Patient question
Why do I feel grinding under my kneecap?
Dr. Pablo GelberOrthopaedic Knee Surgeon
Quick answer
Grinding under the kneecap usually comes from the back of the kneecap gliding over a slightly roughened or irritated cartilage surface. With no pain it is often harmless, but grinding plus aching on stairs or after sitting suggests patellofemoral pain or softened cartilage, says Dr. Pablo Gelber, knee surgeon at Aman Hospital, Doha.
What you are feeling
The kneecap sits in a groove at the end of the thigh bone, and both surfaces are covered with smooth cartilage. When you bend the knee under load, such as on stairs, squats or standing up from a low seat, the pressure between them rises. If the surfaces are a little uneven, or the kneecap is pulled slightly to one side, you can feel or hear a fine crunching. Doctors call this patellofemoral crepitus.
You can often feel it by resting a hand on the kneecap while you bend and straighten. Feeling it does not mean the cartilage is wearing away.
Common causes
- Patellofemoral pain, common in runners, teenagers and people who increase training quickly
- Chondromalacia patella, a softening of the cartilage behind the kneecap
- Arthritis behind the kneecap in older adults, often with stiffness and aching
- A kneecap that tracks off-centre, sometimes after previous dislocation
- An old injury to the cartilage from a direct fall onto the knee
What helps
Grinding responds well to reducing load on the kneecap while making the muscles around it stronger. Cut back on deep squats, lunges, kneeling and long stair sessions for a few weeks. Keep moving with cycling at a comfortable resistance, swimming or flat walking.
A physiotherapy programme for the quadriceps and hip muscles is the main treatment and often reduces both the pain and the sensation. Losing some weight, if relevant, noticeably lowers pressure behind the kneecap. When sitting for long periods at a desk, in the car or on a flight, straighten the leg every so often.
When to see a specialist
Book an assessment if the grinding comes with pain that lasts more than a few weeks, swelling, catching, or the kneecap feeling unstable. Seek prompt care if the kneecap has slipped out of place. At Aman Hospital in Doha, Dr. Gelber examines the kneecap's tracking and the cartilage behind it, and an X-ray or MRI is used when it will change the plan.
Frequently asked questions
Does knee grinding mean I will need a knee replacement?
No. Most people with kneecap grinding never need surgery. Even when there is early cartilage wear, strengthening and load management usually keep the knee working well for many years.
Is stair climbing bad if my kneecap grinds?
Stairs are not harmful, but they load the kneecap. If they hurt, use the handrail, take one step at a time for a while and focus on strengthening, then build back up.
Can injections help kneecap grinding?
Injections are not a first step for grinding. In selected patients with arthritis behind the kneecap they may be considered after physiotherapy, and that depends on examination.
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