Limping is a common complaint in pediatric emergency care, but the differential is broad and the stakes are high. In this episode, we walk through a detailed, age-based approach to the evaluation of the limping child. You’ll learn how to integrate the Kocher criteria, when imaging and labs are truly necessary, and how to avoid being misled by small joint effusions on ultrasound. We also highlight critical mimics like appendicitis, testicular torsion, and malignancy—and remind you why watching a child walk is one of the most valuable parts of the exam. Whether it’s transient synovitis, septic arthritis, or something much more concerning, this episode gives you the tools to manage pediatric limps with confidence.

Learning Objectives

1. Apply an age-based approach to the differential diagnosis of limping in children.





2. Demonstrate diagnostic reasoning by integrating history, physical exam, imaging, and lab findings to prioritize urgent conditions like septic arthritis and SCFE.





3. Appropriately select and interpret imaging and lab studies, including understanding the utility and limitations of ultrasound, MRI, and the Kocher criteria.

Connect with Brad Sobolewski

Mastodon: @bradsobo@med-mastodon.com

PEMBlog: PEMBlog.com

Blue Sky: @bradsobo

X (Twitter): @PEMTweets

Instagram: Brad Sobolewski

References

1. 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):1662-70. doi:10.2106/00004623-199912000-00002





2. UpToDate. Evaluation of limp in children. Accessed September 2025.





3. UpToDate. Differential diagnosis of limp in children. Accessed September 2025.





4. StatPearls. Antalgic Gait in Children. NCBI Bookshelf. Accessed September 2025.





5. Pediatric Emergency Care. “Approach to Pediatric Limp.” Pediatrics in Review. 2024.

Transcript

Note: This transcript was partially completed with the use of the Descript AI and the Chat GPT 5 AI

Welcome to PEM Currents, the Pediatric Emergency Medicine podcast. As always, I’m your host, Brad Sobolewski, and in this episode we’re gonna tackle the evaluation of a child presenting with limp. We’ll cover, age-based differential diagnosis. How to take a high yield history and do a detailed physical exam, imaging strategies, lab tests, and when to worry about systemic causes.

We’ll also talk about the Kocher criteria for septic arthritis and how to use and not misuse ultrasound when you’re worried about a hip effusion. After listening to this episode, I hope you will all be able to apply an age based. Approach to the differential diagnosis of limp in children. Demonstrate diagnostic reasoning by integrating history, physical exam, imaging, and lab findings to prioritize urgent conditions like septic, arthritis, and scfe, and appropriately select and interpret imaging and lab studies, including understanding the utility and limitations of ultrasound MRI and the Kocher criteria.

So let me start out by saying that a limp isn’t a diagnosis, it’s a symptom. It can result from pain, weakness, neurologic issues, or mechanical disruption. So think of limping as the pediatric equivalent of chest pain. In adults. It’s common, it’s broad, and it’s sometimes could be serious. And the key to a good workup is a thought.

Age-based approached and kids under three think trauma and congenital conditions between three and 10 transient synovitis range Supreme and over 10 think SCFE and systemic disease. And your differential diagnosis always starts with history. So you gotta ask the family, when did the lymph start? Was it sudden or gradual?

Is there a preceding viral illness or an injury? Is the limp worse in the morning? Does it get better with activity? Do the kid complain of pain or are they just favoring one leg? And then are there any systemic symptoms such as fever, rash, weight loss, fatigue, or joint swelling elsewhere? And you wanna find out whether or not the kid is actually bearing any weight at all.

Have they had recent travel or known tick exposure? Are they potty trained and are they having accidents now? Have they had any prior episodes of joint swelling or limping like this in the past? And don’t forget a developmental history, especially in kids under preschool age. Most children begin to stand at nine to 12 months.

Cruise at 10 to 12 months and walk independently by 12 to 15 months. A child who has never walked normally may have a neuromuscular or congenital problem. When you are evaluating limp, obviously you wanna watch the kid walk, get them outta the exam room if needed. First of all, your exam room is small.

Kid may feel confined and they might be more willing to take some steps. If you have ’em out in the hallway, obviously have the caregiver nearby and a toy, a phone, some object of enticement. You wanna watch their stance phase, or they just avoiding bearing weight on one limb. When they’re standing the swing phase, do they hold that leg stiff?

Does it bend normally? And are they in balance? Are they symmetric? And again, don’t just settle for a few steps. Try to get ’em walking at least 10 to 15 feet if possible, and if they’re refusing to walk in, the ED asks parents for a video. You wanna examine every joint head to toe, and even if the child only complains about one area, palpate every limb.

I usually start distally so at the fingertips or toes and really systematically work my way up watching for any signs of pain, you check range of motion and observe resistance to movement log. Roll the hips externally and internally rotate them as well. See if you can feel an A fusion, you know, squeeze the calf to localize pain.

And in a kid with limp, you always gotta check the feet too, right? Look for puncture wounds on the plantar surface. Splinters, ingrown, toenails, cellulitis, or even, you know, gravity dependent swelling or petechiae. And certainly your systemic exam should include the abdomen. You know, look for signs of appendicitis or sous irritation, testes for testicular torsion.

And you wanna look at the skin diffusely to make sure there’s no petechiae, target shape, rashes, or bruising. Now for most kids with limp, I find that the history and physical exams sort of guide where you’re going, right? If they had a fall or an injury, well, you’re just looking at a kid who may have sprained or broken something, and you can really target towards imaging as your workup.

You know, there’s some kids though that may benefit from labs and in general, they depend on the scenario. So if you see A C, B, C, well you’re gonna get leukocytosis, but C, B, C. In the context of limp is most useful when you’re considering a differential. So if you see blasts, well, you know you’ve got a new malignancy.

If you have a general elevation of the white count and use it in context with the Kocher criteria, it could be more valuable. So A CBC alone is not gonna get you the cause it supports your differential. ESR and CRP are often ordered and they’re just general inflammatory labs. CRP rises and falls faster than ESR, and they co vary and either can be used in prediction rules.

I’ll talk about that in a little bit if you think the kid’s bacteremic, yeah. Get a blood culture. If you’re in an endemic area and you’re considering Lyme on the differential, you can send off serology. And let’s be honest, a NA and rheumatoid factor are really only useful if there’s a chronic history and you can have about 15% of kids with a false positive a NA anyway, and they’re not really helpful in acute limp.

So get them if rheumatology recommends them, but otherwise, they’re not really a useful part in the initial differential diagnosis. And again, I alluded to Lyme a moment ago, but if Lyme arthritis is your top diagnosis, especially with a known rash. You can start treatment while serologies are pending.

That’s totally okay. So in conjunction with Labs, imaging is generally recommended in most kids with Limp, and I would say in most cases you start with plain films. Sometimes it’s easy, right? They hurt in one particular occasion. You take a picture, you see a fracture, but two views, the affected and unaffected side can be really helpful, especially in cases of SCFE or in subtle or perhaps occult toddler’s fracture.

If you’re not sure where the problem is, you can’t isolate it on your exam or history. Consider imaging the entire leg. I mean, that’s when you’re looking at like the hip femur, knee tib fib, even the ankle and foot. It’s not that much radiation. Ultrasound is useful for seeing joint effusions, especially of the hip.

It’s fast, generally painless and radiation free, but not all effusions are infected. Ultrasound is not part of the Kocher criteria. I’ll get back to that in a minute. And a normal ultrasound or an ultrasound without effusion doesn’t rule out septic arthritis. And then we’ve got MRI, which is definitely best for detecting osteomyelitis, discitis, and soft tissue abscesses.

Among other diagnoses in kids under five, you’re probably gonna need to sedate them, which can delay diagnosis. So in general, you’re admitting those kids and then they can get a sedated MRI later the next day. But if radiolo