Spondylolisthesis – Types, Presentation and Treatment

Last Updated on March 16, 2024

The term spondylolisthesis  is derived from the Greek spondylos, meaning “vertebra,” and olisthenein, meaning “to slip.” Spondylolisthesis is defined as the anterior or posterior slipping of one segment of the spine on the next lower segment.

This slippage causes mechanical or radicular symptoms or pain and can occur due to a range of causes that may be congenital or acquired.

The degree of the slip signifies the severity of the spondylolisthesis.

Spondylolisthesis most commonly occurs in the lower lumbar spine. However, the condition can occur in the cervical spine. It is rare in the thoracic spine and often due to trauma.

Degenerative spondylolisthesis is predominately seen in adults and more common in females.  Isthmic spondylolisthesis is more common in the adolescent and young adult population though the condition may be recognized in adulthood.

It most commonly affects the L5-S1 level followed by the L4-5 level.

Spondylolysis, Spondylolisthesis, and Spondyloptosis

Before we discuss spondylolisthesis in detail let us familiarise ourselves with similar-sounding terms but imparting different meanings.

Spondylolysis

Spondylolysis refers to a break or fracture in the pars interarticular of the involved vertebra. Pars interarticularis is a small, thin portion of the vertebra between the upper and lower facet joints. The pars interarticularis is the weakest portion of the vertebra and fracture can occur on either side [either to midline] of the pars region. This weakness makes it susceptible to break under stress or injury.

Spondylolisthesis

In spondylolisthesis, the fractured pars separates allowing slipping allowing the injured vertebra to slip forward on the vertebra below it.

Spondyloptosis

It is the extreme degree of the spondylolisthesis. When the vertebra slips entirely (100 percent), it is referred to as spondyloptosis.

Relevant Anatomy

The lumbar spine connects with the thoracic spine above the thoracolumbar junction and the sacral spine below the lumbosacral joint. The Lumbar spine consists of 5 lumbar vertebrae and the sacrum consists of 5 fused vertebrae. Together, these perform important functions of the back and pelvis.

The lumbar vertebral body is a major load-bearing structure. Pedicles are short thick rounded bony connections that connect the body to the vertebral arch which is also called the neural arch and consists of laminae and spinous processes.  Transverse processes project on either side of the spinous process.

Another important structure is the facet joint. These are joints between two adjacent vertebrae between articular processes. Each vertebra has 4 articular processes. Two superior and two inferior. The superior processes articulate with the inferior processes of the vertebra on the same side above and the inferior processes with the superior process of the vertebra below. These articular processes are kind of upward and downward projections at the junction of the pedicle and lamina on the right and left sides. Facet joints are also called zygapophysial joints.

The pars interarticularis isthmus is a thin bone between the superior and inferior articular process and is considered part of the lamina, whereas others consider it to be different.

The pars is subjected to tremendous stress and can undergo stress fractures leading to nonunion and spondylolisthesis.

Causes

• Dysplastic: A congenital spondylolisthesis due to malformation of the lumbosacral junction with small, incompetent facet joints. It is very rare and whenever occurs has fast and severe progression. There is no gap or defect in pars interarticularis. A familial predisposition. has been suggested.
• Developmental: This is responsible for 5% of the cases and equally affects males and females. Most spondylolistheses in children and adolescents are developmental. This type of spondylolisthesis is not noticed until later in childhood or even in adulthood. There is a bilateral defect in pars inter articularis that allows the vertebral body to slip forward. The condition is seen more in athletes and sportspersons. Gymnastics and football are generally considered the highest-risk sports.
• Degenerative Spondylolisthesis: This can affect both the cervical and lumbar spine (most commonly L4-L5).  It is seen most commonly above the age of 50 years. With age, as the degeneration sets, the facet joint may not remain competent and allow the vertebral body to slip forward on the other. This can also lead to reduced canal space. Repetitive microtrauma and previous laminectomy are common risk factors. It is the most common type of spondylolisthesis.
• Pathological: This is due to generalized or localized bony disease that weakens the bone.
• Trauma: Trauma can cause the slip of the vertebra.

Pathophysiology

Any process that causes the weakening of vertebral structure or support can be responsible for the development of spondylolisthesis to occur.

In persons with congenital-type spondylolisthesis, dysplastic articular facets are less able to resist anterior shear stress.  predispose the spinal segment to listhesis as a consequence of their inability to resist anterior shear stress. The development of slip can depend on factors like ongoing insult, and elongation of pars.

The dysplastic type spondylolisthesis occurs from a defect in the structures like neural arch. These cases are associated with other lower spine anomalies too.

Degenerative disease of the spine leads to intersegmental instability.

Traumatic spondylolisthesis results due to fracture of posterior structures leading to instability.

Mechanical stresses play an important role in developmental spondylolisthesis. Often, there is a stress fracture of the pars interarticularis that occurs in adolescence. Sports like gymnastics, football, wrestling, weightlifting, and others may cause repetitive microtrauma and increase the load on the spine to the pars interarticularis, resulting in spondylolysis and sometimes spondylolisthesis.

A bilateral pars defect is present allowing forward slip leading to spondylolisthesis.

The following factors are associated with a greater risk of progression of the slip in adolescent-onset –

• Younger age (less than 15 years)
• Listhesis more than 30%
• Ligamentous laxity
• Dysplastic type
• Female gender

Classification of Spondylolisthesis

Wiltse classification

This classification scheme divides the spondylolisthesis into 5 types

• Type I – Dysplastic: Congenital abnormalities of the upper sacral facets or inferior facets of the fifth lumbar vertebra that allow slipping of L5 on S1.The congenital abnormalities of lumbosacral articulation include maloriented or hypoplastic facets, sacral deficiency or poorly developed pars interarticularis. There is no pars interarticularis defect.
• Type II – Isthmic:  There is a defect in the pars interarticularis that allows forward slipping of L5 on S1. There are three subtypes
  -A stress fracture of the pars interarticularis [Lytic type]
  -An elongated but intact pars interarticularis [Elongated type]
  -An acute fracture of the pars interarticularis
  The incidence at birth is zero but rises sharply to 5% at the age of 4 to 5 years. Probably it results from fatigue fracture. Uneven distribution of isthmic ossification results in the formation of a potential stress riser in the region of pars in lower lumbar vertebrae, which could be susceptible to fatigue fracture.
• Type III – Degenerative: This lesion results from the intersegmental instability of a long duration with the subsequent remodeling of the articular processes at the level of involvement.
• Type IV- Traumatic: This type results from fractures in the area of the bony hook other than the pars interarticularis.
• Type V – Pathological: This type results from generalized or localized bone disease and structural weakness of the bone e.g  osteogenesis imperfecta, infection.

Classification of Marchetti-Bartolozzi

Marchetti and Bartolozzi attempted to divide the condition into developmental and acquired forms. To classify according to this classification, it must be first determined if the condition is developmental or acquired.

• Developmental
  • High dysplastic
    • With lysis
    • With elongation
  • Low dysplastic
    • With lysis
    • With elongation
• Acquired
• Traumatic
  • Acute fracture
  • Stress fracture
• Post-surgery
  • Direct surgery
  • Indirect surgery
• Pathological
  • Local pathology
  • Systemic pathology
• Degenerative
  • Primary
  • Secondary

Most spondylolistheses in children and adolescents are developmental.

Meyerding Classification

There is is based on the percentage of slip

• Grade 1:     <25% slip
• Grade 2:    25- 50% slip
• Grade 3:     50-75% slip
• Grade 4:    75-100% slip

Normal Canal Dimension In Lumbar Spine

Normal canal dimensions in the lumbar spine are fairly constant and are given below.

The idea of normal values helps to determine the level of stenosis of the canal.

Presentation of Spondylolisthesis

Patients often present with low back pain in the lumbar region or neck pain for cervical spondylolisthesis. Pain can be exacerbated by movements or direct palpation of the affected segment.The pain in the back is due to an instability of the affected segment whereas pain in the leg is due to nerve root irritation. Pain may radiate to the lower limb if the nerve roots are compressed. Lying supine may ease the pain as this posture relieves the pressure.

Buttock pain, numbness, and weakness of the legs may be present. Symptoms are aggravated by high activity or sports decrease on rest or with medication.

Depending on the severity, physical findings may vary.

In mild cases, there may not be any finding on physical examination.

In cases with a moderate amount of slip, a step may be palpable at the lumbosacral junction and the motion of the lumbar spine is restricted. Hamstring tightness may be felt on straight leg raising.

With a further slip, the patient assumes a lordotic posture above the level of the slip to compensate for the displacement. The sacrum becomes more vertical. In severe slips, the trunk becomes shortened and often leads to the complete absence of the waistline. These children walk with a peculiar spastic gait called pelvic waddle or crouched gait.

Scoliosis associated with spondylolisthesis may be found.

Pseudoclaudication, a feature typical of spinal stenosis may be present in degenerative spondylolisthesis (Spinal stenosis may be present along with it).

Differential Diagnoses

• Lumbar Degenerative Disc Disease

• Lumbar disc herniation

• Lumbosacral facet syndrome

• Lumbosacral injury

Imaging

Radiographs

Routine diagnosis of spondylolisthesis is made on radiographs. These include anteroposterior, standing lateral views and Ferguson coronal view.

The Ferguson coronal view is obtained by making the X-ray beam parallel to the L5-S1 disc. This view depicts a clearer profile of the L5 pedicles, transverse processes, and sacral ala.

Supine radiograms may not reveal listhesis. Standing position radiographs in flexion, and extension, are revealing.

X-rays may be subjected to various measurements

Bone Scan

A bone scan is indicated in children where the plain film does not show any defect but the defect is believed to be present. A bone scan may show the pars defect in stress reaction stage determined by increased uptake.

CT

Mostly not needed,  a CT scan can be used to differentiate between a stress reaction and an acute stress fracture. [Developmental versus traumatic]. CT is the best study to diagnose and delineate the anatomy of the lesion.

Tomograms can help identify fracture as well as root compression.

MRI

MRI is useful in determining the extent of injury to the disc at the level of the spondylolisthesis. Nerve root compression also can be evaluated.  MRI is indicated if neurologic symptoms are present. It is a useful tool to diagnose associated stenosis. MRI can help in diagnosing disc degeneration and help in the decision for fusion level.

Treatment of Spondylolisthesis

The moderate grade of spondylolisthesis in adolescents has a benign course. Spontaneous segmental stabilization occurs as a result of degeneration of the disc at the level of the slip.

With a slippage less than 25% and mild symptom, non-operative treatment helps. Operative treatment is suggested for more than 50% slip.

Thus, for grade I and II spondylolisthesis, treatment typically begins with conservative therapy. Most of the patients will respond to nonoperative treatment. Those who do not should be considered for surgery. The surgical procedure involves decompression, fixation, and fusion. The  procedure needs to be individualized. The reduction of the slip is usually not attempted as it is risk for neurological damage.

Nonoperative Treatment

Symptoms improve with nonsurgical treatment in most patients. Nonoperative treatment includes

• Restriction of the patient’s activities – Avoiding sports and activities that stress the lower back
• Ice or heat application
• Physical therapy – Rehabilitation and stretching exercises of spinal, abdominal, and trunk muscles
• Intermittent use of a rigid back brace
• Analgesics- NSAIDs can help with pain and swelling
• Epidural Injections

Nonoperative treatment is useful if symptoms are few and the spondylolisthesis is mild. A gradual increase in activity is allowed if symptoms improve. For nonsymptomatic patients, no active treatment is required but contact sports and high energy that might injure the back are to be avoided  A follow-up every 6-12 months til the completion of growth is required.

Operative Treatment

Indications for surgery include

• Failure of conservative treatment (after 6-9 months of treatment)
  • Persistent neurological issue
    • Radicular pain that fails to respond to conservative treatment
    • Myelopathy
    • Neurogenic claudication
  • Persistent tight hamstrings
• Listhesis> 50%
• Abnormal gait
• Spine instability with the progression of slip
• Traumatic spondylolisthesis
• Degenerative listhesis with instability

Following procedures are included in the surgery and mostly, a combination of two or more procedures is required.

• Fusion– There are multiple types of fusion to choose from
  • Posterolateral (As in with pedicle screw fixation)
  • Interbody
    • Transforaminal lumbar interbody fusion (TLIF)
    • Posterior lumbar interbody fusion (PLIF)
    •  Anterior lumbar interbody fusion (ALIF)
    • Extracavitatory lateral interbody fusion (XLIF)
    • Oblique lateral interbody fusion (OLIF)
  • Pars repair – It is done in young patients only to repair the defect in the isthmus or pars interarticularis.
• Fixation- Fixation, when indicated, helps to achieve fusion
• Decompression- Posterior laminectomy and facetectomy are often done to relieve neural compression.
• Reduction- Mostly not indicated as associated with higher risk of nerve root injury

A posterior fusion with pedicle screw instrumentation is generally considered the gold standard.

Complications of surgical procedures are

• Nerve root injury
• CSF leak
• Failure to fuse
• Loss of fixation

Prognosis

Most of the patients with degenerative spondylolisthesis get relieved by nonsurgical measures and surgery is rarely required. Surgery may be considered in disabling pains not relieved by nonsurgical management and in cases of progressive neurologic deterioration. Decompression surgery ( laminectomy) without fusion alone is not advisable as it can lead to instability.

The majority of patients are free from pain and other symptoms and can gradually resume sports and other activities.

References

• Weinstein JN, Lurie JD, Tosteson TD, Hanscom B, Tosteson AN, Blood EA, et al. Surgical versus nonsurgical treatment for lumbar degenerative spondylolisthesis. N Engl J Med. 2007 May 31. 356 (22):2257-70. [Link].
• Alfieri A, Gazzeri R, Prell J, Röllinghoff M. The current management of lumbar spondylolisthesis. J Neurosurg Sci. 2013 Jun;57(2):103-13. [Link]