Spondylolysis
Encyclopedia
Spondylolysis is a defect of a vertebra. More specifically it is defined as a defect in the pars interarticularis of the vertebral arch. The great majority of cases occur in the lowest of the lumbar vertebrae
(L5), but spondylolysis may also occur in the other lumbar vertebrae, as well as in the thoracic vertebrae
.
Spondylolysis occurs in three to six percent of the population.
of the bone, and is especially common in adolescents who overtrain in activities such as tennis, diving, martial arts and gymnastics
. Linemen in American football are also at risk due to their bending over at the line. It has been proposed that the pars interarticularis
is especially vulnerable when the spine is in an extended position, and a force suddenly presses the vertebrae together, such as when landing on one's feet after a hop. This pressure acts like a nut-cracker on the pars interarticularis and can fracture it in susceptible individuals.
Spondylolysis (spon-dee-low-lye-sis) also runs in families and is more prevalent in some populations, suggesting a hereditary component such as a tendency toward thin vertebral bone.
Spondylolysis is the most common cause of spondylolisthesis
(spon-dee-low-lis-thee-sis) in pediatric patients with a classic presentation that of a female gymnast. In the older population, degenerative disc disease commonly leads to spondylolisthesis without spondylolysis; in these instances, the spinal canal narrows because the spino-laminar arch at one level slides forward on the lower level effectively flattening the canal. The hereditary factor mentioned above is quite notable, since the frequency of spondylolisthesis among the Inuit
peoples is 30–50%; however, there is controversy about this, as can be seen on the wiki page for spondylolisthesis
: "(This statistic is controversial, however, because further anthropological studies have shown that the occurrence of spondylolysis in Inuit people living in Western-style communities is within the normal variancy at 7%. These people are hereditarily linked to the study group showing ~40%. It is theorized that the nomadic Inuit have a higher incidence of spondylolysis due to trauma acquired as infants by being carried in an amauti
. While in an amauti, the baby is put into compressive extension with each step taken by the mother. Also, all other studies have shown a normal variance of spondylolysis within cultures of 6-10%, further suggesting that spondylolysis is an environmental abnormality and that a hereditary tie is very unlikely)."
An oblique x-ray of the lumbar spine shows what appears to be a "scotty dog" first described by Lachapelle:
Lumbar vertebrae
The lumbar vertebrae are the largest segments of the movable part of the vertebral column, and are characterized by the absence of the foramen transversarium within the transverse process, and by the absence of facets on the sides of the body...
(L5), but spondylolysis may also occur in the other lumbar vertebrae, as well as in the thoracic vertebrae
Thoracic vertebrae
In human anatomy, twelve thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. They are intermediate in size between those of the cervical and lumbar regions; they increase in size as one proceeds down the spine, the upper...
.
Spondylolysis occurs in three to six percent of the population.
Causes
It is typically caused by stress fractureStress fracture
A stress fracture is one type of incomplete fracture in bones. It is caused by "unusual or repeated stress" and also heavy continuous weight on the ankle or leg...
of the bone, and is especially common in adolescents who overtrain in activities such as tennis, diving, martial arts and gymnastics
Gymnastics
Gymnastics is a sport involving performance of exercises requiring physical strength, flexibility, agility, coordination, and balance. Internationally, all of the gymnastic sports are governed by the Fédération Internationale de Gymnastique with each country having its own national governing body...
. Linemen in American football are also at risk due to their bending over at the line. It has been proposed that the pars interarticularis
Pars interarticularis
The pars interarticularis, or pars for short, is the part of vertebra located between the inferior and superior articular processes of the facet joint. In the transverse plane, it lies between the lamina and pedicle. In other words, in the axial view, it is the bony mass between the facets that is...
is especially vulnerable when the spine is in an extended position, and a force suddenly presses the vertebrae together, such as when landing on one's feet after a hop. This pressure acts like a nut-cracker on the pars interarticularis and can fracture it in susceptible individuals.
Spondylolysis (spon-dee-low-lye-sis) also runs in families and is more prevalent in some populations, suggesting a hereditary component such as a tendency toward thin vertebral bone.
Spondylolysis is the most common cause of spondylolisthesis
Spondylolisthesis
Spondylolisthesis describes the anterior or posterior displacement of a vertebra or the vertebral column in relation to the vertebrae below. It was first described in 1782 by Belgian obstetrician, Dr. Herbinaux. He reported a bony prominence anterior to the sacrum that obstructed the vagina of a...
(spon-dee-low-lis-thee-sis) in pediatric patients with a classic presentation that of a female gymnast. In the older population, degenerative disc disease commonly leads to spondylolisthesis without spondylolysis; in these instances, the spinal canal narrows because the spino-laminar arch at one level slides forward on the lower level effectively flattening the canal. The hereditary factor mentioned above is quite notable, since the frequency of spondylolisthesis among the Inuit
Inuit
The Inuit are a group of culturally similar indigenous peoples inhabiting the Arctic regions of Canada , Denmark , Russia and the United States . Inuit means “the people” in the Inuktitut language...
peoples is 30–50%; however, there is controversy about this, as can be seen on the wiki page for spondylolisthesis
Spondylolisthesis
Spondylolisthesis describes the anterior or posterior displacement of a vertebra or the vertebral column in relation to the vertebrae below. It was first described in 1782 by Belgian obstetrician, Dr. Herbinaux. He reported a bony prominence anterior to the sacrum that obstructed the vagina of a...
: "(This statistic is controversial, however, because further anthropological studies have shown that the occurrence of spondylolysis in Inuit people living in Western-style communities is within the normal variancy at 7%. These people are hereditarily linked to the study group showing ~40%. It is theorized that the nomadic Inuit have a higher incidence of spondylolysis due to trauma acquired as infants by being carried in an amauti
Amauti
The amauti is the traditional eastern Arctic Inuit parka designed to carry a child in the same garment as the parent so that the child is warm and safe from frostbite, wind and cold. The amauti can be made from a variety of materials including sealskin, caribou skin or duffle with a windproof...
. While in an amauti, the baby is put into compressive extension with each step taken by the mother. Also, all other studies have shown a normal variance of spondylolysis within cultures of 6-10%, further suggesting that spondylolysis is an environmental abnormality and that a hereditary tie is very unlikely)."
Diagnosis
The defect is seen in this oblique lumbar radiograph: Image of Pars Defect.
An oblique x-ray of the lumbar spine shows what appears to be a "scotty dog" first described by Lachapelle:
| Apparent part of dog | Part of vertebra |
|---|---|
| nose | costal/transverse process |
| ear | superior facet |
| neck | pars interarticularis |
| collar | pars defect (dark on x-ray) |
| eye | pedicle seen end on |
| body | lamina |
| hind foot | spinous process |
| tail, if pointing straight up | the opposite superior articular facet |
| tail, if pointing horizontally | the transverse process of the opposite side |
| forefoot | the inferior articular process |
- Image with Pars Defect outlined and fracture marked with arrow
- Image of a spine with the Scotty defect and no fracture
External links
- Information from the American Academy of Orthopaedic Surgeons
- A Patient's Guide to Lumbar Spondylolysis
- http://www.orthoseek.com/articles/spondyl.html