Billy is a very active 8-year-old that I have taken care of since his birth.

 

He is in excellent health, but he has had his share of bumps and bruises. And I have had the pleasure of putting sutures in him. Billy’s mom has two other boys and is hardly an alarmist when it comes to mild illnesses and trauma. That is why I was concerned about the call I got from her on a Saturday night.
 

She called me around 10 PM. She said that Billy seemed “off” that day.

 

Luckily I was on call. He didn’t want to play which was out of character for him He just wanted to engage in video games on the couch. His leg was held in a funny position. Walking was with a mild limp or even on his tip toes.

 

He denied any trauma whatsoever.

Mom felt he was fine in the morning. The family was going out to dinner at his favorite restaurant. Billy literally limped from the car. Upon completion of the meal dad had to carry him to the car.
 

When they got home they took his temperature which was 99.0.

He refused to bear weight on the right leg, There was no redness or swelling but he said that his hip hurt when he moved his leg. This was so unlike Billy, he being a stoic and tough little guy. But that is what prompted mom’s call.
 

Since it was a Saturday night I didn’t want to waste any time.

 

I instructed mom to take him in to the ER. I would call ahead so they would be waiting for him. Since there was no history of trauma nor did he have fever, it made me less concerned about a serious condition since it had all occurred only that day. However, there was no way to be sure without doing some tests.

A limp in a child could be a number of things. Some are benign and of no consequence and some can be an orthopedic emergency. It sounded to me like he had toxic synovitis. This is a fairly common condition in children that is self-resolving and not serious. I wanted to be sure that he did not have a septic arthritis, a bacterial infection within the joint. This is usually a rapidly moving infection that occurs with fever, s painful hip and decreased movement of the hip joint with a certain limp. Septic arthritis is considered an orthopedic emergency requiring drainage of the hip joint to prevent permanent destruction of the joint itself.
 

Another cause of a limp in children can be from Legg-Calve-Perthes disease.

 

This is a condition that occurs when the head of the femur (the round portion of the large bone of the leg that fits in the hip socket) has a compromise of the blood supply to the bone.This portion of bone can actually die and collapse. And lastly, another condition that can cause a limp in children is called slipped capital femoral epiphysis (SCFE). This occurs when the growth plate, cartilage that sits on the bone and is the source of bone formation, slides off the bone and can cause a limp, hip pain and/or knee pain.
 

The ER was waiting for Billy. He still did not have a fever. He did have mild limitation in range of motion of the right hip and definitely had a limp.

 

The labs that were done included a CBC, a complete blood count that looked at the white blood cell count. His was normal which was reassuring. In an infectious process such as a septic arthritis (SA) the white blood count would usually be elevated. His platelet count was also normal. The platelets can be an “acute phase reactant” meaning that in an infectious (erythrocyte sedimentation rate) and a CRP (Creactive protein). These are non-specific markers of inflammation meaning that they are indicative of an inflammatory process but not specific for infection. As in Billy’s case, when they are normal it is again reassuring that there is no infection. Hip X-rays were ordered, and these were also normal, This ruled out SCFE or trauma. An ultrasound of the hip showed a normal joint space with no fluid in the joint indicating that this was NOT a septic hip. Given the negative work-up, the ER doctor was certain this was a transient or “toxic” synovitis. After phoning me Billy was sent home with instructions for a follow up in our office.
 

Toxic or transient synovitis is a relatively common condition in children between the ages of 3 and 10 years more common in boys than in girls.

 

It typically involves one hip but can be bilateral in 1-4% of the cases. There is no known actual cause but it is commonly preceded by a viral infection such as a mild cold or vomiting and diarrhea.
 

The name toxic synovitis is a misnomer since it is NOT due to sepsis or a bacterial infection.

 

The child is not very sick. A common complaint is a low grade fever along with a limp and hip pain. They may also complain of thigh or knee pain. Once one has confirmed the diagnosis of toxic synovitis (a diagnosis of exclusion) the treatment is mainly supportive and includes rest, non-steroidal anti inflammatories such as Ibuprofen, heat and often massage. As for activities, I would let them limit their activities accordingly, using pain as their guide. I would keep them out of recess and sports until they are back to baseline.
 

The vast majority of cases will resolve within 7-10 days.

 

They should be followed closely in the office until it resolves. A concern would be a spike in fever, worsening of limp or pain, any redness or warmth of the hip area, or symptoms that persisted beyond 10 days.
 

After Billy left the hospital, the ER doctor phoned me to suggest a follow-up on Monday. I gave Mom a call on Sunday to get a report. She said he was much better. By Monday he was 90% better and with no fever.

 

His last dose of Motrin was Sunday night. He was restricted from recess and sports until his visit on Wednesday. He was 100% back to baseline and anxious to get back to soccer. He was allowed to go to soccer practice the next day, but limited to running and practice at 50% of his maximal exertion. If he did well with this, he could go back to soccer the following day with no restrictions. She called me the following Monday to tell me that he was doing great and scored two goals in his soccer game on Saturday.