(3) Isthmic Spondylolisthesis Flashcards
What is meant by an isthmic cause of spondylolisthesis?
involves the pars interarticularis (lumbar only)
What is the most common location of spondylolisthesis with an isthmic cause?
L5
What are the 3 subtypes of isthmic spondylolisthesis?
2A: fatigue Fx of the pars
2B: elongating but intact pars
2C: acute traumatic pars Fx
What is the most common subtype of isthmic spondylolisthesis?
2A: fatigue Fx of the pars
What is another name for a 2A isthmic spondylolisthesis, which is often interchanged with “isthmic”?
spondylolytic
What is the most common type of spondylolisthesis in people under age 50?
isthmic 2A (spondylolytic)
What is meant by isthmic 2A spondylolisthesis?
due to a fatigue Fx of pars (typically in adolesence) that heals non-union
Can an isthmic 2A spondylolisthesis be congenital?
NO (never seen in infants)
When describing isthmic 2A spondylolisthesis, what is a better term to use than “pars fracture”?
pars defect
(pars Fx implies acute/active Fx)
What is the theory for differences in incidence of isthmic 2A spondylolisthesis?
thinner pars are more susceptible to fatigue Fx
What is the series of unfortunate events (pathogenesis) leading to isthmic 2A spondylolisthesis?
- repetitive hyperextension loads in adolescence (10-15)
- fatigue Fx of pars interarticularis
- continuation of activity
- heals non-union
What patient histories would increase your concern for an isthmic 2A spondylolisthesis?
hyperextension sports:
- gymnast
- high diver
- cheerleader
- wt lifting
- pole vaulting
What is the number 1 high school sport with significant injuries?
cheerleading
If there is suspicion of an active pars fatigue fracture in an adolescent, what should you do first?
AP & lateral radiographs
(NCBE: obliques)
What is a better choice to view a fatigue fracture of L5 pars?
Fergusons view
(better than 2 oblique views)
If there is suspicion of an active pars fatigue fracture in an adolescent that is not visible on radiographs within 21 days, what should you do next?
MRI
(better than SPECT scan which has more radiation)
What is the concern with using a SPECT scan for an isthmic spondylolisthesis?
3 REM (10 yrs worth of radiation) to the gonads
If imaging is positive for an active pars defect in an adolescent, what are your next steps?
- discontinue activity
- Boston brace (often requires spinal orthopedic referral)
What age group do fatigue fractures of the pars occur in?
adolescents
If there is suspicion of a pars defect in an adult, what should be done first? What should be done if you see defects?
AP & lateral radiographs
If defects, no reason for additional views
If there is suspicion of a pars defect in an adult, and you are unsure about the L5 pars on the AP and lateral radiographs, what should be done next?
Fergusons view
If there is suspicion of a pars defect in an adult, and you are unsure about the pars on the AP and lateral radiographs, what should be done next?
look carefully on AP, then consider oblique views (if not at L5)
What part of the Scotty dog should you look at for pars defects?
neck
Once a pars fracture heals non-union, how may a spondylolisthesis patient present clinically?
- majority ASx
- if Sx, chronic recurring back pain (poor correlation between degree of slippage & Sx from spondylo.)
- accentuated lordosis
- SP palpable step defect
What physical exam test may be positive in a patient with an active pars fatigue fracture?
Stork test (standing Kemps on 1 leg)
How does the step defect in an isthmic spondylolisthesis differ from that of a degenerative spondylolisthesis?
Isthmic: SP of segment above moves fwd (affected SP left behind)
Degenerative: SP of affected segment moves fwd
What are the major concerns in an adult patient with an isthmic spondylolisthesis?
- progression
- instability
What are the indicators of possible progression of an isthmic spondylolisthesis?
(only 2-3% progress)
- ^likely w/in 2yrs of Fx
- poor response to conservative management
- serial progression of slippage
What are the indicators of possible instability of an isthmic spondylolisthesis?
- higher grade slippage
- rounding of sacral base (doming)
- trapezoidal shape of L5
- pt describes feeling unstable
What are positive factors for no progression of an isthmic spondylolisthesis?
- male
- low grade slippage
- buttressing (big ol’ osteophyte to stabilize)
- > 18yrs (skel. mature)
What is meant by a isthmic 2B spondylolisthesis?
cycle of fatigue Fx -> healing -> fatigue Fx allowing for lengthening of pars w/o overt defect
What is meant by isthmic 2C spondylolisthesis?
acute pars Fx secondary to acute hyperextension
(need CT or MRI to determine)
What is the mechanism of a unilateral spondylolysis? What are the potential outcomes?
- hyperextension w/ asymmetry
- may heal or progress to bilateral defects
- no spondylolisthesis visualized
What is the radiographic finding describing a unilaterally enlarged/sclerotic pedicle opposite a contralateral pars defect in the spine?
Wilkinson syndrome
Describe the spondylolisthesis.
L5 anterolisthesis grade 5, isthmic
