Lumbar and SIJ

Why are mechanical stresses high in lumbar spine?

Supports weight of upper body and thoraco-abdominal mass

Why subtle changes in lumbar osseous alignment can be significant?

They can place substantial stress on the osseous and ligamentous structures

Why are the lumbar vertebral bodies wedge-shaped?

Help maintain lumbar lordosis

What do L5-S1 facet joints help resist?

Anterior shear forces

What is primary functional of Anterior Longitudinal Ligament (ALL)?

Limits excessive lumbar extension and helps resist anterior separation of vertebral bodies

What motion does the Posterior Longitudinal Ligament (PLL) primary limit?

Excessive flexion of lumbar spine

Function of ligamentum flavum?

Helps limit excessive flexion and assists in returning spine toward neutral

What motion primarily limited by the interspinous ligament?

Excessive flexion

What motion primarily limited by the supraspinous ligament?

Excessive flexion

What do the intertransverse ligaments primarily limit?

Excessive lateral flexion, particularly toward the opposite side

What is function of facet joint capsules?

Help stabilize the facet joints and limit excessive flexion, rotation and translation

Important function of iliolumbar ligament?

Stabilize the L4-5/L5-S1 region and helps limit excessive lumbar flexion, lateral flexion, rotation and anterior translation

General motion is limited by many of the posterior lumbar ligaments?

Excessive lumbar flexion

General role of lumbar ligaments?

Provide passive stability and limit excessive spinal motion

Where is central ray directed for AP lumbar radiograph?

L3-4 interspace

What structures visible on an AP lumbar radiograph?

Vertebral bodies
Spinous processes
Pedicles
Transverse processes
Superior/inferior articular processes
Sacrum
Psoas shadow

What additional alignment findings can be seen on AP?

Special alignments, including butterfly-shaped shadow

How is patient positioned for lateral lumbar radiograph?

Sidelying with knees flexed

What structures demonstrated on lateral view?

Vertebral bodies
IV disc spaces
Spinous processes
IV foramina

What important junction can be evaluated on the lateral view?

Lumbosacral junction

When assessing alignment, what is relationship of L3 to sacrum?

Vertical line from center of L3 through sacrum should pass though the anterior third of the sacrum

What does line falling 1-2cm anterior to sacrum suggest?

Increased anterior shear forces on the facet joints, which can contribute to spondylolisthesis

What structures best identified on lumbar oblique views?

Facet joints
Superior/inferior articular processes
Pars interarticularis
Pedicles

What classic structure is seen on lumbar oblique views?

“Scottie Dog”

What part of the Scottie Dog is associated with spondylolysis?

Pars interarticularis

What is purpose of lateral L5-S1 view?

Close-up eval from L4 through the sacrum

What two angles are important when evaluating the L5-S1 region?

Barge’s Angle and Ferguson’s Angle

What does Berge’s Angle evaluate?

The amount of anterior shear force/axial loading relationship through the vertebrae and IV discs

What does Ferguson’s angle evaluate?

The amount of anterior shear force/axial loading relationship through the vertebrae and IV discs

What does an AP axial SIJ view demonstrate?

Both SIJ with greatest amount of joint surface exposed

What additional structures can be seen on AP axial SIJ?

L5-S1 disc space
Sacrum
Coccyx

Purpose of right and left SI oblique views?

To isolate a specific SIJ without superimposition of the ilium

Advantage of SI oblique views have compared to AP?

May provide greater visualization of the joint-space margins

What forces commonly cause lumbar trauma?

High-impact or energy forces

Where are fractures most common in thoracolumbar region?

At thoracolumbar junction

What lumbar region has greater ligamentous support and stability?

L2-5

What structure is involved in the different forms of “spondys”

The pars interarticularis

What is projection of choice for evaluating spondylolysis or spondylolisthesis?

Oblique lumbar radiographs

What is spondylolysis?

Defect/separation of the pars interarticularis

What can cause spondylolysis?

Congenital factors
Degenerative changes
Chronic strain

What type of loading stresses the pars during hyperlordosis?

Repetitive loading associated with trunk extension

How can chronic stress lead to spondylolysis?

Progressive stress reaction can develop into a stress fracture

What position can increase the risk of pars stress from axial compression?

Lumbar spine in a hyperlordotic position

What is Spondylolisthesis?

Anterior displacement/slipping of one vertebra relative to another

What is “fracture spondylolisthesis”

Anterior vertebral displacement associated with a pars fracture

Can spondylolisthesis occur without a pars fracture?

Yes. Degenerative spondylolisthesis

What are the following Spondylolisthesis grades:
1
2
3
4
5

1 = 25% anterior displacement
2 = 50% anterior displacement
3 = 75% anterior displacement
4 = 100% anterior displacement
5 = vertebral body completely fallen off (spondyloptosis)

What are three common degenerative lumbar conditions?

DDD
DJD
Spinal stenosis

What causes DDD?

Dehydration/degeneration of the IV disc

What structures affected in DJD?

Facet joints

What radiographic findings can occur with DJD?

Facet joint narrowing and osteophytes at the joint margins

What is an IV disc herniation?

Extension of nucleus pulposus through the fibers of the annulus fibrosus

What happens to disc when no visible disc material outside annulus?

Considered dehydrated/degenerative

Most common site of lumbar disc herniation?

L4-5

Do anterior disc herniations without trauma typically produce symptoms?

No

What type disc herniation is associated with symptoms?

Posterior displacement following trauma

What region is generally covered by lumbar CT?

Lower thoracic spine through SIJ

Why might CT be limited to certain spinal levels?

To reduce radiation exposure (pediatrics)

What region does a basic lumbar MRI cover?

T12-SIJ