Hip dysplasia is an abnormal formation of the hip socket. When it is severe dysplasia, can eventually cause crippling lameness and painful arthritis of the joints. It can be found in many animals and occasionally in humans, but is most commonly associated with dogs. It is common in many dog breeds, particularly the larger breeds of dogs.
Normal Hip Anatomy
In the normal anatomy of the hip joint, the femur (the thigh bone) is connected to the pelvis at the hip joint. The almost round end of the femur (femur head) fits into the a concaved socket (acetabulum) which is located in the pelvis. The bony surface of the femur head and the acetabulum are covered by cartilage. Bones provide the strength necessary to support body weight while cartilage ensures a smooth fit and allows bones to move against each other. Normal hip function can be affected by congenital conditions such as dysplasia, trauma and by acquired diesease such as osteoarthritis.
In hip dysplasia, the head of the femur is not sat deeply or tightly held by the acetabulum. Instead of being a snug fit, it is a loose fit or a partial fit. Secondly, the acetabulum (the sockets) are not smooth and round, but a misshaped, causing abnormal wear and tear or friction with the joint as it moves. The body reacts to this in several ways. Firstly the joint itself is continually repairing itself and laying down new cartiage.