Low back pain is one of the most common reasons patients see primary care doctors. To understand this condition, it’s necessary to understand the anatomy of the low back.

The lower (lumbar) spine consists of 5 vertebrae, L-1 through L-5, stacked on top of each other, held together by what are called facet joints. Just below L-5 is the sacrum and below that the coccyx (“tail bone”). The sacrum is connected to the pelvic bones by an immovable joint on each side called the SI (sacroiliac) joint. The spinal cord runs vertically through holes in the vertebrae. Nerves exit from the spinal cord on each side between each pair of vertebrae, and carry impulses to the lower body and legs. Discs are cushions between each pair of vertebrae — each disc consisting of a soft, jelly-like center surrounded by a fibrous band called the annulus fibrosis.

Muscles attach to the vertebrae, and the most common low back injury is a simple muscle strain, often caused by improper lifting. People with a low back strain have pain and tenderness in the area of the strained muscle, made worse with forward, backward, or sideways bending. X-rays and MRIs are not useful in diagnosing a simple muscle strain. Treatment is intermittent ice for up to 48 hours, then heat. The safest analgesic is acetaminophen; aspirin and anti-inflammatories such as ibuprofen and naproxen having more side effects. Symptoms usually resolve within several days. Although people with back strain should avoid activities that cause increased pain, bed rest is counterproductive–“active recovery” such as walking is best. If symptoms persist, physical therapy, chiropractic manipulation, and acupuncture often help.

Arthritis of the facet joints can cause back pain, and usually occurs in people middle-aged or older. Pain is usually located deep in the low back, just to one side of the midline, and often radiates into the buttock. Another cause of low back pain is a strain of the SI (sacroiliac) joint. Pain and tenderness are usually located on one side of the sacrum, often radiating into the thigh. Patients with SI strain often complain of pain in their “hip.”

Another cause of low back pain is injury to a disc. The annulus fibrosis of a disc can develop a weak spot, like a weak spot in a tire or balloon, causing the annulus to bulge—which stretches the nerve fibers in the annulus, resulting in pain. If the bulging disc touches nerve fibers exiting from the spinal cord, pain in the back of a leg called sciatica can occur; as can numbness and tingling; and sometimes weakness. X-rays and especially MRI are useful in diagnosing lumbar disc abnormalities. Disc injuries can heal on their own, and it’s always best to avoid surgery with its possible complications; plus, sometimes surgery fails relieve the symptoms. “Failed low back syndrome” is when a patient has had one or more operations and their pain is no better or even worse. If fusion is recommended consider a second opinion, because this involves major surgery, with a long recovery, and is not always successful. It’s interesting to note that the number of back operations done in a geographic area is proportionate to the number of back surgeons. However, surgery is urgent when nerves to bowels or bladder are affected or if leg weakness is persistent or progressive.

Some serious, even life-threatening conditions such as tumors, infections, and abdominal aneurysms can cause low back pain. If you have significant back pain with no obvious injury, or which is not made worse by bending, seek medical attention right away. Back pain in children should always be evaluated promptly.

Why is it that some people never suffer from low back pain and others do? People who are physically fit, with good core strength, are at much less apt to suffer low back strains. Proper lifting can avoid back strains: lift with your legs, not your back; and don’t lift and twist. In regard to disc injuries, the structures in the back receive nutrients from blood flowing through small vertebral arteries. If these arteries are partially or totally blocked from atherosclerosis, the discs become damaged and are more prone to rupture.

Dr. Greg Feinsinger is a retired family physician who started the non-profit Center For Prevention and Treatment of Disease Through Nutrition. For questions or to schedule a free consultation about nutrition or heart attack prevention contact him at gfmd41@gmail.com or 970-379-5718.