What Is Spondylolisthesis

The term Spondylolisthesis is a mouthful, so it may be useful to break down this mammoth of a word before we go into any further detail. ‘Spondylo’ refers to the spine and its components, and ‘listhesis’ means slippage.¹ So, if we put those two derivatives together, a spondylolisthesis means the slippage of one vertebra in the spine.¹ The importance of this medical condition is encompassed by the subsequent effects on the spinal cord (a critical component of our central nervous system). Therefore, if one of the vertebrae of our spine slips out of place, this can cause detrimental consequences if left untreated. This article aims to shed light on the causes, symptoms, and treatment of spondylolisthesis, thus enabling early intervention and prevention and improving the quality of life of those affected.

Anatomy of the spine 

Functionally, the spine has many functions in the human body. It has both protective and stability facets, which, without either, we would not be able to function. The spine provides structural support to our bodies, which enables us to stand upright, bend flexibly and move freely.² Its protective aspect alludes to the spinal cord, as mentioned in the introduction. The spinal cord forms one-half of our central nervous system, and its connection to the brain forms the whole.² The spinal cord and the brain essentially work to keep us alive. Electrical impulses from both of these structures supply everything in our body, from our organs to our muscles. 

The anatomy of the spine is complex but can be easily simplified. If you imagine a ‘s’-shaped tower containing 24 levels, this essentially resembles the structure of the spine. The ‘s’ curvature of the spine is called lordosis and kyphosis.³ However, it is important not to confuse these with spinal disorders of the same name. Lordosis is a forward curve in the spine, and kyphosis is a backward curve.³ These curves aid the distribution of mechanical stress during rest and movement [3]. Moving onto the ‘levels’ of the spine, these represent the vertebrae (bones). There are 33 vertebrae in the spine, which are divided into 5 sections: cervical (C), thoracic (T), lumbar (L), sacrum (S) and coccyx. 

The grouping of these vertebrae is dependent on their location in the spine:⁴

• Cervical: comprised of the first 7 vertebrae (C1-C7), these aid the connection between the spine and the skull via the atlas and axis bones.
• Thoracic: composed of the vertebrae in the chest region (T1-T12) and serve as connections for the ribs.
• Lumbar: this section contains the vertebrae from the lower back (L1-L5); they function as the main weight-bearing vertebrae.
• Sacrum: these vertebrae are located at the base of the spine (S1-S5).
• Coccyx: the coccyx is formed from a fusion of 4 vertebrae located at the base of the spinal column.

Types of spondylolisthesis 

There are six types of spondylolisthesis:⁵

1. Traumatic 
2. Iatrogenic 
3. Congenital/ dysplastic 
4. Degenerative 
5. Pathologic 
6. Isthmic 

Traumatic spondylolisthesis is a forward slip of the vertebral body, commonly occurring in the cervical and lumbar spine. Large exertions of force or movement (specifically hyperextension) can fracture the vertebral bodies.⁶ This type of spondylolisthesis is, however, uncommon. Iatrogenic (subsequent to medical intervention) spondylolisthesis is directly caused by prior spinal surgeries. However, this is only if the surgery involves decompression of the spine without stabilisation. Decompression surgeries encompass the removal of a small portion of the spinal vertebrae in order to alleviate pressure on the spinal cord. However, when too much bone is removed, vertebral bodies can slip.

Congenital or dysplastic spondylolisthesis is a rare condition present at birth. It is caused by a defect in the joints connecting the vertebrae in L5 or S1. It can also occur in both vertebrae, thus causing a gradual slippage of the L5 vertebrae. 

Degenerative spondylolisthesis refers to arthritic changes in the spine that cause weakening of spinal vertebrae and slippage with age. This commonly occurs in the lumbar spine but can also happen in the cervical spine.

Pathologic spondylolisthesis is caused by invasion of the vertebrae by tumours or bone diseases (for instance, osteoporosis). Although this is a rare type, it can cause severe destruction of the posterior (back) area of the vertebrae. 

Lastly, isthmic spondylolisthesis is the most common type of spondylolisthesis, containing three subtypes of its own. Each subtype affects the same area; the pars interarticularis. This is a thin bone segment which connects two vertebrae.⁷ Subtype A (a stress fracture) causes misalignment of the vertebral bodies affected, thus allowing it to move and slip. 

Symptoms 

Some of the main symptoms of spondylolisthesis include:⁸

1. Increased pain in your back (commonly lower back) when walking and relief when sitting down or bending forward
2. Pain radiating to the thighs or bottom
3. Tight or tense hamstrings 
4. Sciatica (the radiation of pain from the lower back down one thigh) 

Although symptoms may be present in spondylolisthesis, it is important to recognise that it may be asymptomatic (have no symptoms); therefore, understanding its causes is imperative for recognition of the condition.⁸ Spondylolisthesis could cause serious complications; therefore, if symptoms mentioned above have been prolonged for 3-4 weeks, a healthcare professional should be contacted to investigate further and help in the best way possible.⁸ 

Diagnosis and classification 

In a clinical setting, a variety of methods are used to elicit the cause of spondylolisthesis and confirm the diagnosis. This may include taking a medical history, conducting a physical exam of the legs and spine, a neurological exam, and imaging studies [9]. 

Medical histories are used as a sieve to filter through the symptoms experienced and collate differential diagnoses to investigate the problem more specifically. The physical exam of the legs and spine involves gentle manipulation of the legs and spine, and your healthcare professional may ask you to perform some movements to see if there are any limitations and determine the location of the problem.9 Additionally, the neurological exam is similar to the physical exam; however, here, the clinical exam looks at any nerve damage that may be precipitating symptoms.⁹

Imaging studies may also be used as additional investigation for the cause of the spondylolisthesis. X-rays, CT scans, MRI scans and bone scans can either be used individually or in conjunction with each other to utilise images produced and confirm the diagnosis.⁹ The clinician will then be able to inform you of the diagnosis and discuss the most appropriate treatments. 

The classification of spondylolisthesis is determined by imaging, specifically X-ray. The Myerding classification defines the extent of vertebral slippage and is separated into 5 categories:⁶

• Grade 1: <25%
• Grade 2: 26-50%
• Grade 3: 51-75%
• Grade 4: 76-100%
• Grade 5: >100% (this is complete slippage of the vertebrae and is called spondylosis) 

Treatment and prevention 

Treatment is dependent on the severity of the symptoms; therefore, some presentations of spondylolisthesis may not require any treatment, and some may require a combination.⁸

Common treatments include :

1. Conservative measures such as avoiding strenuous activity that may make symptoms worse such as bending, lifting heavy weights and athletics. Physiotherapy can help to train with a professional and work on gaining muscle and strength in the lower back, abdomen and legs.
2. Pharmacological (medications): Anti-inflammatory painkillers such as ibuprofen or stronger ones that are prescribed. Steroid injections can be prescribed or given in the clinic to relieve pain and other symptoms, such as tingling and numbness.
3. Surgical: Spinal fusion is an option that fuses the slipped vertebrae to the bone below with metal rods. Lumbar decompression is used to relieve pressure on the spinal nerves.

Complications 

If left untreated or undiagnosed, spondylolisthesis may result in further complications. These include:¹⁰ 

1. Chronic back pain 
2. Loss of bladder control 
3. Weakness of the legs
4. Change in sensation (tingling or numbness)
5. Temporary or permanent damage of spinal nerve roots

Stressing the importance of early detection and prevention is critical in the mitigation of spondylolisthesis; therefore, contacting a healthcare provider at the earliest instance if any of these symptoms feel familiar is in your best interest.

Conclusion 

Spondylolisthesis is a spinal condition that demands our attention and comprehension. It represents so much more than just a medical term, epitomising the lives of people affected by this condition; we hope this article enlightened the true meaning of spondylolisthesis and provided a basis to move forward with and seek further advice or help. By promoting awareness and understanding, we hope to encourage timely detection and intervention, thus improving the quality of life for individuals as well as family and friends of those with spondylolisthesis.