HIP ARTHRITIS

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What is Hip Arthritis?

Hip arthritis is a condition that occurs when the cartilage wears out and the lubricating and shock absorbing capacity of a joint is lost. As a result the bones that make up the joint begin rubbing against each other with a lot of friction, which causes a lot of pain and deformity.

Arthritis can occur in any joint, but the hip joint is one of the most common, largely due to the fact that it bears the weight of your entire body with every step. The force across the hip is often more than just your body weight.In fact, when running, the hip experiences forces 200-500% of your body weight! This means that your body weight dramatically affects the force on your joints, and can have a major effect on the degeneration of a joint. Obesity cause tremendous increased force on the hip and can cause it to prematurely wear out. For example, if you stop working out, and gain 50 lbs, your joint may actually experience 200 lbs of increased stress across it. Over many years that increased stress makes a big difference.

Another cause of arthritis is a abnormal shape of the hip. This is called hip dysplasia, and is actually the major cause of hip arthritis in people under 50 years old. This condition is related to FAI (femoroacetabular impingement, see talk). A misshaped hip can also occur if the hip collapses due to a disrupted blood supply (think of bone like a flower, if it doesnt receive its nutrients through the blood, it will whither and die). This is called avascular necrosis (AVN).

Another cause of arthritis can be trauma (post-traumatic arthritis), where the normal cartilage is damaged, or the smooth surface of the joint is disrupted by a fracture.

How is Hip Arthritis diagnosed?

People with hip arthritis will complain of pain in their hip which gradually worsens over time. Oftentimes the pain originating from the hip feels like groin pain, thigh pain...or even knee pain. Thats why its important for your doctor to look at all the bones around site of pain to make sure nothing gets missed. Our body can mistake the source of pain because a lot of our sensory nerves (the nerves that report pain) enter the spinal cord at the same place, so our brain will cross wires.

X-rays are ordered and will show degenerative changes to the hip joint. Cartilage does not show up on x-ray but we know its there because there is a space between the two bones. As the cartilage wears away, the joint space on x-ray becomes smaller and smaller (so we also know when cartilage is not there). Eventually all the cartilage is worn away and the two bones (femur and acetabulum) are actually touching, and we call that “bone-on-bone” arthritis (very advanced disease).

There are other changes to be seen on x-ray. The bone around the joint becomes very hard (subchondral sclerosis) and sometimes cysts (cysts look like bubbles) form around the joint. Lastly, as the joint begins to degenerate, small particles of worn out bone begin to accumulate at the edges of the joint and form mounds of bone called “osteophytes”. Think of when you shovel snow in your driveway, the snow will build up in mounds around the edges, that’s what osteophytes are.

The x-rays should be taken with the person standing up to best show the amount of remaining cartilage (our body weight pushes the bones together). X-rays of both hips should be taken (even if just one is bothersome) to get a good comparison (everyones hips look a little different, even when they are normal).

An MRI is not necessary to diagnose arthritis. It may be useful however in diagnosing conditions that eventually lead to arthritis (like osteonecrosis, or an cartilage injury).

How is Hip Arthritis treated?

Arthritis is essentially a condition of worn out cartilage. Unfortunately, once cartilage is worn out, it wont come back. There are no treatments currently in use that regrow cartilage (but the future holds a lot of promise!). Therefore, there are two approaches to treatment. Overall, arthritis should be treated in a stepwise fashion, from less invasive (anti-inflammatory medicine) to more invasive (ie surgery).

Nonsurgical treatment aims to relieve the painful symptoms of arthritis. Many people have some pain, but not enough to warrant an aggressive surgery like a total hip replacement. In such cases, anti-inflammatory medications, and physical therapy regimens can be very effective in minimizing pain and allowing people to have normal daily function. Also the use of a cane or 4-point walker can take pressure off the effected side and provide significant relief (you old the cane on the unaffected side, so that you can lean that way with each step).

However, hip arthritis can reach a point where it prevents people from performing daily activities, it keeps them awake at night, and the pain is a constant reminder that their hip has seen better days. In such cases, a total hip replacement has been shown to be a safe and very effective treatment for most people. Over the last 50 years, great strides have been made in the development of hip replacements, that allow people to perform daily activities, and usually athletic activities as well without pain and disability. Total hip replacements are one of the best surgeries in all of medicine and have changed millions of peoples lives for the better (see talk).

What is the long term outcome of hip arthritis?

Although arthritis is a progressive condition, science and medicine have developed a lot of great treatments to alieviate pain and return normal function to the affected hip.