Spondylolisthesis is a condition in which one vertebra (bones that make up the spine) slides forward over the vertebra below it. Spondylolisthesis usually occurs towards the base of the spine in the lumbar area. There are several causes of this slippage, and this
Type I: This is also called dysplastic or congenital spondylolisthesis. Congenital means that you’re born with it. Type I spondylolisthesis, then, is a defect in the articular processes of the vertebra (the part that’s supposed to control the movement of the vertebra; your facet joints are made of the articular processes). It usually happens in the area where the lumbar spine and the sacrum come together: the L5-S1 area. The defect allows the L5 vertebra (your last vertebra in your lumbar spine) to slip forward over the sacrum.
Type II: Also called isthmic, this is the most common kind of spondylolisthesis. With type II spondylolisthesis, there’s a problem with the pars interarticularis, a particular region of your vertebra. (You can see an illustration of this in Anatomy of Spondylolisthesis). Isthmic spondylolisthesis is divided further:
Type II A: Gymnasts, weight lifters, and football linemen are especially prone to this kind of spondylolisthesis. It’s caused by multiple micro-fractures on the pars interarticularis—micro-fractures that occur because of hyperextension (overarching) and overuse. The pars fractures completely in type II A.
Type II B: This type is also caused by micro-fractures. The difference, though, is that the pars don’t fracture completely. Instead, new bones grow as the pars heals, causing it to stretch. A longer pars can then cause the vertebra to slide forward.
Type II C: Like type II A, this type has a complete fracture. However, it’s caused by trauma. The impact in a car accident could fracture your pars, for example.
A pars fracture can lead to a mobile piece of bone; the detached inferior articular process can actually move around. This bone fragment, also called a Gill fragment, can pinch the exiting nerve root, so the bone may need to be removed.
Spondylolisthesis can be described according to its degree of severity. One commonly used description grades spondylolisthesis, with grade 1 being least advanced, and grade 5 being most advanced. The spondylolisthesis is graded by measuring how much of a vertebral body has slipped forward over the body beneath it.
25% of vertebral body has slipped forward
Vertebral body completely fallen off (i.e.,spondyloptosis)
How do People Get Spondylolisthesis ?
Approximately 5%-6% of males, and 2%-3% of females have a spondylolisthesis.
It becomes apparent more often in people who are involved with very physical activities such as weightlifting, gymnastics, or football.
Males are more likely than females to develop symptoms from the disorder, primarily due to their engaging in more physical activities.
Although some children under the age of five may be pre-disposed towards having a spondylolisthesis, or may indeed already have an undetected spondylolisthesis, it is rare that such young children are diagnosed with spondylolisthesis. Spondylolisthesis becomes more common among 7-10 year olds. The increased physical activities of adolescence and adulthood, along with the wear-and-tear of daily life, result in spondylolisthesis being most common among adolescents and adults.
Types of Spondylolisthesis
Different types of spondylolisthesis may be caused in a various ways. Some examples are:
Developmental Spondylolisthesis: This type of spondylolisthesis may exist at birth, or may develop during childhood, but generally is not noticed until later in childhood or even in adult life.
Acquired Spondylolisthesis: Acquired spondylolisthesis can be caused in one of two ways:
With all of the daily stresses that are put on a spine, such as carrying heavy items and physical sports, the spine may wear out (ie, degenerate). As the connections between the vertebrae weaken, this may lead to spondylolisthesis.
A single or repeated force being applied to the spine can cause spondylolisthesis; for example, the impact of falling off a ladder and landing on your feet, or the regular impact to the spine endured by offensive linemen playing football.
What Symptoms Might I Notice ?
Many people with a spondylolisthesis will have no symptoms and will only become aware of the problem when it is revealed on an x-ray for a different problem. However, there are several symptoms that often accompany spondylolisthesis:
Pain in the low back, especially after exercise
Increased lordosis (ie, swayback).
Pain and/or weakness in one or both thighs or legs
Reduced ability to control bowel and bladder functions
Tight hamstring musculature
In cases of advanced spondylolisthesis changes may occur in the way people stand and walk; for example, development of a waddling style of walking. This causes the abdomen to protrude further, due to the lowback curving forward more. The torso (chest, etc.) may seem shorter; and muscle spasms in the lowback may occur.
Spondylolisthesis has several main causes. Doctors have developed a classification system to help talk about the different causes of spondylolisthesis.
Problems with the pars interarticularis can also be called spondylolysis. The word looks like spondylolisthesis, and they are somewhat related. Micro-fractures in the pars interarticularis—the kind that gymnasts, football linemen, and weightlifters are prone to—are a form of spondylolysis. The fractures are called spondylolysis; if the vertebra slips forward because it’s not being held in place properly, it’s called spondylolisthesis.
Type III: Aging can also cause spondylolisthesis. As you grow older, the parts of your spine can degenerate; they can wear out. Usually your intervertebral discs change first. The older you get, the less water and proteoglycan content the discs have—and less fluid makes them less able to handle movement and shock. Less fluid can also cause the disc to thin, and a thinner disc brings the facet joints closer together. Without the disc acting as the cushion, the facets can’t control the spine’s movement as well, and they become hypermobile. Eventually, a vertebra can slip forward because the facets aren’t holding it in place effectively as the spine moves. Type III spondylolisthesis usually happens at the L4-L5 region (the fourth and fifth vertebrae in your low back), and it’s more common in women older than 50 years old.
Type IV: Similar to type II C, type IV involves a fracture. However, it’s a fracture of any other part of the vertebra other than the pars interarticularis. Your facet joints, for example, can fracture, separating the front part of your vertebra from the back part.
Type V: Tumors on the vertebra can also cause spondylolisthesis because they weaken the bones and can cause fractures that split your vertebra, leading to instability and a potential slip.
Type VI: You have this type of spondylolisthesis if surgery caused your vertebra to slip forward. It’s also known as iatrogenic spondylolisthesis, and it’s caused by a weakening of the pars, often as a result of a laminectomy (a typical back surgery, but type VI spondylolisthesis isn’t a typical result of the surgery).
As a quick summary, spondylolisthesis can be caused by:
a birth defect
spondylolysis (a defect or fracture in the pars interarticularis)
degeneration due to age or overuse