Limp

Chad D. McCalla, MD

Section of Pediatric Emergency Medicine

Wake Forest University School of Medicine

Objectives

At the end of this module, the student should know how to:

• Obtain a detailed history, including specific questions to ask the limping child
• Perform a focused, yet thorough physical exam for the limping child
• Develop an appropriate differential diagnosis taking into consideration the onset of pain, associated symptoms, physical exam findings, and age of the child.
• Determine and implement an appropriate workup for the child
  

Initial Actions and Primary Survey

Primary surveys are focused are typically focused on the extremity when evaluating the limping child.  However, several life threatening conditions may exist in connection to the affected extremity, such as the child that sustains a traumatic leg injury and has other potentially life-threatening traumatic injuries, (see the section on “The Approach to the Trauma Patient” for more information), or for the child with a potential septic arthritis who is in septic shock (see section on “Approach to Shock”).  While these presentations in children are the exception and not the norm, the approach to the child with a limp should consider many factors to arrive at the correct diagnosis.

History

The differential for a limping child is very broad, but can be very easily narrowed down with a thorough, yet focused history and physical examination.  This can be difficult with preverbal or uncooperative children who can’t (or won’t) effectively communicate what hurts, how they hurt themselves, or give a detailed history of symptoms. 

Additional considerations other than the typical “who, what, where, when, why” questions are as follows:

1. Age of the child.  Depending on the child’s age, different diagnoses can be considered.  Toddler fractures more commonly occur in 9-36 month old children, Legg-Calve-Perthes is seen more frequently in the 5-8 yr old child and slipped capital femoral epiphysis (SCFE) are more prevalent during mid-adolescence.
2. Duration of symptoms. Is the pain an acute or a more chronic, insidious onset?  Acute onset of pain suggests an injury; things like bone tumors, SCFE, overuse injuries often have a more gradual course.
3. History of trauma. This may not be as obvious initially, especially if the child was playing with other children or being poorly supervised at home.
4. Recent illnesses. Always ask about previous febrile illnesses or even minor viral illnesses within the past few weeks to months.  Certain inflammatory conditions such as transient (toxic) synovitis or reactive arthritis typically occur in response to previous viral or bacterial illnesses.
5. Exacerbating factors. Pain that gets worse with activity is suggestive of an overuse injury; pain that improves with activity suggests rheumatologic etiology.  Nighttime pain that is not present during the day, but wakes the child up from sleep should raise suspicion for an oncologic problem; this may also be as benign as normal childhood “growing pains.”
6. Associated symptoms. Presence of fevers, joint pain, joint swelling or redness, rashes and recent weight loss are all important historical clues that can lead to the correct diagnosis.

Physical exam

General appearance

The first step of the physical exam, as with most other pediatric illnesses, is to judge “sick” versus “not sick.”  What does the child look like, is he happy and smiling, or ill appearing and fussy?  The more ill a child appears, or the more pain he/she is in suggests more severe disease/injury.  A child with hip pain secondary to transient synovitis is generally well appearing, as opposed to the septic hip patient who appears more ill and toxic.  How is the child laying in the bed?  Typically children will be lying in the position of most comfort, for example a child with a septic hip or transient synovitis will have the affected hip flexed and externally rotated, whereas a child with a knee or lower leg injury will hold the affected limb straight.

Inspection

Inspect the child’s leg, looking for any obvious deformities, areas of swelling or redness and foreign bodies, etc.  The extremities should be palpated looking for areas of tenderness.  When assessing for swelling or redness it is easiest to compare both limbs side by side and check for differences.  Also, getting the child undressed and into a gown is necessary to ensure a proper exam.  Much information can be lost if the child is wearing pants or other articles of clothing over the affected leg.

Palpation

Start with the unaffected leg first, then proceeding to the affected leg.  If the child is anxious, it may be helpful to have the parents palpate the extremity for pain.  Examining the child in the parents lap can also help to ease this anxiety.  For suspected toddler’s fracture, the examiner should palpate at 1-2 cm intervals down the child’s tibia looking for areas of tenderness.  Pain with palpation of the proximal anterior tibia in an athletic pre-adolescent is suggestive of Osgood-Schlatter’s disease. Palpate pulses and remember to check for a pulse both above and below an injury.  Absence of one necessitates a more urgent evaluation and treatment by either the ED physician or orthopedic specialist.

Range of Motion

Hips and knees should also be checked for both passive and active range of motion.  For example, a child with transient synovitis may resist active ROM, however will allow for passive, while the child with a septic hip will not tolerate either. Pain with tibial torsion is suggestive of a toddler’s fracture. To do this maneuver, simply grasp the child’s ankle and then invert/evert the distal tibia.  Joint laxity with varus and valgus stress on the knee suggests MCL and/or LCL tears, while laxity with anterior and posterior drawer test suggests ACL or PCL tears.

Gait Analysis

At some point during the examination the gait needs to be evaluated. Take the child off the bed and observe him or her walking up and down the hallway; just having them walk in the room is not adequate. Look where the child is placing their foot. Is it heel to toe, walking on tiptoes, or walking on the side of their foot? Are they appropriately flexing at the knee or hip? Will they bear weight at all?  Placing the uncooperative child away from the parent and having them walk towards them can be helpful. Holding them upright in either the examiner or parent’s arms can assess non-ambulatory children by seeing how much weight they will place on the affected extremity.

Diagnostic Testing

Routinely the limping child will get x-rays of the affected extremity done, especially if thought to be secondary to a traumatic cause. For foot injuries oftentimes just an x-ray of the affected foot will suffice, however for femur or tibia fractures, additional x-rays of the joint above and below the injury may be required.  For example, the child presenting with a femur fracture typically requires x-rays not only of the femur, but also of the knee, pelvis, and tibia/fibula. For the child with hip pain it is helpful to get an x-ray of the entire pelvis and not just the affected hip.  This allows for comparison to the other side to evaluate for normal variants, and also for conditions are likely to be seen bilaterally (i.e. SCFE and Legg-Calvé-Perthes). The pre-verbal limping child may get the entire lower extremity x-rayed due to unreliability of the history and physical exam. Keep in mind that toddler fractures may need additional views of the tibia as many are occult and cannot readily be seen on initial films.

For inflammatory or infectious conditions, imaging plus additional lab workup may be required. A complete blood count (CBC), a sedimentation rate (ESR), and a C-reactive protein (C-RP) are helpful when a septic joint, osteomyelitis, or transient synovitis are suspected.  Further lab workup beyond these initial tests is not typically required and should be considered only on a case-by-case basis.  Additional imaging may include a hip ultrasound which can detect the presence of an effusion associated with transient synovitis or a septic hip. AP and frog leg lateral pelvis x-rays are useful to evaluate for SCFE, or LCP.

Differential Diagnosis

The differential diagnosis for the limping child is broad.  Perhaps the best approach is to divide it up into traumatic versus non traumatic injuries (i.e. infection, inflammatory, etc).

Traumatic:

• Fractures
• Toddler fractures
• Stress fractures/overuse injuries
• Other lower extremity fractures
• Dislocations, i.e. patellar, hip, ankle
• Muscle strains/sprains
• Ligament tears, i.e. ACL, MCL injuries
• Foreign bodies
  

Non-traumatic

• Inflammatory
• Transient synovitis
• Reactive arthritis
• Rheumatologic conditions (juvenile idiopathic arthritis {JIA}, ankylosing spondylitis)
• Infectious
• Septic joint
• Osteomyelitis
• Developmental
• Slipped Capital Femoral Epiphysis (SCFE)
• Legg-Calvé-Perthes LCP)
  

References:

1. Barkin RM, Barkin SZ, Barkin AZ. The limping child. J Emerg Med 2000; 18:331.
2. Chasm RM, Swencki SA.  Pediatric Orthopedic Emergencies.  Emerg Med Clin North Am 2010; 28(4):907-926
3. Kost S. Limp. In: Textbook of Pediatric Emergency Medicine, 5th ed, Fleisher GR, Ludwig S, Henretig FM (Eds), Lippincott Williams & Wilkins, Philadelphia 2006. p.415.
4. Lawrence LL. The limping child. Emerg Med Clin North Am 1998; 16:911.
5. Wai Lin B, et al.  Pediatric Limp.  Retrieved from http://emedicine.medscape.com/article/802506-overview