Could you tell me what are best gym equipment to use if you have a knee injury?

Closed chain: So not knowing what type of knee injury you have this will be a bit generic. Usually for knee injuries i would recommend what is called closed chain exercises, which are any exercises in which the sole of the foot contacts the ground or a platform. This would include squats, leg press, cycling, elliptical trainer, calf raises. And not isolation exercises such as quad extension/hamstring curls.