Sore Kneecaps or Patellofemoral Joint Pain

Anatomy

In my opinion, your kneecap is one of the COOLEST joints in the body. The reason being, that it’s a sesamoid bone, which means the bone lives inside your quad tendon. Most joints in your body are bones held together by ligaments, which stabilise the joint from being able to move in weird and wonderful directions. Your kneecap in comparison relies alot more on joint alignment and muscle activation. It still has important ligaments (medial/lateral patellofemoral ligaments and medial/lateral patellotibial ligaments which are all part of the medial and lateral retinaculum), but the shape of the joint and how we position our knee during movement actually contributes a lot more to joint health than simply the ligaments. 

Figure 1: Trochlear groove- where the patella (kneecap) makes contact with the femur (thighbone).

In particular, your kneecap sits inside a groove on the end of your femur (Figure 1). The kneecap is perfectly shaped to fit inside this groove, kinda like a puzzle piece. When your quad contracts, and if the kneecap is aligned well along this groove, it sinks deep into the groove, giving the joint beautiful stability as you move and exercise on the knee. 

Why is it Painful?

Kneecaps get sore when they aren’t aligned well within the femoral groove. This occurs for a multitude of reasons, some of these are unmodifiable and others we have capacity to manipulate. 

For example unmodifiable factors include:

• Genetics
  • shallow femoral groove
  • high sitting kneecap
  • wider pelvis
  • being hypermobile or “double jointed”.
• Dislocating your kneecap
  • causes a rupture in the medial ligaments of the kneecap making it easier for the knee to maltrack when your knee falls in
• Age
  • teens grow quickly causing regular change to the body’s biomechanics
  • children and teens have higher elasticity in their ligaments which for most people stiffens as they mature
  • Degeneration of the joint surface as we age can reduce the threshold for irritability in the joint.
• Biological sex
  • biological females are more prone to PFJ pain due to factors that are specific to their biology e.g: wider pelvis, increased elastin in ligaments due to hormones (less prominent if hormone suppressant medication begins prior to onset of puberty, but will be present if suppressant begins post puberty), typically lower muscle tone and peak strength on average compared to male.

Figure 2: Q (Quadriceps) Angle in males vs females

And modifiable factors include:

• Weak glutes – cause the knee to roll in.
• Weak quads – cause increased force to translate through joint instead of muscle/ less bulk changes tilt of patella on groove.
• Trying new exercises (particularly single leg) and adding lots of weight quickly or doing large volumes
• Large increases in activity i.e. recently began running, went on holidays and did 10x normal amount of stairs
• Other knee or lower limb injuries that cause you to limp/ move through your knee differently.

Now, before you freak out and think “Oh no, I have a few of these, so I must be destroying my joint!” … keep reading

Remember that the issue is irritated cartilage, not the lists of factors above. We have just explored a list of factors that make it more likely for your cartilage to become inflamed, but it is important to remember the reason PFJ pain is present is because the cartilage has become inflamed. And good news! Inflammation is fixable! Joint cartilage is beautifully resilient. It is designed for joint load, rubbing and grinding. I think the best way to understand inflamed joint cartilage is to think of a blister. You’ve added a new type of friction load to your knee that it isn’t used to, whether by doing a new activity too quickly +/- some unmodifiable factors or because you’ve recently injured yourself, and the joint has become blistered. If you ignore the issue, the blister will probably get worse, but you also know that if you make some slight adjustments you can help offload the blister, and it will get better. Once the pain settles, your knee should regain the capacity to move and perform all the activities you love to do.

The most common reason for kneecap pain is poor joint mechanics. Remember that your patella sits in a groove and these fit together like a puzzle piece? Well, when these two aren’t properly aligned, this causes excess rubbing through the cartilage making it blistered or inflamed. The list of risk factors above are what contribute to this occurring as you’re loading the knee i.e going up stairs, doing squats or lunges, running, changing direction in sport.  

Treatment/Ex Vids

Ultimately Kneecap pain is a tracking issue, and we can improve this with strength training no matter the cause. Therefore you NEED to keep training. However, painfree movement helps desensitise the kneecap (blister) and training through pain will prolong your recovery. Fortunately there are some helpful ways we can make the joint feel better as you train:

1. Learn how to align the knee well as you train or do daily activities that load the knee.
2. Use offloading tape techniques to help with joint alignment and allow you to do things that would otherwise feel painful.
3. Modify your activities so they’re less painful rather than avoiding, for example:
   1. Go up stairs leading with your good leg and down with your bad.
   2. If you’re a runner, switch your cadence to a shuffle, this shortens the time your leg is being used in a single leg phase which will improve knee position.
4. Part practice painful exercises in the gym
   1. do half depth 
   2. change the angle 
   3. lighten the weights. 
5. Single leg exercises might need to be put on pause and reverted back to double leg. This way you can still load the knee heavy but you have more control of position.
6. Strengthen those glutes!! Rotation in the knee comes from the hip so if your glutes aren’t controlling the hip well, your knee gets impacted.
7. At times, a short course of anti-inflammatories with the advice of your pharmacist or GP is necessary to help calm the joint down enough to load. Doing this with physio guidance around how to use the knee well, you can be sure that you’re not “masking the problem”.

Figure 3: Banded squat exercise for strengthening

Figure 1: Trochlear groove | KNEEguru

Figure 2: Impact of the Quadriceps Angle

Figure 3: 7 Most Effective Squats with Bands