There are numerous conditions that can affect the hip joint and cause variable symptoms in individual symptoms.
When one or more structures within the hip are damaged or injured, the joint can become painful and movements can be restricted. Commonly, pain is felt in the groin, but it can also be experienced down the front of the thigh and inside of the leg, into the knee and sometimes down as far as the ankle. This is because of referred pain pathways. It can also be felt in the buttock but rarely in the back.
The pain can worsen on activities which load the joint, such as walking or standing for long periods. There can be difficulty in dressing, and putting on shoes and socks. Sleep can be disturbed with pain at night especially on rolling and changing position. Getting out of bed in the morning can be difficult with pain and stiffness which may ease off after a short while, but increasing activity during the day will make the symptoms of pain and stiffness worse as the day goes on. Some patients may experience a sensation that the hip is “catching” or “snapping” with specific movements and actions. This is often secondary to damage to the labrum or the articular cartilage of the joint surface. There may have been a history of previous injury or trauma. The way that one walks can be affected; typically limping is common with any painful condition of the hip.
The hip is a ball and socket joint. The femoral head (ball) is at the top of the femur (thigh bone) and the acetabulum (socket) is part of the pelvis.
The surfaces of the femoral head and acetabulum are coated with articular cartilage, which is very smooth and slippery with a low coefficient of friction. The hip joint capsule is lined by synovium, which produces synovial fluid which helps lubricate the joint.
The rim of the acetabulum is extended by a rim made of a mixture of fibrous tissue and cartilage (fibro cartilage) that is triangular in cross-section; this is called the labrum.
The labrum serves to deepen the socket, improve the stability and seal the synovial fluid within the hip joint. The capsule of the hip joint joins the outer edge of the acetabulum with the femur and completes this seal.
The hip is one of the most stable joints in the body and at the same time allows an extensive range of movement. Some of the strongest ligaments found in the body help stabilise the hip joint. With the surrounding muscles around the hip joint it is able to provide smooth, pain free movement of the hip joint.