Dear Brittany:
You wrote: “I would never maliciously try to hurt someone”- we have to do our best, as human beings, not to hurt someone maliciously or not maliciously. Hurting someone by an act of inattention and neglect is still hurting someone and it is our responsibility to minimize the chances of doing so. An example of hurting someone not with malice but because of inattention is texting while driving. When a person dies as a result of another driver texting while driving, the person is dead regardless of there not being malice.
You asked what you can do regarding hurting your friend’s knee- you can offer her a financial compensation and/or to do physical chores for her, such as to clean her home, her car, do errands for her, etc.
anita