What are the main causes of knee pain for people who are obese?

Osteoarthritis: Hi, great question... The biggest thing is premature osteoarthritis. The increased stress across the joint results in articular cartilage damage and loss and ultimately osteoarthritis. Now in the same spectrum and biomechanical etiology there is increased stress on the meniscus (cushion) between the femur and tibia. This can result in meniscus tear and another pain generator. Best wishes.

Joint overload: For every one lb. A person is overweight, the knee sees 4 lbs. Being 25 lbs. Overweight means the knees are seeing an extra 100 lbs. With each step. Frequently loss of this weight is associated with decrease in pain. Pain is the first signal that something is wrong. Over time the overloading of the joint leads to articular cartilage breakdown, bone stiffness & sclerosis, and arthritis.