Ice Skates on the Patellofemoral Dance Floor
Is it time to retire the term ‘Chondromalacia Patellae’?
This blogpost is a ‘guide’ only, should not be taken as medical advice and does not replace the recommendations from a registered and regulated healthcare professional who has conducted a comprehensive assessment.
This is an adjunct blog to ‘Saving The Unhappy Kneecap Joint — Evidence-Based Management of Patellofemoral Pain’.
Blog Summary/Abstract
- Chondromalacia Patellae is outdated — The term “Chondromalacia Patellae” doesn’t explain the cause of knee pain, fails to guide treatment, and can create unnecessary anxiety for patients.
- Load distribution is key — Healthy patellofemoral joint function depends on optimal load distribution across joint surfaces, which minimizes wear and supports long-term joint health.
- ‘Quads Strength’ decreases joint load — Joint load = Force (kg) / contact area. If we can increase contact area (via quads strength) we can decrease joint load.
- Patella Alta and load-bearing — Conditions like Patella Alta, where the patella sits higher, reduce contact area and increase joint load, often leading to symptoms during high-stress activities. Patella Dysplasia also needs to be screened in those patients who aren’t progressing as expected.
- Bone-cartilage injuries (OCLs) affect long-term outcomes — Damage to the joint’s “dance floor” (cartilage and underlying bone) can lead to osteonecrosis and early osteoarthritis, emphasizing the importance of targeted rehab.
- Rethinking knee pain treatment myths — Common ideas like “Patella Maltracking” don’t fully address the issue; treatment success often lies in maximizing patella contact area rather than adjusting tracking.
Introduction
I’m going to get Meta about Floors and introduce a Dance Floor Metaphor.
Let’s talk about the ‘dance floor’ in your knee — the smooth cartilage behind your patella and the one in the trochlear groove of your femur.
The Dance Floor is a metaphor for the lovely hyaline cartilage that covers your weight bearing bones — which keeps the joints happy, healthy, and provides force absorption whilst you run and jump around.
Here is the catalyst for this blog:
I don’t like the term ‘Chondromalacia Patellae’.
Apart from the literal meaning of ‘abnormal softening of cartilage behind the patella’ it does very little to explain anything or provide any guidance on what we do.
‘Chondromalacia Patellae’ is a radiological term to describe radiological appearances which can have very little clinical meaning. The term itself looks very scary to patient, it’s sounds almost… cancerous. In fact, the term itself can be nocebic — a scientific word for “something sounds bad, therefore makes pain worse”.
It seems like the term was introduced in medical schools briefly and those who don’t work closely with the condition have little idea what it means either. I’ve been neck deep in the Patellofemoral pain literature for the past 10 years and not once did ‘Chondromalacia Patellae’ pop up in any meaningful way other than in a list of outdated nomenclature for Patellofemoral Pain. I just don’t get it, even if it was a thing how on earth are we meant to measure ‘softness’ of cartilage?
I was triggered recently listening to a poor uni student on placement who was asked by our team to present for us. They chose an old uni presentation on Chondromalacia Patellae, which included a whole bunch of outdated patellofemoral pain concepts such as ‘patella maltracking’, ‘q-angles’, ‘valgus’, ‘ITB tightness’ and all the rest.
Following their presentation I outlined the content of this blog to my team, which I’ll now present to you.
First — let’s get to know The Dance Floor.
The Dance Floor
A healthy and functional joint surface is like a dance floor.
It’s smooth, it’s shiny, and it bears weight millions of times over one’s lifespan, as long as it is maintained and kept polished.
I’m sure you can imagine if dancers used the entire dance floor, it’d wear out and lose its shine much less instead of dancers using one corner of the dance floor repeatedly.
A dance floor might have localised spots where it has worn out, lost its shine, and perhaps even have small pieces of it loose. Perhaps the dancers wore inappropriate shoes, with pointy soles, whilst they were dancing.
Yes, we can repair the rough and degraded dance floor — sanding it down, polishing it up, however inevitably there’d be less dance floor than before— even if it did appear smooth and shiny again.
Let’s take this metaphor and implant it into the patellofemoral joint by segueing via quick physics lesson.
Joint Load = Force / Contact Area
How much load goes through a weight-bearing joint depends on the force applied (example 80kg bodyweight) and how much that load is spread over the joint surface (contact area between two bones).
Increase the force, increase the joint load.
Increase the contact area, decrease the joint load.
For a dance floor, this means if we reduce loads through the floor and use as much of the dance floor as possible, it will preserve it better into the future.
Question for you — Which of these footwear will create more load if the dancers weighed the same?
Ice skates have very little contact area — sometimes with a high force, this is a big load. The load is so big that the way ice skates normally work is they melt the ice underneath them from pressure, the pressure creates heat, the heat melts the ice, this means ice skaters are skating on water.
We don’t want ‘ice skates’ on our dance floor because they focus a lot of force on a tiny area.
Instead, ‘boots’ spread the load across a bigger surface, reducing pressure on the joint.
Similarly, stronger knee extensors (quads) increase the contact area by pulling the patella deeper into its groove. More contact area means less joint load, even with the same force.
In short, the stronger your quads, the more they protect the ‘dance floor’ of your knee. Quads as a whole unit, not just VMO.
Too Little Dance Floor
Patellar Hypoplasia is incomplete growth of the Patella. (Hypo = Less/Incomplete, Plastic = Growth). This falls under the umbrella of ‘Patellar Dysplasia’ — abnormal growth of the kneecap.
Where there is less foundation (bone), there is less dance floor (cartilage).
Trochlea Dysplasia is where there is less dance floor on the opposite bone, the femur.
Up to 1 in 10 of us have Trochlear Dysplasia (DeVries, Bomar, & Pennock, 2021). 85% of those who’ve have recurrent wobbly kneecap episodes (patellofemoral instability) have Trochlear Dysplasia.
If there is too little dance floor, there is less contact area, joint loads are increased and in this case — due to the shape of the trochlear dance floor (a groove), it affects stability.
Dancing off the dance floor
Patella Alta (literally ‘North Patella’) is when the patients patella sits higher than normal (usually genetic). This causes less contact with the trochlea — essentially, the dancer is dancing off the dance floor.
Around 3% of the population has Patella Alta but may not notice it, especially if they don’t engage in high-intensity patellofemoral joint activities like heavy deep squatting, jumping sports, or hiking. However, among those with recurrent patellofemoral instability (‘wobbly kneecaps’), 24% have Patella Alta, making it a primary risk factor (Magnussen, De Simone, Lustig, Neyret, & Flanigan, 2014). A 21-year study on patella dislocations found that 15% of patients had Patella Dysplasia (Sanders et al., 2018).
Clinically, these patients are often surprised when their knee ‘blows up’ (swells in and around the patellofemoral joint) after a weekend hike. Although they don’t normally hike, they’re puzzled because their friends were fine. Yet, for some reason, their knee couldn’t tolerate the high volume of up-and-down loads from hiking. Similarly, a young adult might come in on Monday, complaining that their knee swelled up after a Saturday music festival, where they were moshing (jumping up and down).
In other words, seemingly tolerable activities that repeatedly irritate the patellofemoral joint, with or without a history of wobbly kneecaps, might signal they have Patella Alta — essentially, their patella is dancing off the floor. Recognizing this can change management and help set long-term expectations for recovery.
There’s a hole in the Dance Floor
Every dancer dreads the thought of a hole in the dance floor, especially if they’re dancing blind. They may not know exactly where it is, but they sense that something’s off — performance suffers, injuries follow, or things just don’t feel right.
An Osteochondral Lesion (OCL), which is a bone-cartilage injury, represents damage to both the dance floor and the solid foundation beneath it. On an MRI, this can appear as a distinct, well-localized area with fluid (bony oedema), or in severe cases, as a loose fragment sitting in a pothole. When that fragment shifts out of place, it’s called Osteochondritis Dissecans (‘dissecans’ comes from the Latin word meaning ‘to separate’), resulting in a ‘loose body’ inside the joint.
To put it bluntly, this is not an ideal situation. A ‘loose body’ inside the joint is far from ideal. It can cause dysfunction, pain, locking, and instability in the knee, and it significantly increases the risk of early-onset osteoarthritis.
For an undisplaced OCL, meaning the fragment is still in place, we can take a more conservative approach. In the acute to sub-acute phases (up to 6 months), we avoid loading the injured section of the dance floor. Since the patella and femoral trochlea engage with different parts of the dance floor at varying ranges of motion, we focus on strengthening the surrounding areas and avoid excessive strain on the injured region.
Clinically, we focus on building strength in the safer ranges, gradually reintroducing load to the injured area, and progressively conditioning it over time. This process takes patience — it can last up to 12 months — but it’s essential for full recovery and minimizing long-term complications. This also requires access to good assessment gear, such as an inline dynamometer that allows for max isometric testing in varying angles.
In short, while there’s a hole in the dance floor, we can work around it by strengthening and conditioning the other areas, ensuring the dancer can eventually glide across the entire floor without risk.
Dance Floor Foundations
Above all, we’re trying to protect the dance floor’s foundations — specifically, the subchondral bone (the bone beneath the cartilage).
On an MRI, damage to these foundations will show up as a “glow,” representing excess fluid or water content in the subchondral bone. This indicates that the dance floor above, whether there’s an Osteochondral Lesion (OCL) or not, isn’t doing its job properly. If the cartilage is compromised, the underlying bone gets overworked and starts to suffer.
If this process continues unchecked, it can lead to osteonecrosis (literally, “death of bone”). And without solid foundations, there’s no dance floor to support movement. The last thing we need is for the bone near a weight-bearing surface, like the knee joint, to weaken — this can lead to joint collapse over time, which inevitably results in the need for a knee replacement.
In Orthopaedics the Sperner Classification system is sometimes used grading articular cartilage defects/changes based on MRI radiology (Browne & Branch, 2000):
- Grade 0: Normal articular cartilage
- Grade I: Softening, blistering or swelling of the cartilage
- Grade II: Partial thickness fissures and clefts <1 cm diameter
- Grade III: Full thickness fissures, to subchondral bone >1 cm diameter
- Grade IV: Exposed subchondral bone
However during a trial of conservative management, the stage they are at on Radiology won’t change management decisions too much (unless there is a significant osteochondral lesion or dissecans), but it can help set expectations and timeframes for the patient.
It’s also important to note here that it has been reported (Horga et al., 2020) up to 50–60% of people without pain (asymptomatic) have significant ‘changes’ in their cartilage (25% with Grade IV changes) and sub-chondral bone.
A tip for Clinicians organising an MRI. If you suspect that the MRI might demonstrate subtle signals for a patient, if it’s safe to do so, recommend that patient exercises or trains in the lead-up to the MRI so any subtle signals are increased so findings are more obvious. This is better achieved with patients who are active but get persistent, predictable but tolerable anterior knee pain flare-ups. These patients are usually happy to do this.
Patella Maltracking
You may have noticed I haven’t mentioned ‘Patella Maltracking’ in this blog — that old idea (but still taught in some universities) where the primary cause of patellofemoral fain is the patella ‘tracking’ laterally (to the outside) instead of up and down in the centre of its groove. It’s supposedly then targeted by taping it medially (McConnels Taping), or stretching the ITB while strengthening the VMO. To keep this bit brief: you can’t lengthen the ITB, and you can’t isolate the VMO so the concept is flawed from beginning to end. I’ll leave the debunking of this maltracking theory to the scientific heavyweights.
But I will say this: experts have observed that even when McConnell’s Taping accidentally pulls the patella further into “maltracking”, it still seems to help. Why? Maybe because it’s not about where you dance on the dance floor — it’s about how much of the dance floor you use.
Summary
As you can see, the term Chondromalacia Patellae doesn’t provide much insight into knee pain, nor does it help guide management. It also sounds scarier than it needs to be, which can create unnecessary fear — a phenomenon known as nocebic language, which can actually worsen pain and dysfunction.
We have two wonderful joint surfaces (dance floors) in the patellofemoral joint. The better these surfaces contact each other, the more evenly they distribute load, and the happier the joint will be. In other words, we want ‘boots’ on our dance floor, not ‘ice skates.’
Increasing contact between the patella and the femoral trochlea spreads the load and leads to a happier joint, regardless of “patella tracking”. However, the Clinician needs to rule out reasons why (Patella Dysplasia, Osteochondral Lesions etc.) the Patient wouldn’t tolerate loads that others would — and why they aren’t progressing in rehab as well as others.
So, after reading this blog, do you still find the term “Chondromalacia Patellae” valid, relevant or useful in any meaningful way?
Did you enjoy this blog or learn something new that will help you with your clinical practise?
Are you a patient and has this helped you in some way?
‘Buy Me A Coffee’ to say thanks and help me continue to be motivated to share everything I’ve learned in the clinic with the world for free.
References
Almeida, G. P. L., das Neves Rodrigues, H. L., Coelho, B. A. L., Rodrigues, C. A. S., & de Paula Lima, P. O. (2021). Anteromedial versus posterolateral hip musculature strengthening with dose-controlled in women with patellofemoral pain: A randomized controlled trial. Physical Therapy in Sport, 49, 149–156.
Browne, J. E., & Branch, T. P. (2000). Surgical alternatives for treatment of articular cartilage lesions. JAAOS-Journal of the American Academy of Orthopaedic Surgeons, 8(3), 180–189.
DeVries, C. A., Bomar, J. D., & Pennock, A. T. (2021). Prevalence of Trochlear Dysplasia and Associations with Patellofemoral Pain and Instability in a Skeletally Mature Population. JBJS, 103(22), 2126–2132. doi:10.2106/jbjs.20.01624
Farr, S., Huyer, D., Sadoghi, P., Kaipel, M., Grill, F., & Ganger, R. (2014). Prevalence of osteoarthritis and clinical results after the Elmslie-Trillat procedure: a retrospective long-term follow-up. International orthopaedics, 38, 61–66.
Horga, L. M., Hirschmann, A. C., Henckel, J., Fotiadou, A., Di Laura, A., Torlasco, C., . . . Hart, A. J. (2020). Prevalence of abnormal findings in 230 knees of asymptomatic adults using 3.0 T MRI. Skeletal radiology, 49, 1099–1107.
Magnussen, R. A., De Simone, V., Lustig, S., Neyret, P., & Flanigan, D. C. (2014). Treatment of patella alta in patients with episodic patellar dislocation: a systematic review. Knee Surgery, Sports Traumatology, Arthroscopy, 22, 2545–2550.
Sanders, T. L., Pareek, A., Hewett, T. E., Stuart, M. J., Dahm, D. L., & Krych, A. J. (2018). Incidence of first-time lateral patellar dislocation: a 21-year population-based study. Sports health, 10(2), 146–151.
Uimonen, M., Ponkilainen, V., Paloneva, J., Mattila, V. M., Nurmi, H., & Repo, J. P. (2021). Characteristics of osteochondral fractures caused by patellar dislocation. Orthopaedic Journal of Sports Medicine, 9(1), 2325967120974649.
