Osteoarthritis of the Hand: A Bigger Problem Than You Might Think
If we asked you which joints are affected most often by osteoarthritis (OA), what would you say: hips? knees? shoulders?

While those joints are indeed affected, two-thirds of all women over the age of 55 have X-ray evidence of osteoarthritis of the hand. And just slightly more than half (55 per cent) of the men in the same age group have clearly visible arthritic changes in at least one joint of the hand.

There are three major finger joints: the knuckles across the fist or metacarpal phalangeal joints (MCPs), the middle joints (proximal interphalangeal joints or PIPs), and the tips (also known as the distal interphalangeal joints or DIPs).

In this article, the focus is on the proximal interphalangeal joints (PIPs) starting with the incidence of osteoarthritis (OA) and the main risk factors. Four types of OA are mentioned: no erosive, erosive, posttraumatic, and primary.

A description is provided of what happens to the cartilage, bone, and soft tissues of the affected joints for the nonerosive and erosive types of OA. And finally, treatment ideas (both general and specific) are offered for these two types of arthritis at the proximal interphalangeal (PIPs) joints.

We've mentioned how often osteoarthritis affects the joints of the fingers. Let's take a look at who is at risk. You might think the way people use their hands at their jobs would make a difference. But researchers have not been able to clearly establish a link between occupation and arthritis. Cotton-pickers and industrial workers are at a disadvantage and are more likely to develop hand arthritis. But that's as far as the evidence goes.

Okay, so what about age? Are we agreed that the older you get, the more likely it is you will develop arthritis? Well, yes, in a way age is related because the majority of people who have osteoarthritis of the hands are older (over 55). But what about all the older folks who don't have arthritis? There are plenty of adults up into their 80s and 90s who are arthritis-free. How do we explain that?

Genetics. It seems the most recent scientific research has been able to put a finger on the contribution of genetics as a potential risk factor. Gene mutations have been identified that when present may explain the higher incidence of hand arthritis in some, but not all, people.

Hormones seem to play a role here, too. Postmenopausal women are more likely to see their arthritis get worse despite treatment. But even this risk factor is inconsistent because only certain joints (for example, the base of the thumb) are affected. If low estrogen levels are linked with arthritis, then why aren't all the joints involved? Scientists are still scratching their heads over that one -- they simply don't know.

Racial/ethnic background and hand dominance are two final risk factors under investigation. So far, it looks like there may be something here as both being Caucasian (white) and favoring one hand over the other for most activities may lead to a greater risk of developing finger arthritis. Using one hand more than the other and ending up with arthritis is probably due to the added biomechanical load on the joints.

Why Caucasian Americans have much more hand arthritis of the proximal interphalangeal (PIP) joints compared with Chinese people is unknown. There may be genetic, lifestyle, joint mechanics, or other protective factors in the Chinese group that have not yet been identified.

Treatment for most conditions like arthritis is based on what is causing the problem as well as what is happening inside the joint. Researchers are having trouble here, too. It appears that the biologic cascade of steps that lead to osteoarthritis are much more complex than was ever imagined. It's not just a matter of overuse and repetitive motion causing wear and tear on the joint surface.

Even being able to tell whether a person has inflammatory versus erosive arthritis is difficult. And it's possible to have inflammatory arthritis that is erosive! Studies looking at immune pathways have been able to identify signaling molecules and degradative enzymes that are part of the process.

They are also taking a look at the chondrocytes (cartilage cells) more closely because it seems that they have a major role in the process. Somewhere along the line, the chondrocytes start to break down. The bone under the cartilage called subchondral bone compensates by stiffening up. But it's possible the stiffer bone only leads to increased (or abnormal) biomechanical forces on the joint.

So there are more questions than answers and more unknowns than knowns in the search for understanding of osteoarthritis. If you are experiencing hand pain that you think might be caused by osteoarthritis, don't let this lack of clear understanding of the disease process lead you to adopt a wait-and-see attitude.

Early diagnosis to detect small joint changes and treatment are still two important keys in maintaining motion, strength, and function of the hand(s). The orthopedic surgeon has at his or her disposal a wide range of imaging tools (e.g., X-rays, ultrasound, thermography, MRIs, bone scans) to help evaluate the painful joints.

Conservative (nonoperative) care begins with antiinflammatory drugs. Uncontrolled or severe joint damage may only be resolved with surgery to replace the joint, a procedure referred to as arthroplasty. In rare cases (and usually only because there is some specific reason), joint fusion may be performed.

Joint implants for the proximal interphalangeal (PIP) joint are usually made of silicone or pyrocarbon. They work well to reduce pain and improve motion but the implants have a bad reputation for breaking, settling into the bone, squeaking, loosening, and dislocating.

The authors conclude by saying that overall, treatment for finger and hand osteoarthritis is still fairly limited. Until more is known about the various causes, risk factors, and pathogenesis of the disease, treatment will remain dependent on medications that ease the symptoms but don't change the disease process and surgery with all of its potential complications.

Knowing how important the hand is for daily activities, especially self-care (grooming, toileting, preparing and eating food), research needs to continue placing an emphasis on unraveling the mysteries of this disease. There are many avenues to explore from genetics to types of arthritis, risk factors, and joint changes. Prevention may eventually be possible and when that isn't successful, then finding treatment techniques that work is next.
Benjamin J. Jacobs, MD, et al. Proximal Interphalangeal Joint Arthritis. In The Journal of Hand Surgery. December 2010. Vol. 35A. No. 12.