The traditional rules relating to surgery say that it is not recommended to do any surgery close to the Full Moon and that the Moon should not be in the sign of the Zodiac that rules the operated part of the body, in your case it's Sagittarius.
It is also reasonable to avoid New Moons as vital force is low at that time.
I am not sure about whether to prefer waning or waxing Moon for your surgery. In any case I'd say that this is a secondary consideration. The general idea is that if something is removed from the body, it should be done during the waning Moon, but if the surgery creates something good in the body, like restores a function, why not to do it on the waxing Moon.