The hip joint is one of the most versatile and important joints in the human body, and the hips absorb tremendous amounts of force and stress on a daily basis. Pain in the hip area and true hip pain are clinically and significantly different. Some conditions can cause pain in an area that many people describe as the hip, but in reality, the source of pain is not actually the hip itself. Both types of pain display symptoms in the same areas, however, and can be difficult to separate.
Osteoarthritis
Doctors diagnose degenerative arthritis of the joint cartilage surfaces of the ball and socket of the hip joint as osteoarthritis. According to the Centers for Disease Control and Prevention, 1 in 5, or 22 percent of adults in the United States report having a doctor-diagnosed arthritis and 50 percent of adults 65 years and older report receiving the same diagnosis.
As the layer of smooth cartilage that covers both the ball and socket of the hip joint degrades, the underlying bone becomes exposed. The friction of these exposed surfaces rubbing together can cause considerable pain.
Bursitis
While not involving the actual joint surfaces directly, hip bursitis can cause considerable aggravation. The hip bursa is a fluid-filled sac that covers the outer prominence of the femur---the part of the upper thigh bone that's easy to see under the skin---and protects it from injury and pressure. This prominence is called the greater trochanter. The greater trochanter is one of two prominences in each hip that serve as attachment points for tendons of various surrounding muscles. This trochanter is readily palpable, or easy to feel, over the outside portion of the hip---the area between the front and back pockets of a pair of pants.
Bursitis, or inflammation of the bursa sac, can result from direct trauma to the sac, overuse, and repetitive activities such as stooping, squatting, running and excessive walking, which can cause friction and pressure on the sac.
Avascular Necrosis
"Avascular" means without blood supply, and "necrosis" refers to bone death. Avascular necrosis refers to the death of bone marrow that results when it loses the internal blood supply that keeps it alive. The ball of the hip is the most common location of this condition. Avascular necrosis can be caused by chronic use of steroids in bodybuilding or in the treatment of conditions such as rheumatoid arthritis. Another cause of this condition is damage to the blood vessels from previous injury, such as a hip dislocation. The ball of the hip dies when vital nourishment from blood vessels no longer reaches it. The blood vessels can shut down because of extreme pressure from bone marrow swelling, which constricts, or closes, the vessels until they permanently stop working.
Lumbar Disk Disease
An example of hip area pain that can be caused by conditions not directly involving the hip is lumbar disk disease, a condition of the lower back. Pain results when one or more intervertebral disks, the shock absorbers between the vertebrae, deteriorates and bulges out into the area of the spinal canal, where nerves exit the canal on their way to areas of the lower extremities. Pressure on these nerves can cause pain in the area that the nerve serves, such as the hip, leg or foot. Patients frequently misinterpreted this pain as true hip pain, complicating the diagnosis.
