Can it be possible for standing too long to cause chondromalacia patella?

Possible: You likely already have chondromalacia patella and the standing too long is causing an increase in your symptoms. Chondromalacia patella (runners knee) is due to overload of the patellofemoral joint (knee cap against the end of the thigh bone). Running caused high forces in this portion of the joint. So does arising from a chair, going up/down stairs.