Printed on: May 21st, 2024

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Paediatric MSK red flags and normal variants

Paediatric MSK problems: red flags and normal variants

Children are different from adults. When they present with bone, joint or muscle pain, we need to think of a different set of differential diagnoses. We also need to talk to them and examine them differently.

The challenge is that many of the paediatric MSK problems that present in primary care are benign ‘normal variants’ that time will solve.

But for each of these innocent presentations that will form our ‘bread and butter’ in general practice, there is an occasional lurking ‘evil twin’, and we need to have these at the back of our mind so we don’t miss them!

A note about ‘trauma’ and falls:

It isn’t always easy to get a clear history, and beware: a history of a simple fall/trauma “a few days ago” may be a red herring, both because these can be common in children and children with joint or muscle problems may be more likely to fall. Children also like to create an explanation for what is happening to them, and linking a symptom with an event is a natural thing to do, even if they are not connected. We also need to consider the possibility of non-accidental injury.

The clinical review highlighted some useful questions to ask children and their grown-ups when they present with acute MSK problems (Paeds and Child Health 2019;29(12)503):

We all have different levels of skill at this. If you have not come across the pGALS musculoskeletal assessment system before or need a refresher in your paediatric MSK examination skills, we strongly recommend taking a look at this. There is a link to the pGALS site in the useful resources section below. We have also created a one-page summary of this, which can be found in the pGALs article in the online handbook.

We should think carefully about any of the following presentations in children:

• Acute painful limp (or a chronic persistent limp).
• Acute joint pain.
• Joint swelling.
• Night pain: persistent or not responsive to simple analgesia, e.g. paracetamol, ibuprofen.
• Deep and throbbing ‘bone pain’ – the child often points to the bone rather than joint.
• Systemic symptom, e.g. loss of appetite, fatigue, weight loss, pallor, lymphadenopathy.
• Delayed, loss or regression of motor milestones.
• Weakness.

Let’s look at the ‘big 6’ serious MSK conditions that relate to these red flag presentations.

Here are the ‘big 6’ things we don’t want to miss:

• Malignancy.
• Infection.
• Non-accidental injury.
• Inflammatory arthritis.
• Progressive muscle disorders.
• Orthopaedic emergencies (non-traumatic).

This is one of the most common primary care ‘red flag’ MSK presentations in children. So, who needs referral? The most likely cause(s) of an acute limp varies with age. As we assess the child, we need to keep the differential diagnosis in mind and ask ourselves a number of questions (BJGP 2020;70:467-468):

• Is there a history of trauma? (remembering the caveat above that children may link a pain to a minor incident some days before which is actually a red herring).
• Could this be septic arthritis?

Refer children with an acute limp for same-day assessment if they are:

• Aged <3y.
• Unwell: fever or systemically unwell.
• Non-weight bearing.
• Experiencing painful or restricted joints.
• Immunosuppressed.
• Age >9y with painful or restricted hip movements (to exclude slipped upper femoral epiphysis).
• Or if non-accidental injury is suspected.

A period of watchful waiting in primary care may be reasonable for a child aged between 3 and 9y who is well, afebrile, mobile and limping for less than 72 hours (NICE CKS accessed December 2020).

• Transient synovitis is the most common diagnosis in this group.

• Recommend rest and simple analgesia.
• Safety-net carefully: advise parents to take the child immediately to A&E if symptoms worsen or the child develops fever or systemic symptoms.
• Reassess after 48–72h: if symptoms are resolving, a diagnosis of transient synovitis can be made without further investigation.
• Offer further follow-up at 1 week: if symptoms have resolved completely, no further action is required. If symptoms have not resolved or any uncertainty about diagnosis remains, refer to paediatrics or paediatric orthopaedics for further assessment.  

Having considered red flag presentations and conditions in some detail, let’s now look at their more benign twins – the normal variants.

“Are Jani’s legs normal?…They look a bit wonky.”

25–50% of new paediatric orthopaedic referrals are for normal physiological variants of the growing child.

Before determining that something is a normal variant/benign, we should ensure that we have considered and ruled out the red-flag conditions detailed above, and that the following rules are met (BMJ 2015;351:h3394):

This table summarises the range of what is considered normal variation.

This is pretty impossible to remember but good to know where to look!

Essentially, in the developing child, things point out, then in, then straighten up.

“Petra (age 5) gets these pains in her legs. They happen once or twice a week as she is getting ready for going to bed…they don’t seem to stop her doing anything. She never seems to complain of them in the morning.”

This is a fairly typical story of growing pains, but this will not be a quick consultation in primary care as growing pains are a diagnosis of exclusion, and a careful assessment is required.

Growing pains are common and may occur in up to one-third of children at some point. Their cause is unknown, but they are a common source of misdiagnosis and delayed diagnosis because both parents and GPs may mislabel symptoms as growing pains when they are actually something else (Sports Health 2017;9(2):132).

Before considering/suggesting that pain could be growing pains, ask whether the story and presentation meet ALL the rules of growing pains?

• Age 3–12y.
• Pain symmetrical in lower limbs and not limited to joints.
• Pains never present at the start of the day after waking.
• Child doesn’t limp.
• Physical activity is not limited by the pain.
• Physical examination normal.
• Systemically well.
• Major motor milestones are normal.

If all the rules are met and no other explanation is identified as part of a full assessment (including examination), then management is usually simple measures such as massage, stretching and, if required, simple analgesia with paracetamol or ibuprofen.

We should safety-net carefully about presenting again if symptoms become more severe or if new symptoms develop. If you have remaining uncertainty, reassess in a few weeks and use a test of time to observe what happens.

Paediatric MSK problems: red flags and normal variants Remember the normal variants and their evil twins. Explicitly look for red flags and consider non-accidental injury. Beware asymmetry, a limp, children who are systemically unwell, children with fever without a focus, loss or regression of motor skills, loss of function, an unwillingness to do things they would normally enjoy. A history of a fall or trauma may be a red herring. If there are no red flags, we can cautiously observe children aged between 3 and 9y who are well, afebrile, mobile but limping for less than 72h; transient synovitis is a common diagnosis in this age group – but we should proactively follow-up and safety-net. Younger children may not report pain, and a change in function may be the first sign of a problem. Normal variants are usually painless, symmetrical and do not impact function. Growing pains are a diagnosis of exclusion and must ‘follow the rules’.

Useful resources: Websites (all resources are hyperlinked for ease of use in Red Whale Knowledge) Paediatric Musculoskeletal Matters (videos of how to examine children) Child Muscle Weakness (video library) Versus Arthritis – young people