Tutorial 43 - Hip Pain in a Child

Question 1

What is the most common cause of a limp in a child?

Answer 1

Transient Synovitis

Question 2

What tests should be ordered in a child presenting with a limp with focal findings on physical exam?

Answer 2

anteroposterior and
lateral radiography of the involved site

Question 2

What are other causes of a limp in a child?

Answer 2

contusion, foreign body in the foot, fracture, osteomyelitis, septic arthritis, reactive arthritis, and Lyme
arthritis

Question 3

What initial tests should be order in a child presenting with a limp with no focal findings on physical exam?

Answer 3

Radiography of both lower extremities

Question 4

A 9 year old boy presents to the ER with his parents, refusing to bear weight. He has an oral temperature of 39°C. Bloodwork was done on arrival, which now shows he has an ESR of 45 mm/hr, and a WBC count of 15,000 per mm3. What is at the top of your differential?

Answer 4

Septic arthritis

Question 5

Parents come in with their child who has had hip pain for several months. On history, the parents say that the pain is often severe at night and it wakes their child up. What is this history concerning for?

Answer 5

Malignancy

Question 6

Is developmental dysplasia of the hip more common in males or females?

Answer 6

Females

Question 7

Is Legg-Calvé-Perthes disease (idiopathic osteonecrosis of the proximal femoral epiphysis) more common in males or females?

Answer 7

Males

Question 8

Is a slipped capital femoral epiphysis (SCFE) more common in males or females?

Answer 8

Males

Question 9

If a child presenting with hip pain has a longer duration of illness, what etilogies are on your differential diagnosis?

Answer 9

Legg-Calvé-Perthes disease, SCFE, overuse syndromes, apophysitis, or systemic illness (e.g., rheumatic disease, tumor).

Question 10

An arthrocentesis was performed on the knee of a child presenting with a limp. The synovial fluid appeared turbid, and had a WBC count of 74,000 per mm3, and a PMN of 86%. Is transient synovitis or septic arthritis most likely?

Answer 10

Septic arthritis.

Septic arthritis:
- turbid synovial fluid
- WBC count > 50,000 to 100,000 per mm3 (50 to 100 × 109 per L)
- polymorphonuclear neutrophils > 75%

Transient synovitis:
- yellow, clear synovial fluid
- WBC count 5,000 to 15,000 per mm3 (5 to 15 × 109per L)
- polymorphonuclear neutrophils < 25%

Question 11

What is the most common pathogen isolated in patients with septic arthritis?

Answer 11

Staphylococcus aureus

Question 12

KOCHER CRITERIA

You are assessing a seven year old boy with pain in his right knee. His parents say that he first started complaining about it two days ago, but deny any trauma or injury. Since then, he has been complaining about the pain more and more, and now he will not weight bear on his leg. On exam, he has a temperature of 38.2°C, and his bloodwork came back with an WBC of 12.2x10^9/L, an ESR of 44mm/hr (normal <10mm/hr) and a CRP of 21 mg/L (normal <5mg/L).

How many Kocher criteria does this patient have?

Answer 12

3.

1. Non weight bearing
2. ESR > 40 mm/hr OR CRP > 20 mg/L
3. WBC >12x10^9 / L

Question 13

You are assessing a 6 year old girl whose parents brought her in to the clinic due to some left upper thigh pain. She appears mostly well, and is walking with an antalgic gait. She does have a fever of 38.1°C. Her bloodwork showed a mildly elevated WBC (14x10^9/L), and a CRP of 21 mg/L, so an arthrocentesis was done. The synovial fluid analysis showed a yellow fluid, with an WBC count of 7x10^9/L, and a PMN count of 24%.

What are the positive predictors for transient synovitis in this stem?

What are the positive predictors for septic arthritis?

Answer 13

Transient synovitis:
- Appears well
- Weight bearing
- Normal synovial fluid analysis
- Temperature < 38.5°C

Septic arthritis:
- CRP >20mg/L