his left leg. He did not want to walk around today. She denies any recollection of recent falls or other trauma.
Time Out! Lets review!
2 year-old + Fevers + Limp = ?
There are many different causes of limping in children, including inflammatory, infectious, musculoskeletal, and even malignancy. However, in our case when you have fever and no report of trauma, you must be concerned about a potential septic hip. Yes, it could very well be other things like transient synovitis, which is the most common cause of a painful limp in childhood, but this should be diagnosis of exclusion.[1] Septic hip is a surgical emergency, and early recognition and treatment is necessary to prevent joint damage.[2]
Are there clinical tools to help identify septic hip?
Yes, Kocher’s Criteria!
Dr. Kocher and colleagues created a clinical tool based on their retrospective study involving 282 patients to help guide or differentiate septic hip from transient synovitis.[3] Complications from untreated septic hip can be major, including osteonecrosis, growth arrest, and sepsis/septic shock, and therefore, septic hip requires urgent intervention.
4 independent variables that seem to increase the chance of septic hip:
- Inability to tolerate weight-bearing
- Fever > 38.5 oC (101.3 oF)
- ESR > 40 mm/hr
- WBC > 12 cells/mm3
Probability of septic hip based on Kocher’s study:3
0 criteria = 0.2%
1 criteria = 3%
2 criteria = 40%
3 criteria = 93 %
4 criteria = 99.6%
In order to validate previous retrospective study,3 a prospective study of the Kocher criteria was performed in 2004 by Kocher et al.[4] This study included 213 patients and found similar results but diminished probabilities. Zero criteria found 2% probability of septic hip, and (+) 1 = 9.5 %, (+) 2= 35%, (+) 3 = 72.8%, (+) 4 = 93%. Other outside groups who attempted to replicate the study found even smaller diagnostic probabilities. One thing to keep in mind is that although a useful decision-making tool, the presence of 0 criteria does not rule out the disease; any criteria should raise suspicion.
What should we do next?!
In a stable/non-toxic-appearing patient, pain medications/anti-pyretics should be given. Labs including a CBC, ESR, CRP, should be obtained.
What about imaging?
In terms of imaging, the American College of Radiology, has different initial recommendations that depend on presentation:[5]
In the absence of trauma and signs of infection such as a fever, you should start with an x-ray and consider an ultrasound (US) if x-ray is negative.
In a limping child without trauma AND signs of infection such as fever, US should be the primary modality to evaluate for joint effusion and if negative, then consider an X-ray. If still suspicious for septic hip, and both US and X-ray are negative, consider MRI.
As discussed by Kim, et al, there have been studies focused on detecting hip effusions with US in patients with presumptive septic arthritis.[6] Ultrasonography appears to be better at identifying abnormalities than X-ray, however it is not perfect. According to one of the studies discussed in Kim et al,6 four of the 73 children with confirmed septic arthritis had negative US. Also, presence of an effusion does not necessarily mean the patient has septic arthritis, because transient synovitis may also cause an effusion[7]. Although US is a great non-invasive imaging technique, it cannot be used alone and does not completely rule out septic hip.
If there is still a concern the patient will need arthroscopy, and orthopedics should be consulted.
But wait!… what does a concerning exam look like?
Typically children will try to avoid moving the leg and may complain of pain in the groin area that radiates down the leg. They will keep the leg flexed and externally rotated at the hip, and pain will worsen with internal rotation.
Back to the case…
Exam of our boy demonstrated that he would not move his left lower leg. The patient’s hip could be passively flexed bilaterally, but the child was irritable during evaluation. No warmth or swelling was appreciated, but the patient would not bear weight on the affected leg.
So far, we have 2 criteria with temp > 101.3 and inability to tolerate weight-bearing.
Imaging of the hip was negative for alternate diagnoses such as SCFE, Legg-Calvé-Perthe Disease, and fracture.
Labs: WBC = 24.59; ESR = 82
Uh Oh! Our child meets 4 out of 4 criteria! If we wanted to confirm our suspicion of septic hip, the next step is arthroscopy. The patient is started on antibiotics, and orthopedics is on board to take patient to the OR for arthroscopy and possible lavage.2
Time to Review:
Who tends to be high risk for development of septic hip?- Pediatric patients age ≤ 2 years with peak incidence 6-24 months
- Immunocompromised patients
- Functional asplenia (such as our sickle cell patients)
What is the most common bacteria associated with this?
Staphylococcus aureus is the most common organism across the different ages accounting for just over half of all cases.6 During the pre-immunization era, we used to find Haemophilus influenza in many cases, but this has dramatically decreased. Other frequently seen organisms include Kingella kingae, Streptococcus pyogenes, and Streptococcus pneumoniae. Less commonly seen are Neisseria gonorrhea, Candida, and Staphylococcus epidermidis.
*Special populations to consider for other causative organisms:
– Sickle cell populations more susceptible to Salmonella
– Neonates are susceptible to Group B streptococcus and E. Coli.
– Adolescents more commonly have N. gonorrhea.
What is the treatment of septic hip?
- Emergent drainage2
- Admission for IV antibiotics and wash out8
- There are conflicting data on best empiric antibiotics to start, but most important treatment is aspiration/wash out of joint! Ideally obtain culture and tailor antibiotic regimen to organism
- Ages < 3 months: Nafcillin vs oxacillin vs vancomycin AND cefotaxime, ceftazidime, or cefepime
- Above 3 months: cefazolin, clindamycin, nafcillin, vancomycin, ceftriaxone have been mentioned
Transient Synovitis Review:6
- May present similarly to septic hip (atraumatic + fever)
- Generally is a self-limiting inflammation of the synovial lining
- Typically resolves in 3-10 days
- Most common painful limp in childhood
- Typically presenting following a viral illness
Complications of delayed diagnosis or sequelae of Septic Hip:2
Osteonecrosis
- Growth arrest
- Sepsis/Septic shock
- Predispostion to dislocation, subluxation, dysplasia
- Need for multiple reconstructive surgeries
- Leg length discrepancy
Take Home Points:
- Have a high suspicion for septic arthritis in children with a limp. Surgical Emergency! (Especially under 2 years of age)
- Kocher’s Criteria can be a useful tool but does not rule out disease
- Transient Synovitis, although common, should be diagnosis of exclusion!
Written by:
Dr. Jaramillo (PGY 2 EM)
Content Reviewed by:
Dr. Subramaniam (3rd year PEM fellow)
[1] Fischer SU, B. T. (1999). The limping child: Epidemiology, assessment, and outcome. . J Bone Joint Surgery Br. , 81 (6), 1029-32.
[2] Wheeless, C. R. (2015, April 7). Wheeless’ Textbook of Orthopaedics. Septic Arthritis: Pediatric Hip . Duke, NC, USA.
[3] Kocher MS, Z. D. (1999). Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am. , 81 (12), 1662-70.
[4] Kocher MS, e. a. (2004). Validation of a clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children. JBJS , 86 (8), 1629-35
[5] Clearinghouse, N. G. (2012, Jan 01). Guideline Summary: ACR Appropriateness Criteria limping child – ages 0-5. Retrieved May 05, 2017, from National Guidline Clearinghouse (NGC): https://guideline.gov/summaries/summary/37914?
[6] Kim, T. e. (2006). Limping: Evaluation, Diagnosis, and Management in the Pediatric ED. Pediatric Emergency Medicine Practice , 3 (8), 1-24.
[7] Plumb, J. (2015). The role of ultrasound in the Emergency Department evaluation of the acutely painful pediatric hip. Pediatric Emergency Care , 31, 54-61.
[8] Swaminathan, A. (2017, March 6). Pediatric Septic Hip. Retrieved April 20, 2017, from R.E.B.E.L. EM: http://rebelem.com/pediatric-septic-hip/
JJaramillo
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