A rowing machine is a great tool to help you injured knee get back into shape. The most important thing to be aware of when using a rowing machine, is the proper technique, as to not injure your knee any farther.
Rowing machines should be used by children 12 and older. A child younger than that does not have the proper skills to operate the machine properly.
elliptical machines, are for general body exercises and the use of them does involve all joints such as hip, knee and ankle .All the same these exercises are less strenuous on knees as compared with jogging and skipping ropes.
How to label machines and equipment to create a safe working environment
Ergonomics is the science concerned with designing safe and comfortable machines for humans.
Assuming you do it with your legs fairly straight it'd be quite safe for the knees.
No
get the heck inside before you get injured
computers
No, it is not safe to run with injuries. Injuries must be given time to heal, enduring strenuous exercise while injured my further aggravate the injuries, causing them to worsen to debilitating levels. Consult your doctors.
Ergonomic designs are engineered with comfort and safety in mind. Ergonomics offers a safe and comfortable use for humans when they use and interact with machines such as computers.
Make it Sew- Sewing Machine by As You Wish are safe for children 8 and up.
Nike is one of the best brands on the market, I would assume it is a safe bet.