Overview

The patellofemoral joint is a very complex joint at the front of the knee, formed by two bones: the patella (kneecap) and the front portion of the femur (thigh bone), just beneath the kneecap. The patella sits within a groove on the femur known as the trochlea, and this joint relies on a delicate interplay of muscles, tendons, ligaments, and bony anatomy to function correctly. A problem with any one of these components can lead to pain and instability around the patellofemoral joint.

What is Patellofemoral Pain Syndrome (PFPS)?

Patellofemoral Pain Syndrome is a common condition causing pain at the front of the knee, affecting athletes and non-athletes, and men and women of all ages. It's sometimes referred to as chondromalacia patella or patellofemoral disorder — these terms are used interchangeably with PFPS or anterior knee pain.

What causes Patellofemoral Pain Syndrome (PFPS)?

The exact cause of anterior knee pain isn't fully understood, but it's commonly linked to overloading of the patellofemoral joint, particularly in people who take part in sports involving running or jumping, such as tennis, football, or badminton.

It can also affect non-athletes, often due to softening of the cartilage behind the kneecap (chondromalacia patella), which means that even normal, everyday forces through the knee can begin to cause pain.

A number of factors may contribute to anterior knee pain, including:

  • Abnormal movement or tracking of the patella
  • Weakness in the surrounding muscles
  • Poor gait or training errors
  • Tightness in surrounding structures, such as the iliotibial (IT) band
  • Previous injury to the front of the knee

Symptoms

Patellofemoral pain syndrome typically presents as a dull, aching pain around or behind the kneecap, often creeping in gradually rather than following a specific injury. Common symptoms include:

  • Pain that worsens with squatting, kneeling, or climbing stairs
  • Discomfort after prolonged sitting with the knee bent (the classic "moviegoer's knee")
  • A grinding or grating sensation when bending or straightening the knee
  • Mild swelling around the kneecap
  • Pain that flares with running, jumping, or other repetitive knee-loading activities

Symptoms are usually gradual in onset and tend to worsen with activity, easing with rest — though without addressing the underlying cause, they often become a recurring, nagging problem.

Treatment 

Physiotherapy is the cornerstone of treatment if the problem is due to muscle weakness or gait imbalance. A structured program targeting hip, thigh, and core strength — along with flexibility and movement retraining — helps correct the mechanics that overload the kneecap. Most people improve significantly without any need for surgery.

Many people notice improvement within 6 to 8 weeks of consistent physical therapy, though full resolution can take a few months, especially for symptoms that built up gradually over a long time. Consistency with the exercise program tends to matter more than any single quick fix.

Surgery is only indicated if there is a significant mal-tracking or anatomical problem or if after assessment, we find a different cause for the pain such as patella-femoral cartilage damage or osteoarthritis

Frequently asked questions

Usually not entirely — complete rest isn’t typically necessary and can even make it harder to rebuild strength. Most people benefit more from adjusting training load (reducing mileage, avoiding hills or stairs temporarily) while building strength, rather than stopping activity completely.

The pain has some very recognisable triggers, since it’s driven by load on the kneecap:

  • Stairs — especially going down, which loads the kneecap the most.
  • Squatting — deep bends increase pressure behind the kneecap.
  • Prolonged sitting — aching after sitting with a bent knee, sometimes called the “movie sign”.
  • Running — symptoms often build gradually with mileage or hills.

Programmes typically focus on strengthening the quadriceps (especially the inner thigh muscle) and hip muscles — particularly the glutes, which help control how the knee tracks during movement. Stretching tight structures like the IT band or calf muscles is often included too. A physiotherapist can tailor this to your specific movement patterns.

PFPS is primarily a pain condition — the kneecap generally stays in place, it just hurts, often due to overload rather than structural damage. Patella instability involves the kneecap actually shifting or slipping out of its groove. A cartilage injury involves physical damage to the joint surface. These can sometimes overlap, which is why a proper examination matters.

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