The quadriceps set is the easiest exercise to start with after a knee replacement. This low-stress exercise strengthens the quadriceps muscle and increases the knee's extension range gradually. Lie in bed with your arms at your side and your legs straight out in front of you. Straighten your leg by tightening your quadriceps and slowly pressing the back of your knee down into the bed. Keep the muscle tightened for 5 seconds, then relax it. Repeat this 10 to 20 times per leg, depending on your current strength and stamina.
Once your leg is strong enough to do the quadriceps sets without pain or fatigue, you can move on to straight leg raises. Start in the same position as before, then tighten your quadriceps muscle and lift your leg slightly off the bed. Hold your leg in the air for 5 to 10 seconds, then lower it slowly. To increase the difficulty level, do a seated leg raise instead. Sit in a chair and straighten one leg until the quadriceps muscle is fully contracted. Hold this position for 5 to 10 seconds.
Ankle pumps will strengthen the muscles of your lower leg. Move your foot up and down to contract the shin and calf muscles. Do this for 2 minutes or until your leg muscles become fatigued, then rest for several minutes and repeat the process. There will often be swelling in the lower leg after knee replacement surgery. Ankle pumps usually help reduce this swelling by improving blood circulation in this area. Increased swelling may be a sign of lingering damage from the operation, so consult your doctor if the swelling does not go down.
This exercise will extend your range of motion safely by using the bed to support the weight of your leg while you bend it. Lay in bed and slide your foot toward you until you cannot bend the knee any farther. Hold this position for several seconds, then slowly straighten your leg. Repeat this 5 to 10 times every few hours to keep your leg from stiffening up.