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Despite what you may have read, a fracture across a growth plate is a very serious matter. if not put in proper alignment and fixation, the growth plate could potentially become damaged to the point that it loses its blood supply and undergoes tissue death, a condition known as necrosis.
If necrosis were to occur, at best, XXXXX XXXXX arrest growth of that limb and create a limb substantially smaller than the other one (allot of growth occurs between 3 months to a year of age). At worst, necrosis of the growth plate could be limb threatening.
In fractures involving growth plates, to prevent damage and necrosis, as well as maintain the proper growth of the bone and the limb, unless fractures are hairline in nature, they usually need some type of fixation, either pin, bone plate, lag screw, or some combination of the three. What type of hardware that is used is dictated by the nature of the fracture, how displaced it is, and if there are multiple fragments that have to be fixated.
Regarding your direct questions, what should you ask to ensure that surgery is the right choice?
1.) Is the fracture more than just a hairline fracture that necessarily requires aggressive surgical fixation? This is important, because may hairline fractures will heal with a simply cast. However, if the fracture is more substantial than that, and if there is displacement and/or multiple fragments, then casting will not be effective.
2.) When you said that the growth plate that is fractured is at the bottom of the femur, I am assuming that you mean that it is the distal end of the bone, that is, the end closest to the foot. If that is the case, then that plate contributes less overall growth of the bone that the more proximal (the ones closest to the hip) growth plates. That bodes better for the kitty than if it were a proximal growth plate. However, since that plate may still be responsible for 20% of the growth, I would ask the veterinarian his plan to maintain that growth...for example, after healing, will the hardware need to be removed after the bone is healed?
Whether or not hardware would have to be pulled post heal to maintain the growth of the plate and therefore the bone and limb, really comes down to what method of fixation is necessary. Pins generally can stay in without having much influence on growth plate integrity, whereas, bone plates sometimes need to be removed later on to maintain normal growth. Lag screws can go either way depending on their direction and alignment.
I was involved in a growth plate fracture repair on a 5 month old Labrador retriever puppy that was so severe, it required 2 pins, a bone plate, and a lag screw to provide fixation. Ultimately, since the plate was not situated in a manner that was impinging on the growth plate, and the pins were not a concern for growth plate integrity, they were able to stay. The lag screw, however, had to be removed at a later time.
I would not worry, however, if hardware has to come out at a later time, as its removal generally require a minimal incision and minimal trauma.