The hip joint functions as one of the most important joints in the human body. Designed for both mobility and stability, the hip allows the entire lower extremity to move in three planes of motion, while providing an important shock absorption function to the torso and upper body. The hip is a ball and socket joint, uniting the femur (thigh bone) with the pelvis. As a result of this configuration, the leg moves forwards and backwards, side to side, and rotates to the right and left.
• Bones -
The pelvis features two cup-shaped depressions called the acetabulum, one on either side of the body. The femur, or thigh bone, is the longest bone in the body and connects to the pelvis at the hip joint. The head of the femur, shaped like a ball, fits tightly into the acetabulum, forming the ball and socket joint of the hip.
• Cartilage -
Embedded within the acetabulum of the pelvis lies an important structure known as articular cartilage; this cartilage has two very important functions. First, the smooth, low friction surface of the cartilage allows the hip joint to move freely in all planes of movement. Second, the articular cartilage cushions the hip during weight bearing activities, providing an important shock absorption function to the entire lower extremity.
• Ligaments -
The hip joint also features a complex system of ligaments that provide stability for the pelvis and lower extremity. The ligaments of the hip joint connect the femur to the pelvis and are essential to keeping the hip from moving outside of its normal planes of movement.
• Muscles -
The muscles of the hip joint have dual responsibilities. They provide the dynamic functions necessary to raise and lower the lower extremity as well as the stabilizing functions required during standing, walking, or other weight-bearing exercises. This complex system of muscles works synergistically to provide the power for the hip to move in all directions, as well as to stabilize the entire lower extremity during weight bearing activities.
Arthritis of the hip is a disease which wears away the cartilage between the femoral head and the acetabulum, the two bones will scrape against each other, raw bone on raw bone. When this happens, the joint becomes pitted, eroded and uneven. The result is pain, stiffness and instability. In some cases, motion of the leg may be greatly restricted.
Osteoarthritis, which is the most common form of arthritis in the United States; it is degenerative and although it most often occurs in patients over the age of 50, it can occur at any age, especially if the joint is in some way damaged.
It is usually confined to the large weight-bearing joints of the lower extremities, including the hips and knees, but may affect the spine and upper extremity joints, too. Patients with osteoarthritis often develop large bone spurts, or osteophytes, around the joint, further limiting motion.
Osteoarthritis of the hip is a condition commonly referred to as "wear and tear" arthritis. Although the degenerative process may accelerate in persons with a previous hip injury, many cases of osteoarthritis occur when the hip simply wears out. Some experts believe there may be a genetic predisposition in people who develop osteoarthritis of the hip. Abnormalities of the hip due to previous fractures or childhood disorders may also lead to a degenerative hip. Osteoarthritis of the hip is the most common cause for total hip replacement surgery.
The first and most common symptom of osteoarthritis is pain in the hip or groin area during weight bearing activities such as walking. People with hip pain usually compensate by limping, or reducing the force on the arthritic hip. As a result of the cartilage degeneration, the hip loses its flexibility and strength, and may result in the formation of bone spurs. Finally, as the condition worsens, the pain may be present all the time, even during non weight-bearing activities.
Before considering total hip replacement surgery, your doctor and you may try various non-surgical therapies. An appropriate weight reduction program may be beneficial in decreasing force across the hip joint. However, weight reduction can be difficult for people with hip arthritis since the arthritis pain precludes them from increasing their activity and burning calories. An exercise program may be instituted to improve the strength and flexibility of the hip and the other lower extremity joints. Lifestyle and activity modification may be undertaken in an attempt to minimize the activities that are associated with hip pain. Finally, various medications such as non-steroidal anti-inflammatory drugs (NSAIDs) and/or nutritional supplements (Chondroitin/Glucosamine) to reduce pain and inflammation associated with the disease may be considered.
Assistive devices like a cane or a crutch can help to reduce the force transmitted through the hip joint during walking and thereby may help to decrease hip arthritis pain. If non-surgical treatment is unsuccessful, you and your surgeon may decide that a total hip replacement is the best available treatment option.