3 of The Leading Causes of Lower Back Pain & Sciatica

For a lot of people with back pain, their pain is caused by irritation of a nerve. Sciatica is a symptom specifically referring to nerve pain that radiates down the back of the leg. Nerve irritation can occur anywhere along it’s pathway from the spinal cord to the toes and can also cause pins & needles, numbness, and tingling sensations.

In the picture below, the opening to the right of the disc is where nerves pass through as they branch off the spinal cord.

Of the many reasons nerves can become irritated, 3 common causes that lead to lower back pain and sciatica are outlined below.


Also referred to as a slipped disc or a bulging disc, this is a condition usually experienced by 25 to 35-year-olds.

The disc is the shock-absorbing separator between each vertebra. Usually, people with a herniated disc will experience pain when they bend forward because this pushes the disc backward onto a nerve (like biting into an ice cream sandwich and having the ice cream squish out the other side).

Bending forward and hinging at one segment instead of spreading the load throughout the spine and hips can cause the disc to start to bulge out of its outer layer (a bulging disc) and with enough time and force the disc can burst out of its outer layer (a herniated disc). At no time can a disc slip out of place.

How would you stop the ice cream in your ice cream sandwich from squishing out the other side? Bite closer to the center. A similar basic principle can help you visualize what physical therapy aims to achieve. By changing your movement mechanics and how you carry objects, we can change how forces move through your body to prevent things like discs from bulging out.


Stenosis literally means narrowing of a passageway. Stenosis can occur in your arteries, but in the case of back pain, it’s referring to narrowing of the bony tunnels where nerves exit the spinal cord. This narrowing makes it much easier for nerves to get squeezed at these exit points. Often, this narrowing occurs due to degenerative disc disease, a name that sounds much scarier than what is actually occurring in the body.

Stenosis usually affects people 50 years and older because degenerative disc disease is generally caused by the discs dehydrating, which is a normal part of aging. Is anyone taller when they’re 50 than they were at 18? Usually people get shorter with age and this is the result of the discs dehydrating and the vertebrae moving closer together. As the vertebrae move closer together, this causes the narrowing of the tunnels where the nerves exit the spinal cord.

The ‘disease’ part of degenerative disc disease comes when poor movement mechanics start to wear on these more vulnerable dehydrated discs. You’ll want to save your discs with physical therapy not just to prevent pain but because if a certain part of the vertebra experiences more pressure, it will lay down more bone to protect itself (osteophyte formation). This happens when inefficient mechanics lead you to load the same parts of your vertebra over and over again without spreading the load.

Unfortunately, the vertebrae do a haphazard job of laying down this extra bone and it leads to the lumpy bumpy looking vertebrae some people see on their scans. Sometimes these lumps and bumps are as harmless as wrinkles but sometimes they can contribute to pain as part of the bigger clinical picture.


SI stands for sacroiliac and it’s where the fused end of your spine, the sacrum, meets your pelvis (more specifically the ilium). Not much movement occurs at the SI joint but because it is a joint, there is a small amount of movement that is supposed to occur, otherwise it would be a fused joint like the sacrum (which is actually 5 segments purposely fused together by your body during development).

There are two problems people can have at their SI joints – too much movement or too little movement. Usually, only pregnant women and people with connective tissue disorders experience too much movement at their SI joints. For everyone else, their pain is usually caused by too little movement.

SI joint problems are easy to diagnose in the clinic but can’t actually be detected on any scans. This is because it is a movement problem, not a structural problem. Until x-rays and MRIs produce videos instead of images, a movement assessment by a physical therapist will be much more effective (and less expensive) for identifying the cause of your pain. If you know someone who’s scans came back clean but they are still experiencing pain, they might have an SI joint problem.

If you think you’re experiencing any of the conditions listed above (or a condition not listed above, like facet joint pain), please reach out to us for help. We offer free screens so that you can find out what exactly is causing your pain and then, based on your goals, we’ll come up with a treatment plan that works for you. Your physical therapist is trained to pick up on the signs and symptoms that indicate you need further medical assessment by your physician, which may include a scan to rule these out.

If you have lower back pain or sciatica, don’t let it become a pain in the neck! Schedule your free screen today and start on your journey to better health.

As always, consult with your Licensed Physical Therapist for individualized advice. For those in Illinois and California, visit your PT immediately without a prescription or referral.

Give us a call at (877) 709-1090 for more information or fill out the contact us form and we will contact you.

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