As we find many of our clients to have knee issues (replacements, discomforts, etc.), these are some movements that help alleviate knee pressure and recruit muscles that are used in a general bodyweight squat.
Two movements that you can substitute for the bodyweight squat:
Lateral Lunge with a Slider/Frisbee/Paper Plate
Key pointers in the Lateral Lunge: Push your hips back as you slide the leg with the slider. Think of sitting back to engage hips and mobility. If needed, stick arms out in front to help with balance.
Rear-Foot Elevated Split Squat
Key pointers in the Rear-Foot Elevated Split Squat: Feet are parallel; think railroad tracks, to keep from curtsy-ing and providing balance. Rear-foot’s toes should feel like squishing a bug to make sure the foot is firmly planted.
Note: Sliders can be found in either TPC or Fitness Floor, and the elevation in the split squat doesn’t have to the height of the bench. It can be even two inches off of the floor. If balance is an issue, you may choose to use a counter/railing/PVC pipe to help.