Hi Knee pain,

The idea of referred pain is now apparently old-fashioned.

But referred pain is very common.
You mentioned a previous Sacroiliac (S/I) joint problem. The most common referred pain from the S/I joints is groin pain.

But S/I problems are invariably associated with lower back problems, usually L4,5,S1,2. Leg symptoms are frequent from this area.

In my experience anterior quadriceps pain and medial knee pain are from T12, L1 and 2.
Hamstring, posterior knee, calf and foot pain are often / usually from L5, S1, 2, 3.

"Excessive" activity will aggravate all of these whilst sitting in deep seats and prolonged standing will always make things worse.

So treatment has to be to the areas shown above. Treating the symptoms can give you short term relief only.

Good luck.

Tony Woodall
Physiotherapist Retired.