Lumbar Disc Pathology

Welcome to the club no one wants to be in. Spinal disc injuries are very (very) prevalent, with as many as 20 case per 1000 adults annually. Lumbar disc injuries are the most common, followed by cervical disc injuries. The majority of these cases are injury based, with only 5% being attributed to degenerative disc disease. This month, we’ll explore the anatomy of the spine, break down how disc injuries occur, and share the latest research on recovery.

Back injuries can feel overwhelming. Understanding the structures involved, how they function normally and how they can become dysfunctional, can help focus your rehabilitation goals.

There are 23 discs in the human spine: 6 in the cervical region (neck), 12 in the thoracic region (mid-back), and 5 in the lumbar region (lower back).  Each intervertebral disc (IVD) lies between two adjacent vertebrae in the spinal column, allowing the spine to be flexible without sacrificing a great deal of strength. They also provide a shock-absorbing effect within the spine and prevent the vertebrae from grinding together. 

They consist of three major components: the core, nucleus pulposus (NP), the outer ring, annulus fibrosus (AF) and the cartilaginous endplates that anchor the discs to adjacent vertebrae.

So why does it hurt so much, and how does this even happen?!

Disc “bulge”, “protrusion”, “herniation”, even “slipped disc”, as well as disc degeneration all refer to interruption of the normal disc anatomy. Damage to the outer ring, or AF, can occur from sudden trauma to the disc or from disc degeneration due to age and repetitive use. Without the structure of the AF, the NP can be displaced.

Image Credit

While the discs are designed to move to counter spinal movement, repetitive asymmetric compressive loading isn’t ideal. For example, during forward bending, or flexion of the lumbar spine, the NP migrates posteriorly or backwards. Conversely, the nucleus is squeezed anteriorly or forwards during backwards bending, or extension of the lumbar spine. Adding extra weight to one of these positions over and over can cause injury. Research shows the damage to the AF appears to be associated with fully flexing the spine for a repeated or prolonged period of time. 

Like everything else, our Intervertebral discs age. The NP shrinks as it’s gelatinous material becomes dries out over time and is replaced with fibrotic tissue. This places increased strain on the AF. The resulting flattened disc reduces mobility and may impinge on spinal nerves leading to pain and weakness

Due to the proximity of the disc to the spinal cord, if the disc extends beyond its normal resting position, it can result in pain. This pain is due to a combination of the mechanical compression of the adjacent nerve by the bulging NP and localized inflammation and swelling. The symptoms you experience are dictated by what nerves are irritated. Nerve compression can often cause radiculopathy - or radiating symptoms along the path of the compressed nerve into the legs and feet.

To learn more, check out these articles:

1. Waxenbaum JA, Futterman B. Anatomy, Back, Intervertebral Discs. InStatPearls [Internet] 2018 Dec 13. StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470583/ (last accessed 27.1.2020)

2. Dulebohn SC, Massa RN, Mesfin FB. Disc Herniation.Available from:https://www.ncbi.nlm.nih.gov/books/NBK441822/ (last accessed 25.1.2020)

3. L. G. F. Giles, K. P. Singer. The Clinical Anatomy and Management of Back Pain. Butterworth-Heinemann, 2006.

Mama Bear Energy

To wrap up our section on lumbo-pelvic pain, I had a chance to chat with Kathleen about how to manage this from the patient perspective. Kathleen is our unofficial in-house champion of new moms. Her passion for this population is obvious- read more on how she views rehabilitation and fitness as crucial to pre-natal and postpartum health.

---

SV: For the past month, we’ve been sharing the latest research on lumbo-pelvic pain during pregnancy. As a recap, what are your top three take aways for mom-to-be who's been experiencing back pain?

KM: Sure thing! First, and maybe the most important take away, low back in pregnancy shouldn't be considered just part of the process, something you have to endure. There's no need to be in pain unnecessarily! Next, we have to think outside the box to find an exercise activity that feels right for you during these weird times - whether it’s strength, pre-natal yoga, pilates, or aquatic. Many yoga and pilates studios are offering virtual classes during the shelter-in-place orders. Last, don’t be afraid to speak to your doctor. Advocate for the support you need to help make your pregnancy as comfortable as you can be. Working with a skilled clinician, like a PT or ATC, to address your specific needs can not only reduce pain but also keep you and your baby healthy throughout the pregnancy.

SV:  How does this differ from the type of back pain someone who's not pregnant might experience?

KM: Back pain in pregnancy stems not only from the obvious changes that are occurring in the woman's body from the growing baby, but is also impacted by the hormonal changes that create ligamentous laxity in preparation for childbirth. The pain itself can evolve throughout the pregnancy, shifting in location, intensity and ancillary symptoms. Additionally, lumbo-pelvic pain can coincide with altered balance as the center of mass moves with the growing belly.

SV: According to some, back pain is practically inevitable during pregnancy. What could someone trying to get pregnant do to proactively prepare physically?

KM: Any muscle weakness or joint instability coming into the pregnancy will increase the difficulty of dealing with the demands of pregnancy. Get started now! It’s smart to be proactive, working on strength and overall fitness to prepare for pregnancy!

SV: Pregnancy is NOT easy. Some moms may be feeling overwhelmed just thinking about adding exercise to their day, while others might be eager to feel better and get back to their routine. Can you talk through what a home program might look like?

KM: As we shared, the American College of Obstetricians and Gynecologists recommends 30 minutes of moderate intensity exercise most days of the week throughout pregnancy. This could be a 30 minute walk at a pace in which you can still talk, a 45 minute prenatal yoga or pilates class, or a 30 minute home routine that you could even split up into 15 minutes in the morning and 15 minutes in the evening. Exercises will vary between individuals, but all expecting mothers should include stability, core strength, and proper squat and hinge techniques in their programs. Upper body strength is a great bonus, too!

Postpartum it is important to give your body the time it needs to heal; it is recommended to rest 6 weeks before starting exercise post-childbirth. If feeling unsure where to start, meet with a professional who can guide you through a program to safely get you back to exercising.

SV: At Physical TheraPT, as many of our patients know, we love staying current on the latest innovations in exercise and rehab equipment. What’s your favorite product out there right now for pregnant patients?

KM: There’s been a lot of chatter about abdominal binding postpartum by a certain celebrity. Do your own research on what makes the most sense for your recovery; too much downward pressure following delivery isn’t always safe. Bao Bei Maternity offers physio-designed appropriate support garments for both during pregnancy and postpartum. Check them out at www.baobeimaternity.com or on instagram at @baobeimaternity

SV: Last question- what’s your go-to strategy for pain relief with this type of injury?

KM: Heat can be very helpful - whether a warm bath or a heating pad on the couch with your feet up, this is a great strategy for both pain relief and stress reduction.

Jump Into Prenatal Fitness

The literature has shown exercise can decrease pain, improve function, and limit time off work due to pregnancy-related back and pelvic pain. In general, strengthening routines should focus on muscles of the back, core and pelvic floor. Bonus circuits can also include upper body strengthening in preparation to lifting and carrying your bundle of joy. Depending on your experience with exercise, you can choose between independent sweat sessions, or working one-on-one with a coach. Prenatal group exercise classes are recommended for individuals who find themselves needing modifications for greater than 50% of the class. But what if you feel too pregnant to exercise?

Enter water aerobics.  While the class may conjure images of senior citizens in shower caps, aquatic therapy is frequently used with patients who are pregnant. Being in the water up to chest level takes off 70% of your body weight. This can be extremely helpful for soon-to-be moms who are having painful back and pelvic girdle issues, allowing for exercise until they can tolerate more land therapy.

A 2016 systematic review of literature, found strong evidence demonstrating benefit of combined aquatic and resistance for maternal cardiorespiratory fitness and prevention of urinary incontinence. Additionally, a 2011 study found that aquatic therapy is effective in reducing peripheral edema (swelling in the ankles and feet). 

Depending on your community, access to a pool may vary. Some health clubs and specialty physical therapy clinics offer individual and group classes depending on local health regulations. Your OB-GYN can be a great resource for other options. Just be sure to double-check with your primary medical team before jumping in the nearest lake!