The Limping Child

Background

Most children begin walking between 12 and 18 months. Their initial gait starts broad-based, often with short asymmetric steps. At faster speeds, they often develop foot slapping and asymmetric arm swinging. By ages 3-5 years-old, children start to walk with more fluidity and symmetric strides. By ages 5-7 years-old, their gait begins to resemble the same pattern as an adult.An antalgic gait is often the first sign of an injury or disease process in a limping child. However, it can be difficult to localize the affected joint (hip, knee, or ankle) in peds due to minimal history that can be provided by a child. Therefore, it is important to Xray the entire limb as to not miss the etiology of the limp.

The differential for a limping child is long. The most common cause is by far trauma or overuse injuries. In the absence of this finding, it is important to broaden the differential. A general approach with causes is included below.

General Work-Up

Trauma/Fractures

Most common cause of limp in children. Of note, initial Xrays may be subtle or at times not existent. Important to ensure follow-up as Xrays at 1-2 weeks may show fracture (think of scaphoid fractures).

Toddler’s Fracture

• Often in 9 mo – 3 year olds (e.g. they must be toddling!). Usually occurs from twisting movement, but can also be from trivial falls from standing. Not unusual for families to not recall inciting injury or event.
• Physical exam is often benign and does not show swelling or limb deformity.
• Xrays often show a distal, non-displaced spiral fracture of tibial shaft. Initial Xrays are often negative and become positive 10-14 days after injury once the bone healing process starts

• Treatment
  • Splint:  Long Leg Posterior Splint
    • Splints can lead to pressure sores on heals so make sure to place lots of padding on this area. Important to see Ortho in few days to be put in permanent cast
  • Important for children not to walk on leg

Septic Arthritis

Septic arthritis is a crucial diagnosis to make in the ED. However, it is much more common for the diagnosis to be transient synovitis (see below). Luckily, there is a set of criteria to help distinguish between the two.

Kocher Criteria

• From study in 1999 which provides likelihood of septic arthritis
  • • • 
• Caird, et al regarding use of CRP in algorithm
  • determined that CRP >2.5 is also solid indicator of septic arthritis
• Arthrocentesis Criteria
  • WBC >80-100k with greater than 70-75% neutrophils indicates septic arthritis.

Septic Arthritis of Hip

Typically, septic arthritis of a joint is evident on exam (we can all recall the red, swollen, immovable knee or ankle we’ve seen). One caveat to this, however, is septic arthritis of the hip. It can be a difficult diagnosis as the hip joint is deep to surrounding muscle, therefore, edema and erythema that characterizes most septic joints may not be evident in the hip. Therefore, using the above criteria is of useful importance as other exam findings may not be present.

Often the child will present affected hip in flexion with slight abduction and external rotation and resist passive hip movement due to pain. Timely diagnosis is important as damage to the hip cartilage and blood supply of the femoral head can start 6-12 hours after infection onset and can be irreversible after 1-2 days.

Transient Synovitis

Self limiting virus related inflammation of a joint. Virus often occurs 2-4 weeks prior to onset of joint pain. Often more mild symptoms with milder increases in inflammatory markers. Much more common than septic arthritis accounting for nearly 85% of atraumatic hip pain and limping in children

Often seen in children 3-8 yoa. Treatment is NSAIDs with activity modification. Complete resolution occurs typically between 7-10 days.

Osteomyelitis

Also a difficult diagnosis to make as exam findings can be non-specific or non-detectable early in its course. Characterized by fever, erythema, and tenderness with insidious onset. More common in males than females. Most common sites include:  femur (25%), tibia/fibula (25%), and humerus (13%). Labs often show elevated CRP/ESR but can include elevated or normal WBC.

Xrays are unlikely to demonstrate osteomyelitis (periosteal reaction) until 7-14 days after onset of symptoms. MRI with contrast is gold standard, and can help demonstrate co-associated abscess, fasciitis, myositis, and pyomyositis).

Fun Board Questions about Osteomyelitis

• Neonates:  can affect multiple bones, can present as pseudoparalysis, GBS is common organism and enjoys attacking the right proximal humerus
• Sickle Cell Disease:  Salmonella
• TB:  Pott’s Disease (lower thoracic vertebrae)

Legg-Calve-Perthes Disease

• Idiopathic avascular necrosis of capital femoral epiphysis. Older children typically have more severe disease, which places them at increased risk of premature osteoarthritis of hip.
• Occurs in school-age children (4-10 yoa). Male > Female
• Presents with mild pain, worse with activity
• Bilateral in ~25% of patients (onset of contralateral hip pain within 2 years)
• Xrays are often diagnostic

• Treatment
  • NWB with referral to Ortho
  • <6 yoa:  conservative treatment with limited activities and PT
  • >6 yoa:  often requires surgery

Slipped Capital Femoral Epiphysis (SCFE)

• Most common hip injury in pediatrics
• Occurs in males 13-15 yoa and females 11-13 yoa
• Greatest risk factor is obesity
• Left > Right
• Presents as limp with leg externally rotated
• Xray
  • Ice cream falling off cone
    • 
  • Kline’s Line
    • 

Juvenile Idiopathic Arthritis (JIA)

Autoimmune disease in children <16 yoa. Characterized by joint pain, swelling without a large effusion, and stiffness for >6 weeks without other identifiable cause. Often, will include systemic symptoms including lethargy and decreased appetite. Work-up should include ESR and CRP (however, not always elevated). Can also send RF (rheumatoid factor), however, note that may be negative in specific JIA subtypes (e.g. polyarticular disease).

Lyme Disease

With summer officially started and patients visiting Lyme-filled Wisconsin, also wanted to include a quick blurb on Lyme Disease (Borrelia burgdorferi). Knee is most commonly affected joint. Includes systemic symptoms:  headache, malaise, and fatigue with characteristic erythema migrans (bullseye) rash. Recall that our peds population cannot receive Doxycycline. Amoxicillin is antibiotic of choice in kids <8 yoa.

Neoplasms

Neoplasms are uncommon cause of limping. Classically described as pain worse at night leading to interrupted sleep

Osteochondromas

Benign tumor. Surgical excision if bothersome.

Osteoid Osteoma

Benign cortical lesion. 3x more common in males. Occurs in 5-20 year-olds. Characterized by discrete vascular nidus surrounded by reactive sclerotic bone, accounts for 3% of primary bone tumors. Pain worse with activity and at night. Responds extremely well to NSAIDs. Often Xrays are equivocal with delayed diagnosis (as NSAIDs relieve pain well) until CT scan shows nidus within sclerosis. Tx is surgical excision

Osteosarcoma

Peak incidence is after 10 yoa. Xray shows sunburnt pattern. 5-year survival rate 60-80% if malignancy is localized at time of diagnosis. Usually lacks constitutional symptoms such as fever, weight loss, or malaise.

Leukemia

• Pain out of proportion to exam
• pain increased at night or at rest
• Pain is from rapidly expanding bone marrow
• Can be difficult to distinguish from osteomyelitis
• screen for systemic signs:  Fevers, night sweats, weight loss
• Work-up
  • CBC. Make sure to get differential and to look at %Blasts
• Xray

  • 

    Lymphoma causing irregular lytic lesions of bilateral hips

• MRI and technetium bone scan for extent of disease