As the song goes, the foot bone's connected to the leg bone; the leg bone's connected to the knee bone. If you want to sing the song properly to Scout, you'll call his knee joint the stifle. It's a complex joint that can be complicated to repair after an injury.
Scout's stifle is the joint connecting his femur, or thigh bone, with his tibia and fibula, his two lower leg bones. Strong ligaments stabilize his stifle. Two attach crosswise; they're referred to as the anterior and posterior ligaments or cross ligaments. They work with two outer bands of ligaments, known as the lateral collateral ligaments. Together with his kneecap, this system of ligaments provides him stability through a wide range of movement. The two most common problems vets see with the stifle are dislocating kneecaps and torn or stretched cruciate ligaments. If Scout's a very athletic guy, he may be like other active dogs who occasionally injure their knees in the course of their vigorous activities. Continuous strain on the ligament, or obesity, can stress the ligaments in a pup's knee, causing problems with the stifle. Treatment ranges from surgery to medical treatment that includes exercise restriction, rest, anti-inflammatories and hydrotherapy.