I love walking and go with my friend three times a week. How do you prevent knee pain?

This is an issue you MUST discuss with your doctor.

no
knee replacement pain is gone after 3 months max
if you kneel on that knee, that will cause you pain as that is a no no for knee replacements
go back to the specialist doctor who did the operation, ask for ultra sound and x-rays to see if something has gone wrong
If he is evasive , get a second opinion

Go and see you doctor .

Knee pain is not a rare problem. It happens due to the tearing and wearing at the knee joint. Every one can have this problem, women are more prone to knee pain. To treat it effectively, the simplest way is applying cold compress because it can constrict the blood vessels and then reduce the blood flow coming to the pain area. as well as relieve the swelling.

Reference: Home Remedies for Knee pain- Authority Remedies

which knee? hit the other one two or three times with an 18-22 oz hammer ,that should equalize the pain and you can limp on both legs.

Yes But for that you need to follow these exercise if you are facing Knee pain:
1. Step-Ups
2. Partial Squats
3. Calf Raises
4. Straight-Leg Raises
5. Side-Lying Leg Lifts
6. Short-Arc Knee Extensions


https://www.lybrate.com/raipur/orthopedist

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Here are two exercises that I like to use for my back. They aren't complicated to do, you just need a bit of space;

Back Flexion Exercise;

Lie on your back and pull your knees to your chest while stretching the head forward, until a comfortable stretch is felt.

Knee to Chest Stretch;

Lie on your back with your knees bent and both heels on the floor. Put both hands behind one knee and pull it up to your chest.