Ask somebody with knee pain what they find difficult and stairs come up more often than anything else. Ask them which direction is worse and the answer is almost always the same. Down. That surprises people, because going up feels like the effort. You are lifting your body weight against gravity, you get breathless, it seems obviously harder.
And yet the knee complains on the way down.
There is a symptom that identifies this condition more reliably than almost any test. Sitting with your knee bent for a long period hurts. A long car journey. A flight. A cinema. You get out stiff and sore at the front of the knee, and you find yourself straightening the leg out or shifting position to relieve it.
Combine that with pain just below the kneecap that warms up during activity and is worse the next morning, and you have the characteristic picture of patellar tendinopathy.
A child complains of knee pain. Somebody says growing pains. Everybody moves on.
Sometimes that is right. A great deal of knee pain in children and adolescents is related to growth and activity, is self limiting, and settles with sensible management. And occasionally it is not, including one scenario where knee pain is not coming from the knee at all and needs urgent attention. Here is how to tell the difference.
