Your Knee Has a Pothole. Here’s What That Means.

Posted on: November 2nd, 2026 by Our Team

Cartilage damage shows up on a lot of MRIs. Whether it matters depends on far more than the picture.

Patients often come to my office holding an MRI report with one word circled: cartilage. Sometimes it sits next to “defect” or “lesion” or “chondral injury,” and the person across from me wants to know one thing: Is my knee wearing out?

The honest answer is usually that it depends. Most people have heard of cartilage, but few know what it actually does, and that gap can make a report sound scarier, or sometimes less serious, than it really is.

The simplest way I’ve found to explain it is to talk about a road.

A freshly paved street

The ends of the bones inside your knee are capped with a layer called articular cartilage. When it’s healthy, it works like new pavement: smooth, slick and built to let the bones glide past each other with almost no friction. It lets the knee bend, straighten, pivot and absorb the force of every step, landing and staircase.

It is a remarkable material. It is also a poor healer. Cartilage has almost no blood supply, so when it’s damaged it doesn’t mend the way skin, muscle or even bone does. A cut on your hand closes in a week. A gouge in your cartilage may still be there years later.

So when cartilage is injured, think of it as a pothole.

One pothole isn’t a ruined road

A small pothole may barely register. You roll over it and keep going. A bigger one jolts the car every time you hit it. Let it deepen and it starts eating into the roadbed underneath, and the edges begin to crumble.

That brings me to the most important distinction I make with patients: A cartilage injury is not the same thing as arthritis.

A focal cartilage defect is one pothole in an otherwise good street. Arthritis is a neighborhood where the pavement has worn thin everywhere, with cracks, rough patches and holes on every block. A 22-year-old soccer player with a single defect from a hard landing may have pristine cartilage across the rest of the knee. A 60-year-old with decades of gradual wear has a different problem, and usually needs a different solution.

The MRI doesn’t tell the whole story

Here is something that surprises many people: Cartilage damage on an MRI doesn’t necessarily hurt. Plenty of people have defects on their scans and little or no pain. Others have a modest-looking injury that keeps them off the court for months.

That’s because an MRI shows anatomy, not pain. To figure out whether a defect is actually causing someone’s symptoms, I look at how big it is and how deep it goes, where in the knee it sits, whether the bone beneath it is healthy, and what shape the meniscus, ligaments and alignment are in. Then I put all of that next to what the patient tells me and what I find on examination. The scan is one piece of evidence. It isn’t the verdict.

When the damage goes deeper

Cartilage sits on bone. A shallow injury may stay a surface problem. A deeper one can reach the bone underneath, the way a pothole that breaks through the asphalt starts damaging the foundation. That is a bigger repair.

Symptoms vary, but people with a troublesome defect often describe swelling after activity, pain with impact, a catching sensation, or aching with stairs, squatting, running or long periods on their feet.

Why alignment matters

If every truck on a highway drives in the same lane, that lane wears out first. You can patch the pothole, but the trucks keep coming.

Knees work the same way. Few legs are perfectly straight. If someone’s alignment puts extra load on the inner side of the knee, and that’s exactly where the cartilage defect is, repairing the cartilage alone may only buy time. The new surface takes the same beating as the old one.

So a good cartilage evaluation asks a second question beyond what’s damaged: Why did this spot get overloaded in the first place? Sometimes the answer involves correcting the alignment itself with an osteotomy, a procedure that shifts weight toward the healthier side of the joint.

The shock absorber

The meniscus, a pair of rubbery, C-shaped cushions between the thighbone and shinbone, is the knee’s shock absorber. When a meniscus is torn, partly removed or pushed out of position, more force lands directly on the cartilage beneath it.

That’s why cartilage, meniscus and alignment problems have to be evaluated together. Treat one in isolation and you can miss the reason it failed.

Can cartilage be fixed?

Sometimes, and not always with surgery. Many cartilage injuries improve with physical therapy, strengthening, better movement patterns, changes in activity, weight management when it applies, or injections in select cases.

For people with a focal defect that keeps causing symptoms despite those measures, there are surgical options. Some stimulate the body to fill the defect with repair tissue. Some move a plug of healthy cartilage and bone from a less critical part of the knee into the damaged spot. Some use donor tissue to resurface a larger area. Others grow the patient’s own cartilage cells in a lab and implant them into the defect.

Which one fits depends on the patient’s age and goals, the size, depth and location of the defect, the health of the surrounding cartilage and bone, and the condition of the meniscus, ligaments and alignment. No single cartilage operation is right for everyone.

Understand the road

A cartilage injury is more than “something abnormal on an MRI.” Before deciding what to do, I want to know how big the pothole is, how deep it goes, where it sits, what the rest of the road looks like, and why traffic keeps hitting that one spot.

Answering those questions takes the patient’s story, a careful exam, the imaging, the person’s activity goals and the mechanics of the whole knee. The aim isn’t to treat the picture. It’s to understand the knee.