Patellofemoral Arthritis
Arthritis of the joint between the kneecap and thigh bone
Quick Facts
- Type: Joint (cartilage) condition
- Main area: Front of the knee, behind the kneecap
- Typical pain triggers: Stairs, squatting, kneeling, prolonged sitting
- Common in: Adults over 40, athletes with past kneecap injuries
Overview
Patellofemoral arthritis is the loss of the smooth cartilage that normally lets the kneecap (patella) glide painlessly against the groove at the front of the thigh bone (femur). This part of the knee is called the patellofemoral joint. When the cartilage thins and roughens, the surfaces no longer slide smoothly, leading to pain, grinding, and stiffness at the front of the knee.
It is one form of knee osteoarthritis, but it specifically affects the kneecap compartment rather than the inner or outer parts of the joint. Many people have patellofemoral arthritis alone, while others have it together with arthritis elsewhere in the knee. With the right combination of exercise, weight management, and activity changes, most people manage symptoms well without surgery.
Symptoms
The hallmark is a dull or aching pain at the front of the knee that gets worse with activities loading the kneecap.
- Pain going up or especially down stairs and inclines
- Pain when squatting, kneeling, or rising from a low chair
- Aching after sitting for a long time with the knee bent (sometimes called the "theater sign")
- Grinding, clicking, or a catching sensation behind the kneecap
- Stiffness and a feeling that the knee may give way
- Mild swelling around the kneecap after activity
Symptoms often build slowly over months or years and tend to flare with heavy use.
Causes
Patellofemoral arthritis develops when cartilage in the kneecap groove wears down. Contributing factors include:
- Aging and general wear: Cartilage naturally thins over time, as with osteoarthritis elsewhere.
- Past kneecap injury: A fracture, a dislocation, or repeated dislocations can damage the joint surface and speed up arthritis.
- Poor kneecap tracking: If the kneecap does not glide centrally in its groove, pressure concentrates on one area and wears the cartilage unevenly.
- Shape of the groove: A shallow or abnormally formed groove (trochlear dysplasia) raises long-term risk.
Long periods of high load through the front of the knee, such as heavy squatting or kneeling work, can also contribute over many years.
Risk Factors
- Age over 40
- Previous kneecap dislocation or fracture
- A history of chondromalacia patella or patellofemoral pain syndrome
- Being overweight, which increases force across the kneecap
- Weak thigh (quadriceps) and hip muscles
- A shallow trochlear groove or kneecaps that sit too high
- Repetitive kneeling, squatting, or jumping sports
Diagnosis
A clinician diagnoses patellofemoral arthritis from your history, an examination, and imaging.
- Physical exam: Checking where the pain is, how the kneecap tracks, and whether pressing or moving the kneecap reproduces pain and grinding.
- X-rays: A special skyline or sunrise view taken with the knee bent shows narrowing of the space behind the kneecap, bone spurs, and how the kneecap sits in its groove.
- MRI: Used occasionally to see cartilage detail or rule out other causes of front-of-knee pain.
Treatment
Most people are treated without surgery. The goals are to reduce pain, strengthen the muscles that support the kneecap, and lower the load on the joint.
- Exercise and physical therapy: Strengthening the quadriceps (especially the inner part), hips, and core helps the kneecap track better and shares load away from the worn surface. Low-impact aerobic exercise such as cycling on a high seat or swimming is encouraged.
- Activity changes: Reducing deep squatting, kneeling, and stair use during flares, and pacing demanding activities.
- Weight management: Even modest weight loss meaningfully reduces force across the kneecap.
- Pain relief: Acetaminophen or anti-inflammatory medicines (oral or topical) for flares, used as advised by a clinician.
- Bracing and taping: A patellar brace or taping can ease pain for some people during activity.
- Injections: Corticosteroid injections may give temporary relief for stubborn flares.
If pain is severe and persistent despite these measures, surgical options range from arthroscopic clean-up to realignment procedures or, in advanced cases, partial or total knee replacement. Surgery is generally a last resort.
Prevention
- Keep the quadriceps, hip, and core muscles strong
- Maintain a healthy body weight
- Warm up and progress training loads gradually in jumping or squatting sports
- Address kneecap dislocations or front-of-knee pain early rather than ignoring them
- Choose low-impact cross-training to protect the joint
- Use good technique and supportive footwear for repetitive kneeling work
When to See a Doctor
See a clinician if you have front-of-knee pain that lasts more than a few weeks, limits stairs or activity, or keeps returning. Seek prompt medical care if the knee suddenly becomes very swollen, hot, and red, if you cannot bear weight or straighten the knee, if it locks or gives way repeatedly, or if symptoms follow a significant injury. These may point to a different or more serious problem.
Frequently Asked Questions
What is the difference between patellofemoral arthritis and general knee arthritis?
Patellofemoral arthritis specifically affects the joint between the kneecap and the thigh bone at the front of the knee. General knee arthritis can also involve the inner or outer compartments. The patellofemoral type tends to hurt most with stairs, squatting, and rising from sitting.
Can I still exercise with patellofemoral arthritis?
Yes, and staying active usually helps. Low-impact options such as cycling with a high seat, swimming, and strength training for the thigh and hip muscles reduce pain and improve function. It is best to limit deep squats, lunges, and prolonged kneeling during flares.
Does patellofemoral arthritis always need surgery?
No. Most people manage well with exercise, weight management, activity changes, and pain relief. Surgery, including realignment or partial or total knee replacement, is considered only when pain is severe and other treatments have not helped.
Why does my knee hurt more going down stairs than up?
Descending stairs loads the kneecap with a large bending force while the muscles work to control the movement, which presses the worn cartilage surfaces together. This is a classic feature of patellofemoral problems and often improves with quadriceps and hip strengthening.
References
- American Academy of Orthopaedic Surgeons (AAOS). Arthritis of the Knee.
- Mayo Clinic. Osteoarthritis — Symptoms and causes.
- Arthritis Foundation. Osteoarthritis.
- MedlinePlus, U.S. National Library of Medicine. Osteoarthritis.