Cartilage damage is a relatively common type of injury. It often involves the knees, although joints such as the hips, ankles and elbows can also be affected. Cartilage is a tough, flexible tissue found throughout the body. It covers the surface of joints, acting as a shock absorber and allowing bones to slide over one another. It can become damaged as a result of a sudden injury, such as a sports injury, or gradual wear and tear (osteoarthritis).
While it is still too early to clearly make out boy or girl parts at 12 weeks gestation, apparently the gender can be determined based on the angle of the nub (the genital tubercle). To determine gender based on a 12-14 week ultrasound, a profile view of the genital region is needed.
And there are also the old wives tales. There is also a new method of finding out the sex that is gaining in popularity, it's called the Ramzi's Method or Ramzi's Readings. This uses ultrasound in early pregnancy, as early as six weeks pregnant, to be able to tell the gender of your baby based on locating the placenta. Most physicians don't offer this per se, but you can certainly ask about it.