Patellofemoral Pain Syndrome (Runner's Knee)
This is the most common cause of knee pain in active adults. Your kneecap (patella) should glide smoothly in a groove on your thigh bone. When it tracks off-center due to muscle imbalances or hip weakness, the cartilage underneath gets overloaded. Think of it like a train being pulled off its tracks: the problem isn't the train, it's the forces acting on it.
| Feels like | Dull, aching pain behind or around the kneecap; hard to pinpoint exactly |
|---|---|
| Worse with | Going down stairs, prolonged sitting with knees bent (the "theater sign"), squatting, running downhill |
| Better with | Keeping the leg straight, gentle movement after sitting, avoiding deep knee flexion |
| Key insight | Descending stairs hurts more than climbing because your quad has to control gravity while your kneecap is compressed against the femur. (Lexington Physio, 2023) |