Navigating adolescent knee pain: Beyond growing pains explained

Patellofemoral Pain (PFP) is a common complaint in the general population. It doesn’t discriminate against age as both adolescents and adults can be affected. Unfortunately, knee pain in the adolescent population is often brushed away as growing pains – but recent research suggests it may not be that innocent, and many cases do not resolve with age. In this blog, I hope to outline why adolescent knee pain should be taken seriously; there are treatable aspects, like patellofemoral joint instability, which can contribute to knee pain in this specific subgroup, and as physios we need to know when adolescent knee pain might be more than just growing pains.

If you’re interested in this topic and want to delve further, I highly recommend you watch Claire ‘Patella’ Robertson’s magnificent Masterclass on this topic: ‘Mastering adolescent knee pain: A comprehensive guide to patellofemoral pain & joint instability’ – watch it HERE.

Causes and promising interventions

Up to 28.9% of adolescents have PFP, and 75% of them are still in pain one year after onset. There isn’t usually just one cause of PFP, but rather an accumulation of multiple factors which make its onset more likely. While a proper subjective examination is always important, this is particularly true for this population as it will identify any potentially relevant extrinsic risk factors. In many cases, teens with PFP are very active, often playing multiple sports, as well as dealing with everyday demands of stairs, standing and kneeling/crouching for long periods. These activities not only increase the likelihood of experiencing PFP, but are also driving factors for knee pain. Gaining a good understanding of demanding activities, and temporarily decreasing the load on the Patellofemoral Joint (PFJ) can result in a significant decrease in pain.

Interestingly, a recent study by Rathleff et al. (2019) implemented a load management intervention program that significantly decreased load for four weeks, then slightly increased it again over a three week period with home exercises, after which a gradual return to sport was encouraged. Results were astonishing, as 68% were back to playing sports after three months, 79% after six months and 81% after a year, along with many clinically relevant improvements when it comes to pain and quality of life.

Why it’s more than just knee pain

Quality of life and participation are factors which are significantly affected in adolescents experiencing knee pain and should be closely monitored. Feelings of worry, sadness and unhappiness are very common, and more than half of teens with PFP say they’re aware of their knee problem every single day. Kinesiophobia is a reality in most cases – always consider assessing it using questionnaires, and try to identify movements which elicit fear and lead to altered movement patterns. The best way to address kinesiophobia is by educating your patient about the pain. What is it? Where does it come from? How long will it last? How can it impact their life? And most importantly, what can they do to gain control over the situation? This can positively impact not only kinesiophobia, but also pain catastrophizing, fear avoidance and many other yellow flags.

Patellofemoral instability

Now, PFP isn’t always just a case of overload and too many extrinsic risk factors, there are certain intrinsic risk factors that can contribute to knee pain in adolescents as well – one of the more common factors being the presence of patellofemoral instability. Patellar instability refers to excess movement of the patella relative to the trochlea. It can range from minor instability where there is just pain without the true feeling of instability, all the way to dislocation. It’s very likely the first subgroup will come to you in clinic – it’s up to you to figure out the degree to which patellar instability is contributing to their pain.

When it comes to instability, there are certain things we cannot change. Anatomical anomalies like a shallow trochlea, patella alta, a poor position of the tibial tubercle, a ruptured medial patellofemoral ligament or a long patellar tendon are all examples of this. Even though we cannot influence these morphological changes, it’s important to know about them because we might be able adapt our therapy accordingly. A high riding patella results in the patella taking longer to enter the trochlea, delaying the stability offered by this anatomical groove, which makes the knee more unstable in the first 40 degrees of flexion. Translating this into our therapy, this means we should target these first 40 degrees in our dynamic stability training! There is a way to figure out whether patella alta may be contributing without having to get an MRI. Claire Robertson explains this nifty little trick very well, check out the video taken from her Masterclass below:

Luckily, there are also lots of factors which contribute to instability that we CAN change. Poor quads, poor proximal control, excessive foot movement, poor movement patterning, functional valgus etc. These are all things that should be checked during our objective examination and included into therapy when necessary.

Physio management

So what are the things we must include in our therapy? This of course depends on your patient, as your treatment should always be tailored to the individual, but there are some key concepts to remember:

1. Education and building confidence should always be part of our treatment regime.
2. We must also try to settle the knee asap. Swelling appears to inhibit the Vastus Medialis, therefore increasing functional instability and increasing the likelihood of another subluxation or dislocation. Icing pre-exercise is an easily applicable trick that can make exercise possible without exacerbating swelling or pain.
3. Closed kinetic chain exercises between 0 and 50° flexion have the lowest chances of aggravating the PFJ and are almost always safe to start with. Open kinetic chain exercises between 90 and 45° flexion will also maximally load the quads with minimum load on the PFJ.
4. Furthermore, we want to try and remove unnecessary movement and increase dynamic stability for compensation of decreased structural stability.

The best exercise programs will look at the whole kinetic chain including trunk and also include proprioceptive training. Dr. Robertson gives an excellent explanation of what the early stages of rehab after dislocation or surgery should look like in the below video taken from her Masterclass:

To operate or not?

The more extreme anatomical anomalies causing severe cases of patellofemoral instability leading to subluxation or dislocation might need to be addressed with more than just physio. Parents of children/adolescents who have dislocated their knee might ask you about the risk of re-dislocating, and whether they should opt for surgery. The answers to these questions aren’t straight forward, but as a rule of thumb try to remember that the chances of dislocation are very high if your client is under the age of 13 at their first dislocation, has a long patellar tendon and trochlear dysplasia, and has experienced a dislocation on the other side. In these cases, it’s important to manage expectations and counsel both patient and parents.

Lastly, if your adolescent with knee pain isn’t moving in the right direction, be aware of the things that could be masquerading as PFP; think Osgood Schlatter, the lesser known Sinding-Larsen-Johansson syndrome, which is often misdiagnosed for tendinopathy, an osteochondral defect or even cancer.

Wrapping up

That’s it for this blog! I hope it helps you to keep in mind that knee pain in adolescents should be taken seriously, as it has a high impact on these kids’ lives and there are many things that can be done to improve pain and quality of life.

If you found this interesting and want to know more, then you’ll like Claire Robertson’s Masterclass even more, so make sure you go and check it out HERE.