Child with a Limp

Our six-year-old started limping a couple of days ago. When should we start worrying?

Maybe now. A child with a limp is something you should take seriously. We do. Let’s start with what we mean by a “limp.” This is a jerky, uneven gait that’s usually caused by pain, muscle weakness, or if chronic, by some sort of deformity. Since it only started a couple of days ago, this isn’t chronic, so we can narrow our focus on what might be causing it. The good news is that most of the time the cause is going to be benign and will quickly get better. It’s usually brought on by some kind of minor trauma. It’s the other causes that we’re concerned about.

When we talk about a limp, there are several kinds, based on where the problem lies. Watching your child carefully as they walk will give us important clues. Two types of limp are especially helpful. The first is straight-forward, and is seen when a child quickly hops after planting their foot on the floor. That usually locates the affected side of the problem, since the pain of pressure in that leg make them want to get off of it. The pain could be anywhere—hip, knee, foot, ankle. If the pain is coming from the hip, another type of limp can help localize it. This happens when there is a downward tilt of one side of the pelvis. The downward side is where the problem lies. We’ll talk in a while about what can cause that, but watch your child walk and study their limp. Keep in mind that a three to four-year-old normally walks in a peculiar fashion. They typically flex their hips, knees, and ankles, keeping a lower center of gravity and more balance. In addition, their feet normally splay out a little, and they walk faster, with shorter strides. That’s not a limp. They didn’t walk this way when they were two, and they won’t when they’re five.

Once we’ve established the presence of a limp, we’re going to ask a bunch of questions.

• How long has this been going on? A recent onset (several days) is typical of trauma or an acute infection. A longer duration (gradually increasing over weeks or months) is suspicious for overuse problems or certain types of hip pathology.
• Has there been any recent trauma? We’re interested in minor falls, contusions, or sprains. Something called a “Toddler’s Fracture” can occur with minimal or even unnoticed trauma, and if you have a child in that age range, we need to keep that in mind. If your child has older siblings (who may have been involved in some unsanctioned rough-housing), their historical accounts are not always going to be accurate.
• Has there been any recent fever? This is important, since this can be a red flag for the presence of two serious problems—an infected joint or an active bone infection.
• What’s the pain like? (If your child is able to articulate). We all need to be patient here, since most children aren’t able to accurately locate their pain and just point to the entire extremity. That goes for a lot of adults as well. But the type of pain will tell us a lot. Constant, localized pain is seen with fractures, joint infections, and bone infections. Pain that’s less severe and comes and goes is what we see with some of the degenerative hip problems (more about that later). Pain that worsens with activity might be coming from a stress fracture or overuse injury. Pain that occurs at night or awakens your child from sleep is another red flag. This might suggest the presence of a boney tumor, either benign or malignant. And if your young child refuses to walk and will only crawl on their knees, their problem is frequently in their feet. One last point. There’s something called “referred pain,” and it can confuse and mislead patients and physicians alike. Your child complains of knee pain but the knee exam is completely normal. The problem resides in the hip and the pain is “referred” to the knee. That’s commonly seen in adults as well. Not sure why, but this happens a lot.

After we get a detailed history, we’re going to take a good look at your child, locate the site of their pain, and more than likely order some x-rays. Most experts recommend getting “plain” x-rays if your child has a definite limp, even in the presence of some kind of minor trauma. (Some studies have found as many as one in five children will have a subtle fracture in this circumstance. Something we don’t want to miss.) Blood work might be needed as well, but most often, that’s not going to be the case. However, if we find any of those red flags (fever, swollen joints, boney tenderness, or pain that occurs at night, among others), we might need to order some studies. Focused blood work will help us with identifying infection and inflammation. Generally this won’t be necessary if your child has no fever, there’s been a minor isolated injury, and the limp has been present for less than 24 hours. If we’re still concerned after the initial x-rays, an ultrasound might be helpful, or even an MRI. Occasionally, if a specific joint is involved, it might need to be aspirated (joint fluid drawn through a needle), with the fluid studied for evidence of a joint-destroying infection. Painful, but necessary. And it should be done by an orthopedist.

A word about x-rays. While wanting to limit your child’s exposure to radiation, it’s frequently necessary to get “comparison views”—x-rays of both hips, for example. Subtle findings might be missed with only one side being looked at, or what might appear to be a problem on the right side is also present on the left, hence a normal variation and not of significance.

We’ve noted some red flags here, so let’s consider a few of the serious problems we could be facing.

An infected joint is an emergency. Undiagnosed and untreated, this can lead to a whole host of problems, with life-long consequences. Children with this problem will typically have fever and appear quite sick. The knee and hip are the joints most often affected, with the hip most often involved in infants and young children.

A bone infection (osteomyelitis) is another emergency, and usually occurs in children younger than five years of age. The diagnosis can be difficult, since fever is not always present and the symptoms can be nonspecific—dull pain, swelling, maybe some redness, and a history of minor trauma/contusion or a seemingly insignificant puncture wound. Your physician will need to maintain a high level of suspicion.

Slipped capital epiphysis is one of the most common hip problems in teenagers. It develops gradually, is associated with being over-weight, and presents with dull, achy pain and a limp. There’s no trauma involved, and no fever. The problem lies in the growth plate of the hip, which “slips” off to one side. You can see this on an x-ray, but the longer it’s out of place and the more it’s slipped, the greater the potential for a lasting problem. This needs the attention of an orthopedist.

The last thing we want to consider is something called aseptic necrosis of the hip. You may know it as Legg-Calve-Perthes disease, or maybe not. Don’t let the name fool you. This isn’t some rare problem that’s only of interest to medical students taking exams. We saw two cases of this just in the past month. Something happens to the blood flow to the hip and the head of the hip eventually collapses. The peak incidence for this is between five and seven years of age, more boys than girls are affected (by a ratio of about 4:1) and it can occur on both sides in up to 1 in 5 children. Interestingly, African-American children are rarely affected. The cause is unknown, and any pain will only be mild. A limp will develop, the one we described with the affected hip tilting downward. Early diagnosis is critical, along with management by an experienced orthopedist. Two cases in the past month. It’s out there.

So yes, if your child starts to limp, pay attention. Here’s what we would recommend:

• A toddler with a limp needs to be checked out.
• If your child won’t bear any weight at all, someone needs to see them.
• If there’s been no trauma, no fever, no swelling, no redness, no joint involvement—watchful waiting is probably safe. But only for 24 hours.
• Everything else (know your red flags) needs attention.
  …This is an excerpt from the new book I’m writing with pediatrician Dr. Robert Alexander. The book will address 100 questions from parents regarding their children’s health. Feel free to email us with questions: askthedox@yahoo.com