Hip

In order to understand hip injuries, an understanding is needed of the structure the hip joint.

The hip joint is a ‘ball-and-socket’ joint, and is the largest weight-bearing joint in the body. It is formed by a ‘ball’ at the top of the thigh bone (femur) moving in the socket of the cup-like part of the pelvis (hip) called the acetabulum.

In a normal joint, these bony surfaces are covered by an articular cartilage. The body has articular cartilage everywhere that two bony surfaces move against one another, or ‘articulate’. Articular cartilage is ‘slippery’ as so allows the joint surfaces to slide against one another without causing any damage or friction. The function of articular cartilage is to absorb shock and provide an extremely smooth surface to make movement easier.

In the hip, articular cartilage covers the end of the femur and the socket portion of the acetabulum in the pelvis. This articular cartilage is important since it can wear away or tear, resulting in hip pain and/or stiffness. Unfortunately, cartilage does not have the ability to repair or replace itself like other tissues in the body. Once cartilage is damaged or destroyed, it is gone forever.

The hip joint is strengthened by five ligaments (ligaments are soft tissue structures that connect bones to bones), and supported by several thick muscles that, together, allow a full range of movement in the hip of a healthy person.

The hip joint forms the main point of connection between the bones of the lower limb and the lower skeleton of the trunk and pelvis. The main role of the hip joint is to support the weight of the body, both when it is still and when it is moving. The ball-and-socket arrangement gives the hip the large amount of motion that is needed for everyday activities, such as walking and stair-climbing.

Osteoarthritis, the most common form of arthritis, is a condition that causes “wear and tear” to the hip joint cartilage. It typically develops after years of constant motion and pressure in the joints. In an osteoarthritic hip, the articular surfaces have worn away. As the cartilage continues to wear away, the joint becomes increasingly painful and difficult to move.

Osteoarthritis of the hip is a common condition affecting 20 in every 100 people over the age of 65. It commonly presents with pain in the hip and groin which is worsened by walking. The pain can also occur at night. The hip may become stiffer, which makes everyday activities, such as walking and putting on and off shoes and socks, difficult.

Treatment for osteoarthritis of the hip first involves lifestyle changes, such as reducing activity, weight loss and physiotherapy, and the use of pain-killers. If these changes don’t work, or become less effective over time,  total hip replacement may be considered.