The above article talks about some common unintentional injuries to children.
Regarding the position of your toddler's leg when spinning, a toddler's legs are not massive enough to pull on the toddler's hip joints with enough force to cause injury. In an abundance of caution, spin your toddler with their shoes off, so there isn't any additional weight that would pull on their legs.
From your description, your toddler's legs during the spinning are approximately in a position that resembles their position when they sit on the floor with their legs in front of them. This would indicate that the position of your toddler's legs are within a normal range of motion.
In my view the bigger risk might be that you accidentally get too close to a wall or a bookcase, and your toddler's foot/feet hit a solid object.
As always, a toddler's head is very heavy for their neck, so the position and support of your toddler's head is an important consideration in all physical play.
Engaging in physical play with your toddler has many physical and mental benefits to their growth and development. You might consider working with your wife to negotiate ground rules that provide a level of fun and safety that you are both comfortable with going forward.