I had a horse with sidebone. He also had high/low and the sidebone was more pronounced on the high side. Vet thought it was likely because that foot tended to be contracted and didnt absorb shock as well. You could see and feel it just at the hoof/pastern hairline. The horse had lameness issues at times, but the sidebone didnt appear to cause any of it. It was well-established when we found it and it didnt seem to change significantly over 14 years, maybe due to better trimming and therapeutic shoeing.
I know. I was in a hurry to post before going outside and all the correct anatomy terms ( learned decades ago in 4-H) escaped me. I corrected it the next day when I remembered.
My only excuse is menopause, lack of sleep due to my dogs sharing our bed and being in a hurry.