Arthritis can affect any joint in the human body. When it affects the larger, weight-bearing joints of the hips and knees, significant changes in activity level and lifestyle can occur. Arthritis of the hips can begin as a mild ache or soreness, and develop over time into serious life-altering and crippling pain. There are many different causes of arthritis in the hip.
Obesity
The more weight placed on the hip joint, the more stress placed on the smooth joint surface cartilage, called hyaline cartilage. Obesity, over a long period of time, can result in accelerated wear and tear of the hip joint, causing degeneration and eventual destruction of the articular cartilage, which is the cartilage that covers the ends of the bones in a joint. This can lead to the uncovering of underlying bone, resulting in substantial pain and mobility deficits.
According to the U.S. Centers for Disease Control and Prevention, or CDC, more than 60 percent of adults who reported a doctor-diagnosed arthritis were either overweight or obese, compared to only 16 percent of under/normal weight adults reporting a doctor-diagnosed arthritis.
Trauma
Direct trauma to the hip joint can increase the risk of the development of arthritis significantly. In a review of 100 patients with traumatic hip dislocation, the Orthopedic Service of the Royal Air Force, London found that more than one-fourth developed post traumatic hip arthritis.
When a hip dislocates, the femoral head, or ball of the thigh bone, is violently separated from the hip socket, or acetabulum. The blood supply to the head is disrupted. As a result, this lack of blood supply can cause a condition known as avascular necrosis, avascular meaning without blood supply and necrosis meaning death of the bone.
Hip fractures can also precipitate arthritis. Certain fractures that occur close to the junction between the femoral head and the neck of the bone can cause similar disruption to the blood supply, also causing avascular necrosis. This is called a sub-capital fracture.
Infection
Arthritis caused by infection is known as septic arthritis. This occurs mainly because microorganisms that settle in the hip joint produce a thick dense fluid, called exudate, as a by-product of their metabolism and multiplication. Since the hip is an encased joint, ultimately the pus will fill the space. As the bacteria continue to produce pus, it begins to exert pressure against the joint articular cartilage. If left untreated or under pressure for any length of time, the pus will destroy the hyaline cartilage causing resultant arthritis.
The University of Maryland Medical Center reports that septic arthritis, which can be experienced at any age, is less common after age 3 unless there is trauma or microbial seeding. Seeding occurs when bacteria enter the bloodstream from a remote location such as an intravenous line or puncture wound, or through the gum manipulation that occurs with dental cleanings.
Altered Anatomy
Arthritis in the hip can also be caused by abnormal variations of the anatomy of the joint. One of the more common conditions/diseases seen is called congenital hip dysplasia. Congenital hip dysplasia refers to the abnormal formation of the components that comprise the hip joint: the femoral head, or ball of the thigh bone, and the acetabulum, or the socket of the pelvis. These abnormalities are typically present at birth. The abnormal hip does not fit together properly because of irregularities in the shape of the ball as it sits in the socket. These incongruities are what cause friction and abnormal wear and tear, resulting in arthritis.
