Written by: Tommy Ng, MD (NUEM ‘24) Edited by: Patricia Bigach, MD (NUEM ‘22) Expert review by: Terese Whipple, MD '20
So your kid won’t walk
One of the most common complaints in a pediatric Emergency Department is a child refusing or inability to ambulate. For normal development, a child is typically able to stand at 9 months, walk at 12 months, and run at 18 months. There is a certain degree of variability for these age constraints however any acute decrease in mobility should prompt an evaluation. A limp is defined as any abnormality in gait caused by pain, weakness, or deformity [1]. There are a plethora of conditions that can manifest with an antalgic gait or refusal to bear weight and it may be difficult to distinguish between etiologies given a child’s age.
History and physical
Age is an important factor as certain conditions are more likely depending on the patient’s age
Acuity should be determined as the chronicity of limp as certain etiologies are more acute while others are indolent. Additionally, certain infectious etiologies are more likely to present acutely or chronically.
Fever may suggest an infectious or rheumatologic cause
Trauma can help distinguish soft tissue vs orthopedic injuries
Past medical history is important to be focused on recent illnesses, antibiotic use, history of sickle cell disease, or hormonal diseases.
Physical examination should always include an attempt to ambulate the child unless there is an obvious contraindication noted immediately (eg open fracture). If the child refuses to bear weight, the child should be made non-weight bearing until serious pathology which can be worsened by walking is ruled out. Strength and range of motion of both lower extremities should also be examined [2].
Normal gait cycle (orthobullets.com)
Differential: the bad, the worse, and the ugly
Infectious
Transient Synovitis - Relatively common with a lifetime risk of 3%. Affects ages 3-8, males to females 2:1 [3]. Typically well appearing with normal labs, however, this is a diagnosis of exclusion and a septic joint should be ruled out. Management includes NSAID use and return to activity as tolerated [4].
Septic Arthritis - A “do not miss” diagnosis, commonly ages 3-6 with a slight male predominance [5]. Typically presenting with fevers and abnormal labs. The Kocher Criteria (originally developed in 1999 and validated in 2004) can be helpful in determining the likelihood of septic arthritis [6]. Management includes imaging studies, typical ultrasound to assess for a joint effusion, then a diagnostic arthrocentesis & antibiotics. The antibiotic regimen should be tailored to the child’s age and other predisposing factors to certain pathogens.
Osteomyelitis - Occurs in 1:5000-7700 kids in increased prevalence with MRSA communities; 2:1 male to female predominance with half of all cases occurring in ages less than 5 [7]. Commonly hematogenous spread from bacteremia; clinical suspicion should prompt radiologic evaluation. X-rays may be likely to be normal/inconclusive early in the disease course and MRI may be often indicated. Labs can be helpful but are not specific; a systematic review of >12,000 patients showed that elevated WBC was only present in 36% of patients [7]. ESR and CRP are non-specific but have a sensitivity of 95% [7]. Antibiotic therapy guidelines are similar to the management of septic arthritis. Surgical intervention may be indicated if there is a lack of improvement after 48-72 hours [8].
Osteomyelitis of the distal tibia (orthobullets.com)
Orthopedic
Legg-Calve-Perthes / Avascular Necrosis of the Hip - Age range 3-12 with a peak at 5-7, male to female ratio 3:1, can be bilateral in 10-20% of patients [9]. Radiographs should be obtained with high clinical suspicion but are often normal early in the course. An MRI would show fragmentation of the femoral head. The patient should be made non-weight bearing and be referred to a specialist. Children under 8 typically have a better prognosis however long-term management is poorly defined as there has been no long-term study [10].
Avascular necrosis of bilateral hip (orthobullets.com)
SCFE of left hip (orthobullets.com)
Slipped Capital Femoral Epiphysis - Typically obese child, median age 12, bilateral in 20-40% of cases [11]. Presentation is classically chronic hip pain with antalgic gait however may present with knee pain. Physical exam classically shows external rotation and abduction of the hip during hip flexion. Management is orthopedic consultation for operative stabilization [12].
References
Smith E, Anderson M, Foster H. The child with a limp: a symptom and not a diagnosis. Archives of disease in childhood - Education & practice edition. 2012;97(5):185-193. doi:10.1136/archdischild-2011-301245.
Naranje S, Kelly DM, Sawyer JR. A Systematic Approach to the Evaluation of a Limping Child. Am Fam Physician. 2015 Nov 15;92(10):908-16. PMID: 26554284.
Landin LA, Danielsson LG, Wattsgård C. Transient synovitis of the hip. Its incidence, epidemiology and relation to Perthes' disease. J Bone Joint Surg Br. 1987;69(2):238-242.
Kermond S, Fink M, Graham K, Carlin JB, Barnett P. A randomized clinical trial: should the child with transient synovitis of the hip be treated with nonsteroidal anti-inflammatory drugs?. Ann Emerg Med. 2002;40(3):294-299. doi:10.1067/mem.2002.126171
Bennett OM, Namnyak SS. Acute septic arthritis of the hip joint in infancy and childhood. Clin Orthop Relat Res. 1992;(281):123-132.
Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am. 1999;81(12):1662-1670. doi:10.2106/00004623-199912000-00002
Dartnell J, Ramachandran M, Katchburian M. Haematogenous acute and subacute paediatric osteomyelitis: a systematic review of the literature. J Bone Joint Surg Br. 2012;94(5):584-595. doi:10.1302/0301-620X.94B5.28523
Kaplan SL. Osteomyelitis in children. Infect Dis Clin North Am. 2005;19(4):787-vii. doi:10.1016/j.idc.2005.07.006
Johansson T, Lindblad M, Bladh M, Josefsson A, Sydsjö G. Incidence of Perthes' disease in children born between 1973 and 1993. Acta Orthop. 2017;88(1):96-100. doi:10.1080/17453674.2016.1227055
Canavese F, Dimeglio A. Perthes' disease: prognosis in children under six years of age. J Bone Joint Surg Br. 2008 Jul;90(7):940-5. doi: 10.1302/0301-620X.90B7.20691. PMID: 18591607.
Herngren B, Stenmarker M, Vavruch L, Hagglund G. Slipped capital femoral epiphysis: a population-based study. BMC Musculoskelet Disord. 2017;18(1):304. Published 2017 Jul 18. doi:10.1186/s12891-017-1665-3
Reynolds RA. Diagnosis and treatment of slipped capital femoral epiphysis. Curr Opin Pediatr. 1999;11(1):80-83. doi:10.1097/00008480-199902000-00016
Expert Commentary
Thank you to Drs. Ng and Bigach for compiling a concise approach to a common chief complaint encountered by Emergency Physicians across the county: a child with a new limp or the refusal to bear weight.
The first step to this often-challenging problem is to try to localize the pain, and in non-verbal kiddos, this can be the most difficult task. As highlighted above, if the child is able, observe their ambulation and establish laterality of the limp and when it occurs during the gait cycle. Most of the disease processes we as Emergency Physicians are concerned about will cause an antalgic gait or a shortened stance phase. Shortening the stance phase decreases the amount of time that the child is bearing weight on the painful limb in an effort to decrease their pain. Sometimes this is so effective that their parents will observe a limp, but the child will not complain of any pain. A thorough exam of the back and lower extremities including inspection, palpation, and range of motion of all joints is also imperative for trying to localize the cause of their symptoms.
Let your exam and history guide lab evaluation and imaging, however, a good place to start is usually basic labs and inflammatory markers and a plain film of the affected joint. In some cases, you won’t be able to localize pain or exam findings at all, and a broad workup including plain film imaging of the entire extremity may be necessary.
A few additional pearls:
Always consider non-accidental trauma in children with new limp or refusal to bear weight.
Systemic symptoms such as fever should raise your suspicion for infectious etiology such as osteomyelitis or septic arthritis.
Classically children with transient synovitis will have had a recent viral illness, but this is not always the case.
Always examine the hips and consider hip plain films in children complaining of knee or thigh pain, but with a benign knee exam. They could be hiding an SCFE or Leg-Calve-Perthes disease.
Don’t forget to examine the SI joint, as it too can become infected or inflamed.
History of night pain should raise your antenna for malignancy like osteosarcoma, Ewing’s sarcoma, or leukemia.
Consider Lyme arthritis in your differential for joint pain and swelling in endemic areas.
Ultrasound can be useful when evaluating for septic arthritis and transient synovitis and can be performed at the bedside. However, both septic arthritis and transient synovitis can cause effusion, and therefore it is not useful in differentiating between the two. (That’s where the Kocher Criteria should be used to risk-stratify and determine if joint aspiration and fluid analysis are warranted)
Ultrasound evaluation of a pediatric hip joint demonstrating effusion courtesy of Dr. Maulik S Patel (https://radiopaedia.org)
Finally, make sure that the parents understand the diagnosis, expected course, and follow-up plan. If the child continues to refuse to bear weight, their symptoms worsen or do not improve, or they develop new concerning symptoms such as new fever or new urinary retention, they should return to the Emergency Department or their pediatrician for re-evaluation. More than once I’ve had patients who seemed for all the world to have transient synovitis eventually be diagnosed with spinal cord tumor, chronic recurrent multifocal osteomyelitis, etc.
Terese Whipple, MD
Assistant Professor
Department of Emergency Medicine
University of Iowa Hospitals and Clinics
How To Cite This Post:
[Peer-Reviewed, Web Publication] Ng, T. Bigach, P. (2021, Dec 20). Hip Pain in Pediatrics. [NUEM Blog. Expert Commentary by Whipple, T]. Retrieved from http://www.nuemblog.com/blog/hippainpediatrics
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