I thought this was very interesting. See:

http://www.marvistavet.com/html/body_hip_dysplasia.html

Where it says:

Nutritional factors are also important in the development of hip dysplasia. For example, it has been popular to try to nutritionally “push” a large breed puppy to grow faster or larger by providing extra protein, more calcium, or even just extra food. Practices such as these have been disastrous, leading to bones and muscle growing at different rates and creating assorted joint diseases of which hip dysplasia is one. One study showed that when puppies of hip dysplasia prone breeds were allowed to free feed, two thirds went on to develop hip dysplasia while only one third developed hip dysplasia when the same diet was fed in meals. Another study showed German Shepherds were nearly twice as likely to develop hip dysplasia if their adult weights were above average.
Though cavaliers are not a large breed dog, they are one of the small breeds prone to hip dysplasia and as we now, patella luxation, another join/bone development problem. Some large breed puppy foods are designed to NOT give extra protein etc but most puppy foods generally have higher levels of protein, supplements etc that many breeders have long felt cause accelerated growth that is detrimental.

As also regularly noted, free feeding in this obesity-prone breed is the worst way to manage feeding. And the note that obesity itself leads to hip dysplasia is yet another reason why it is so important to keep cavaliers lean and trim (their endemic heart problems are the other, setting aside all the other obvious benefits! ).