The human knee joint is one of the most complicated in our bodies. Unlike the hip and ankle, there is no surrounding bone tissue to protect and stabilize the joint, Spray said. Instead, it is held in place by ligaments, which are subject to injuries.

"The entire weight of the body is borne by a small contact area between the femur (thigh bone) and the tibia (lower leg bone). In view of these factors, it is not surprising that many of us develop knee trouble," he said.

Spray received his medical degree from George Washington University in Washington D.C., and completed his residency in orthopedics at the Mayo Clinic. He is board certified in orthopedic surgery and is a fellow of the American College of Surgeons, the International College of Surgeons and the American Academy of Orthopedic Surgeons. Spray is also a member of the Clinical Orthopedic Society and the International Society of Orthopedic Surgery and Traumatology. He is an honorary member of the World Orthopedic Concern.