There has been a historic debate in scoliosis research that has looked at the changes in the bones vs the changes in the paraspinal musculature, which comes first. It’s the old “chicken or the egg” debate.
A recent study has tried to examine this issue by looking at the lengthen of the 12th rib and the imbalance in the main muscle that attached to it called the quadratus lumborum and it’s affect on the rotational deformity found in scoliosis. The idea was to find out which occurred first.
Unfortunately, researchers were not able to make a definitive conclusion based on their analysis as they couldn’t distinguish the difference between a 12th rib being lengthened by abnormal biometrical forces or simply a congenital difference. For more info read the article below.