There is a medical condition called
Peyronie's Disease that can cause curvature. Sometimes caused by trauma. I had a "slight traumatic moment" (meaning it hurt like hell) during sex several years ago. Began to curve to the right and I experienced painful erections for several weeks afterwards, to the point that I didn't want to become aroused. Eventually, it healed and I'm back to normal. Or at least what is normal for me.
Fortunately, I didn't develop Peyronie's Disease but that was a consideration at the time.