I had ACL/meniscus repair surgery in 2017. After surgery, my old trampoline caused a lot of pain in my knee. I got rid of it and invested in my Cellerciser. I’m pain free, my knee (and whole body for that matter), is stronger. My knee is pain free when I’m on my Cellerciser. I was recently asked to jump on a regular rebounder, it was terrible! It was instantly painful on my knee. Confirmed for me that my Cellerciser is definitely superior!