Interesting article, Bill.
Presumably, if left to itself, evolution would eventually sort out these problems, but modern medical techniques probably militate against that.
Two different issues here.
Evolution will not fix my/your/our bad backs. Evolution is a "good enough" mechanism, not an optimization mechanism. Unless having a sore back has a fitness cost (i.e. leads to fewer offspring), there will be no selective pressure to 'fix' the issue. In other words, evolution doesn't care if you hurt; it only cares if you reproduce.
As for medicine preventing evolution, that is simply a mistaken belief based on the general poor understanding of evolution common in society. Evolution is measured as the rate of genetic change in a population. Selection *slows* this process - it is a break on evolution - as it limits the rate of genetic change by selecting for or against certain genotypes. In the western world we've greatly reduced the impact of selection - ergo, we as a species are accumulating mutations faster, and thus are evolving faster than before.