If you’ve ever complained to a friend about your aching back, chances are he or she responded with some version of: Been there, had that. Back pain is the second most common reason Americans go to the doctor (after upper respiratory infections, that is, colds and the flu). Studies show that four out of five adults suffer a bout with back pain at some time in their lives.

With an aging U.S. population, back pain may be growing into an even greater problem, since osteoarthritis (OA) typically emerges in people over 40, and the spine is a prime target for this common joint condition. But just how much of our nation’s back pain is caused by OA? “That’s the $64,000 question,” says University of Pittsburgh pain specialist Debra K. Weiner, MD. Back pain is a complex condition, say Dr. Weiner and other physicians who treat it, and OA is often just one piece of the puzzle.

OA and the Spine

OA is a disease of the joints, and your back has plenty of those. The spine is a column of 33 bones called vertebrae. Five of the vertebrae are fused into a single unit at the base of the spine, known as the sacrum; another four vertebrae combine to form the coccyx, or tailbone. The rest of the vertebrae are connected by so-called facet joints. Tucked between each vertebra are cushion-like pads called disks, which protect the spine and give it flexibility. Resting within the column of vertebrae lies the spinal cord, which connects the brain to every part of the body through an unfathomably complex networks of nerves.

Viewed from the side, the spine forms a graceful S shape. Yet this elegant-looking contraption is vulnerable to OA — especially in the lower, or lumbar, region — thanks in large part to one of the very qualities that sets humans apart from the rest of the animal kingdom: We walk on two legs. “That produces a constant loading on the spine,” says Michael Marks, MD, an orthopaedic surgeon in Norwalk, Conn., and a spokesperson for the American Academy of Orthopaedic Surgeons.

As we age, persistent pressure on the spine wears away the tough cartilage lining facet joints. Meanwhile, disks in the spine begin to narrow due to water loss, adding to pressure on the facet joints (and subtracting from your overall height, which is why people shrink as they age). As a result of these changes, says Dr. Marks, the facet joints can develop inflammation.

What’s more, OA can make the spine unstable, explains Dr. Marks. In response, growths called osteophytes, or bone spurs, can form in the joints. While bone spurs appear to be the body’s attempt to restore stability, they can cause the spine to stiffen. As OA worsens, bone spurs can narrow the “frames” where nerves exit the spinal cord. This condition, called spinal stenosis, can pinch nerves and cause numbness and weakness in the legs.

Not Just Joints

Trauma to the spine, from an accident or engaging in certain activities, increases your likelihood of having spinal OA (also known as spondylosis). “If you were a football lineman with constant impact all the time, you’re more likely to have it than someone who was a swimmer,” says Dr. Marks. However, genetics plays a role, too; if one or both of your parents had OA in the spine, your odds rise, too. Dr. Marks estimates that OA is the likely culprit in about 20 percent of 40-year-old men and women who develop back pain, a figure he says rises to as much as 75 percent among people over 60.

However, some doctors who treat back pain feel that OA gets too much of the blame. They are quick to note this phenomenon: X-rays reveal that the vast majority of middle-aged and older men and women have OA and disk degeneration in their spinal joints, yet many have no symptoms. “They’re walking around on the street, pain free,” says Norman Marcus, MD, author of End Back Pain Forever (Atria, 2012) and director of muscle pain research in the department of anesthesiology at the New York University School of Medicine.

Dr. Marcus argues that weak, stiff or damaged muscles are responsible for three out of four bad backs, regardless of age. Back pain is often “referred,” he says; that is, a muscle damaged in another part of the body triggers anguish felt in the back. Dr. Marcus believes that doctors who target OA of the spine as a significant contributor to this common problem are misguided. “We’re spending a huge amount of money on back pain,” says Dr. Marcus, “and our results are getting worse.”
 

To wit: A recent study by researchers at The Dartmouth Institute in Lebanon, N.H., found that spending on back and neck problems has doubled in the United States since the late 1990s, to $90 billion a year. And while the study didn’t find that outcomes are worsening, they don’t seem to be getting better: The number of annual office visits for spine-related woes is about the same today as a decade ago. 

Dr. Weiner feels that while there’s “definitely too much focus” on OA as a source of back pain, she says it can be part of the problem for some patients.

“Back pain is usually multifactorial,” she says, noting that OA of the spine may conspire with other conditions to produce discomfort in the lumbar region. For instance, studies show that seven percent of women over 60 have fibromyalgia, a condition of unknown origin that can cause back pain.

OA is also linked to scoliosis, or abnormal curvature of the spine. Depression and anxiety, or even having mismatched leg lengths can contribute, too, says Dr. Weiner.

Exercise Is a Must

Given that back pain has many causes beyond OA, it’s no surprise that experts say that there’s no one-size-fits-all treatment. Some patients respond well to simple over-the-counter pain relievers such as ibuprofen (Advil) and other nonsteroidal anti-inflammatory drugs (NSAIDs). For severe inflammation, cortisone injections can provide relief, though it’s often temporary. When nothing else helps, surgery is a last resort. According to Dr. Marks, many patients with OA of the spine respond well to a procedure called a laminectomy, in which a surgeon removes a portion of bone from vertebrae to relieve pressure on the spinal cord and nerves.

Regardless what’s causing your back pain, all doctors agree that getting it under control requires exercise to increase the strength and flexibility of muscles that surround and support the spine. But for some, that means overcoming tension in the muscle between their ears.

“People often believe their pain is unsafe,” says Carol Hartigan, MD, a spine physician at New England Rehabilitation Hospital in Boston. “They become fearful of moving, and start to anticipate pain and avoid activities. That makes your muscles weak and tight, which makes you more sensitive to pain.”

Once Dr. Hartigan and her colleagues rule out fractures, infections, tumors and other potentially serious causes of back pain, they start educating patients. “We tell them: ‘You have discomfort and pain, but it’s not dangerous. It’s safe to move, even if you initially experience some pain,’” says Dr. Hartigan. 

Persuading a patient to start exercising works best when he or she understands that physical activity increases blood flow to the back, which nourishes joints and muscles with oxygen and nutrients, while clearing away destructive inflammatory waste products.

Just as importantly, a patient’s fear gradually clears away, too. For many, realizing they can once again unload the dishwasher or take out the trash without wincing is a revelation. “They feel less afraid to move,” says Dr. Hartigan. “They say, ‘Oh my gosh, I actually did that — and it was okay.’”