patellofemoral pain

This is the dull ache felt right at the front of the knee, around or behind the kneecap, that flares with stairs, squatting, kneeling, or sitting with the knee bent for a long time (the so-called 'theatre sign'). It is extremely common in active young people, especially runners — hence the nickname 'runner's knee' — and it is one of the most frequent knee complaints seen without any single dramatic injury.

The kneecap (patella) glides in a groove at the end of the thigh bone every time you bend and straighten the knee. Patellofemoral pain arises when the kneecap's tracking and the load on its joint surface are disturbed — by overload (a sudden jump in running volume), or by how the whole leg lines up and moves under load: weak or poorly timed hip and thigh muscles, the knee collapsing inward, tight tissues, or foot mechanics. It is usually a load-and-movement problem of an otherwise healthy joint, not structural damage; importantly, despite older theories, it is generally not caused by the kneecap being permanently 'out of place', and cartilage softening behind the kneecap (chondromalacia) is a related but separate finding.

Because the problem is mechanical and behavioural, rehabilitation is the main treatment and works well for most people. The core is exercise — strengthening the hip and thigh muscles (the quadriceps and the gluteal muscles that control the leg's alignment) and retraining movement patterns like squatting and landing — combined with sensibly managing training loads, and sometimes taping, bracing, or foot orthoses as short-term aids. The reassuring point is that this is generally a benign, treatable condition, not a sign the knee is being destroyed.