
- a twisted knee affecting the upper leg muscles
- demanding sports that put excess stress on the upper leg and muscles around the knee (i.e. dance, climbing, gymnastics, martial arts)
- starting up a seasonal activity (i.e.skiing, gardening) too quickly without keeping the muscles active throughout the year
- tight hamstrings causing overstress on the quads and knee
- one leg shorter than the other
- sitting for long periods of time
- repetitive forceful hip flexion (i.e. soccer kicks, jogging, hurdling)
- a direct hit to the quadriceps
- repeated bending and straightening (i.e. squats, deep knee bends, jumping)
- training on a steep slope