Spine Flashcards
What is the average lumbar lordosis?
60 degrees in sagittal plane
Where is the apex of lordosis in lumbar spine?
L3
Pars interarticularis
- mass of bone between superior and inferior articular facets
- site of spondylolysis (consistent with the “collar” on the “Scotty dog projection)
Facet orientation in lumbar spine
-facets start as more sagittal and become more coronal as you move inferior in the axial plane
What is the pedicle orientation in the lumbar spine?
-pedicles angularity more medial as you move distal
what are the smallest pedicles in the entire spine?
T4
Nerve root anatomy in lumbar spine
- nerve root exits foramen under same numbered pedicle
- central herniations affect traversing nerve root
- far lateral herniations affect exiting nerve root
At what level does the spinal cord terminate?
L1-L2
At what spinal level is the iliac crest?
L4-5
Pelvic incidence formula
Pelvic tilt + sacral slope = pelvic incidence
How is pelvic incidence measured?
- a line is drawn from the center of S1 endplate to the center of the femoral head
- a second line is drawn perpendicular to a line drawn along the S1 endplate, intersecting the point in the center of the S1 endplate
- the angle between these 2 lines is the pelvic incidence
What is the formula for pelvic tilt?
Pelvic incidence - sacral slope = pelvic tilt
How do you measure pelvic tilt?
- a line is drawn from the center of the S1 endplate to the center of the femoral head
- a second vertical line (parallel w/ side margin of radiograph) line is drawn intersecting the center of the femoral head
- the angle between these two lines is the pelvic tilt
What is the formula for sacral slope?
Pelvic incidence - pelvic tilt = sacral slope
How do you measure sacral slope?
- a line is drawn parallel to the S1 endplate
- a second horizontal line (parallel to inferior margin of radiograph) is drawn
- the angle between these 2 lines is the sacral slope
Surgical approaches to lumbar spine
Posterior:
-posterior midline (used for PLIF or TLIF)
-Wiltse paraspinal approach
Anterior:
-retroperitoneal (anterolateral) approach
Lateral:
-transposable approach (lumbar plexus moves dorsal to ventral moving down lumbar spine; L4-L5 is lowest accessible disc space and highest risk of iatrogenic nerve injury; ilioinguinal and iliohypogastric nerves most likely injured at this level)
what are the surgical indications for vertebral osteomyelitis?
- progressive neuro deficit
- standard is non-op tx with IV abx and lumbar orthosis
risk factors for proximal junctional kyphosis in setting of instrumented fusions performed for degenerative scoliosis?
- advanced age
- 360 deg fusions
- extension of fusion constructs to sacrum
- upper instrumented vertebrae at level of T1-3
known risk factors for post-surgical infection following spine fusion procedure?
Diabetes, obesity
most frequent complication following revision surgery for proximal junctional kyphosis?
need for further surgery
triggered EMG testing of pedicle screw values
- > 10mA indicated a well-placed screw
- < 4-6 mA indicated a screw directly contacting a neural structure
- 9-10mA suggest a breach of the pedicle may be present
what structure is at greatest risk during a cervical corpectomy?
- vertebral artery
- due to aberrant course w/ midline migration in 7.6% of cases
- vertebral artery also at increased risk during posterior C1 arch exposure, which should be limited to 1.5 cm lateral to midline (7.25mm on each side of midline)
when is the recurrent laryngeal nerve at risk?
during anterior midcervical spine approaches
-can lead to post-op dysphagia
when is internal carotid artery at risk?
-lies just anterior to anterior arch of C1 and is at risk during bicortical fixation w/ either a C1 lateral mass or C1-2 transarticular fixation
greatest risk after posterior laminectomy and instrumented fusion?
C5 nerve palsy (occurs in approx 7% of cases)
what is chief mechanism of action of parathyroid hormone in tx of osteoporosis?
- stimulates osteoblastic bone formation and reducing osteoblastic apoptosis
- tx reduces vertebral fxs by 65%
surgical indications for thoracolumbar burst fractures?
- neurologic deficit
- PLC injury
- polytrauma (relative indication)
medical management of ankylosing spondylitis?
- PT and NSAIDS in conjunction w/ GI protective therapy
- after adequate trial of therapy w/ two NSAIDs exceeding 3 months or limited by med toxicity, the pt may undergo TNF-a blockade therapy (eg INFLIXIMAB)
The risk of spinal cord ischemia is higher in pts w/ renal disease, because they are thought to be less able to compensate for the changes in spinal cord blood flow
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Pseudoarthrosis of the tibia is common in pts w/ what?
Neurofibromatosis (NF-1)
what spine condition routinely requires early surgical intervention in pts w/ Marfan syndrome?
-Progressive scoliosis
The mechanism of action of etanercept in the treatment of rheumatoid arthritis is based on its ability to act as an…
Antagonist of TNF-a
what mJOA score represents severe cervical spondylotic myelopathy?
mJOA score LOWER than 12
In patients with severe cervical spondylotic myelopathy (mJOA score lower than 12), how is the quality of life expected to change following decompressive surgery?
A large prospective study analyzed the quality of life after surgery compared with preoperative levels for patients with cervical myelopathy. Fehling and associates found that the quality of life statistically improved after surgery even when patients were analyzed based on their preoperative mJOA scores (mild, medium, or severe myelopathy). All groups had statistical improvement in quality of life after surgery, regardless of disease severity.
rate of C5 nerve root palsy after cervical decompression?
C5 nerve root palsy occurs relatively commonly after cervical decompression, with an incidence of about 5% (Lim and associates). One study by Lee and associates reported the rate to be 28.9% after posterior decompression and fusion. Most patients (92%) improve by 2 years after surgery. Risk factors for persistent symptoms included a motor grade of less than or equal to 2 of 5, multisegment dysfunction involving more than C5, and loss of sensation with pain (Lim and associates).
Is periop infection more common with an anterior or posterior cervical approach
POSTERIOR (risk increased by presence of diabetes)
Increased risk of periop complications after cervical decompression in which groups?
A recent prospective study by Tetreault and associates revealed an increased risk of perioperative complications in patients with diabetes mellitus, ossification of the posterior longitudinal ligament, longer surgical duration, and more medical comorbidities.
which factors are associated w/ a poorer clinical outcome after surgical decompression for cervical spondylotic myelopathy?
The authors found that certain patient factors were associated with a poorer clinical outcome, including older age, a worse baseline myelopathy score, impaired gait, more medical comorbidities, smoking, and a longer duration of symptoms.
which structure is at greatest risk of injury during anterior midcervical spine exposure?
Recurrent laryngeal nerve
-can lead to post-op dysphagia
which structure is at greatest risk of injury during cervical corpectomy or posterior C1 arch exposure?
Vertebral artery
-Increased risk to the vertebral artery occurs during cervical corpectomy due to an aberrant course of the vertebral artery. The incidence of midline migration of the vertebral artery is 7.6%. The vertebral artery is also at increased risk during posterior C1 arch exposure, which should be limited to 1.5 cm lateral to the midline!
which structure is at greatest risk of injury during bicortical fixation w/ either a C1 lateral mass or C1-2 transarticular fixation?
Internal carotid artery
-The internal carotid artery lies just anterior to the anterior arch of C1
which structure is at greatest risk of injury during posterior laminectomy and instrumented fusion?
C5 nerve palsy
- During posterior laminectomy and instrumented fusion, multiple structures are at low risk, but the greatest risk is of C5 nerve palsy, which occurs in approximately 7% of cases and has reported rates ranging from 0% to 30%.
- 90% have resolution by 2 yrs
When to treat lumbar disc herniations?
- The Spine Patient Outcomes Research Trial (SPORT) showed that after 6 weeks of failed nonsurgical treatment, surgical intervention is indicated.
- A microdiskectomy is indicated, and evidence shows that removal of disk debris within the canal is the most important step to alleviate symptoms. Further debridement into the disk space can result in early Modic changes, increased analgesic requirements, and decreased health-related quality-of-life scores.
Important consideration in pts w/ NF-1 and shortness of breath or fatigue?
Aortic stenosis requiring cardiac eval!
-the new onset of cardiac symptoms should prompt an urgent cardiology evaluation for aortic stenosis, which occurs in approximately 2% of cases.
What is the most common sequela of vertebral fracture in patients with an ankylosed spinal disorder such as ankylosing spondylitis?
Spinal cord injury
-In a retrospective study of 112 patients with spinal fractures and an ankylosing spinal disorder, ankylosing spondylitis or diffuse idiopathic hyperostosis spinal cord injury was present in 58% of all patients. Of the total, 19% experienced a delay in the diagnosis of fracture. During the follow-up period, 32% of the patients died (Caron and associates). The radiographic findings of an ankylosed spine are readily apparent, but the specific diagnosis of ankylosing spondylitis is often absent owing to the lack of a unified method of diagnosis (Taurog and associates).
Tandem stenosis
Tandem stenosis is the occurrence of concurrent cervical and lumbar stenosis. The prevalence has been estimated to be from 5% to 25%. Symptomatic tandem stenosis can present with a confusing scenario of both neurogenic claudication and myelopathy symptoms.
- The association of cervical and lumbar stenosis was found to be statistically significant (p < .05). Stenosis in one part of the spine positively predicts for stenosis in the other area of the spine 15.3% to 32.4% of the time.
-Tandem stenosis should be considered when evaluating a patient with mixed claudication and myeloradiculopathy symptoms.
Surgical versus nonoperative treatment for lumbar disc herniation: four-year results for the Spine Patient Outcomes Research Trial (SPORT).
In a combined as-treated analysis at 4 years, patients who underwent surgery for a lumbar disc herniation achieved greater improvement than nonoperatively treated patients in all primary and secondary outcomes (bodily pain, physical function, disability) except work status (equivalent)
Spinal osteotomies
- The aims of spinal deformity surgery are to achieve balance, relieve pain and prevent recurrence or worsening of the deformity.
- The main types of osteotomies are the Smith-Petersen osteotomy (SPO), pedicle subtraction osteotomy (PSO), bone-disc-bone osteotomy (BDBO) and vertebral column resection (VCR), in order of increasing complexity.
- SPO is a posterior column osteotomy in which the posterior ligaments and the facet joints are removed and correction is performed through the disc space. A mobile anterior disc is essential. SPO is best in patients with +6-8 cm C7 plumbline. The amount of correction is 9.3° to 10.7°/level (1°/mm bone).
- PSO is a technique where the posterior elements and pedicles are removed. Then a triangular wedge through the pedicles is removed and the posterior spine is shortened using the anterior cortex as a hinge. The ideal candidates are patients with a severe sagittal imbalance. A single level osteotomy can produce 30° 40° of correction. A single level osteotomy may restore global sagittal balance by an average of 9 cm with an upper limit of 19 cm.
- BDBO is an osteotomy done above and below a disc level. A BDBO provides correction rates in the range of 35° to 60°. The main indications are deformities with the disc space as the apex and severe sagittal plane deformities.
- VCR is indicated for rigid multi-planar deformities, sharp angulated deformities, hemivertebra resections, resectable spinal tumours, post-traumatic deformities and spondyloptosis. The main indication for a VCR is fixed coronal plane deformity.
- The type of osteotomy must be chosen mainly according to the aetiology, type and apex of the deformity. One may start with SPOs and may gradually advance to complex osteotomies.
Degenerative spondylolisthesis
Degenerative spondylolisthesis is a radiographic sign of substantial degeneration of a disk space and is often associated with spinal stenosis. The primary procedure typically planned to address a degenerative spondylolisthesis is a laminectomy. An adjacent-level degenerative spondylolisthesis is typically instrumented and fused to the previous fusion construct.
-The degeneration of the adjacent disk is also associated with a loss of disk height. A concern in this patient is the development of kyphosis at the L5-S1 disk space. Kyphosis at the lumbosacral junction can lead to sagittal imbalance issues.
Patients with sagittal imbalance are at increased risk for proximal junctional kyphosis or a more acute complication of proximal junctional failure.
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spinopelvic parameters
The sagittal vertical axis is a plumb line dropped from C7 and should fall behind the hip joints and within 4 to 5 cm of the posterior corner of S1 (an easily identifiable radiographic marker). Pelvic incidence is a constant that is unique to each patient’s spinopelvic anatomy. Pelvic incidence typically is within 10 degrees of the lumbar lordosis in an upright adult. Pelvic tilt (PT), on the other hand, can vary based on a patient’s stance. PT is an indicator of the amount of compensation a patient has developed by retroverting their pelvis to stand upright. In an upright patient who is not compensating for loss of spinal sagittal alignment, the PT should be less than 20 degrees.
posterior cervical decompression for cervical spondylotic myelopathy
A large prospective study analyzed the quality of life after surgery compared with preoperative levels for patients with cervical myelopathy. Fehling and associates found that the quality of life improved after surgery even when patients were analyzed based on their preoperative mJOA scores (mild, medium, or severe myelopathy). C5 nerve root palsy occurs relatively commonly after cervical decompression, with an incidence of about 5% (Lim and associates). One study by Lee and associates reported the rate to be 28.9% after posterior decompression and fusion. Most patients (92%) improve by 2 years after surgery. Risk factors for persistent symptoms included a motor grade of less than or equal to 2 of 5, multisegment dysfunction involving more than C5, and loss of sensation with pain (Lim and associates). Infection is another complication that is more common with a posterior cervical spine approach, and the risk of infection is increased by the presence of diabetes. A recent prospective study by Tetreault and associates revealed an increased risk of perioperative complications in patients with diabetes mellitus, ossification of the posterior longitudinal ligament, longer surgical duration, and more medical comorbidities. Another large, multi-institutional study by Tetreault and associates sought to predict which patients would improve after surgical decompression of cervical spondylotic myelopathy. The authors found that certain patient factors were associated with a poorer clinical outcome, including older age, a worse baseline myelopathy score, impaired gait, more medical comorbidities, smoking, and a longer duration of symptoms.
What is the advantage of percutaneous pedicle screw fixation over open instrumentation and fusion for a thoracolumbar burst fracture without neurologic deficit?
Less blood loss
-A prospective randomized study on short-segment treatment of burst fractures with and without fusion demonstrated similar outcomes at 5 years with lower blood loss in the nonfusion group. There is by definition no fusion performed with percutaneous stabilization, so patients often develop hardware failure. Some surgeons routinely remove instrumentation following percutaneous stabilization, thus revision surgery is common. Clinical outcomes are not improved compared to open methods.
For patients with rheumatoid arthritis who are undergoing surgery for symptomatic cervical myelopathy, neurologic recovery after decompression is best predicted by what presurgical measurement?
posterior atlanto-dens interval (PADI) 14 or greater
Differentiate infection from metastatic disease in the spine on imaging
Disk is spared in metastatic disease, whereas diskitis and osteomyelitis will show destructive changes in the disk and blurring of disk margins
Which condition routinely requires early surgical intervention in patients with Marfan syndrome?
Progressive scoliosis
- Rapidly progressive scoliosis in immature patients is associated with higher surgical complications, but surgery is indicated. Overcorrection is associated with significant cardiovascular complications and should be avoided.
when do you NOT need an emergent cervical MRI for a pt w/ perched or dislocated facets?
If pt is awake, oriented, and able to cooperate w/ exam, then proceed to immediate serial traction for reduction
-Cervical MRI is not always readily available and can delay reduction. MRI can be performed after facet reduction.
Factors associated w/ increased risk of complications for surgical tx of cervical spondylotic myelopathy?
the vast majority of complications were treatable and without long-term impact. Multivariate factors associated with an increased risk of complications include greater age, increased operative time, and use of combined anterior-posterior procedures.
how long should you wait to perform surgery for symptomatic lumbar disc herniation?
usually at least 6 wks of non-op treatment should be performed first
Athetoid cerebral palsy
This type of CP occurs more frequently in patients who had kernicterus during the neonatal period. These patients are more likely to develop cervical stenosis, disk degeneration, and listhetic instability with related myelopathy during their adult years. This condition’s exact cause is unknown.
Conditions seen in spastic quadriplegic CP?
Bilateral hip subluxation, scoliosis, and insufficiency fractures of the long bones are more commonly seen in spastic quadriplegic CP.
Risk factors for type 2 dens fx nonunion?
- displacement > 5mm
- angulation > 10 deg
- posterior displacement
- age > 40 yrs old
- fx gap > 2mm
- tx delay
Indications for ANTERIOR odontoid screw osteosynthesis in type 2 dens fx?
- type 2 fractures
- fx line perpendicular to path of screw
- anatomy permitting proper screw placement
What sum of lateral mass displacement on open mouth odontoid view indicated a transverse ligament rupture requiring surgery due to instability?
> 7mm overhang of lateral mass on C2
Risk factors for the failure of nonsurgical care for epidural abscess?
history of intravenous drug abuse, diabetes, age older than 65 years, CRP higher than 115, WBC higher than 12.5, and cultures positive for Staphylococcus aureus. A progressive neurologic deficit should be considered a sign that nonsurgical care has failed and that surgery should be considered.
Sagittal vertical axis
plumb line dropped from C7 and should fall behind the hip joints and within 4 to 5 cm of the posterior corner of S1 (an easily identifiable radiographic marker).
Pelvic incidence
a constant that is unique to each patient’s spinopelvic anatomy. Pelvic incidence typically is within 10 degrees of the lumbar lordosis in an upright adult.
Pelvic tilt
can vary based on a patient’s stance. PT is an indicator of the amount of compensation a patient has developed by retroverting their pelvis to stand upright. In an upright patient who is not compensating for loss of spinal sagittal alignment, the PT should be less than 20 degrees.
Pedicle subtraction osteotomies
considered 3-column osteotomies that remove the entire lamina, the facets, the pedicles (the posterior column), the underlying posterior vertebral wall and posterior vertebral body (middle column), and the underlying anterior vertebral body (anterior column) in a wedge fashion.
Smith-Petersen osteotomy
single-column posterior osteotomy that can provide a lesser amount of sagittal plane correction than pedicle subtraction osteotomy.
The use of halogenated inhaled anesthetic agents has been shown to abrogate the signals detected during neurophysiologic monitoring. Intravenous agents such as propofol should be used in favor of inhaled agents such as isoflurane and nitrous oxide. Neurophysiologic signals also can be dampened when hypotension and hypothermia are issues.
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Horner syndrome
manifested by ptosis, miosis, anhydrosis, occasional reddish conjunctiva, swelling of the lower eyelid, and decreased tear production.
how does injury to the recurrent laryngeal nerve manifest?
hoarseness
how does injury to the superior laryngeal nerve manifest?
voice fatigue and difficulty in singing in high pitch
Osteoporosis may be associated with polymorphisms of what gene?
COL1A1 gene
Odontoid fractures in elderly
Increased displacement and angulation of odontoid fractures have an increased risk of nonunion. Surgical stabilization has reduced the risks of mortality without increasing the risk of complications compared with nonsurgical treatment options. When treating odontoid fractures, halo vest immobilization has been shown to increase the risk of dysphagia in the elderly.
When performing open transforaminal interbody fusion, the use of cortical medial to lateral trajectory screws rather than traditional pedicle screws has been shown to
-Reduce intraop blood loss
The use of bone morphogenetic protein-2 (BMP-2) is cost effective compared with autologous iliac crest bone graft when
-productivity and lost wages are included in the analysis
Rate of post-op C5 nerve palsy in pts following cervical decompression surgery?
- 0-30%
- commonly, symptoms occur several days post-op
- symptoms typically achieve near complete resolution within 6 months without any surgical intervention, but can take more than 12 months in some cases
What structure is most at risk when dissecting too far laterally during a C1-2 posterior fusion?
Vertebral artery
-dissection of the posterior arch of C1 should be limited to 1.5cm laterally on either side to the midline to avoid injury to the vertebral artery
Risk factors for proximal junctional kyphosis in the setting of instrumented fusions performed for degenerative scoliosis?
-advanced age, 360 deg fusions, extension of fusion construct to the sacrum, and upper instrumented vertebrae at the level of T1-T3.
C6 nerve root (motor, sensory, reflexes)
- Wrist extension (ECRL, ECRB), sometimes biceps for motor
- radial forearm for sensation including thumb and index finger
- brachiradialis reflex
C7 nerve root (motor, sensory, reflexes)
- Elbow extension (triceps), wrist flexion (FCR, FCU, ECU), finger extension (EDC) for motor
- Middle finger for sensation
- Triceps reflex
what are the threshold for triggered EMG testing in neuromonitoring?
thresholds exceeding 10mA indicate a well-placed pedical screw. Thresholds lower than 4mA to 6mA indicate that a screw is directly contacting a neural structure. Thresholds between 9-10mA suggest that a breach of the pedicle may be present, but the screw is not contacting a neural structure
T1 nerve root (motor, sensory, reflexes)
- Interossei (finger abduction and adduction; lumbricals and interossei) for motor
- medial arm for sensation
- No reflex
L4 nerve root (motor, sensory, reflexes)
- knee extension (quad), ankle dorsiflexion and inversion for motor (tib anterior)(foot inversion isolates the tib ant and is the best to isolate L4)
- medial ankle and calf and big toe for sensation
- patellar tendon reflex
L5 nerve root (motor, sensory, reflexes)
- toe and great toe extension for motor (EDL, EHL)
- central dorsal foot, lateral calf for sensation
- No reflex
S1 nerve root (motor, sensory, reflexes)
- Foot plantar flexion (gastroc/soleus) and eversion (Peroneus longus and peroneus brevis) (foot eversion isolates the peroneals and is best for isolating S1) for motor
- posterior calf, lateral and plantar foot for sensation
- Achilles reflex
S2-S5 nerve roots (motor, sensory, reflexes)
- clawing of toes, bowel/bladder loss for motor
- perianal sensation for sensory
- anal wink and cremasteric for reflex
Most lumbar HNPs are paracentral herniations and thus affect which nerve root?
-Traversing nerve root (e.g. the L5 root at an L4-L5 herniation)
C6 nerve root (motor, sensory, reflexes)
- Wrist extension (ECRL, ECRB, ECU), sometimes biceps for motor
- radial forearm for sensation including thumb and index finger
- brachiradialis reflex
C7 nerve root (motor, sensory, reflexes)
- Elbow extension (triceps), wrist flexion (FCR, FCU) for motor
- Middle finger for sensation
- Triceps reflex
C8 nerve root (motor, sensory, reflexes)
- Finger flexion (FDP, FDS) for motor
- Ulnar forearm including small and ring finger for sensation
- No relfex
T1 nerve root (motor, sensory, reflexes)
- Interossei (finger abduction and adduction; lumbricals and interossei) for motor
- medial arm for sensation
- No reflex
L4 nerve root (motor, sensory, reflexes)
- ankle dorsiflexion and inversion for motor (tib anterior)(foot inversion isolates the tib ant and is the best to isolate L4)
- medial ankle and big toe for sensation
- patellar tendon reflex
4 main clinical entities that result from cervical spondylosis?
- Discogenic neck pain (axial pain)
- Radiculopathy (root compromise)
- Myelopathy (cord compression)
- Myeloradiculopathy (combinations of spinal cord and root compromise)
S1 nerve root (motor, sensory, reflexes)
- Foot plantar flexion and eversion (Peroneus longus and peroneus brevis) (foot eversion isolates the peroneals and is best for isolating S1) for motor
- lateral and plantar foot for sensation
- Achilles reflex
3 main manifestations of cervical rheumatoid spine?
- Atlantoaxial subluxation (typically first manifestation)
- Atlantoaxial invagination (basilar invagination; typically occurs after AAS)
- Subaxial subluxation (typically occurs after AAS and AAI)
Most lumbar HNPs are paracentral herniations and thus affect which nerve root?
-Traversing nerve root (e.g. the L5 root at an L4-L5 herniation)
most common level for cervical disc herniations to occur?
-C5-C6
L2/L3 nerve roots (motor, sensory, reflexes)
- hip flexors for motor
- anterior thigh for sensation
- no reflex
motor grading
- Grade 0: no movement, no contractions
- Grade 1: Flicker, contraction without movement
- Grade 2: Movement WITH GRAVITY REMOVED
- Grade 3: Movement AGAINST GRAVITY (“Meaningful” motor)
- Grade 4: Movement against gravity and against some resistance
- Grade 5: Full motor strength against resistance
Types of disc herniations
- Disc protrusion (bulging nucleus, intact annulus)
- Disc extrusion (through annulus but confined by PLL)
- Disc sequestration (disc material free in canal)
Differential diagnosis for high-intensity signal changes on T2 weighted imaging?
- Spinal cord edema
- Myelomalacia
- Syrinx
- Enlarged central canal
- Demyelinating disease
- Transverse myelitis
- Spinal cord infarct
4 main clinical entities that result from cervical spondylosis?
- Discogenic neck pain (axial pain)
- Radiculopathy (root compromise)
- Myelopathy (cord compression)
- Myeloradiculopathy (combinations of spinal cord and root compromise)
What is the cutoff for cervical spinal canal diamater as measured on plain lateral radiograph from posterior aspect of vertebral body to spinolaminar line?
-Diameter less than 14mm is cause for concern of canal stenosis
3 main manifestations of cervical rheumatoid spine?
- Atlantoaxial subluxation (typically first manifestation)
- Atlantoaxial invagination (basilar invagination; typically occurs after AAS)
- Subaxial subluxation (typically occurs after AAS and AAI)
Posterior atlantodens interval (PADI) or space available for the cord (SAC) limit of normal?
greater than 14mm is normal
Cervicalmedullary angle (CMA) limit of normal?
135 deg
anterior atlantodens interval limit of normal
less than 10mm is normal
Classifications of lumbar spinal stenosis
- central stenosis
- lateral recess/subarticular/entry zone stenosis
- foraminal stenosis
- MUST DESCRIBE THE SPECIFIC AREA OF STENOSIS
Types of disc herniations
- Disc protrusion (bulging nucleus, intact annulus)
- Disc extrusion (through annulus but confined by PLL)
- Disc sequestration (disc material free in canal)
Approaches for thoracic disc herniations
- Anterior transthoracic approach (typically for midline or central HNP)
- Posterior transpedicular/lateral extracavitary approach (for lateral HNP)
- Thorascopic discectomy
- LAMINECTOMY IS CONTRAINDICATED
most common level for lumbar disc herniations?
-L4-5 (followed closely by L5-S1)
manifestations of lumbar spondylosis?
- Discogenic back pain
- Lumbar disc herniations
- spondylolisthesis
- lumbar spinal stenosis
disc herniations in the lumbar spine?
- Central
- Posterolateral (or paracentral)
- Far lateral
What levels of disc herniation is straight leg testing tension sign for?
L4, L5, and S1
What levels of disc herniation is femoral tension sign for?
L2, L3, and L4
Lasegue sign?
relief of radiating leg symptoms with knee flexion while hip is flexed
Classifications of lumbar spinal stenosis
- central stenosis
- lateral recess/subarticular/entry zone stenosis
- foraminal stenosis
- MUST DESCRIBE THE SPECIFIC AREA OF STENOSIS
What is tandem stenosis?
-occurrence of both cervical and lumbar stenosis and can manifest as neurogenic claudication, radiculopathy, and myelopathy
what are the borders of the central canal in the lumbar spine?
-central canal is defined as space posterior to the PLL, anterior to the ligamentum flavum and laminae, and bordered laterally by the medial border of the superior articular process
what is defined as absolute stenosis in the lumbar spine?
-cross sectional area of less than 100mm2 or less than 10 mm of AP diameter as seen on CT cross section
how to differentiate neurogenic claudication from vascular claudication based on symptoms?
In neurogenic claudication: pain starts proximal and extends distal, pain relieved only when sitting and not with standing, normal vascular exam
Standard treatment for degen spondylolisthesis of lumbar spine?
Fusion usually is considered necessary in the setting of degenerative spondylolisthesis because of instability issues. Flexion-extension radiographs can help confirm this instability. If stable, a simple decompression may be considered. However, for this patient who desires definitive treatment, fusion is indicated because of the higher revision surgery rates associated with decompression alone. Additionally, fusion rates are higher with instrumented fusion, making it the standard of care when fusion is indicated.
What is the highest impact on cost of care in spinal cord injury patients?
-severity of the injury (AS|A classification) has highest impact on cost of care
cervical spondylotic myelopathy
Given the progressive nature of the neurologic symptoms, surgery is recommended for patients with worsening symptoms. Physical therapy potentially could provide pain relief but would not address the spinal cord compression. Cervical epidural steroid injection is not recommended because of the increased neurologic risk in the setting of substantial spinal cord compression. Given the multiple levels involved and the extension to the C2-3 level, an anterior approach would increase the risk of morbidity and pseudarthrosis compared with the posterior approach, which would allow adequate decompression of the central and foraminal stenosis.
-Surgery for cervical myelopathy is performed to decompress the spinal cord, stabilize the spine, and prevent further neurologic injury. Most patients obtain considerable pain relief and some improvement in balance and clumsiness, depending on the severity of the symptoms. Complete resolution of all symptoms should not be expected.
Epidural abscess
Epidural abscess once was considered an absolute indication for surgery. Nonsurgical management has been gaining ground for select patients, however. Kim and associates reported the results of a large series of patients treated for epidural abscess. Many of the patients were treated successfully without surgery, and nonsurgical management was chosen for many of the patients who presented without signs or symptoms of neurologic dysfunction. The authors identified four risk factors that were highly associated with the failure of nonsurgical management, however, including age older than 65 years, diabetes, MRSA, and neurologic compromise.
What is the most appropriate treatment for lumbar degen spondylolisthesis w/ neurogenic claudication?
Posterior laminectomy and instrumented fusion
most likely complication following revision corrective sagittal imbalance surgery?
Substantial blood loss
degrees of correction w/ various osteotomy techniques
The posterior based osteotomies can provide 3 degrees to 5degrees of correction per level. A transforaminal lumbar interbody fusion with complete fasciotomy has been shown to produce 8 degrees of correction. Posterior fusion alone is not likely to result in any correction. Releasing the anterior longitudinal ligament and using a hyperlordotic graft while performing a lateral interbody fusion has been shown to result in 10 degrees to 15 degrees of correction. The addition of posterior column osteotomies has been shown to increase this correction to 22degrees.
structures most at risk during various cervical spine procedures
Increased risk to the vertebral artery occurs during cervical corpectomy due to an aberrant course of the vertebral artery. The incidence of midline migration of the vertebral artery is 7.6%. The vertebral artery is also at increased risk during posterior C1 arch exposure, which should be limited to 1.5 cm lateral to the midline. During anterior midcervical spine exposure, the recurrent laryngeal nerve is at risk and nerve injury<strong> </strong>can lead to postoperative dysphagia. The internal carotid artery lies just anterior to the anterior arch of C1 and is at risk during bicortical fixation with either a C1 lateral mass or C1-2 transarticular fixation. During posterior laminectomy and instrumented fusion, multiple structures are at low risk, but the greatest risk is of C5 nerve palsy, which occurs in approximately 7% of cases and has reported rates ranging from 0% to 30%.
Which clinical signs are consistent with the diagnosis of cauda equina syndrome?
urinary retention, saddle anesthesia, EHL weakness
-Cauda equina syndrome is a lower-motor neuron deficit. Hyperreflexia, clonus, and other upper-motor neuron findings would not be seen. Saddle anesthesia, motor weakness, and neurogenic bladder are elements critical to the diagnosis of cauda equina syndrome.
what is the only nerve root innervation to EHL?
L5
Congenital scoliosis
- result of segmentation anomalies that occur between the fourth and eighth week of gestation
- Other organ systems that are developing at the same time may have associated defects. Renal ultrasonography and echocardiography are appropriate screening tests, considering that rates of anomalies can be as high as 50%. Neural axis abnormalities are present in approximately 40% of patients and a screening spine MR image is important to evaluate for findings such as Chiari malformation or a tethered cord.
SINS score?
- determines spinal instability in the setting of metastatic or primary spine tumors
- SINS has six components, and a score of 6 or less describes a stable spine, 7 to 12 describes impending instability, and 13 and above defines an unstable spine.
what is the most common complication following spine tumor surgery?
wound complications such as infection or dehiscence
What are likely outcomes if a patient is treated with a posterior foraminotomy instead of anterior cervical diskectomy and fusion (ACDF)?
- higher incidence of postsurgical neck pain and radiculopathy recurrence at the same level
- Studies have shown that both ACDF and posterior foraminotomy confer similar results in terms of pain relief and functional outcome. Patients treated with posterior foraminotomy are at higher risk for neck pain and recurrence of radiculopathy at the same level. Those who receive ACDF are at higher risk for occurrence of radiculopathy at an adjacent level.
Type II SMA (spinal muscle atrophy)
- usually diagnosed when patients are between 6 and 18 months of age
- caused by a loss of motor neurons, which presents as hypotonia, delayed motor milestones, and proximal muscle weakness.
- Patients with type II SMA can sit, but they may not be able to walk. Scoliosis develops in almost all patients with SMA types I and II and is usually progressive. SMA type II is not responsive to physical therapy or bracing. In very young children, growing-rod constructs can control the curves, improve pelvic obliquity, and improve thoracic growth. In older juveniles and adolescents with adequate pulmonary function, posterior spinal fusion to the pelvis has been shown effective to halt curve progression.
The highest likelihood of a recurrent fragility fracture occurs after an initial fracture of the…?
-vertebral body
Which factor is most important when attempting to prevent interbody graft subsidence?
Bone quality
-Osteoporosis can affect all aspects of spinal stability and is the most critical factor regarding spinal implant failure.
factors that point toward a patient being a reasonable candidate for a trial of culture-specific IV abx in setting of epidural abscess?
Infections w/ MSSA, age younger than 65, absence of neuro deficit, lumbar abscess location
Which deformity pattern is most commonly associated with talar neck fractures?
- Extension and varus
- usually medial and dorsal comminution of the talus.
- Caution is suggested when compressive fixation is used in the medial column of the talus, especially in the presence of medial comminution, because excessive compression may result in varus deformity.
- Malunion after inaccurate reduction of talar neck fractures has a reported incidence as high as 32%, with varus malunion occurring most frequently. Correction of the deformity involves lengthening of the medial column or shortening of the lateral column of the foot in conjunction with derotation of the forefoot.
metastatic bone disease in the spine
The management of metastatic bone disease in the spine requires an understanding of the biology of common metastatic tumors in bone. Multiple myeloma is actually a blood-born tumor that is associated with substantial lytic bone lesions. It also can be associated with soft-tissue masses that compress the spinal cord. It is among the most radiation-sensitive tumors
MRI findings of cervical spondylotic myelopathy that are poor prognostic indicators?
MR imaging with decreased signal on T1- and increased signal on T2-weighted imaging is associated with poorer prognosis than findings of either normal signal on both T1- and T2-weighted imaging or increased signal on T2-weighted imaging. Increased signal on T2-weighted imaging is nonspecific.
Which nerve root contributes to both the sciatic and femoral nerves?
L4
-The lumbosacral plexus is formed from the lumbar and sacral roots that are redistributed into the obturator, femoral, and sciatic nerves. The obturator nerve is composed of the L1, L2, and L3 roots. The femoral nerve has contributions from the L3 and L4 roots. The sciatic nerve contains the L4, L5, S1, and lower sacral roots. Therefore, only the L4 root contributes to the femoral and sciatic (via the lumbosacral trunk) nerves, which allows it to innervate the quadriceps and the anterior tibialis muscles.
Distinguishing between vascular and neurogenic claudication
important because both are degenerative diseases that can cause similar symptoms of lower extremity pain exacerbated by walking or exercise. The etiology of vascular claudication or peripheral arterial disease is an inadequate arterial blood supply to the lower leg muscles. Vascular claudication will classically produce a burning pain that is relieved by standing still or stopping the aggravating activity. Patients with peripheral artery disease may have loss of distal extremity pulses, hair loss, poor capillary refill, aggravation of pain with leg elevation, and rest pain at night that improves by using gravity to assist with distal blood flow by hanging the feet over the bed.
Neurogenic claudication is associated with several contributing factors but is primarily associated with central lumbar canal stenosis. Improving the spinal canal diameter with flexion can improve symptoms and extension can increase pain (although these are nonspecific signs). Neurogenic symptoms often are not dermatomal, may produce back pain only, and may be asymmetric. Typically, sitting down will relieve symptoms of neurogenic claudication and standing will aggravate neurogenic, but not vascular, claudication. Riding a bicycle and leaning over a grocery cart produces flexion of the lumbar spine, resulting in increased spinal diameter; these activities are more easily tolerated by patients with spinal stenosis vs vascular claudication. Lumbar spinal stenosis independently is associated with various comorbidities such as hypertension, which may partially explain why significant canal compromise may be asymptomatic.
Anterior cervical fusion in patients with AS typically will not work because the anterior fixation is compromised by osteopenia and lack of fixation with anterior cervical instrumentation (envision a short plate on an osteoporotic femur fracture).
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Risk factors for proximal junctional kyphosis in the setting of instrumented fusions performed for degenerative scoliosis
-advanced age, 360-degree fusions, extension of fusion constructs to the sacrum, and upper instrumented vertebrae at the level of T1-3.
What is a unique consideration in patients with ankylosing spondylitis with sagittal imbalance when planning your procedure?
- Smith-Petersen osteotomies necessitate flexibility of the anterior column, which is not seen in this diagnosis.
- you will likely need to perform a PSO, or in very severe cases of sagittal imbalance, a VCR
The use of bone morphogenetic protein-2 (BMP-2) is cost effective compared with autologous iliac crest bone graft when…?
- productivity and lost wages are included in the analysis
- The use of BMP-2 in lumbar spine surgery is cost effective compared with autologous iliac crest bone graft, because fewer additional treatments are needed, including a decreased incidence of revision surgery. This cost effectiveness is evident when evaluating productivity and lost wages. BMP-2 is contraindicated in tumor surgery.
Treatment of thoracolumbar burst fractures
In the absence of a neurologic deficit or a posterior ligamentous complex injury, nonsurgical treatment is as effective as surgery. The degree of spinal canal compromise is not a risk factor for neurologic symptoms. Similarly, although kyphosis may be a marker of more significant injury, the degree of kyphosis does not correlate with chronic pain. In the setting of a burst fracture, MRI can be used to evaluate the integrity of the posterior ligamentous complex. Polytrauma may be considered a relative indication for surgical intervention in the setting of a stable burst fracture.
what is the criteria for instability in a Jefferson (C1 arch fx) fx?
-combined lateral mass displacement > 7mm on open mouth plain films (not CT scan)
Studies in dogs and subsequent follow-up studies in humans have shown that in most patients, three levels of bilateral segmental nerve roots can be transected safely (Fujimaki and associates, Nambu and associates, Ueda and associates). The risk of SPINAL CORD ISCHEMIA is higher in patients with renal disease, however, because they are thought to be less able to compensate for the changes in spinal cord blood flow compared with patients who have normal renal and vascular function (Colman and associates).
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Incidental durotomies during lumbar spine surgery
- Primary repair of incidental durotomies is the standard of care. The repair may be supplemented by sealants such as dural seal or fibrin glue; however, these sealants would not serve as stand-alone treatment. Bed rest may be used postoperatively, but the duration of bed rest is controversial and not standardized.
- Incidental durotomies are a common complication of lumbar spine surgery. In the Spine Patient Outcomes Research Trial (SPORT), 409 patients undergoing surgery for spinal stenosis had a 9% rate of incidental durotomies. At 4-year follow-up, no difference in clinical outcome was observed between the patients who sustained a durotomy and the group that did not sustain a durotomy.
Which factor should most influence a patient’s decision to have surgery for adult scoliosis if he or she is younger than age 50?
- INCREASING CORONAL PLANE DEFORMITY
- Bess and associates found that surgical treatment for patients younger than 50 years of age was driven by increased coronal plane deformity, and surgical treatment for older patients was mandated by pain and disability. They also concluded that age, comorbidities, and sagittal balance did not influence treatment decisions.
- take home point: younger pts have more time to progress their deformity and may need intervention before pain develops, vs older pts who have less time to progress their deformity and quality of life is primary concern
Dens fxs in the elderly
- test answer is typically fix them if significantly displaced or angulated, even in neuro intact pts
- halo vest is never the correct answer on the test!
- Increased displacement and angulation of odontoid fractures have an increased risk of nonunion. Surgical stabilization has reduced the risks of mortality without increasing the risk of complications compared with nonsurgical treatment options. When treating odontoid fractures, halo vest immobilization has been shown to increase the risk of dysphagia in the elderly.
Pain emanating from the sacroiliac (SI) joint is best identified by which of the following maneuvers?
- More than 75% pain reduction following fluoro guided SI joint injection
- Though no gold standard exists, a reduction of concordant pain by at least 75 to 80% following an intra-articular, image-guided anesthetic injection is considered to be the most reliable method of identifying the SI joint as the cause of a patient’s pain
- Although provocation tests including the Gaenslen test, the compression test, thigh thrust, and Yeoman test are commonly used and can be helpful in diagnosing non-specific SI joint pain, individually they are not as reliable as the response to a diagnostic, anesthetic injection. Of note, the combination of all 4 manuevers has proven to be more useful than any one individual test. An MRI of the SI joint showing bony erosion and bone marrow edema suggests inflammatory arthritis and may not necessarily be associated with pain
When compared with posterior decompression and fusion, the addition of an interbody fusion for the treatment of degenerative spondylolisthesis and stenosis has been shown to…?
- Increase hospital costs
- Gottschalk and associates found no change in Oswestry Disability Index (ODI) or 36-Item Short-Form Health Survey (SF-36) scores when comparing patients fused using either posterior fusion or transforaminal interbody fusion. They also found no change in fusion rates at 3 years after surgery.
- take home point: you do NOT need to place an interbody fusion device when performing posterior decompression and fusion for degenerative spondylolisthesis. This adds cost without clear benefit.
