Hip Pain in a Child: Myositis or Appendicitis

1
Hip Pain in a Child Myositis or Appendicitis

• Andaleeb Raja MD
• Muhammad Waseem MD
• Husayn Al-Husayni MD
• Lincoln Medical Mental Health Center
• Bronx, New York

2
Case Presentation

• 11 year old boy presenting with fever hip pain
  for 2 days
• Denied abdominal pain, vomiting or change in
  bowel habits
• Denied knee pain or history of trauma/falls
• Denied recent travel or sick contacts
• Denied family history of joint disease
• Discharged home after Hip X rays were negative
  and initial labs were reviewed

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Pelvis X-Ray
4
Labs

• WBC 11,200/mm with 74 Neutrophils
• ESR 5 mm/hr
• CRP 15.51 mg/L (0.25-3.0)
• Blood Culture Gram () cocci in clusters

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Case Presentation

• Recalled to the ER the next day
• Blood cultures - Gram () cocci in clusters
• Still c/o fever, but now walking with a limp
• Described right hip and groin pain
• Pain was constant in nature, sharp achy
• Pain was exacerbated when he walked
• He was unable to walk without being supported

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Physical Exam

• Vitals T100.5 HR 120 RR 20 BP 125/85
• General ill appearing, but alert, awake
• HEENT dry mucous membranes
• Chest clear to auscultation, B/L breath sounds
• CVS tachycardic
• Abd mild RLQ tenderness initially, but not
  reproducible. No masses, no guarding
• GU () cremasteric reflex, no hernia, no scrotal
  swelling
• Ext
• () tenderness over pelvic area and anterior
  thigh
• No deformity, bruising or swelling noted over
  hip.
• Equal thigh measurements. Unable to elicit hop
  test (patient refused to walk)
• ROM hip intact
• Palpable small inguinal lymph nodes bilaterally

7
Labs

• WBC 13,900/mm with 85 neutrophils
• Hemoglobin 14.1 g/dl
• Platelets 204/mm
• CRP 116.56 mg/L
• CK 91 U/L (40-210)
• UA specific gravity gt1.045, 0-2/hpf WBC RBC
• Electrolytes WNL

8
Radiology

• Plain film Pelvis with Right hip normal on
  previous visit
• Non-contrast CT scan hip/Lower abdomen
• Inflamed tip of the appendix with mild
  peri-appendiceal fluid

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CT Scan Hip
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CT Scan Hip
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Learning Objectives

• Understanding the atypical presentation of acute
  appendicitis in children
• Recognize pyomyositis as a rare but important
  etiology to be considered in patient with hip
  pain and fever
• Review of the differential diagnoses of hip pain
  in children

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Case Discussion

• Appendicitis is a difficult diagnosis in children
  as it may have an atypical presentation
• Classic symptoms are often not seen
• Can lead to misdiagnosis
• High morbidity/mortality
• Pathophysiology in children may be different due
  to the change in anatomic location
• Inability to walk/walking with limp reported to
  be a significant finding
• 1/4 of patients may present with a limp or right
  hip stiffness

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Case Discussion

• Pyomyositis - Rare
• Hip pain, limp, fever
• Uncommon infectious process involving skeletal
  muscle
• Caused by pus producing bacteria (staph aureus
  most frequently involved)
• This patient had () staph aureas in Blood
  cultures
• CK may remain normal, while ESR and CRP are
  usually elevated
• Child had normal CK but elevated CRP,
  leukocytosis
• CT can be used to identify and localize the
  abscess
• No abscess was seen on CT
• Large muscle groups (thigh) are likely targets
• Correct diagnosis is based on high index of
  suspicion
• Important to recognize to reduce
  morbidity/mortality associated with the condition

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Differential Diagnosis

• Transient Synovitis
• Most common cause of hip pain in children
• Consider in absence of trauma history
• Self limiting
• Usually more frequent in boys
• Important to distinguish between this and septic
  arthritis, which requires drainage and
  antibiotics

15
Differential Diagnosis

• Slipped Capital Femoral Epiphysis
• Present with limp or vague thigh/hip pain
• Typically involves obese children
• Legg-Calve-Perthes Disease
• Avascular necrosis of femoral head
• Pain localized to hip, limping
• Plain films may show epiphyseal fragmentation
• MRI more sensitive

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Differential Diagnosis

• Psoas Muscle Abscess
• Relatively rare in children
• Vague symptoms because of the posterior location
  of the psoas mucle
• Classic symptoms limp with fever and abdominal
  pain
• Blood cultures often positive
• Physical Exam psoas cannot be examined easily
  (deep structure)
• Psoas sign pain when the hip is passively
  extended or actively flexed against resistance
• Attributed to inflammation causing spasm of psoas
  muscle

17
Differential Diagnosis

• Pelvic Osteomyelitis
• Rare but should be considered in a child who
  presents with hip pain
• MRI should be obtained in presence of suspicion

18
References

• Frick SL. Evaluation of the child who has hip
  pain. Orthop Clin North Am. 2006 Apr37(2)133-40
• Yang WJ, Im SA, Lim GY, Chun HJ, Jung NY, Sung
  MS, Choi BG. MR imaging of transient synovitis
  differentiation from septic arthritis. Pediatr
  Radiol. 2006 Nov36(11)1154-1158
• Katz DA. Slipped capital femoral epiphysis the
  importance of early diagnosis. Pediatr Ann. 2006
  Feb35(2)102-111
• Weber-Chrysochoou C, Corti N, Goetschel P,
  Altermatt S, Huisman TA, Berger C. Pelvic
  osteomyelitis a diagnostic challenge in
  children. J Pediatr Surg. 2007 Mar42(3)553-557

19
References

• Becker T, Kharbanda A, Bachur R. Atypical
  clinical features of pediatric appendicitis. Acad
  Emerg Med. 2007 Feb14(2)124-129
• Reynolds SL. Missed appendicitis in a pediatric
  emergency department. Pediatr Emerg Care. 1993
  Feb9(1)1-3
• Bundy DG, Byerley JS, Liles EA, Perrin EM,
  Katznelson J, Rice HE. Does this child have
  appendicitis? JAMA. 2007 Jul 25298(4)438-451
• Colvin JM, Bachur R, Kharbanda A. The
  presentation of appendicitis in preadolescent
  children. Pediatr Emerg Care. 2007
  Dec23(12)849-855
• Sakellaris G, Tilemis S, Charissis G. Acute
  appendicitis in preschool-age children. Eur J
  Pediatr. 2005 Feb164(2)80-83

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References

• Kumar A, Anderson D. Primary obturator externus
  pyomyositis in a child presenting as hip pain a
  case report. Pediatr Emerg Care. 20082497-98
• Iyer S, Lobo M, Capell W. Obturator internus
  pyomyositis a differential diagnosis for septic
  arthritis of the hip. J Paediatr Child Health.
  200541534-535
• Fowler T, Strote J. Isolated obturator externus
  muscle abscess presenting as hip pain. J Emerg
  Med. 2006 30137-139

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Question

• A 12 year old male presented to the ED with a 2
  day history of fever and right hip pain. He was
  noted to be limping on arrival. He denied any
  history of trauma. Abdominal physical examination
  findings revealed no guarding, but there was
  minimal tenderness in the right lower quadrant.
  Laboratory evaluation revealed a WBC 15.2. Hip
  radiographs were normal. What is the next best
  step in his management?
• Admit for observation
• Joint aspiration
• CT scan abdomen and pelvis
• Pelvic ultrasound
• Administer a dose of IV antibiotics, then
  discharge home with 24-hour follow up

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Answer - C

• Because of the varied location of the appendix,
  the presentation of pain in a patient with acute
  appendicitis can be diverse. A patient with a low
  lying appendix can present with hip pain without
  significant abdominal findings.
• It is important to include appendicitis in the
  differential diagnosis of hip pain. If the
  diagnosis is delayed, appendicitis is associated
  with significant morbidity and mortality. A
  computed tomography of the abdomen and pelvis is
  the imaging modality of choice.