Since it is so prevalent throughout the world, “what causes low back pain?” is a question millions of people want answered. Is it normal and expected as we age? Is it genetic? Will you need to get surgery? As you can expect, the answer is different for different people. First of all, the pain is not identical from person to person. Some people get low back pain on the right side; some get it on the left side. Some get low back pain into the hip.
In this post, I will do my best to help you understand what causes low back pain and at the end of the article provide you a tool to pinpoint what is causing your particular low pain.
The Lumbar Spine and Its Significance
Your low back or lumbar spine engineering-wise is your body’s lynch-pin– along with your pelvis, it connects your upper body to your lower body and is tasked with balancing and moving your torso. If you injure your low back it can put you out of commission: any attempt at moving places a load on your low back and makes pain worse. In extreme cases it is even painful to take in a deep breath! Acute low back pain can instantly stop a 250 pound football player in his tracks; that’s the power it has.
While most cases of low back pain self-resolve over a few days, about 20% of them become chronic, or recurring. For some, it strikes every couple of months; for others, it’s enough to impede their daily activities and quality of life. In fact, low back pain is said to be the number one reason for lost work days (disability) in industrialized nations, and therefore lost productivity.
The reason why low back pain is so prevalent is a societal phenomenon, made possible by evolution. You see, humans are the only bi-pedal animal on the planet. Dancing bears and meerkats don’t count because although they can walk a few steps their pelvic design is still quadri-pedal (walking on four limbs
). When nature selected homo sapiens to be bi-pedal, it freed up his arms to carry things–heavy things. Carrying and lifting things and bending the low back places a tremendous load on the lumbar spine, and like any machine, the components bearing the most stress will be the first to break down.
Secondly, the invention of the chair and desk. When our ancient ancestors roamed the plains and forests 30,000 years ago there weren’t any chairs around to sit in for hours, placing pressure on the low back and weakening the postural muscles of the 
spine. Today, many jobs require sitting at a desk in front of a computer, doing just that. Also, food these days is abundant and much less nutritious causing humans to gain excess weight, placing constant stress on the low back throughout the day.
Causes of Low Back Pain
The vast majority of low back pain cases are mechanical in nature; meaning caused by a breakdown of some physical component of the lumbar spine. These components are the muscles, fascia (muscle sheath), ligaments and tendons; vertebrae, vertebral joints, and discs (which are technically ligaments). If the dysfunction causes compression of nerve roots, then nerve pain is involved, which usually means shooting / radiating pain and/ or numbness down the buttock to lower extremity; sometimes as far down to the sole of the foot.
Here are the main categories of mechanical low back pain:
Congenital Malformations
Sometimes there are abnormalities in the development of the spinal column which interfere with proper movement and balance placing excess stress on soft tissues and sometimes nerves, generating pain or constant stiffness and aches, and loss of range of motion/flexibility. Examples include fused vertebrae (two adjacent vertebrae fused together instead of forming a joint); scoliosis; spina bifida, pars defect, hyperkyphosis (hunchback); and hyperlordosis (swayback).
Injuries
Low back pain is often due to injuries to tissues: sprains to ligaments; ruptured intervertebral discs from a herniated or prolapsed nucleus pulposus (jelly-like shock absorbing substance in all discs); strains (tears, small and large) to muscles and tendons; muscle spasms, and fractures. These can be traumatic from a specific incident such as a sports injury, or can be cumulative over time, often years, from performing a certain movement repeatedly or sitting/slouching causing gradual degenerative disc disease. With acute tissue injury, the inflammatory response is initiated, which is responsible for the pain generation.
Degenerative Changes
Joints wear out over time. Most doctors will tell patients their condition is from “normal” wear and tear. But that’s not accurate. For some people, joints deteriorate at an abnormally fast rate, mainly due to lifestyle factors under their control. I’ve seen X-rays of 60 year-olds look much better than 30 year-olds, on many occasions.
Factors that promote lumbar spine degeneration include:
- Being overweight
- Genetic predisposition
- Sedentary lifestyle/ lack of physical activity
- Sitting frequently (airline pilot, police officer, truckers, data entry)
- Heavy labor job
- Contact sports, especially football
- Occupation or recreation that involve hard landings (basketball, gymnastics, parachuting, etc.)
- Previous injuries/accidents such as falls and car accidents
- Poor diet (your body needs proper nutrients to heal tissues)
- Smoking (smoking reduces oxygen to cells and may trigger inflammation)
Doctors use three terms to describe spinal degeneration:
- Spondylosis when referring to the vertebrae as a whole;
- Degenerative joint disease or DJD if referring to the vertebral joints: facet joints and intervertebral joints; and
- Degenerative disc disease or DDD if referring to the intervertebral discs
In all cases, the joint surfaces of the vertebrae lose their smooth borders and form jagged bone spurs called osteophytes. You can have a lot of osteophytes in your spine and not feel pain at all. In fact, if you are over age 40 you probably have them yourself. But if the osteophytes get big enough to narrow the openings where nerves pass through, called foramen, problems start. This narrowing of the 
foramen is called spinal stenosis and can occur with the intervertebral foramen (IVFs), the small holes formed by adjacent vertebrae which nerve roots pass through; and also the central canal where the spinal cord and cauda equina reside. This can lead to shooting pain down one or both legs; numbness and tingling in the legs, and leg muscle weakness, atrophy and loss of sensation.
Since osteophytes do not resorb (shrink) and only get bigger with time the only option is spinal decompression surgery which involves shaving off the osteophytes to make more room for the nerves.
And there is another problem: when spinal discs degenerate, they lose height (this is part of the reason why most people get shorter as they age). A healthy L5-S1 disc can be in excess of 1 cm thick while a degenerated one can be just 2-3 mm thick. When this happens, the posterior and anterior longitudinal ligaments that run down the front and back of your vertebral column slacken, or buckle, at those levels. Like osteophytes, buckled ligaments can cause stenosis, compressing or irritating nerves and causing the same neurological symptoms.
When the degenerative changes involve deterioration of cartilage, you have bone on bone contact. The cartilage in your spine is located in the encapsulated facet joints, located behind the vertebral bodies. This triggers inflammation, which leads to osteoarthritis. It’s the same process as osteoarthritis of the knees and hips, occurring in the spine.
Like knee osteoarthritis, people with spinal OA will feel burning pain in their lumbar spine especially when standing, and stiffness which is worse upon waking in the morning. Osteoarthritis is a chronic, degenerative disease that is best managed by lifestyle modification (anti-inflammatory diet, exercises, stress reduction). Those with severe cases sometimes elect to use prescription anti-inflammatory medication.
Non-Mechanical Causes of Low Back Pain
Less than 1% of low back pain cases are due to other factors, most of which are “red flag” cases that require immediate medical attention. These include pelvic tumors, kidney stones, metastatic cancer (usually from prostate cancer), infection, and endometriosis. A brain tumor is capable of causing sciatica-like symptoms if it affects the sensory neurons that go to the leg. While rare, if you have low back pain that does not improve with physical therapy or rest, it is a good idea to see your doctor and get some tests done to rule out these conditions.
Summary and Main Take Aways
If you have low back pain, chances are very good it will go away with rest. Apply ice for the first 1 to 2 days. If severe, you can try taking over the counter anti-inflammatory medications (NSAIDs) such as Motrin or Ibuprofen to knock down some of the pain. And if you are lucky to have a cryotherapy center near you, you can do a couple of visits to shorten the healing time.
If the pain lasts more than 4 days, then it usually means something is perpetuating it: perhaps you are not resting it properly; are re-aggravating it; or have some kind of contributing factor such as a rotated vertebra or disc protrusion. These issues can be dealt with by visiting a good physical therapist or chiropractor. You can even do some home exercises and home therapy for low back pain on your own and still get great results.
While most cases of low back pain go away, it doesn’t mean that it will stay away for the rest of your life: 20% of people who get low back pain will experience it again in the future; either from a new injury/event or a flare-up of a pre-existing injury. And remember, some cases become chronic (pain decreases, but the improvement plateaus and remains, with some days worse than others). Your prognosis will depend on what is causing your low back pain (see below for a self-diagnosis tool) and other factors related to your medical history and daily activities.
When dealing with low back pain, besides focusing on reducing the pain think of what things caused it and eliminate those causes as best you can. It may mean:
- Getting a stand up desk (standing puts less stress on your low back than sitting)
- Losing some weight
- Eating a healthier diet
- Stopping smoking
- Exercising more often
- Reducing emotional stress in your life
- Improving the ergonomics of your work station
- Learning how to lift properly
- Getting your back adjusted by a chiropractor periodically to improve joint movement and joint health
And lastly, remember that low back pain should noticeably and progressively improve each day after initial onset. If you notice that pain does not get better with rest, express your concern to your doctor: demand an X-ray, MRI and/or a blood test. Red flag cases like cancer are often misdiagnosed by doctors (dismissed) as general back pain due to spasms because doctors know that the medical literature estimates red flag cases to be 1% or less of all low back pain cases. Remember to be persistent; it is your life you are dealing with.
Below is a low back pain algorithm I created to help you diagnose your particular low back pain so that you can take appropriate action. Use the top one if your low back pain onset was sudden; use the bottom one if the onset was gradual. This is only a guide; always check with you doctor who can examine you, to get an accurate diagnosis.
