Chondromalacia patella means the cartilage on the back of the kneecap looks softened, roughened or thinned on an MRI, and reports grade it from 1 to 4. It is a description of the cartilage, not a measure of how much the knee hurts: the same changes are common in knees that have never been painful, and people with kneecap pain and people without it show the same findings on scans. The grade matters less than how the knee behaves on stairs, in squats and after sitting.
Assessing and treating knee pain at the Burlington clinic. Convenient for Waterdown, Oakville, Hamilton, Flamborough, and Carlisle residents.
When to see a doctor firstBroader Knee Pain GuideThe cartilage behind the kneecap. The underside of the kneecap is covered with a thick layer of cartilage that glides in a groove on the thigh bone. Chondromalacia literally means soft cartilage. On an MRI the radiologist looks for changes in that layer’s signal, surface and thickness, and reports what they see with a grade.
The grades. Most reports use a four-step scale adapted from a classification first written for what surgeons saw at operation (Outerbridge, 1961). The MRI version is read from the images, so it is an estimate of the same stages.
| On the report | What it means |
|---|---|
| Grade 1 | Signal change or softening in the cartilage with the surface still intact. |
| Grade 2 | Surface roughening, fraying or fissures that reach less than halfway through the cartilage thickness. |
| Grade 3 | Fissures or thinning that go more than halfway through, without exposing bone. |
| Grade 4 | Full-thickness loss, with bone exposed in that spot. |
| Medial or lateral facet, apex, trochlea | Which part of the kneecap surface, or the groove on the thigh bone opposite it, is involved. |
| Focal defect, fissure, delamination | The shape of the change: a small pit, a crack, or a flap lifting from the bone. |
| Subchondral bone marrow edema | Bright signal in the bone just under the cartilage. The bone marrow edema guide covers what that does and does not mean. |
| Patellar tilt, lateral subluxation, trochlear dysplasia | How the kneecap sits in its groove and how deep the groove is. These are descriptions of shape, and many people with them have no pain. |
| Hoffa fat pad edema | Bright signal in the fat pad below the kneecap. It was as common in people without kneecap pain as in people with it (van der Heijden et al., 2016). |
A hot, red, swollen knee, with or without fever
Same-day medical assessment to rule out infection, or go to emergency if you feel unwell.
A knee that locks in one position, or that you cannot fully straighten after a twist
Same-day medical assessment. A loose fragment or a displaced meniscus tear needs to be ruled out.
A kneecap that has visibly slipped out of place, or a knee that gave way with a pop and swelled quickly
Get medical assessment today; a dislocation or a ligament injury needs to be checked before rehabilitation.
Knee pain in a child or teenager with a limp, or hip or groin pain alongside it
See your family doctor first. Knee pain in young people can come from the hip.
Pain at night that does not settle, unexplained weight loss, or a history of cancer
See your family doctor for a medical review before starting physiotherapy.
Cartilage changes are common in knees that do not hurt. Across 63 studies of uninjured adults with no knee symptoms, 24 percent had a cartilage defect on MRI, rising to 43 percent over the age of 40 (Culvenor et al., 2019). In 230 knees of asymptomatic adults scanned at 3 tesla, cartilage abnormalities at the kneecap joint were found in 57 percent, and moderate or severe lesions were not rare (Horga et al., 2020).
People with kneecap pain and people without it look alike on MRI. In a study of 64 young adults with patellofemoral pain and 70 without, minor patellar cartilage defects were found in 23 percent of the patients and 21 percent of the controls, and no structural finding was linked with having the pain once age, sex, weight and sport were accounted for (van der Heijden et al., 2016). Chondromalacia on the report is not the explanation for the pain in most people.
The grade is not a pain score. Cartilage has no nerve supply of its own. The grade describes the surface, and a knee with a grade 2 change can hurt more than a knee with a grade 3 change. What tends to decide the pain is how much load the kneecap joint is taking relative to what it is currently used to.
It is not the same as arthritis of the knee. Chondromalacia describes cartilage at one joint surface. Patellofemoral osteoarthritis is a wider picture that includes bone changes, and most knees with chondromalacia on a report in a younger adult are not arthritic.
It is not expected to grow back. Cartilage has a limited ability to repair, and no routine treatment restores it. Pain and function improve without the scan changing, which is why follow-up scans are not part of the usual plan.
The force pressing the kneecap into its groove rises steeply as the knee bends under load. Stairs, squatting, lunging and running produce several times the kneecap joint force of level walking, and sitting with the knee bent for a long time loads the same surface at rest (Hart et al., 2022). That is why these are the activities people with kneecap pain name first, and why the plan works on the load rather than on the cartilage.
How much load the joint tolerates depends on the strength of the muscles around it, particularly the quadriceps and the hip, on how the knee lines up in those movements, and on how quickly the activity was increased. Those are the parts a plan can change.
Chondromalacia on a report is treated as patellofemoral pain is treated, and the research on that is consistent.
I start with when the knee hurts and what changed before it started: stairs, hills, squats, a new training block, long sitting. Then I examine the knee for swelling and range of motion, watch how it lines up on a step-down and a single-leg squat, and test quadriceps and hip strength. I screen the hip and the back, because pain at the front of the knee can be referred from the hip, particularly in younger people.
The plan is strengthening for the quadriceps and hip, progressed from positions the kneecap tolerates to the deeper bends you need, with the provoking loads trimmed at first and rebuilt. Taping is an option for pain in the early weeks. Running or sport continues wherever it can be kept below the level that flares the knee for the next day. The MRI grade does not set the program; what the knee can do today does.
If something on the report or in the examination points elsewhere, such as a loose fragment, a true dislocation or a problem in the hip, I say so and send you to your family doctor or specialist. I cannot order imaging; when further imaging would change the plan, I flag it and refer you.
Roughening or fissures in the cartilage behind the kneecap that reach less than halfway through its thickness. It is a description of the surface, not of the pain, and it is a common finding in knees that have never hurt.
No. It describes cartilage at one joint surface. Patellofemoral osteoarthritis is a broader picture with bone changes as well, and most younger adults with chondromalacia on a report do not have arthritis.
Cartilage has a limited ability to repair, and no routine treatment restores it. Pain and function usually improve with strengthening and load management without the scan changing, so follow-up scans are not part of the usual plan.
Usually not altogether. These movements load the kneecap joint heavily, so the depth and the amount are trimmed to what the knee tolerates and rebuilt as the quadriceps and hip get stronger. Avoiding them for long tends to make the knee less able to handle them.
Surgery to smooth the cartilage did not add anything to exercise in a randomised trial of long-standing patellofemoral pain, and the guidelines do not recommend it for this problem. A surgical opinion is for specific situations such as a loose fragment or a kneecap that dislocates.
Running loads the kneecap joint more than walking, and a quick increase in running can set off kneecap pain. The cartilage changes themselves are common in runners and non-runners alike and are not a reason to stop running once the knee is coping.
Because the grade and the pain are measuring different things. Grade 1 is a mild cartilage change that many painless knees share. The pain usually comes from the joint being asked to take more load than it is currently conditioned for, and that is what treatment addresses.
The main sources behind this guide. Other studies are named in the text where they are used.
1961 Outerbridge RE, Journal of Bone and Joint Surgery (British)
The original four-grade description of cartilage change behind the kneecap, written from what was seen at operation. MRI grading is adapted from it.
2019 Culvenor AG et al., British Journal of Sports Medicine
63 studies, 5,397 knees. Cartilage defects in 24 percent of symptom-free, uninjured adults overall, 11 percent under 40 and 43 percent at 40 and over.
2020 Horga LM et al., Skeletal Radiology
Cartilage abnormalities at the kneecap joint in 57 percent of painless knees; moderate and severe lesions were common.
2016 van der Heijden RA et al., American Journal of Sports Medicine
64 patients and 70 controls. Minor cartilage defects, patellar bone marrow lesions and fat pad signal were equally common in both groups, and no finding was associated with having the pain.
2015 van der Heijden RA et al., Cochrane Database of Systematic Reviews
Exercise reduced pain and improved function compared with no exercise, with hip plus knee programs doing better than knee programs alone; the certainty of the evidence was low.
2018 Collins NJ et al., British Journal of Sports Medicine
International consensus: combined hip and knee exercise is recommended; foot orthoses and tailored taping can help in the short term; electrotherapy is not recommended.
2019 Willy RW et al., Journal of Orthopaedic & Sports Physical Therapy
Guideline. Exercise combining hip and knee strengthening, tailored taping for short-term pain relief, and a recommendation against braces, sleeves, straps and electrotherapy.
2007 Kettunen JA et al., BMC Medicine
Adding arthroscopy to a home exercise program gave no better outcome than exercise alone at nine months, at higher cost.
2022 Hart HF et al., British Journal of Sports Medicine
Systematic review of kneecap joint force across activities: deeper knee bends under load, such as stairs, squats and running, produce several times the force of level walking.
Condition pages for the problems that usually sit behind a report that mentions chondromalacia.
The core is strengthening and load management. These are the pieces that fit around it.
I see patients for knee pain at Endorphins Health & Wellness Centre in Burlington. The clinic serves people coming in from Burlington, Waterdown, Oakville, Hamilton, Flamborough, and Carlisle, with free parking on site and a ground-floor entrance.
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