What Is Hip Osteoarthritis?

Everyday activities can be greatly affected by hip arthritis symptoms, which can include limited range of motion, joint stiffness, and pain in the hip, groin, leg or back. As symptoms get worse over time, hip arthritis can greatly affect mobility and quality of life.

The most common type of hip arthritis is osteoarthritis. Inflammatory forms of arthritis—such as rheumatoid arthritis, an auto-immune disease, and gout, a metabolic disease—have similar symptoms but are less common.

Two major signs of hip osteoarthritis that can be seen on an x-ray are:

• Deterioration of the articular cartilage that covers the surfaces of the hip’s ball-and-socket
• The appearance of bone spurs, called osteophytes

The hip is the third most susceptible body part to develop osteoarthritis, after the hand and knee.¹Murphy et. al, "One in four people may develop symptomatic hip osteoarthritis in his or her lifetime," Osteoarthritis and Cartilage 18 (2010): 1372-1379.^,2Allen KD, Golightly YM. Epidemiology of osteoarthritis: Curr Open Rheumatol. 2015 May:27(3): 276-283.^,3Bannuru RR et al. OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis. Osteoarthritis Cartilage. 2019 Jul 3. pii: S1063-4584(19)31116-1. doi: 10.1016/j.joca.2019.06.011. Health professionals do not know the cause of hip osteoarthritis but have identified several risk factors that increase the likelihood of its development.

There is no known cure for hip osteoarthritis. With a large percentage of the American population aging, health professionals continue to grow and refine knowledge about prevention, diagnosis, and treatment options for hip osteoarthritis.

Hip Joint Anatomy

The hip is located where the head of the femur, or thighbone, fits into a rounded socket of the pelvis, called the acetabulum. This ball-and-socket construction allows the leg to move back and forth and side-to-side, as well as rotate, pointing toes inward and outward.

Both the acetabulum and the rounded femur head are lined with articular cartilage. The articular cartilage is an extremely slippery, strong, flexible material that provides a buffer between the bones as the hip flexes and bears weight.

See Hip Anatomy

How Hip Osteoarthritis Causes Pain

Hip osteoarthritis is associated with many changes in the hip that may lead to pain.

• Cartilage is damaged or wears away. The femur and pelvic bones that make up the hip’s ball-and-socket may rub and grind against one another. The bone-on-bone friction can cause hip pain.
• The bones may produce small, scalloped growths, called osteophytes or bone spurs, to compensate for the deteriorated cartilage. In turn, the bone spurs can create even more friction.
• The bone underneath the damaged cartilage can develop lesions, and these lesions are associated with pain.⁴Eriksen EF. Treatment of bone marrow lesions (bone marrow edema). Bonekey Rep. 2015;4:755. Published 2015 Nov 25. doi:10.1038/bonekey.2015.124.
• The delicate lining that surrounds the hip joint can become inflamed. This lining, called the synovium, produces and contains joint fluid, which supplies nutrients to the joint. During osteoarthritis, the inflamed synovium becomes thicker, and the quantity and composition of the joint fluid it produces may change. This potentially painful condition⁵Mathiessen A, Conaghan PG. Synovitis in osteoarthritis: current understanding with therapeutic implications. Arthritis Res Ther. 2017;19(1):18. Published 2017 Feb 2. doi:10.1186/s13075-017-1229-9. is called synovitis.

In addition, osteoarthritis can change the hip’s mechanics, causing tendons, ligaments, and bursa to undergo excess strain and friction. Inflammation or injury of these tissues may be a painful side-effect of hip osteoarthritis.

Not everyone who has hip arthritis will experience pain. It is not clear why some people who have arthritic damage to a hip experience pain while others do not.