Welcome to HCM.
Probably when you broke your leg at that time there must have been some spinal injury
as well, in the low back area (Lumbo-Sacral region of the spine). This must have compressed the pair of nerves coming out of the spinal cord and supplying the urinary bladder
, resulting in incontinence
You need to consult an urologist
who will have to do tests including MRI, if indicated to find out the cause.
Wish you all the best.