I did a little research and so far it seems like the LifeSpan TR2000e https://www.lifespanfitness.com/fitness/exercise-equipment/treadmills/tr2000e-electric-folding-treadmill is the best treadmill to...
This first happened to me when I was jump roping one day. I was doing alternating high knees and when I landed on my right foot I felt this quick sharp pain behind my right knee.