A grade I, or mild, sprain is characterized by some tearing or stretching of fibers of the ligament (a tough band of connective tissue). The fibers have not been extended too far so there is no looseness in the ligament. Also there is minimal internal hemorrhaging (bleeding) and no residual instability or unsteadiness in the ankle when it is healed. Grade I sprains require, on the average, about 12 days to heal. A grade II, or moderate sprain is a full tear of the ligament with mild instability. Unlike a grade I, the ligaments in a grade II have been stretch beyond their limits, so there is also a slight reduction in function and strength. Grade II sprains require approximately two to six weeks before you can return to your previous slam-dunking, crossover-dribbling and shot-blocking form.
Ligaments
Ligaments are bands of tough tissue that connect bones together. The most commonly injured ligament is the anterior talofibular ligament (ATFL), located on the lateral side (or outside) of your ankle. When your foot turns inward excessively, the ATFL can be stretched beyond its normal limits, resulting in a sprain.