If you have found this article, it likely means you have some basic questions about the back. Namely, why does my back hurt and how do I make the pain go away? If I may restate the questions: What are the possible causes of lower back pain and what are the solutions to this pain? I aim to tackle the former in this post and we will start that discussion with a bit of anatomy.
The back is a series of bones that sit on top of one another. There is a disc that sits between the bones in the front and the vertebrae form joints on the backside. Sitting between the joints and bone-disc column are bony rings that form a tube which houses the spine, spinal nerves, spinal fluid, and their protective coverings. Adding support to these elements are the ligaments that further connect the bones, the muscles around the spine, and the tendons which attach these muscles to the bones.
With this information, we can give a very basic answer to our first question. Lower back pain is caused by one or more issues with one or more of these structures. Pain that arises from the bones can come from a fracture (broken bone) or degeneration (breakdown) of the bone itself. This degeneration can happen in a joint (bone meeting bone) or where the bone meets another non-bony structure. Degeneration of the disc itself can cause pain. Nerve pain results when a nerve is pressed on by bone, discs, ligaments, tumors, infection, blood clots, or some combination of these. Sprains (overstretching ligaments), strains (tears in muscle or tendon), and/or spasms in the muscles represent a final broad category of pain generators.
For completeness’ sake, there are issues outside of the spinal structures listed above which can present as lower back pain. A non-exhaustive list includes hip pain, kidney stones, endometriosis, autoimmune disease, infection, or tumors. These are outside of the scope of this post and therefore we will end our discussion of them here and move to a more detailed description of the spinal issues specifically.
Some of the Common Causes of Back Pain
The most common site for a fracture is the body of the vertebrae which is the cylinder “block” on the front side of the vertebrae. This generally happens because of trauma and the force needed to cause the fracture decreases if osteoporosis is present. Other parts of the bone can be fractured but these are less common and usually require high energy trauma. Fractures generally cause pain with movements that apply additional pressure to the damaged area and get better by lying down and resting. Unsurprisingly, it can also be painful to apply pressure to the fractured area.
Facet joints are the joints on the back side of the spine where the vertebrae meet. Degeneration of these joints can result from wear and tear (e.g., osteoarthritis) or may be related to excessive inflammation leading to destruction of the joint (e.g., rheumatoid arthritis, ankylosing spondylitis, etc.). Pain in these joints is generally located in the middle of the spine though it can radiate up the back and into the thighs. It usually is worse with activity and as the day progresses. It also gets worse when leaning backwards and twisting side to side.
Sacroiliac Joint Pain:
The spine ends by resting on a shield shaped bone called the sacrum. There is a pair of large wing shaped bones that form the rest of the pelvic ring called the ilia bones. These are the hip bones on which your belt rests. The sacrum meets each ilium on the back side of the pelvic ring at the sacroiliac joint and there are a host of ligaments that attach across these two bones as well. All the forces of your upper body are passed through your spine and into the pelvic ring before splitting evenly into the two legs. If there is an imbalance in this process of equal load splitting (e.g., scoliosis, spinal degeneration, chronic pain in one leg, etc.) or other excess pressure on the area (e.g. pregnancy, minor trauma), the joints can become inflamed leading to pain in the buttock that can radiate down the leg or into the groin. It is usually worse with prolonged sitting or riding in the car and can improve with standing or walking. It may at times feel like a burning across the buttocks.
Between the discs and the vertebrae on the front of the spinal column there is a thin layer of cartilage called the vertebral endplate. Constant, excessive pressure through the spine and consequently on the endplate leads to damage of this structure. Unfortunately, it has many nerves that when they become inflamed can cause pain that is often “non-specific” though unresponsive to other conservative measures.
The discs are made up of an inner gelatinous layer and an outer fibrous layer. If the disc is damaged through a single event or repeated injuries of varying severity over time, degeneration happens within the disc. The changes that result because of this degeneration lead to increased inflammation within the disc which causes pain that is generally worse with prolonged sitting or standing and feels as though it is “deeper” in than pain than pain from a muscle would be. It is helped by laying down but may be worse in the morning upon waking.
Sciatica is a broad term that means pain that appears to originate from a nerve that radiates into one or both legs. You may also hear it described as radiculopathy when specifically speaking about a spinal cause of these symptoms. Anything that causes pressure on a nerve can lead to pain that may start in the back and travel into the legs. In the spine specifically, this can be from a disc that has either slowly degenerated or recently herniated (the inner gelatinous layer pops through the outer fibrous layer), overgrowth of the bones or surrounding ligaments, or some combination of them all leading to pressure on a nerve. Sciatic pain is generally a sharp, shooting, stabbing pain that may even feel burning or electrical at times. Certain movements or coughing/sneezing will lead to a “lightning bolt” of pain down the leg. It can be very difficult to find a comfortable position.
Sciatica (outside of spine):
Sciatica symptoms can also occur because of nerves that are being pressed by a structure outside of the spine. The most common is a muscle that runs across the back side of your hip called the piriformis muscle. There are other sites of compression as well. It can be difficult to determine whether the piriformis muscle is the cause of sciatica symptoms but tenderness while pressing the muscle and significant buttock pain are the usual distinctives.
Claudication refers to pain in the legs with walking. The word “neurogenic” simply states that the claudication is specifically resulting from a nerve issue rather than a blood vessel issue (which represents the other source of claudication symptoms). It results from a narrowing of the central canal of the spinal column where the nerves and spinal fluid rest. This is pain in the low back that radiates into the buttocks and/or legs that gets worse with walking and improves with rest or bending forward while walking (such as leaning forward on the grocery cart).
Soft Tissue Injury:
The most common cause of acute (new onset, short-term) low back pain is related to a strain and/or damage to the muscle and tendons surrounding the bony spine. This usually comes on very quickly, often with an identifiable event, and leads to pain in the low back that can radiate into the buttocks and/or back of the legs. An additional source of pain from these soft tissues occurs when there is pain from one of the other above listed conditions. Because certain movements and postures are painful, you may consciously or subconsciously change how you hold and move your body through the world. This can force your muscles to work in ways that are suboptimal and lead to excessive strain and subsequent pain as a result.
When Should I See A Doctor?
I want to end the discussion by listing a few “red-flag” symptoms that if present, warrant immediate evaluation by a healthcare professional.
- Major trauma, minor trauma may still be of concern in elderly or those with osteoporosis
- Fever, chills
- Unexplained weight loss
- Problems controlling bowel or bladder (inability to void when the need is felt or inability to stop voiding despite not feeling the need)
- Loss of sensation in your groin and genital region
- Severe and/or progressive neurological changes (rapid worsening of pain, significant weakness that may or may not be worsening)
- Recent procedure in or around the spine while on blood thinners
I hope that this post provided you with a brief overview of some of the various causes of low back pain. It was not meant to be exhaustive, but the vast majority of lower back pain complaints will fit into one of these categories. Separate posts will tackle the various treatment options available for these and other painful conditions. We would love to discuss your specific low back pain concerns in a formal office visit at your convenience.