In a proper rotation deformity the most common situation is that you come off your motorbike, you fracture your femur, and it unites malrotated.
Then you need to have the femur derotated back to a normal position to either settle the problem down, perhaps in association with a var-ising or valg-ising osteotomy in the coronal plane with a sagittal correction, or to make a knee replacement work. Basically, if someone’s got a very rotated femur and you try to put in a knee replacement without addressing the rotational element it can go wrong.
The same applies to the hip as well. If there is a proximal femoral problem sometimes we do a derotation osteotomy at the hip to sort the femur out so that you get the right rotation. But it’s quite an uncommon problem.
This 'miserable malalignment' is someone who is typically female, 20+, they have valgus alignment of the legs. They have more valgus than the average person so it’s not a deformity they have but an increased valgus alignment of their legs. Their patellae often face each other – kissing patellae – and their tibial tubercles are too far displaced laterally. Usually they are slightly overweight, they are valgus, they have increased Q angles with laterally placed tibial tubercles – the whole lot is trying to take the patella off to the side the whole time.
The pain issue makes it a completely different problem to patellofemoral instability. If you look at individuals who have presented their series of say Elmslie-Trillat realignment procedures they do very well for instability but they don’t do well for pain. Miserable malalignment is different from having a rotational deformity. So what we need to do is almost educate people that it is a series of different elements that make people have pain when they are unlucky and have valgus aligned tibiofemoral knee joints, laterally placed tibial tubercles, tilted patellae off the side and perhaps some soft cartilage on the undersurface of the patella, and all the time the patella is trying to slide laterally - that causes the pain.