Hip arthritis is a degenerative condition that affects the hip joint and often leads to a significant impairment in the quality of life. Approximately 43 million Americans suffer from arthritis and many have significant hip involvement. It can adversely affect one’s ability to walk, work, and live pain-free.
The treatment of hip arthritis generally involves activity modification, various exercises, and treatment with anti-inflammatory medications. The use of assist devices such as a cane can also be helpful. However, when pain and disability become severe, surgical reconstruction of the hip joint with total hip replacement becomes necessary.
The hip is a ball and socket joint. The acetabulum, or socket, is formed by three areas of the pelvic structure: the ilium, the ischium, and the pubis. The femoral head is the “ball”, which is located on the upper end of the femur. There is a high degree of fit and stability within this ball and socket joint. It is stabilized by strong ligaments encapsulating the joint, which prevent dislocation.
Both the femoral head and the acetabulum are covered with a layer of cartilage, which allows the hip joint to move smoothly and provides shock absorption and load distribution within the hip. This cartilage is also a source of nutrition for the joint. Numerous muscles play an important role in the stability of the hip, one of which is the gluteus medius. This is a deep muscle within the buttock, and its proper function is important in normal walking.
Due to the muscle pull and joint forces that occur, approximately 3 times the body weight distributes through the hip with routine activities. The stability of the hip joint is maintained by the precise fit of the femoral head within the acetabulum. The hip allows rotation in many planes. These include: flexion/extension (used most commonly in sitting), internal and external rotation (used with twisting activities), and abduction and adduction (inward and outward motion of the hip used to spread the legs apart). Any degenerative condition within the hip alters biomechanical relationships and can cause limping, leg length inequality, and disability.
What is hip arthritis?
Hip arthritis is any condition that leads to degeneration of the hip joint and its cartilage surfaces. Some of these conditions are osteoarthritis, rheumatoid arthritis, avascular necrosis and congenital (or developmental) dysplasia (dislocation) of the hip. Fractures and other injuries to the hip joint can also lead to hip degeneration.
Osteoarthritis is a degenerative condition that may affect many joints throughout the body. Caused by “wear and tear” on the joint, it is, by far, the most common type of arthritis, and is commonly called “degenerative arthritis.” Osteoarthritis causes changes in the mechanical structure of the cartilage, which lead to its breakdown. Over time complete loss of the articular cartilage can occur resulting in rough, bony surfaces in contact within the hip joint. This results in radiographic joint space narrowing, peripheral osteophytes (bone spurs), stiffness of the hip joint, pain, and disability.
Rheumatoid arthritis is an inflammatory condition that affects the lining of all joints in the body. It causes an inflammatory response in the joint lining which destroys the articular cartilage and surrounding tissues. Rheumatoid arthritis generally results in rapid destruction of many joints of the body and may affect other organ systems in addition to the joints.
Osteonecrosis or avascular necrosis is a condition in which the bone within the femoral head loses its blood supply and dies. This eventually may lead to the collapse of large segments of the bone supporting the cartilage of the hip joint, resulting in destruction of the hip. The main causes of osteonecrosis include:
- injury such as fracture or dislocation of the hip.
- steroid use for the treatment of such ailments as lupus, asthma, and kidney transplantation.
- alcohol abuse.
The final common pathway of hip arthritis is loss of the cartilage cushion between the femoral head and the acetabulum. This results in limitation of joint motion, shortening of the leg, and continual pain and disability.