Spine (Complete)

Question 1

What is the ASIA spinal cord injury scale?

Answer 1

Asia A: Complete

• No motor or sensory function preserved in sacral elements

Asia B: Incomplete

• Sensory but not motor function preserved below neurological level

Asia C: Incomplete

• Greater than half the muscles below affected level are < antigravity power (<3/5)

Asia D: Incomplete

• Greater than half the muscles below affected level are > antigravity (>3/5)

Asia E: Normal

Question 2

How do you determine the ASIA classification in a spinal cord injury?

Answer 2

1. Determine if patient is in spinal shock
   * Check bulbocavernosus reflex
2. Determine neurologic level of injury

• Lowest segment with intact sensation and antigravity (3 or more) muscle function strength
• In regions where there is no myotome to test, the motor level is presumed to be the same as the sensory level

3. Determine whether the injury is COMPLETE or INCOMPLETE

• COMPLETE defined as: (ASIA A)
  
  • No voluntary anal contraction (sacral sparing) AND
  • 0/5 distal motor AND
  • 0/2 distal sensory scores (no perianal sensation) AND
  • bulbocavernosus reflex present (patient not in spinal shock)
• INCOMPLETE defined as:
  
  • Voluntary anal contraction (sacral sparing) OR
    
    • Sacral sparing critical to determine complete vs. incomplete
  • Palpable or visible muscle contraction below injury level OR
  • Perianal sensation present

Question 3

What cervical spine radiographic parameters should be assessed on plain film xrays?

Answer 3

1. Occipitocervical junction

• Harris rule of 12
  
  • Basion-dens interval or basion-posterior axial interval >12 suggests occipitocervical dissociation
• Power’s ratio
  
  • Powers ratio = C-D/A-B
    
    • C-D: distance from basion to posterior arch
    • A-B: distance from anterior arch to opisthion
  • Ratio ~ 1 is normal
  • If > 1.0 concern for anterior dislocation
  • Ratio < 1.0 raises concern for:
• Posterior atlanto-occipital dislocation
• Odontoid fractures
• Ring of atlas fractures

2. Atlantoaxial junction

• ADI
  
  • > 3.5mm considered unstable
  • > 10mm indicates surgery in RA
• PADI/SAC
  
  • <14mm indicates surgery in RA
• Lateral ADI
  • 1-2mm of asymmetry of lateral mass alignment relative to dens may be normal
• Combined lateral mass overhang
  
  • >8.1mm indicates transverse ligament rupture and unstable injury
    
    3. Subaxial spine
• Anterior vertebral line
• Posterior vertebral line
• Spinolaminar line
• Prevertebral soft tissue shadow
  
  • >6mm at C2, >22mm at C6 = abnormal
• Interspinous distance
• Stacked parallelogram facets

Question 4

What is the classification of occipital condyle fractures?

Answer 4

Anderson and Montesano Classification

• Type I - comminuted (3%)
  
  • MOI = axial load
  • Stable injury
• Type II - basilar skull fracture extending into the occipital condyle (22%)
  
  • MOI = shear injury
  • Stable injury
• Type III - transverse avulsion fracture (75%)
  
  • MOI = forced rotation with lateral bending (alar ligament avulsion)
  • Potentially unstable (associated with craniocervical dissociation)

Question 5

What cranial nerve palsies may develop in association of occipital condyle fractures?

Answer 5

CN IX, X, XI

• travel in jugular foramen adjacent to occipital condyle

Question 6

What is the management of occipital condyle fractures?

Answer 6

1. Type I and II = external immobilization (cervical orthosis)
2. Type III = depends on if associated with craniocervical dissociation or ligamentous instability

• Stable = external immobilization (cervical orthosis)
• Unstable = occipitocervical fusion
  
  • C0-C2(or C3) instrumentation and fusion

Question 7

What are the two main presentations of occipitocervical instability?

[Orthobullets]

Answer 7

1. Traumatic – often fatal
2. Acquired – often associated with Down’s syndrome

Question 8

What are the radiographic parameters to be assessed on plain film for craniocervical dissociation?

[JAAOS 2014;22:718-729]

Answer 8

1. Harris lines (Harris rule of 12s)

• Basion-dens interval
  
  • Normal = <12mm
  • Distance from basion to tip of dens
• Basion-axis interval
  
  • Normal = 4-12mm
  • Distance between line parallel to posterior cortex of C2 and basion

2. Powers ratio [Orthobullets]

• Distance from basion to posterior arch C1/distance from opisthion to anterior arch C1
  
  • Normal = 1
  • >1 = anterior dislocation
  • <1 = posterior dislocation, dens fracture, ring of atlas fracture

3. Wackenheim line

• Line parallel along the posterior portion of the clivus to the upper cervical spine
  
  • Normal = tip of dens is <1-2mm from Wackenheim line

Question 9

What is the classification system for occiptocervical instability based on direction of displacement?

[Orthobullets]

Answer 9

Traynelis Classification

• Type 1 - Anterior occiput dislocation
• Type 2 - Longitudinal dislocation
• Type 3 - Posterior occiput dislocation

Question 10

What is the classification system for occipitocervical instability based on degree of instability?

[JAAOS 2014;22:718-729]

Answer 10

Harbourview Classification

• Stage I - minimal or nondisplaced (STABLE)
  
  • Often unilateral injury to the craniocervical ligaments
  • Treatment:
    
    • External immobilization
• Stage II - minimally displaced (STABLE or UNSTABLE)
  
  • MRI indicates significant soft tissue injury (does not indicate instability)
    
    • Proceed with traction test
  • Provocative traction fluoroscopy
    
    • Technique – patient supine with lateral fluoro view centred at C1, Gardner Wells tongs are applied and 5lbs are added (repeat fluoro) then increased to 10lbs (repeat fluoro)
    • Positive traction test = Fracture displacement >2mm, atlanto-occipital distraction >2mm, or atlantoaxial distraction >3 mm indicates CCJ instability
  • Treatment
    
    • Stable = external immobilization
    • Unstable = occipitocervical fusion (C0-C2 or C3)
• Stage III – gross craniocervical misalignment
  
  • BAI or BDI >2mm above upper limit of normal
  • Usually fatal
  • Treatment:
    
    • Occipitocervical fusion (C0-C2 or C3)

Question 11

What are the radiographic parameters to assess for atlas fractures?

[JAAOS 2014;22:718-729]

Answer 11

1. Atlanto-dens interval (ADI)

• Distance between anterior dens and posterior aspect of anterior arch of C1
• Normal = <3mm in adults
• >3mm indicates transverse ligament disruption and C1-C2 instability

2. Lateral atlanto-dens interval

• Distance between the lateral surface of the dens and the medial surface of the lateral mass of C1
• Normal = <2mm of asymmetry

3. Combined lateral mass overhang

• Combined horizontal distance from lateral border of C1 to lateral border of C2 on open mouth radiographs or coronal CT
• Normal = <7mm
• >7mm indicates transverse ligament rupture and C1-C2 instability

Question 12

What is the classification system for atlas (C1) fractures?

[Orthobullets]

Answer 12

Landells Classification

• Type I - isolated anterior or posterior arch fracture
• Type II - Jefferson burst fracture (bilateral anterior and posterior arch fractures)
• Type III - unilateral lateral mass fracture

Question 13

What is the classification system for transverse ligament injuries?

[Orthobullets]

Answer 13

Dickman classification

• Type I - intrasubstance tear
• Type II - bony avulsion from tubercle at lateral mass of C1

Question 14

What is the treatment of atlas (C1) fractures?

[JAAOS 2014;22:718-729]

Answer 14

Depends on the integrity of transverse ligament injury

• If stable (ligament intact):
  
  • Based on ADI <3, lateral ADI <2mm of asymmetry, combined lateral mass overhang <7mm
  • External immobilization (halo or hard cervical orthosis)
• If unstable (ligament disrupted)
  
  • Posterior C1-C2 fusion
    
    • C1 lateral mass screw, C2 pars or pedicle
  • Occipitocervical fusion
    
    • If C1 lateral mass purchase inadequate due to comminution

Question 15

What are the radiographic parameters to assess for atlantoaxial instability?

Answer 15

1. Atlanto-dens interval
   * Normal <3mm in adults (<5mm in children)
2. Space available for the cord – SAC (posterior atlantodens interval – PADI)
   * Normal >13mm

Question 16

What is the classification and treatment of atlantoaxial instability?

[JAAOS 2014;22:718-729]

Answer 16

Type A

• Rotationally displaced in the transverse plane (transverse ligament intact)
• Often nontraumatic
• Treatment – reduction and immobilization

Type B

• Translation between C1-C2 (Unstable)
  
  • Transverse ligament disrupted
• Treatment:
  
  • Type I transverse ligament disruption = C1-C2 fusion
  • Type II transverse ligament bony avulsion = posterior C1-C2 fusion or halo immobilization following traction

Type C

• Distraction between C1-C2 (vertically unstable)
  
  • Similar to craniocervical dissociation and often associated with it
• Treatment:
  
  • C1-C2 fusion
  • C0-C2 fusion if associated with craniocervical dissociation

Question 17

What is the classification system for Odontoid fractures?

[JAAOS 2010;18:383-394]

Answer 17

1. Anderson and D’Alonzo Classification

• Type I - odontoid tip fracture
  
  • Oblique fracture due to bony avulsion of the alar ligament
• Type II - base of the dens fracture
  
  • Does not involve the C2 superior articular facet
  • High non-union rate due to watershed area
• Type III – C2 body fracture
  
  • Does involve the C2 superior articular facet

2. Grauer modification

• Type IIA - transverse fracture, <1mm displacement
• Type IIB- oblique fracture extending from anterosuperior to posteroinferior
• Type IIC- oblique fracture extending from anteroinferior to posterosuperior
  
  • May be associated with significant anterior comminution

Question 18

What is the treatment based on odontoid fracture type?

[JAAOS 2010;18:383-394]

Answer 18

1. Type I

• Stable fractures (at least one alar ligament and the transverse ligament is intact)
  
  • Cervical collar
• Unstable fractures (associated craniocervical dissociation)
  
  • Posterior C0-C2 fusion

2. Type II

• Young patient
  
  • No risk factors for nonunion = halo immobilization
  • Risk factors for nonunion = surgery
• Elderly patient
  
  • Surgical candidate = surgical stabilization
    
    • Posterior C1-C2 fusion
  • Not surgical candidate = cervical orthosis
    
    • Results in fibrous union in most cases
    • Halo vest is associated with high rate of morbidity and mortality in elderly
      3. Type III
• Cervical orthosis

Question 19

What are the risk factors for nonunion of odontoid fractures?

[JAAOS 2010;18:383-394]

Answer 19

1. Age >40
2. Posterior displacement >5mm
3. Angulation >11°
4. Comminution
5. Fracture gap >1mm
6. Delay in treatment (4 day delay)
7. Concomitant neurological injury

Question 20

What are the surgical options for odontoid fractures?

[JAAOS 2010;18:383-394]

Answer 20

1. Anterior fixation (odontoid screw)

• Anatomic reduction and one or two partially threaded screws under biplanar fluoroscopy
• Indications:
  
  • Grauer type IIb
• Contraindications:
  
  • Osteoporosis, comminution, reverse obliquity (type IIc), short neck, barrel chest, nonunion

2. Posterior C1-C2 fusion

• C1 lateral mass, C2 pars or pedicle
• Indications:
  
  • Odontoid screw contraindicated

Question 21

What is the classification for traumatic spondylolisthesis of the axis (Hangman’s Fracture)?

Answer 21

Levine and Edwards Classification

• Type I
  
  • Minimally displaced pars interarticularis fracture
  • Translation <3mm of C2, no angulation
  • MOI = axial load and hyperextension
• Type Ia
  • Oblique fracture through one pars interarticularis and anterior to the pars within the body of the contralateral side (unstable)
• Type II
  
  • Translation >3mm of C2
  • MOI – axial load and hyperextension followed by flexion
• Type IIa
  
  • Angulation (kyphosis) more than translation
  • MOI = flexion-distraction
• Type III
  
  • Similar pars fracture as type I plus C2/C3 facet dislocation
  • MOI = flexion distraction followed by hyperextension
  • ***Note: hyperextension causes the pars fracture and flexion causes PLL and disc rupture

Question 22

What is the treatment of traumatic spondylolisthesis of the axis (Hangman’s Fracture)?

[JAAOS 2014;22:718-729]

Answer 22

Type I - hard cervical orthosis (12 weeks)

Type Ia - halo immobilization

Type II - halo immobilization (12 weeks)

Type IIa

• C2-C3 ACDF or posterior fixation [JAAOS 2014;22:718-729]
• Reduction with gentle axial load + hyperextension, then compression halo immobilization for 6-12 weeks [Orthobullets]

Type III - posterior reduction and stabilization

• C2-C3 or C1-C3 fusion

Question 23

What defines the subaxial cervical spine?

Answer 23

C3-C7

Question 24

What is the classification system for subaxial cervical spine trauma?

Answer 24

1. Allen and Ferguson

• 6 classes based on mechanism of injury and static radiographs (used in research)
• Flexion-compression, vertical compression, flexion-distraction, extension-compression, extension-distraction, lateral flexion

2. Subaxial Injury Classification System (SLIC)

• Three components
  
  • Morphology
  • Integrity of the discoligamentous complex
  • Neurological status
• Score dictates treatment
  
  • <4 = conservative treatment
  • 4 = treatment at discretion of surgeon
  • >4 = surgical treatment

Question 25

What are the main subaxial cervical spine factures and their management?

[Rockwood and Green 8th ed. 2015]

Answer 25

1. Compression fracture

• Characteristics = anterior vertebral height loss, posterior vertebrae not involved
• Nonoperative
  
  • Indicated if stable and PLC intact
    
    • Facet joints are not subluxed or dislocated
    • No vertebral translation
    • Minimal gapping of interspinous spaces
    • Kyphosis <11°
  • Rigid cervical collar for 3 months followed by flex-ex views
• Operative
  • Indicated if unstable or neurological deficit
    
    • Facet joint subluxation or dislocation
    • Vertebral translation
    • Gapping of interspinous spaces
    • Kyphosis >11°
    • MRI findings suggestive of PLC disruption
  • Anterior or posterior stabilization
    
    2. Burst fracture
• Characteristics = comminuted vertebral body fracture involves the posterior vertebral body often with retropulsed fragments
• Nonoperative:
  
  • Indicated if no PLC disruption, no neurological deficit (rare)
  • Halo vest or rigid cervicothoracic orthosis
• Operative:
  • Indicated if PLC disruption, neurological deficit
  • Anterior corpectomy
  • Plus posterior instrumentation and fusion if PLC is disrupted
    
    3. Flexion teardrop fracture
• Characteristics = oblique fracture line from anterior vertebral body to the inferior endplate (quadrangular fragment)
  
  • May have posterior translation of the posterior vertebral body
  • PLC disruption suggested by interspinous and facet gapping
• Nonoperative
  • Minimally displaced, little kyphosis, intact PLC
  • Rigid cervical collar
• Operative
  
  • Neurological deficit, PLC disruption
    
    • Posterior VB translation, kyphosis >11°
  • ACDF
    
    4. Extension teardrop fracture
• Characteristics = small avulsion from anterior vertebral body
• Nonoperative
  
  • Considered a stable injury
  • Rigid cervical collar

Question 26

What is the progression of injury in cervical facet dislocation based on the Allen Ferguson classification of flexion-distraction injuries?

[Neurosurg Clin N Am 28 (2017):125–137][Orthobullets]

Answer 26

1. Facet subluxation
2. Unilateral facet dislocation (25% displacement on XR)
3. Bilateral facet dislocation (50% displacement on XR)
4. Complete dislocation (100% displacement on XR)

Question 27

What is the rate of disc herniation associated with unilateral cervical facet dislocations vs. bilateral cervical facet dislocations?

[Neurosurg Clin N Am 28 (2017):125–137]

Answer 27

Unilateral vs. bilateral = 56% vs. 82.5%

Question 28

What is the significance of a traumatic disc herniation associated with a cervical facet dislocation?

[Neurosurg Clin N Am 28 (2017):125–137]

Answer 28

1. Presence of a disc herniation can lead to neurological injury upon reduction/realignment of the cervical spine
2. Herniations with disc material posterior to the displaced vertebral body are most concerning

Question 29

What is the likelihood of PLC disruption in unilateral vs. bilateral cervical facet dislocations?

[Neurosurg Clin N Am 28 (2017):125–137]

Answer 29

1. Bilateral facet dislocations = complete disruption of PLC and facet capsules
2. Unilateral facet dislocations = PLC may be intact

Question 30

What are features of facet dislocation on CT scan?

[Neurosurg Clin N Am 28 (2017):125–137]

Answer 30

1. “Reverse Hamburger Bun Sign” (normal = “Hamburger bun sign”)
2. “Naked facet sign”

Question 31

In what situations should an MRI be obtained and not obtained prior to a closed reduction in context of cervical facet dislocation?

[Neurosurg Clin N Am 28 (2017):125–137]

Answer 31

1. Obtain MRI

• Neurologically intact patient
  
  • No urgency to perform reduction, if disc is present you can convert a neurologically intact patient to one with deficits if reduction performed
• Obtunded, nonexaminable patient
  
  • If neurologically intact, reduction in presence of disc may lead to neurological deficit
• Planning posterior approach and reduction
• Failed closed reduction or neurological deterioration during closed reduction [Orthobullets]
  2. Omit MRI
• Awake, alert, cooperative patient with incomplete cord injury or worsening neurological deficit
  
  • Patient would benefit from immediate reduction rather than delaying for MRI
• Complete cord injury

Question 32

What is the technique for performing a closed reduction for cervical facet dislocation?

[Wiesel 2016]

Answer 32

1. Requires an awake, alert and cooperative patient
2. Gardner-Wells tongs are applied

• Pins 1cm above the pinna of the ear in line with the external auditory meatus below the equator of the skull
• Placement slightly posterior produces flexion moment (often desirable in cervical facet dislocation)
• Skin is prepped and lidocaine injected subcutaneously and subperiosteally
• Pins are tightened until indicator pin protrudes at least 1mm
  3. 10lbs of weight is applied initially then 5-10lbs added incrementally
• After each weight – lateral radiograph and neurological examination
• Apply additional weight after 10-15mins

4. Once reduction is achieved the weight can be reduced to approximately 10-20lbs to maintain reduction

Question 33

What are the advantages and disadvantages of an anterior approach for reduction and stabilization following facet dislocation?

[Neurosurg Clin N Am 28 (2017):125–137]

Answer 33

1. Advantages

• Removes disc (whether herniated or not) prior to reduction
• Muscle-sparing approach
• May eliminate need for posterior approach and stabilization
• Fuses single motion segment (posterior approach may require more levels)

2. Disadvantages

• Reduction more difficult
• Failure to reduce requires a posterior approach (and possible returning to anterior for fixation)

Question 34

What are reduction techniques for cervical facet dislocation from an anterior approach?

[Rockwood and Green 8th ed. 2015]

Answer 34

1. Caspar pins
2. Laminar spreader
3. Cobb

Question 35

What are reduction techniques for cervical facet dislocation from a posterior approach?

[Rockwood and Green 8th ed. 2015]

Answer 35

1. Towel clip grasping the spinous process
2. Penfield 4 elevator over superior articular process of lower vertebra to lever up the inferior articular process of the upper vertebra
3. Resect tip of superior articular process of lower vertebra

Question 36

What are the indications for anterior approach in the management of cervical facet dislocation?

[Rockwood and Green 8th ed. 2015]

Answer 36

1. Presence of disc herniation
2. Absence of disc herniation (if surgeon prefers over posterior)

Question 37

What are the indications for posterior approach in the management of cervical facet dislocations?

[Rockwood and Green 8th ed. 2015]

Answer 37

Absence of disc herniation

Question 38

What are the indications for anterior and posterior approach to cervical facet dislocation?

[Rockwood and Green 8th ed. 2015]

Answer 38

1. Highly unstable bilateral facet dislocations
2. Presence of facet gap or kyphosis following anterior surgery
3. Delayed presentation with fixed deformity

Question 39

Describe the Denis three-column model of spinal stability

[Rockwood and Green 8th ed. 2015]

Answer 39

1. Anterior column = anterior half/part of vertebral body/disc and ALL
2. Middle column = posterior half/part of vertebral body/disc and PLL
3. Posterior column = posterior elements including pedicles, facets, lamina, spinous process and ligaments

***NOTE – based on this system fractures extending into the middle column are largely considered unstable

Question 40

What defines the posterior ligamentous complex (PLC)?

[Orthobullets]

Answer 40

• Supraspinous lig
• Interspinous lig
• Ligamentum flavum
• Facet joint capsules

Question 41

What are the radiographic features of an injury to the middle column?

[Orthobullets]

Answer 41

1. AP view = widened interpedicular distance
2. Lateral view = loss of height of posterior cortex

Question 42

What is the classification system for thoracolumbar spine injuries?

[JAAOS 2010;18:63-71]

Answer 42

1. Thoracolumbar Injury Classification and Severity Score (TLICS)

• 3 injury characteristics
  
  • Injury morphology
  • Neurological status
  • Integrity of PLC
• Score dictates treatment
  
  • <4 = nonsurgical
  • 4 = nonsurgical or surgical
  • >4 = surgical

2. AO Thoracolumbar Classification (Morphology)

• TYPE A = Compression Injuries
  
  • A0 = Minor, nonstructural fractures
    
    • Fractures which do not compromise the structural integrity of the spinal column (eg. transverse process and spinous processes)
  • A1 = Wedge-compression
    
    • Fracture of a single endplate without involvement of the posterior wall of the vertebral body
  • A2 = Split
    
    • Fracture of both endplates without involvement of the posterior wall of the vertebral body
  • A3 = Incomplete burst
    • Fracture with any involvement of the posterior wall; only a single endplate fractured
    • Vertical fracture of the lamina is usually present and does not constitute a tension band failure
  • A4 = Complete burst
    
    • Fracture with any involvement of the posterior wall and both endplates
    • Vertical fracture of the lamina is usually present and does not constitute a tension band failure
• TYPE B = Distraction Injuries
  
  • B1 = Transosseous tension band disruption (Chance fracture)
    
    • Monosegmental pure osseous failure of the posterior tension band
  • B2 = Posterior tension band disruption
    
    • Bony and/or ligamentary failure of the posterior tension band together with a Type A fracture
    • Type A fracture should be classified separately
  • B3 = Hyperextension
    
    • Injury through the disc or vertebral body leading to hyperextended position of the spinal column
    • Commonly seen in ankylotic disorders
    • Anterior structures, especially ALL are ruptured but there is a posterior hinge preventing further displacement
• TYPE C = Translation Injuries
  
  • C = Displacement/dislocation
    
    • There are no subtypes because various configurations are possible due to dissociation/dislocation
    • Can be combined with subtypes of A or B

Question 43

What patients are the best candidates for nonoperative management of thoracolumbar fractures?

[AAOS comprehensive review 2, 2014]

Answer 43

1. Neurologically intact
2. <25° kyphosis
3. <50% vertebral height loss
4. <50% canal compromise
5. Intact PLC

Question 44

What is the nonoperative treatment of choice for thoracolumbar fractures?

[AAOS comprehensive review 2, 2014]

Answer 44

Hyperextension thoracolumbar orthosis (eg. Jewett) or casting for 3 months

Question 45

What is the operative construct for a thoracolumbar burst fracture?

[Drew]

Answer 45

1. Posterior instrumentation and fusion

• 2 levels above and 2 levels below affected level
• Don’t end at junction

2. Decompression if neurological compromise

Question 46

What is the operative construct for a flexion distraction injury?

[Drew]

Answer 46

Short segment posterior instrumentation and fusion if anterior column intact

Question 47

What are the techniques for decompression from a posterior approach in thoracolumbar fractures?

[AOfoundation]

Answer 47

1. Indirect decompression through ligamentotaxis
2. Direct decompression

• Laminectomy, retraction of thecal sac and direct decompression of bone fragments (tamps to push fragments back into vertebral body)
  
  • Only below level of conus
• Transpedicular decompression
  
  • Can be performed at T1-L5 without risk from retraction to thecal sac
    
    • Superior and inferior laminotomy followed by burring and thinning of the medial pedicle to allow access to tamp fragments back into vertebral body

Question 48

What are the causes of cervical radiculopathy?

[JAAOS 2007;15:486-494]

Answer 48

1. “Soft Disc” herniations
   * Nuclear material from acute disc
2. “Hard Disc” herniations
   * Secondary to degenerative disc disease with annular bulging without frank herniation or uncovertebral osteophytes
3. Disc height loss leading to foraminal height loss
4. Facet joint hypertrophy
5. Inflammatory cytokines from disc herniation

Question 49

What nerve root is affected in a cervical disc herniation?

[JAAOS 2007;15:486-494]

Answer 49

1. Cervical nerve roots exit above their numbered pedicles
   * Except C8 which exits above T1
2. Exiting nerve roots affected
   * Eg. C5-C6 disc herniation affects the C6 nerve root

Question 50

What is the most common levels of nerve root involvement for cervical radiculopathies?

[JAAOS 2007;15:486-494]

Answer 50

C6 and C7

Question 51

What are the presenting symptoms of a cervical radiculopathy?

[JAAOS 2007;15:486-494]

Answer 51

1. Unilateral neck pain
2. Upper trapezial and interscapular pain
3. Radiculopathy patterns/Symptoms

• C2
  
  • Posterior occipital headaches, temporal pain
• C3
  
  • Occipital headache, retro-orbital or retroauricular pain
• C4
  
  • Base of neck, trapezial pain
• C5
  
  • Lateral arm pain
  • Motor loss - Deltoid
  • Reflex - Biceps
• C6
  
  • Radial forearm pain, pain in the thumb and index fingers
  • Motor loss - Biceps, wrist extension
  • Reflex - Brachioradialis
• C7
  
  • Middle finger pain
  • Motor loss - Triceps, wrist flexion
  • Reflex - Triceps
• C8
  
  • Pain in the ring and little fingers
  • Motor loss - Finger flexors
• T1
  
  • Ulnar forearm pain
  • Motor loss - Hand intrinsics

Question 52

What special tests can be performed for cervical radiculopathy?

[JAAOS 2007;15:486-494]

Answer 52

1. Spurling’s test
2. Shoulder abduction test (Bakody’s test)

• For C4-6 impingement
• Patient puts hand on hand, relief of symptoms is positive test

Question 53

What is the management of cervical radiculopathy?

[JAAOS 2007;15:486-494]

Answer 53

1. Nonoperative – First Line

• 75% of patients improve without surgery
• Nonoperative modalities may not alter natural history
• Options include brief immobilization, home traction, medications, PT, manipulations, steroid injections

2. Operative

• Indications:
  
  • Severe or progressive neurological deficit
  • Significant pain that fails to respond to nonoperative treatment

Question 54

What are the advantages and disadvantages of ACDF and posterior decompression?

[JAAOS 2007;15:486-494]

Answer 54

1. Anterior cervical discectomy and fusion*

• Advantages
  
  • Direct removal of anterior pathology without neural retraction
  • Anterior bone graft restores height and provides indirect decompression of neural foramens
  • Fusion may improve associated neck pain
  • Fusion prevents recurrent neural compression
  • Low rates of infection and wound complications
  • Muscle-sparing approach
• Disadvantages
  
  • Pseudoarthrosis
  • Plate complications
  • Adjacent joint disease
  • Speech and swallowing difficulties
  • Autograft harvest morbidity if used
    
    2. Posterior laminoforaminotomy
• Advantages
  
  • Avoids fusion and related complications
  • Can be done with minimally invasive techniques
  • Minimal morbidity
• Disadvantages
  • Possible incomplete decompression
  • Inability to restore disc and foramen height
  • Progressive degeneration in absence of fusion (recurrence of symptoms)
  • Removal of anterior pathology would require neural retraction

Question 55

What is the usual clinical course of cervical spondylotic myelopathy (CSM)?

[JAAOS 2015;23:648-660]

Answer 55

Often stepwise deterioration with periods of stability, can be progressive neurological decline

Question 56

What are risk factors for developing CSM?

[JAAOS 2015;23:648-660]

Answer 56

1. Inherited predisposition
2. Congenital stenosis

Question 57

What structures/pathology is responsible for narrowing of the spinal canal in CSM?

[JAAOS 2015;23:648-660]

Answer 57

1. Degenerative disc (anterior)
2. Uncovertebral joint osteophyte (anterior)
3. Hypertrophied/infolded ligamentum flavum (posterior)
4. Facet joint degeneration (posterior)

Question 58

What are clinical features of CSM?

[JAAOS 2015;23:648-660]

Answer 58

1. Axial neck pain and decreased ROM
2. Gait instability/balance impairment
   * Diminished proprioception due to dysfunction of posterior column
3. Diminished hand dexterity/difficulty with fine motor tasks
4. Bowel/bladder dysfunction (advanced CSM)
5. Inability to ambulate (advanced CSM)

Question 59

What clinical tests are relevant for CSM?

[JAAOS 2015;23:648-660]

Answer 59

1. Gait
2. Heel-toe walking
3. Romberg test
4. Finger escape sign
   * Ulnar two digits drift into abduction with fingers in extension for >1 minute
5. Grip-and-release test
   * Normal = 25-30 in 15 sec
6. Long tract signs

• Babinski
• Hoffmann
• Inverted radial reflex
  
  • BR reflex elicits flexion of the long finger flexors
• Hyperreflexia
• Sustained clonus >3 beats

7. Lower motor neuron signs
   * Hyporeflexia
8. Sensory deficits may be present in UE and LE

Question 60

What are the imaging findings to assess for in CSM?

[JAAOS 2015;23:648-660]

Answer 60

1. Radiographs

• Torg-Pavlov ratio = AP width of spinal canal/AP width of vertebral body
  
  • Stenosis = <0.80
• Categorize the alignment
  
  • Lordotic, neutral, kyphotic, sigmoid

2. MRI

• Myelography effect
  
  • T2 images should demonstrate fluid both anterior and posterior to the cord
  • Effacement of CSF
• Cross sectional cord deformation
  
  • Oval or kidney bean in severe stenosis
• Signal change within the cord
  
  • Poor prognosis = high signal on T2 (myelomalacia) and low signal on T1
• Compression ratio [Orthobullets]
  • Smallest AP diameter of cord/largest diameter of cord (at a single level)
  • Poor prognosis = <0.4
• Modified K-line
  
  • Line connecting the midpoints of the spinal cord between C2 and C7
  • Helps predict if adequate posterior drift back will be achieved from anterior sites of compression
  • Measure the minimum interval distance between the line and anterior compressive factors.
    
    • >4mm of space related with an optimal neurological recovery in non-lordotic patients after laminoplasty
      3. CT
• Assess for spondylotic bars, OPLL, disc osteophyte complex
  4. CT myeolography
• Blockage of flow of contrast indicates regions of compression

Question 61

What is the natural history of CSM?

[JAAOS 2015;23:648-660]

Answer 61

20-60% of patients with mild CSM progress over time in absence of surgery

Question 62

What is the goal of surgery in CSM?

[JAAOS 2015;23:648-660]

Answer 62

Prevent progression of neurological dysfunction

Question 63

What is the management of an intraoperative alert while using intraoperative neuromonitoring?

[JAAOS 2015;23:648-660]

Answer 63

1. Intraoperative pause
2. Communicate with anaesthesiologist, surgeon, neuromonitoring team
3. Check equipment
4. Ensure blood pressure is adequate (MAP >80mmHg recommended)
5. Ensure oxygen saturation is adequate
6. XR to check hardware placement
7. Reverse surgical interventions until baseline achieved
8. If alert persists perform wake-up test

Question 64

What approaches can be used in surgical management of CSM?

[JAAOS 2015;23:648-660]

Answer 64

1. Anterior

• Traditionally, preferred for 1 or 2 segment pathology
• Regional kyphosis >13° is an indication for anterior
• Anterior procedures include:
  
  • ACDF
  • Anterior subtotal vertebrectomy
  • Anterior cervical corpectomy

2. Posterior

• Traditionally, preferred for >2 segment pathology
• Posterior procedures include:
  
  • Laminectomy alone
  • Laminectomy and fusion*
  • Laminoplasty (open door or French door)

3. Combined

Question 65

What is a simplified treatment algorithm for the management of cervical spondylotic myelopathy?

[Orthobullets]

Answer 65

1. >10° rigid kyphosis

• 1 or 2 levels of compression = anterior approach
  
  • ACDF/Corpectomy
• 3+ levels of compression = combined anterior and posterior
  
  • Anterior corrects kyphosis and decompresses
  • Posterior decompresses
    2. <10° rigid kyphosis
• 1 or 2 levels of compression = anterior approach
  
  • ACDF/Corpectomy
• 3+ levels of compression = posterior approach
  
  • Laminectomy + fusion OR laminoplasty

Question 66

What is the most common nerve root palsy following surgery for CSM?

Answer 66

C5 palsy (4.6% of patients)

• Thought to be due to posterior migration of the spinal cord with tethering of the nerve root

Question 67

What is Ossification of the Posterior Longitudinal Ligament (OPLL) by definition?

[JAAOS 2014;22:420-429]

Answer 67

Replacement of the PLL with lamellar bone

Question 68

What are risk factors for the development of OPLL?

[JAAOS 2014;22:420-429]

Answer 68

1. East Asians
2. Male
3. DISH
4. Hyperparathyroidism
5. Hypophosphatemic rickets
6. Hyperinsulinemia
7. Obesity

Question 69

What is the presentation of OPLL?

[JAAOS 2014;22:420-429]

Answer 69

Cervical myelopathy

Question 70

What are the risk factors for the development of myelopathy in OPLL?

[JAAOS 2014;22:420-429]

Answer 70

1. >60% spinal canal stenosis (occupancy ratio)
2. ≤6mm SAC
3. Increased cervical ROM
4. OPLL that is laterally deviated in the spinal canal

Question 71

What imaging should be ordered in the work up of OPLL?

[JAAOS 2014;22:420-429]

Answer 71

1. Radiographs
2. CT
3. MRI

Question 72

What are the 4 types of OPLL based on lateral radiographs?

[JAAOS 2014;22:420-429]

Answer 72

1. Solitary – one vertebral level or space
2. Segmental – multiple separate lesions
3. Continuous – single lesion involving multiple interspaces
4. Mixed – combines features of the other 3

Question 73

What is the kyphosis line (K-line) on a lateral radiograph and what is its significance in OPLL?

[JAAOS 2014;22:420-429]

Answer 73

1. Line from center of the spinal canal at C2 to center of canal at C7
2. Assesses the affect of the size of OPLL and the cervical lordosis
3. Negative K-line = OPLL protrudes posterior to the K-line
4. Positive K-line = OPLL protrudes anterior to the K-line
5. Significance = negative K-line is a negative predictor of outcome for posterior surgery alone

Question 74

What is the importance of the CT scan in assessing OPLL?

[JAAOS 2014;22:420-429]

Answer 74

1. Better detects OPLL
2. Allows assessment of the occupancy ratio and location of the OPLL (central vs. lateral)
3. Detects dural ossification

• Appears as “double layer sign”
• If present >50% dural tear rates with anterior decompression

Question 75

What is the importance of the MRI in OPLL?

[JAAOS 2014;22:420-429]

Answer 75

Assesses the cord compression and condition of the cord

***Note – OPLL appears as hypointense on T1 and T2

Question 76

What are the indications for nonoperative management of OPLL?

[JAAOS 2014;22:420-429]

Answer 76

No symptoms of myelopathy

Question 77

What are the indications for surgery in OPLL?

[JAAOS 2014;22:420-429]

Answer 77

Myelopathy

Question 78

What are the advantages and disadvantages of anterior or posterior surgery for OPLL?

[JAAOS 2014;22:420-429]

Answer 78

1. Anterior decompression and fusion

• Advantages
  
  • Direct decompression, most effective for severe disease (>60% canal occupancy)
• Disadvantages
  
  • Technically demanding
  • Higher complication rate
  • Cannot decompress above C2

2. Laminectomy and fusion

• Advantages
  
  • Allows decompression of entire cervical spine
  • Low complication rate
  • Low risk of kyphotic progression
• Disadvantages
  
  • Indirect decompression
  • Risk of OPLL progression
  • Poor results for severe compression
  • Risk of C5 palsy higher than anterior approach

3. Laminoplasty

• Advantages
  
  • Allows decompression of entire cervical spine
  • Lowest immediate complication rate
  • Motion preserving
• Disadvantages
  
  • Similar to laminectomy and fusion but with higher rates of disease progression
  • Contraindicated with loss of lordosis

Question 79

When is anterior surgery preferred over posterior for OPLL?

[JAAOS 2014;22:420-429]

Answer 79

1. OPLL occupies >60% of the canal
2. Loss of cervical lordosis

Question 80

What is the most common diagnosis prompting spinal surgery in patients >65?

[JAAOS 2016;24:843-852]

Answer 80

Lumbar spinal stenosis

Question 81

What level is most commonly involved in lumbar spinal stenosis?

[JAAOS 2016;24:843-852]

Answer 81

L4/5

Question 82

What is the etiology of lumbar spinal stenosis?

[JAAOS 2016;24:843-852]

Answer 82

1. Acquired

• Secondary to degeneration (spondylosis) – most common
  
  • Degenerative disc disease
    
    • Loss of disc height
    • Bulging of the anulus fibrosis
  • Facet arthropathy
    • Loss of disc height transfers load posteriorly resulting in facet joint hypertrophy, osteophyte formation
  • Ligamentum flavum hypertrophy and buckling
• Others:
  
  • Post surgery
  • Trauma
  • Inflammatory
  • Neoplastic
    
    2. Congenital

Question 83

What inherited condition is associated with lumbar spinal stenosis?

[JAAOS 2016;24:843-852]

Answer 83

Achondroplasia

• Congenitally short pedicles
• Thick lamina
• Interpedicular distance that decreases caudally

Question 84

What are the locations of lumbar spinal stenosis?

[JAAOS 2016;24:843-852]

Answer 84

1. Central
   * Disc-osteophyte complex and ligamentum flavum hypetrophy
2. Lateral recess
   * Facet hypertrophy and osteophytes
3. Foraminal

• Loss of disc height
• Foraminal disc protrusion
• Osteophyte
• Scoliosis

4. Extraforaminal
   * Far lateral disc herniation

Question 85

What MRI slice is best for visualizing foraminal stenosis?

[JAAOS 2016;24:843-852]

Answer 85

Sagittal T1

• Often defined as foraminal diameter <3mm or foraminal height <15mm

Question 86

What are the clinical features of lumbar spinal stenosis?

[JAAOS 2016;24:843-852]

Answer 86

1. Central stenosis

• Neurogenic claudication
  
  • Pain in low back, buttocks and/or posterior thighs
  • Worse with standing and better with sitting or leaning forward
  • Worse with walking, not relieved when standing still
  • Better with activities in flexed position (bicycling, pushing shopping cart)

2. Lateral stenosis
   * Radicular symptoms

Question 87

What are the physical examination findings of lumbar spinal stenosis?

[AAOS comprehensive review 2, 2014]

Answer 87

Usually normal

Question 88

What is the management of lumbar spinal stenosis?

[Orthobullets]

Answer 88

1. Nonsurgical – first line
   * Tylenol, NSAIDs, PT, steroid injections
2. Surgical – failure of nonoperative

• Pedicle to pedicle decompression
• Pedicle to pedicle decompression and instrumented fusion
  
  • Indicated in presence of instability
    
    • Spondylolisthesis
    • Scoliosis
    • Iatrogenic
      
      • Created by complete laminectomy and/or removal of > 50% of facets

Question 89

What is the most common level of lumbar disc herniations?

[JAAOS 2017;25:489-498]

Answer 89

Up to 95% at L4-L5 and L5-S1

Question 90

What are the locations of lumbar disc herniations?

[Orthobullets]

Answer 90

1. Central

• Causes back pain
• Can cause cauda equina

2. Paracentral (posterolateral)
   * Affects the descending nerve root (L4/5 affects L5)
3. Foraminal (far lateral)
   * Affects the exiting nerve root (L4/5 affects L4)

Question 91

What are the 3 lumbar disc herniation morphologies?

[AAOS comprehensive review 2, 2014]

Answer 91

1. Protrusion
   * Eccentric bulging through an intact anulus fibrosus
2. Extrusion
   * Disc material crosses the disrupted anulus fibrosus but is continuous with the disc space
3. Sequestered

• Free fragment
• Disc material is not continuous with the disc space

Question 92

What are the symptoms associated with lumbar disc herniation?

Answer 92

1. Sclerotomal pain (mesodermal)
   * Low back, buttock, posterior thigh pain
2. Radicular pain

• Leg pain in dermatomal distribution
• Worse with Valsalva

3. Cauda equina

Question 93

What are the examination findings with lumbar disc herniation?

Answer 93

1. Weakness
2. Hyporeflexia
3. Positive SLR (sensitive not specific)
4. Contralateral SLR (more specific, less sensitive)
5. Femoral nerve stretch (L1-L4 nerve root involvement)

Question 94

What are nonspecific findings on radiographs of lumbar disc herniation?

Answer 94

1. Loss of lordosis (spasm)
2. Loss of disc height
3. Vacuum phenomenon
   * Collection of gas in the disc space

Question 95

What is the natural history of lumbar disc herniations?

[JAAOS 2017;25:489-498]

Answer 95

In the general population, >90% improve within 6 weeks with nonsurgical treatment

***Note: nonsurgical management does not change the natural history but provides symptomatic relief

Question 96

When is surgery considered for lumbar disc herniation?

[JAAOS 2017;25:489-498]

Answer 96

Failure of a 6 week course of nonoperative treatment

Question 97

What is the surgery of choice for lumbar disc herniation?

[JAAOS 2017;25:489-498]

Answer 97

Laminotomy with discectomy (microdiscectomy)

Question 98

What is the approach to a far lateral disc?

Answer 98

Wiltse approach

• Interval – multifidus and longissimus

Question 99

What are positive predictors of a good outcome following microdiscectomy?

[Orthobullets]

Answer 99

• Leg pain is chief complaint
• Positive SLR
• Weakness correlates with MRI findings
• Married status

Question 100

What are the relative indications for decompression and fusion in context of lumbar disc herniation?

Answer 100

1. Recurrent disc
2. Instability
3. Degenerative disc disease

Question 101

What are the types of spondylolisthesis (Wiltse system)?

Answer 101

1. Dysplastic (congenital)
   * Dysplasia of the upper sacrum or neural arch (the pars is normal)
2. Isthmic

• A. Lytic – fatigue fracture of the pars
• B. Elongated but intact pars (due to repeated micro fractures and healing)
• C. Acute fracture of the pars

3. Degenerative
4. Traumatic (fracture other than the pars)
5. Pathologic
6. Iatrogenic

Question 102

In pediatric population what are the risk factors for spondylolisthesis progression?

[AAOS comprehensive review 2, 2014]

Answer 102

1. Adolescent growth spurt
2. Lumbosacral kyphosis (slip angle >40)
3. Meyerding grade >II
4. Younger age
5. Female
6. Dysplastic posterior elements
7. Dome shaped sacrum

Question 103

What is the underlying pathology leading to slippage in degenerative spondylolisthesis?

[Miller’s, 6th ed.]

Answer 103

Facet arthrosis

Question 104

What are risk factors for the development of degenerative spondylolisthesis?

[Miller’s, 6th ed.]

Answer 104

1. Sagittally oriented facets (congenital)
2. Transitional lumbosacral L5

Question 105

Who is most commonly affected by degenerative spondylolisthesis?

[Miller’s, 6th ed.]

Answer 105

1. Females
2. >40
3. African americans
4. Diabetics

Question 106

What is the most common level affected in degenerative spondylolisthesis?

[Miller’s, 6th ed.]

Answer 106

L4/5

Question 107

What is the pathology that leads to neurological symptoms in spondylolisthesis?

[Orthobullets]

Answer 107

1.Central and lateral recess stenosis

• A. Caused by slippage, hypertrophied ligamentum flavum, facet arthrosis
• B. Affects descending L5 nerve root

2.Foraminal stenosis

• A. Caused by
  
  • i. Vertical stenosis – due to loss of disc height and posterolateral osteophytes from vertebral body compressing nerve root against inferior pedicle
  • ii. Anterosuperior stenosis – due to facet arthrosis and posterior vertebral body osteophytes
• B. Affects exiting L4 nerve root

Question 108

What is the clinical presentation of degenerative spondylolisthesis?

[Orthobullets]

Answer 108

1. Mechanical back pain (most common)
   * Relieved with rest
2. Neurogenic claudication and leg pain (second most common)
   * Same as lumbar spinal stenosis

Question 109

What are the physical examination findings in degenerative spondylolisthesis?

[Miller’s, 6th ed.]

Answer 109

1. Often normal
2. Hamstring tightness
3. Painful lumbar ROM

Question 110

What is the management of degenerative spondylolisthesis?

[Orthobullets]

Answer 110

1. Nonoperative – first line
2. Surgery
   * Posterior decompression and posterolateral fusion (+/- instrumentation)

Question 111

What is the underlying pathology in isthmic spondylolisthesis?

[Miller’s, 6th ed.]

Answer 111

Pars interarticularis defect (spondylolysis)

Question 112

What is the most common level affected in isthmic spondylolisthesis?

[Miller’s, 6th ed.]

Answer 112

L5 spondylolysis (L5 on S1)

Question 113

What are risk factors for the development of isthmic spondylolisthesis?

[Miller’s, 6th ed.]

Answer 113

1. Increased pelvic incidence
   * As PI increases, sacral slope increases requiring an increase in lumbar lordosis to maintain sagittal balance
2. Hyperextension activities
3. Inuit

Question 114

What are risk factors for progression of slip in isthmic spondylolisthesis?

[AAOS comprehensive review 2, 2014]

Answer 114

1. Adolescents <15 years
2. Progressive disc degeneration
3. L4/5 level (iliolumbar ligament stabilizes L5)

Question 115

What is the Meyerding classification for slip grading in spondylolisthesis?

Answer 115

1.Ratio of the overhanging superior vertebral body to the anteroposterior length of the adjacent inferior vertebral body

• Grade I 0-25%
• Grade II 25-50%
• Grade III 50-75%
• Grade IV 75-100%
• Grade V >100% (spondyloptosis)

Question 116

What is a high grade vs. low grade slip in spondylolisthesis (Meyerding Classification)?

[Int J Spine Surg 2015; 9-50]

Answer 116

1. Slip <50% = low grade (Grade I-II)
2. Slip >50% = high grade (Grade III-V)

Question 117

What is the slip angle in isthmic spondylolisthesis?

Answer 117

Angle between the endplates of L5 and S1

Question 118

What are the features of degenerative vs. isthmic spondylolisthesis?

[CORR course]

Answer 118

1. Degenerative

• Level = L4-5
• Central Stenosis = present
• L5 nerve compression = at origin

2. Isthmic

• Level = L5-S1
• Central Stenosis = absent
• L5 nerve compression = foramen

Question 119

What is the management of isthmic spondylolisthesis?

[JAAOS 2016;24:37-45]

Answer 119

1. Nonoperative – first line
2. Surgery

• Indications (Pediatric)
  
  • i. Grade I and II slips with persistent symptoms despite >6 months of nonsurgical treatment
  • ii. Grade III or higher slips

Question 120

What are the surgical considerations for low grade and high-grade spondylolisthesis?

[OKU 5 Spine]

Answer 120

1. Low grade

• Postural reduction and insitu fusion (standard)
  
  • i. Note: postural reduction is achieved with pelvis/hips in hyperextension
  • ii. +/- decompression in the presence of foraminal or central stenosis (indicated by symptoms, exam or imaging)
  • iii. +/- instrumentation
    
    • TLSO if no instrumentation
  • iv. +/- interbody fusion, fibular strut graft, L5-S1 intervertebral body screw
    • Reduces pseudoarthrosis
      2. High grade
• A. In presence of balanced pelvis = Postural reduction and insitu fusion
• B. In presence of unbalanced pelvis = consider reduction and fusion
  
  • i. In the presence of a retroverted pelvis, normal sagittal balance can be achieved by correcting the lumbosacral kyphosis and decreasing the pelvic tilt or retroversion
  • ii. Important points
    • Neuromonitoring intraop
    • L5 nerve root needs to be widely decompressed and visualized prior to reduction
    • Sacral dome osteotomy may be required to correct lumbosacral kyphosis
    • Complete reduction of slip is not required nor desired (max 50% correction)
    • Anterior interbody cages may reduce risk of pseudoarthrosis
      3. Spondyloptosis
• A. Sagittal balance maintained = insitu fusion
• B. Sagittal balance not maintained = consider L5 vertebrectomy and reduction of L4 over S1

Question 121

How is pelvis and spine balance determined?

[OKU 5 Spine]

Answer 121

1.Pelvic balance

• Balanced = SS > PT
• Unbalanced = SS < PT

2.Spinopelvic balance

• Balanced = C7 plumb line falls over or behind the femoral heads
• Unbalanced = C7 plumb line falls infront of the femoral heads

Question 122

What are the AAOS clinical practice guidelines on osteoporotic spinal compression fractures?

[JAAOS 2015;23:253-263]

Answer 122

1. Strong
   * Recommend against vertebroplasty
2. Moderate
   * Recommend calcitonin for 4 weeks in patients who present with acute compression fractures (0-5 days of onset of symptoms) and are neurologically intact
3. Limited

• Kyphoplasty is an option for symptomatic compression fractures
• L2 nerve block for symptomatic L3 or L4 compression fractures
• Ibandronate and strontium ranelate are options to prevent additional symptomatic fractures

Question 123

What are the important considerations when performing spinal surgery in the setting of osteoporosis?

[JAAOS 2015;23:253-263]

Answer 123

1. Prevention of osteoporosis is the most important principle in the management of the condition.
2. Prompt referral to an endocrinologist for preoperative optimization is recommended.
3. Longer fusion constructs and avoiding constructs that start or end at the cervicothoracic or thoracolumbar junction may protect against junctional or segmental failure
4. At least three fixation points above and below the apex of the deformity should be used
5. Hybrid constructs (pedicle screws, hooks, wires) may improve fixation strength
6. Iliac and/or sacral fixation in long fusion constructs is recommended, when feasible, to maximize stability
7. Anterior column support increases load-sharing, decreases strain on constructs, and should be used whenever possible
8. The direction of pedicle screw insertion affects pullout strength, and purchase in subchondral bone (eg, sacral promontory) is recommended to maximize fixation
9. Undertapping increases the insertional torque and pullout strength of pedicle screws
10. Hubbing of pedicle screws adversely affects pullout strength and should be avoided.

Question 124

What are the indications and contraindications of vertebroplasty and kyphoplasty?

[JAAOS 2014;22:653-664]

Answer 124

Indications

• Painful osteoporotic compression fracture that does not improve with 2 to 3 weeks of nonsurgical care
• Patient hospitalized as a result of painful osteoporotic fracture
• Painful pathologic fracture
• Aggressive hemangioma of the spine
• Kümmell disease
  
  • Post traumatic AVN of vertebral body

Absolute Contraindications

• Asymptomatic fractures
• History of vertebral body osteomyelitis
• Allergy to bone fillers or opacification agents
• Irreversible coagulopathy

Relative Contraindications

• Presence of radiculopathy
• Bone retropulsion against neural structures
• Greater than 70% collapse of vertebral body height
• Multiple pathologic fractures
• Lack of surgical backup to manage potential complications

Question 125

What are the complications associated with vertebroplasty and kyphoplasty?

[JAAOS 2014;22:653-664]

Answer 125

1. Cement extravasation
2. Embolization
3. New fracture
   * Due to increased stiffness leading to higher loads on adjacent segments

Question 126

What are the indications for spine surgery in bacterial spine infections?

[JAAOS 2016;24:11-18]

Answer 126

1. Failed medical management
2. Need for open culture/biopsy
3. Spinal instability
4. Neurological deficit or deterioration

Question 127

What are the risk factors for bacterial spine infections?

[JAAOS 2016;24:11-18]

Answer 127

1. Advanced age
2. Malnutrition
3. Immunocompromised
4. Diabetes
5. IVDU
6. HIV/AIDS
7. Malignancy
8. Chronic steroid use
9. Renal failure
10. Septicemia
11. Spinal surgery
12. Intravascular devices
13. Presence of foreign bodies

Question 128

What is the most common organism in bacterial spine infections?

[JAAOS 2016;24:11-18]

Answer 128

Staph aureus

Question 129

What is the most common location of vertebral osteomyelitis, discitis, and epidural abscess?

[JAAOS 2016;24:11-18]

Answer 129

Lumbar spine

Question 130

Where can vertebral osteomyelitis disseminate too?

[JAAOS 2016;24:11-18]

Answer 130

1. Epidural, paravertebral or psoas abscess
2. Mediastinum, supraclavicular fossa and retropharyngeal space in cervical osteomyelitis

Question 131

What are clinical features of bacterial spine infections?

[JAAOS 2016;24:11-18]

Answer 131

1. Insidious neck or back pain
2. Neurological deficits (30%)
3. Fever, weightloss, nausea/vomiting, anorexia, lethargy, confusion
4. Dysphagia

Question 132

What is the workup for bacterial spine infection?

[JAAOS 2016;24:11-18]

Answer 132

1. CBC
2. ESR/CRP
3. Blood culture
4. CT guided or open biopsy (if blood culture negative)
   * Send samples for aerobic, anaerobic, fungal and acid fast bacilli cultures
5. Transesophageal echo (assess for bacterial endocarditis)
6. TB skin test if risk factors present
7. Radiographs
   * Assess for osteolysis, endplate destruction, vertebral collapse
8. MRI

• Imaging modality of choice
• Hyperintense signal on T2 and hypointense signal on T1 (disc and adjacent VB)

Question 133

What is the recommended management of vertebral osteomyelitis, discitis and epidural abscess?

[JAAOS 2016;24:11-18]

Answer 133

1. Pyogenic vertebral osteomyelitis

• Medical management
  
  • 6-8 weeks of antibiotics and bracing
    
    • Duration of antibiotics should be increased in presence of abscess
  • Biopsy or blood culture should be sent prior to administration of antibiotics
  • If patient is septic empiric antibiotics can be started
• Surgery
  
  • If fusion required autograft is preferred (over titanium cages or allograft) unless large defect
    
    2. Discitis
• Medical management
  
  • Mainstay of treatment
• Surgery (rare)

3. Epidural abscess

• Medical management
  
  • Antibiotics
• Surgery
  
  • Absolute indication = progressive neurological deficit

Question 134

What is the most common cause of granulomatous infections of the spine?

[JAAOS 2015;23:529-538]

Answer 134

1. Mycobacterium tuberculosis
2. Others

• Brucellosis (second most common)
• Actinomyces
• Nocardia
• Fungal (candidiasis, asperigillosis, coccidioidomycosis, blastomycosis, and cryptococcosis)
• Parasitic (Echinococcus and Taenia solium)

Question 135

What is the source of colonization of spine TB?

[JAAOS 2015;23:529-538]

Answer 135

1. Hematogenous from a pulmonary source
   * Most commonly
2. Contiguous spread from visceral sources

Question 136

What is the most common bony location of extrapulmonary TB involvement?

[JAAOS 2015;23:529-538]

Answer 136

Thoracic spine

Question 137

What type of granuloma forms with TB?

[JAAOS 2015;23:529-538]

Answer 137

Caseating granuloma

Question 138

What are the 3 major patterns of vertebral involvement in spinal TB?

[JAAOS 2015;23:529-538]

Answer 138

1. Peridiscal (most common)

• Begins adjacent to a single vertebral end plate (metaphysis)
• Spreads peripherally to the adjacent intervertebral disc
  
  • Less severely affected and relatively preserved
• Tracks deep to the ALL to spread to an adjacent vertebra

2. Central

• Abscess formation in the central vertebral body
• Leads to vertebral collapse and spinal deformity

3. Anterior

• Begins anterior to the vertebral body and posterior to the ALL
• Spreads under ALL, scallops vertebral body and may extend multiple levels

Question 139

Who are patients at risk of TB spinal infection?

[JAAOS 2015;23:529-538]

Answer 139

1. Immunocompromised (AIDS, organ transplant)
2. Travel to Asia, Africa, South America
3. Homeless
4. Known exposure (hospital, nursing, homeless shelter employee)

Question 140

What is the presentation of a TB spinal infection?

[JAAOS 2015;23:529-538]

Answer 140

1. Back pain
   * Less severe and more insidious than pyogenic infection
2. Malaise, night sweats, weight loss, fevers
3. Kyphotic or gibbus deformity
4. Cutaneous sinuses
5. Neurologic deficits

Question 141

What diagnostic testing is indicated for TB of the spine?

[JAAOS 2015;23:529-538]

Answer 141

1. Nonspecific – WBC, ESR, CRP
2. Tuberculin skin test
   * Positive = induration >5-15mm after 48-72 hours
3. Interferon gamma release assay
   * Blood test equally sensitive but more specific
4. PCR
5. CXR
   * Segmental or lobar infiltrates with ipsilateral hilar or mediastinal lymphadenopathy
6. Thoracolumbar xray

• Osteolysis of affected vertebra
• Kyphotic deformity (late)

7. MRI

• T1 - Homogenous low signal with subligamentous spread
• T2 – Heterogenous high signal with subligamentous spread

8. CT guided biopsy

• Diagnostic yield = 42-76%
• If nondiagnostic consider open biopsy
• Send biopsy for:
  
  • Aerobic, anaerobic and tuberculous-specific culture (broth cultures)
  • Acid-fast bacilli smear microscopy
  • PCR
  • Pathology (detects caseating granuloma)

Question 142

What are the features of a “spine at risk” of development of kyphosis in TB infection?

[JAAOS 2015;23:529-538]

Answer 142

1. Separation of facet joints
2. Retropulsion
3. Lateral translation
4. Toppling
   * Identified when a line drawn along the anterior surface of the normal caudal vertebra intersects above the middle of the anterior wall of the cranial vertebral body

Question 143

What are the indications for nonoperative management of TB spine?

[JAAOS 2015;23:529-538]

Answer 143

1. No neurology
2. No spinal instability

Question 144

What is the nonoperative treatment for TB spine?

[JAAOS 2015;23:529-538]

Answer 144

Pharmacological

• RIPE – rifampin, isoniazid, ethambutol, pyrazinamide
• Duration – 6-18 months
• Serial clinical and radiographic evaluations

Question 145

What are the indications for operative management of TB spine?

[JAAOS 2015;23:529-538]

Answer 145

1. Failure of medical management
2. Neurological deficits
3. Spinal instability or deformity

Question 146

What are the principles for surgical management of spinal TB?

[JAAOS 2015;23:529-538]

Answer 146

1. Decompression
   * When anterior column is involved a direct resection is required
2. Excision of the pathological lesion
   * Debridement of all purulent material, granulation tissue, caseous tissue, sequestered bone and bone that is compressing neural elements
3. Reconstruction and stabilization of the spine

• Following decompression and debridement structural graft is recommended for stability and correction of kyphotic deformity
  
  • Options include:
    
    • Structural autograft (iliac crest, rib)
    • Structural allograft (fibula)
    • Titanium cages with autogenous or allograft cancellous bone
• Posterior instrumentation and fusion often added
• Options [Orthobullets]
  
  • Single-stage transpedicular
  • Two-stage anterior decompression with bone grafting and posterior kyphosis correction and instrumentation
    4. Continue pharmacological

Question 147

What is the “Hong Kong Technique” (in TB spine)?

[JAAOS 2015;23:529-538]

Answer 147

1. Anterior approach
2. Radical debridement and decompression
3. Correction of the kyphotic deformity with uninstrumented structural allograft

Question 148

What are the 3 forms of cervical spine instability resulting from RA?

[JAAOS 2005;13:463-474]

Answer 148

1. Atlantoaxial impaction (65% of RA patients)
   * AKA Basilar invagination, cranial settling, superior migration of the odontoid
2. Atlantoaxial instability (4-35%)
3. Subaxial instability (7-29%)

Question 149

What is the usual order of development of instability patterns in RA spine?

[JAAOS 2005;13:463-474]

Answer 149

Atlantoaxial instability → atlantoaxial impaction → subaxial instability

Question 150

What is the underlying pathophysiology of each instability pattern in RA spine?

[JAAOS 2005;13:463-474]

Answer 150

1. Atlantoaxial impaction

• Collapse of the lateral masses due to involvement of the atlanto-occipital and atlantoaxial joints
  
  • Erosion of O-C1 and C1-2 joints such that odontoid appears to enter foramen magnum
    • Weakening and collapse of the lateral masses
      2. Atlantoaxial instability
• Due to weakening or rupture of the transverse, alar and apical ligaments
  
  • Synovitis and pannus weaken the transverse, alar and apical ligaments
• Repetitive strain leads to stretching or rupture
• Bony erosion of dens or atraumatic dens fractures possible

3. Subaxial instability

• Due to destabilization of the facet joints with weakening of the facet capsule and interspinous ligaments
  
  • Destruction of facet joints and uncovertebral joints
    • Weakening of interspinous ligaments
• Lack of osteophyte formation results in relative instability
  
  • Versus stability in OA due to osteophytes
• Disc and annulus also degenerative but synovitis does not develop
  
  • Thus, anterior disease does not directly contribute to instability

Question 151

What is the clinical presentation of Rheumatoid Spine?

[JAAOS 2005;13:463-474]

Answer 151

1. Neck pain (most common - 40-80%)
2. Atlantoaxial impaction

• Cervical myelopathy
• C1+C2 nerve compression (occipitocervical pain)
• Compression of the medulla oblongata
  
  • Sleep apnea
  • Sudden death
• Compression of vertebral or anterior spinal arteries
  
  • TIAs, vertebrobasilar insufficiency or neurological deficits
    
    3. Atlantoaxial instability
• Clunking sensation with extension or sensation of head sliding forward with flexion
• Cervical myelopathy
• L’hermittes sign

4. Subaxial instability
   * Cervical myelopathy

Question 152

What is the classification system used for myelopathy? [JAAOS 2005;13:463-474]

Answer 152

Ranawat Classification

• Grade I - normal
• Grade II - Weakness, hyperreflexia, altered sensation
• Grade IIIA - Paresis and long-tract signs, ambulatory
• Grade IIIB - quadriparesis, nonambulatory

Question 153

At what Ranawat stage should surgery be attempted?

[JAAOS 2005;13:463-474]

Answer 153

Prior to IIIB

• I.e. While still ambulatory

Question 154

What are risk factors for progression of atlantoaxial instability?

[JAAOS 2005;13:463-474]

Answer 154

• Male
• RF positive
• Higher initial CRP
• Subcutaneous nodules
• Advanced peripheral joint disease (rapid loss of carpal height)

Question 155

What are the indications for neutral, flexion, extension cervical spine radiographs in a patient with RA?

[JAAOS 2005;13:463-474]

Answer 155

1. Prolonged cervical spine symptoms >6 months
2. Neurological signs or symptoms
3. Scheduled procedures requiring endotracheal intubation in patients who have not had cervical radiographs in 2-3 years
4. Rapidly progressive carpal or tarsal bone destruction
5. Rapid overall functional deterioration

Question 156

What are the radiographic features of Rheumatoid spine?

[JAAOS 2005;13:463-474]

Answer 156

1. Atlantoaxial impaction

• McCrae’s line
  
  • Line between basion and opisthion
  • Normal = tip of dens should be below line
• McGregor’s line
  • Line between hard palate and base of the occiput
  • Abnormal = tip of dens 4.5mm above line
• Ranawat Index
  
  • Distance from midpoint of C2 pedicle along centre of odontoid to horizontal line through C1
  • Abnormal = <15mm in males, <13mm in females
• Cervicomedullary angle (MRI)
  
  • Angle between anterior aspect of cervical cord and anterior medulla
  • <135° indicates impending neurological impairment
• Clark’s station
  
  • C2 divided into thirds (1 is superior, 3 is inferior)
  • Abnormal = anterior ring of C1 is in the 2nd or 3rd station
  • Simplest method to use as the relationship does not change in flexion, extension or neutral
• ***McRae and McGregors inaccurate with odontoid erosion
  2. Atlantoaxial instability
• ADI (atlantodental interval)
  
  • Distance between the anterior dens and the posterior anterior arch of C1
  • Abnormal = >3.5mm
    
    • >5mm suggests instability
    • >10mm suggests complete loss of ligamentous integrity
• PADI/SAC
  
  • Posterior atlantodental interval/space available for the cord
  • Distance between the posterior dens and the posterior arch of C1
  • Abnormal = ≤14mm is an indication for surgery
    
    • Need 14mm for canal (10 cord, 1 dura, 1 CSF)
    • <10mm assoc with poor neuro outcomes
    • ≥14mm assoc with excellent neuro outcomes
  • Better predictor of neuro outcomes than ADI
• ***ADI and PADI can not evaluate cord compression by soft tissues (i.e. pannus)
  3. Subaxial instability
• C2/3 and C4/5 most commonly involved
• Kyphosis
• “staircase” when multiple levels involved
• Facet joint erosions and widening
• Spindling of the spinous processes
• Subluxation
  
  • Abnormal = >4mm or 20% listhesis of vertebral body diameter

Question 157

What are the indications for surgery in Rheumatoid Spine?

[JAAOS 2005;13:463-474]

Answer 157

1. Intractable pain
2. Neurologic deficits
3. ADI >10 [Orthobullets]
4. PADI ≤14mm
5. Dens migration ≥5mm rostral to McGregor’s line
6. Subaxial subluxation with canal diameter ≤14mm
7. Cervicomedullary angle <135°

***Increased function and lifespan compared to non-op

Question 158

What are the options for surgical management for Rheumatoid Spine?

[JAAOS 2005;13:463-474]

Answer 158

1. In general, identify which of the 3 instability patterns are present then address each one
2. Atlantoaxial instability

• Gallie or Brooks wiring
  
  • Contraindicated if subluxation cannot be reduced
• Magerl transarticular C1-C2 screws (95% fusion rate)
• Harms C1/2 lateral mass screws

3. Atlantoaxial instability with nonreducible subluxation
   * C1/2 stabilization (transarticular screws) with C1 decompression with posterior arch removal
4. Atlantoaxial impaction

• Preop halo traction to reduce impaction
• Occipitocervical fusion (occiput to at least C2)

5. Atlantoaxial impaction with failure of preoperative traction
   * Occipitocervical fusion with transoral resection of the odontoid or C1 posterior arch removal
6. Subaxial instability
   * If reducible, may be fused anteriorly or posteriorly
   • Posterior instrumentation and fusion
     
     • Extend fusion to the lowest involved level (do not stop at C7)
       
       • If nonreducible:
   • Anterior decompression/fusion is preferred
   • Posterior fusion if doing laminectomy

Question 159

What is the diagnostic criteria for Diffuse Idiopathic Skeletal Hyperostosis (DISH)?

Answer 159

1. Flowing ossification along the anterolateral aspect of at least 4 contiguous vertebra
2. Preservation of disc height and relative absence of degenerative changes
3. Absence of facet joint or SI joint ankylosis

Question 160

What are the differentiating features of DISH compared to Ankylosing Spondylitis?

[Orthobullets]

Answer 160

Question 161

What area of the spine is most commonly in DISH?

Answer 161

Thoracic spine (right sided due to aorta)

Question 162

What are associated findings in DISH?

Answer 162

1. Cervical involvement

• Dysphagia, hoarseness, sleep apnea, difficult intubation
• OPLL and myelopathy

2. Lumbar involvement
   * Lumbar stenosis due to ligamentum flavum ossification and posterior element hyperostosis
3. Spine fracture and instability

• Similar to AS, prone to spine fractures due to stiffness and long lever arms
• Often follow low energy trauma, result in unstable fractures

4. Enthesophytes
5. Increased risk of HO following THA

Question 163

What is the most common location for spinal fracture in AS?

[JAAOS 2016;24:241-249]

Answer 163

Lower cervical spine followed by thoracolumbar junction

Question 164

What are the characteristics of spinal fractures in AS?

[JAAOS 2016;24:241-249]

Answer 164

1. Unstable
2. Higher prevalence of neurologic injury
3. Higher risk of epidural hematoma and aortic dissection
4. Higher risk of multiple fractures
5. Typically occur through the ossified disc and vertebral body
6. Frequently due to extension-distraction mechanism (opening of the anterior column)

Question 165

What factors lead to increased incidence and prevalence of spinal fractures in AS?

[JAAOS 2016;24:241-249]

Answer 165

1. Osteoporosis
   * Leads to higher rate of vertebral fractures and higher risk from low-energy trauma
2. Loss of flexibility
   * Long lever arms (behave like long bones)
3. Kyphotic deformity

Question 166

What imaging is required in a patient with AS with a suspected spine fracture?

[JAAOS 2016;24:241-249]

Answer 166

1. Radiographs
   * Often nondiagnostic
2. CT scan (full spine)
   * Routine use in patient with suspected cervical fracture
3. MRI (full spine)

• Detects epidural hematoma in patients with neurological deficit
• Detects spinal cord and soft tissue injury
• May detect fractures missed on CT

Question 167

What are the preoperative considerations for spinal fractures in AS?

[JAAOS 2016;24:241-249]

Answer 167

1. Protect against iatrogenic neurological deterioration

• Immobilize patient in their typical position
  
  • Do not force head to spine board (extension) as they often have an increased occiput to wall distance
• Take care during transfers

2. Anaesthesia considerations
   * Difficult intubation (chin to chest deformity)
3. Positioning
   * Restore their normal alignment
4. Construct length

• Longer construct preferred due to osteoporosis and long lever arm (treat like long bone)
• Usually 3 vertebral levels above and below

Question 168

What is the management of cervical spine fractures in AS?

[JAAOS 2016;24:241-249]

Answer 168

Posterior instrumentation and fusion

• Anterior alone is possible but more difficult due to chin-to-chest deformity and has higher failure rate
• Anterior and posterior can be considered if correcting the deformity (not generally recommended)

Question 169

What is the management of thoracic and lumbar fractures in AS?

[JAAOS 2016;24:241-249]

Answer 169

Posterior instrumentation and fusion

Question 170

At what level does the spinal cord end?

[JAAOS 2008;16:471-479]

Answer 170

L1 vertebral body (T12-L2 vertebra)

Question 171

What is the cauda equina?

[JAAOS 2008;16:471-479]

Answer 171

1. Collection of peripheral nerves (L1-S5) in a common dural sac within the lumbar spinal canal
2. Therefore, lesions involving the cauda equina are lower motor neuron lesions

Question 172

What are the causes of Cauda Equina Syndrome (CES)?

[JAAOS 2008;16:471-479]

Answer 172

• Herniated lumbar disc
• Spinal stenosis
• Tumour
• Trauma
• Epidural hematoma
• Epidural abscess
• Iatrogenic

Question 173

What are the presenting symptoms of cauda equina syndrome?

[JAAOS 2008;16:471-479]

Answer 173

1. Bladder dysfunction (required element)
   * Difficulty initiating stream → urinary retention → overflow incontinence
2. Bowel dysfunction
3. Saddle anaesthesia

• Dense sensory loss involving the perineum, buttocks, and posteromedial thighs
• Late sign

4. Low back, groin, perineal pain
5. Unilateral or bilateral sciatica
   * Bilateral is strongly associated with CES
6. Lower extremity weakness and sensory deficits

Question 174

What are the physical examination findings in cauda equina syndrome?

[JAAOS 2008;16:471-479]

Answer 174

1. Reduced sensation to pinprick in the perianal, perineum and posterior thigh
2. Decreased rectal tone
3. Lack of anal contraction with anal wink and bulbocavernosus test
4. Full bladder on palpation
5. Lower extremity hyporeflexia, sensory deficits and weakness

Question 175

What imaging modality is needed in cauda equina syndrome?

[JAAOS 2008;16:471-479]

Answer 175

MRI

Question 176

What is the optimal timing for surgical exploration and decompression?

[JAAOS 2008;16:471-479]

Answer 176

Urgent manner within 48 hours of symptom onset

• Current literature does not demonstrate improved outcomes with surgery performed within 24 hours as opposed to 48 hours

Question 177

What is the goal of surgery for CES?

[JAAOS 2008;16:471-479]

Answer 177

Spinal decompression in a timely manner to avoid permanent disability

• Disability including bowel/bladder dysfunction, motor deficit, sensory deficit, sexual dysfunction

Question 178

What are features of incomplete cord syndromes?

Answer 178

Sacral sparing

• Evaluation consists of perianal sensation, rectal tone and activity of the great toe flexor

Question 179

What is the most common incomplete cord syndrome?

[JAAOS 2009;17:756-765]

Answer 179

Central cord syndrome

Question 180

What are the clinical scenarios/presentations for incomplete cord syndrome?

[JAAOS 2009;17:756-765]

Answer 180

1.Older patient (>60)

• Underlying cervical spondylosis
• Hyperextension injury
• No evidence of bony spine injury

2. Younger patient

• No underlying cervical spondylosis
• High-energy mechanism
• Associated fractures and/or dislocations

3. Younger patient with congenital stenosis
   * Hyperextension injury
4. Younger patient with traumatic disc herniation
   * No spinal fracture or dislocation

Question 181

What is the clinical presentation of central cord syndrome?

[JAAOS 2009;17:756-765]

Answer 181

Classically:

• Motor more affected than sensory function
• Upper extremity more affected than lower extremity
• Distal more than proximal
  
  • Hands and forearms most affected
• Bladder (urinary retention), bowel and sexual dysfunction in severe cases
• Sacral sparing

Question 182

What is the order of neurologic recovery in central cord syndrome?

[JAAOS 2009;17:756-765]

Answer 182

Lower extremities → bowel/bladder control → upper extremity → hand

• Motor recovery occurs caudal to cephalad (toe flexors are first to return)
• Recovery is usually less complete in upper extremities compared to lower extremities
• Hand recovery is variable (most common long term disability)

Question 183

What is the management of central cord syndrome?

[JAAOS 2009;17:756-765]

Answer 183

1. Medical management

• ICU monitoring
• Adequate BP (MAP >85mmHg)
• Hard cervical collar
  
  • Use for at least 6 weeks or until neck pain has resolved and associated neurological improvement is noted
• Early mobilization

2. Surgery

• Absolute indication = spinal instability
  
  • Defined as angular displacement >11° or vertebral body translation >3.5mm
• Early surgery is recommended 2 situations:
  
  • Overt spinal instability with acute dislocation
  • Progressive neurological deficit

Question 184

What are risk factors for dural tear in spine surgery?

[JAAOS 2010;18:537-545]

Answer 184

1. OPLL (greatest risk factor for cervical spine surgery)
2. Revision surgery
3. Surgeon inexperience
4. Age

• Due to:
  
  • Narrowing of the spinal canal
  • Thicker ligamentum flavum
  • Osteophyte formation
  • Redundant dura due to shortening of the spine

Question 185

What are the complications of persistent dural tears?

[JAAOS 2010;18:537-545]

Answer 185

1. Spinocutaneous fistula
2. Pseudocyst
3. Meningitis
4. Nerve root entrapment
5. Cranial nerve palsy
6. Mass effect
7. Wound healing complications and infections

Question 186

What are intraop signs of dural tears?

[JAAOS 2010;18:537-545]

Answer 186

1. Direct visualization of the tear
2. Pulsatile clear fluid from a dry field
3. Pulsatile light swirl of fluid in a bloody field
4. Repeat bleeding in areas previously controlled

Question 187

What are the general principles of management of intraop dural tears?

[JAAOS 2010;18:537-545]

Answer 187

1. Ensure proper visualization

• Dry field
• Adequate hemostasis
• Loupes or microscope

2. Primary repair when possible

• Augment as necessary
  
  • Fat grafts, fibrin glue, collagen matrix, hydrogels
• Dural grafts when primary closure not possible
  
  • Fascia lata, lumbodorsal fascia

3. Test the repair for watertight closure

• Deflated dura should inflate in pulsatile fashion
• Test repair with Valsalva
  
  • Duration of 15-20 sec, supine posture, and 40 mmHg intrathoracic pressure [Can J Anesth (2018) 65: 578.]

4. Tight fascial and wound closure in layers
5. Bedrest until symptoms of CSF leak resolve

• Cervical durotomy – position patient upright
• Lumbar durotomy – position patient supine
• Symptoms managed with opiods, NSAIDs, antiemetics, caffeine

Question 188

What are signs of persistent CSF leaks postoperative?

[JAAOS 2010;18:537-545]

Answer 188

• Positional headache
• Nausea
• Photophobia
• CSF leak from wound or subfascial drain

Question 189

What test is available to assess for CSF leak?

[JAAOS 2010;18:537-545]

Answer 189

B-2 transferrin assay

Question 190

What is the “cone of economy” (in context of spinal deformity)?

[JAAOS 2009;17:378-388]

Answer 190

1. Narrow range of posture positioning in which the body can remain balanced without external support
2. Most persons with symptomatic sagittal plane deformity present with alignment at the periphery of this cone

Question 191

What is normal spinal alignment?

[JAAOS 2009;17:378-388]

Answer 191

1. Thoracic kyphosis = 10-40°
   * Measured via Cobb method from superior end plate of T2 to inferior endplate of T12
2. Lumbar lordosis = 40-60°

• Measured via Cobb method from superior endplate of T12 to superior endplate of S1
• Should be 30° more than the thoracic kyphosis

3. C7 plumb line = pass within a few millimeters of the posterior-superior corner of S1

• Vertical line dropped from center of C7 vertebral body
  
  • If line falls posterior = negative sagittal balance
  • If line falls anterior = positive sagittal balance
• Abnormal = >2.5cm anterior or posterior to posterior-superior corner of S1
  4. Pelvic incidence (PI)
• Angle formed between the line perpendicular to the sacral endplate at its midpoint and a line from this midpoint to the center of the femoral head
• PI = SS+PT

5. Sacral slope (SS)
   * Angle formed between line parallel to the superior endplate of S1 and a horizontal line extending from the anterior-inferior corner of that endplate
6. Pelvic tilt (PT)
   * Angle formed between line from the midpoint of the superior sacral endplate and the center of the femoral head and a vertical line extending from the center of the femoral head

Question 192

What are the compensatory mechanisms for loss of lumbar lordosis?

[JAAOS 2009;17:378-388]

Answer 192

1. Hip hyperextension
2. Knee flexion

Question 193

What imaging is required for evaluation of sagittal deformity?

[JAAOS 2009;17:378-388]

Answer 193

1. Full length 36 inch AP and lateral radiographs
2. Full length lateral flexion and extension radiographs as well as hyperextension films with a bolster placed at apex of deformity to assess flexibility of deformity

Question 194

What are the causes of sagittal deformity of the spine?

[JAAOS 2009;17:378-388]

Answer 194

1. Multilevel degenerative disc disease
2. Iatrogenic

• Flat back syndrome
  
  • Due to distraction instrumentation posteriorly or compressive anterior instrumentation

3. Osteoporosis
4. Ankylosing spondylitis

Question 195

What are the indications for surgery in the management of sagittal spinal imbalance?

[JAAOS 2009;17:378-388]

Answer 195

1. Failure of nonoperative treatment
2. Documented curve progression
3. Significant cosmetic deformity that is unacceptable for the patient
4. Back pain
5. Radicular symptoms
6. Functional deficit resulting from the deformity

Question 196

What posterior column shortening procedures can be used to restore sagittal balance in the presence of a fixed deformity?

[JAAOS 2009;17:378-388]

Answer 196

1. Smith-Peterson Osteotomy

• Posterior column is shortened and anterior column is lengthened
  
  • Requires a mobile disc or osteotomized anterior fusion mass
• The osteotomy hinges on the posterior aspect of the disc
• Posterior pedicle screw instrumentation is required to maintain closure of the osteotomy

2. Pedicle Subtraction Osteotomy

• Posterior column is shortened without lengthening the anterior column
• The osteotomy hinges through the anterior cortex
• Posterior pedicle screw instrumentation is required
  
  • At least 3 levels above and below

3. Vertebral Column Resection

• One or more vertebral segments is removed
  
  • Includes posterior elements, pedicles and entire vertebral body as well as disc above and below
  • Anterior and posterior reconstruction required
    
    • Anterior cage with posterior pedicle screw instrumentation

Question 197

How much correction can be achieved with a SPO vs. PSO?

[JAAOS 2009;17:378-388]

Answer 197

1. SPO

• 10° of lordosis (per level)
• If patient requires 10-20° of lordosis or 4-7cm of correction of the plumb line – perform limited number of SPO rather than one PSO

2. PSO

• One PSO = Two SPO
  
  • Above and below a pair of pedicles
• ~35° (30-40^o) of lumbar lordosis and 25° of thoracic kyphosis can be achieved with PSO

Question 198

What are the indications for PSO?

[JAAOS 2009;17:378-388]

Answer 198

1. Sagittal imbalance >10cm
2. Sharp, angular kyphosis
3. Circumferential fusion along multiple segments

Question 199

What are indications for VCR?

[JAAOS 2009;17:378-388]

Answer 199

• Congenital kyphosis
• Severe sagittal plane deformity plus coronal plane deformity
• Spondyloptosis
• Resectable spinal tumor

Question 200

What are risk factors for pseudoarthrosis following sagittal plane corrective surgery?

[JAAOS 2009;17:378-388]

Answer 200

• Greater patient age (>55 years)
• Longer fusions (>12 vertebrae)
• Thoracolumbar kyphosis (>20°)
• Osteoarthritis of the hip joint
• Positive sagittal balance ≥5 cm at 8 weeks postoperatively
• Incomplete sacropelvic fixation

Question 201

What are the most important factors for a successful outcome following sagittal plane deformity correction?

Answer 201

1. Fusion
2. Reduction of sagittal deformity
3. Restoring lumbar lordosis

Question 202

What is the most common site of metastasis in the skeletal system?

[JAAOS 2015;23:38-46]

Answer 202

Spine

• Thoracic > lumbar > cervical

Question 203

What is the most common mode of metastasis to the spine?

[JAAOS 2015;23:38-46]

Answer 203

Hematogenous

• Via the arterial supply and the valveless venous complex (Batson plexus)

Question 204

What scoring system can help predict prognosis and guide treatment decisions in metastatic spine disease?

[JAAOS 2015;23:38-46]

Answer 204

Modified Tokuhashi scoring system

• 6 components
  
  • Karnofsky performance status
  • Number of extraspinal metastases foci
  • Number of metastases in the vertebral body
  • Metastases to the major internal organs
  • Primary site of cancer
  • Palsy (neurological status)
• Score:
  
  • 0-8 = life expectancy ≤ 6 months
    
    • Conservative treatment versus palliative
  • 9-11 = life expectancy ≥ 6 months
    
    • Palliative surgery
  • 12-15 = life expectancy ≥1 year
    
    • Excisional surgery

Question 205

What classification system can predict spinal instability in spine tumors?

[JAAOS 2015;23:38-46]

Answer 205

SINS (Spinal Instability Neoplastic Score)

• 6 components
  
  • Location
  • Pain
  • Bone lesion
  • Radiographic spinal alignment
  • Vertebral body collapse
  • Posterolateral involvement of spinal elements
• Score:
  
  • 0-6 = stable
  • 7-12 = impending instability
  • 13-18 = unstable

Question 206

What are the indications for nonoperative and operative interventions in metastatic spine disease?

[JAAOS 2015;23:38-46]

Answer 206

1. Nonoperative
   * Radiosensitive and chemosensitive tumors in neurologically intact patients
2. Operative

• Spinal instability
• Neurological deficit requiring surgical decompression
• Rapid deterioration in function
• Intractable mechanical pain
• Need for histological diagnosis

Question 207

What is the general operative management of cervical metastases?

[JAAOS 2015;23:38-46][JAAOS 2011;19:37-48]

Answer 207

1. Preoperative embolization of RCC, thyroid and hepatocellular cancers
2. Intralesional resection followed by stabilization

• C1/2
  
  • Posterior instrumentation with occipital plating
  • +/- transpedicular corpectomy and anterior stabilization
• Subaxial cervical spine
  
  • Anterior corpectomy with anterior and posterior instrumentation and fusion
• Cervicothoracic
  
  • Corpectomy (low anterior or transpedicular) with anterior and posterior instrumentation and fusion
• Thoracolumbar
  
  • Anterior decompression and stabilization with transpedicular approach + posterior instrumentation
    
    3. Conventional radiotherapy
• 3-4 weeks following surgery

Question 208

What is the NOMS framework?

[The Oncologist 2013;18:744 –751]

Answer 208

1. A decision making framework for making treatment decisions in patients with spinal metastasis
2. Considers 4 factors:

• Neurologic
  
  • Degree of spinal cord compromise
    
    • Radiographic assessment (degree of epidural spinal cord compression)
• Oncologic
  • Radiosensitive vs. radioresistant tumors
• Mechanical (instability)
  
  • Mechanical pain (movement related)
  • SINS score
• Systemic
  
  • Ability of patient to tolerate intervention
    
    3. Determines treatment options based on above factors including:
• Conventional external beam radiation
• Stereotactic radiosurgery
• Decompression/separation surgery
• Stabilization surgery

Question 209

What are the radiosensitive and radioresistant tumors?

Answer 209

Radiosensitive = “NOMS LBP”

• Neuroendocrine (carcinoid/pancreatic)
• Ovarian
• Myeloma
• Seminoma
• Lymphoma
• Breast
• Prostate

Radioresistant = “SMRT Cancers”

• Sarcoma
• Melanoma
• Renal
• Thyroid
• Colorectal

Question 210

Osteoid Osteoma of the Spine

Location

Presentation

Imaging

Treatment

Answer 210

1. Location = primarily posterior elements
2. Presentation

• Back pain, often night pain, relieved with NSAIDs
• Avg age is 19
• Most common cause of painful scoliosis in adolescents
  
  • Lesion typically on concavity of curve

3. Imaging

• Radiographs – area of sclerosis
• CT – better defines lesion
• MRI – better for preop planning to assess proximity to neural structures

4. Treatment

• Nonoperative – first line (NSAIDs)
• Radiofrequency thermal ablation – failed nonop
• En bloc resection – indicated for:
  
  • Fixed spinal deformity
  • Neurological compression
  • RFA unsafe

Question 211

Osteoblastoma of the Spine

Location

Presentation

Imaging

Treatment

Answer 211

1. Location = posterior elements
2. Presentation

• Dull back pain, possible neural compression
• Differs from osteoid osteoma in that not worse at night, does not respond to NSAIDs, less frequently associated with scoliosis

3. Imaging

• Radiographs
  
  • Compared to osteoid osteoma:
    
    • Multiple calcifications
    • Aggressive bony destruction
    • Infiltration into surrounding tissues
• CT – better defines lesion and location
• MRI – better assess neural and soft tissue involvement

4. Treatment
   * En bloc resection +/- fusion if instability created

Question 212

Aneurysmal Bone Cyst of the Spine

Location

Presentation

Imaging

Treatment

Answer 212

1. Location = posterior elements
2. Presentation

• Slow, gradual onset of pain
• Possible palpable mass and spinal deformity

3. Imaging

• Radiographs – lytic, expansile
• CT – characteristic septate pattern with cortical expansion and erosion
• MRI – better for neural and soft tissue involvement
  • Fluid-fluid levels on T2
    
    4. Treatment
• Marginal resection

Question 213

Osteochondroma of the Spine

Location

Presentation

Imaging

Treatment

Answer 213

1. Location = posterior elements of the spine
2. Presentation = pain and/or swelling
3. Imaging

• Radiographs – difficult to interpret, spinal deformity
• CT – determines connection of medullary cavity of lesion with vertebra
• MRI – determines thickness of cartilage cap

4. Treatment
   * Complete resection +/- fusion for instability if lesion symptomatic

Question 214

Neurofibroma of the Spine

Location

Presentation

Imaging

Treatment

Answer 214

1. Location = cervical and thoracic most commonly
2. Presentation = pain, scoliosis, nerve root compression
3. Imaging

• Radiographs = sharp angular scoliosis
  
  • Erosion or scalloping
  • Rib thinning
• CT = vertebral destruction
• MRI = surgical planning

4. Treatment

• En bloc resection of symptomatic lesions
• Treat scoliosis with anterior and posterior fusions

Question 215

Giant Cell Tumor of the Spine

Location

Presentation

Imaging

Treatment

Answer 215

1. Location = vertebral body
2. Presentation = back pain, spinal cord compression
3. Imaging

• Radiographs = expansile, lytic lesion
  
  • Compression fractures
• CT and MRI = define bone, soft tissue and neural involvement
• CT chest = pulmonary mets

4. Treatment

• En bloc resection
• Resection with adjuvants if incomplete resection
  
  • Sacrum and cervical spine
• Denosumab

Question 216

Eosinophilic Granuloma of the Spine

Location

Presentation

Imaging

Treatment

Answer 216

1. Location = vertebral body
2. Presentation = back pain, restricted ROM

• Deformity
• Age usually <10

3. Imaging

• Radiographs = lytic lesion of vertebral body
  
  • 40% present as vertebra plana
• Skeletal survey or bone scan
• MRI = confirms diagnosis and associated soft tissue mass

4. Treatment

• Nonoperative
  
  • Usually spontaneously resolves
  • Consider analgesia, orthoses, intralesional CT guided steroid
  • Chemo if systemic disease

Question 217

Hemangioma of the Spine

Location

Presentation

Imaging

Treatment

Answer 217

1. Location = vertebral body
2. Presentation = asymptomatic, incidental
3. Imaging

• Radiographs – corduroy pattern with vertical striations
• CT – punctuate sclerotic foci
• MRI – hyperintense on T1 and T2
  4. Treatment
• If symptomatic consider:
  
  • Radiation
  • Intralesional ethanol
  • Embolization
  • Vertebroplasty/kyphoplasty

Question 218

What are the landmarks for vertebral levels in the Anterior Cervical Approach (Smith-Robinson)

[Hoppenfeld, 2017]

Answer 218

1. Hard palate – arch of the atlas
2. Lower border of the mandible – C2-C3
3. Hyoid – C3
4. Thyroid cartilage – C4-C5
5. Cricoid cartilage – C6
6. Carotid tubercle – C6 (anterior tubercle on C6 TP)

Question 219

What are the steps in the anterior cervical approach?

[Hoppenfeld, 2017]

Answer 219

1. Transverse skin incision at appropriate level
2. Incise fascia in line with skin incision over platysma
3. Split platysma longitudinally bluntly
4. Incise investing layer of deep cervical fascia medial to anterior border of SCM
5. Retract SCM lateral and strap muscle medial
6. Palpate the carotid artery
7. Incise the pretracheal fascia medial to the carotid sheath
8. Retract the carotid sheath lateral and the trachea and esophagus medial
   * Proximally, the superior and inferior thyroid arteries pass from the carotid sheath to the midline, may require ligation
9. Incise the prevertebral fascia, longus colli and ALL longitudinally in the midline
   * Avoid the sympathetic chain laterally over the TPs
10. Elevate subperiosteally and retract muscle laterally to expose vertebral bodies and disc
11. Identify the level with a needle in the disc space with a lateral fluoro view

Question 220

How many levels can be addressed with a transverse incision in the anterior approach to the cervical spine?

[Drew]

Answer 220

2 level discectomy or 1 level corpectomy

Question 221

What are 5 structures that cross horizontally in an anterior approach to the cervical spine?

Answer 221

1. Superior thyroid artery
2. Inferior thyroid artery
3. Ansa cervicalis (loop of nerves in cervical plexus)
4. Hypoglossal nerve
5. Omohyoid muscle

Question 222

What structures are at risk/complications with the anterior cervical approach?

[Orthobullets]

Answer 222

1. Recurrent laryngeal nerve (right > left)
2. Sympathetic chain and stellate ganglion (C6)
3. Carotid sheath contents
4. Esophagus
5. Trachea
6. Postoperative retropharyngeal hematoma

• Presents with respiratory difficulties
• Requires emergent decompression

Question 223

In revision situation in the setting of a previous anterior cervical approach which approach should be used for the revision?

[Drew]

Answer 223

1 .ENT consult to assess for occult recurrent laryngeal nerve injury via laryngoscopy

• If no injury = opposite side
• If injury = same side

2. Bilateral recurrent laryngeal nerve injury results in abductor vocal cord paralysis and potential airway obstruction

Question 224

What are the steps in an occipitocervical fusion?

Positioning

Approach

Fixation

Fusion

Answer 224

1.Positioning

• Prone with Mayfield head holder
• Goal of neutral head position (flexion/extension)

2. Approach
   * Posterior from EOP to lower planned instrumented vertebra
3. Fixation

• Occipital plate
  
  • Placed just below the level of the EOP
  • Bone is thickest in the midline and purchase is greatest
  • Bicortical or unicortical screws can be used (bicortical biomechanically stronger)
  • If poor midline purchase achieved, additional fixation can be achieved laterally
• Cervical fixation
  
  • C1 lateral mass
    
    • Often omitted depending on pathology
  • C2 pars/pedicle
  • Lower cervical lateral mass (depending on pathology)
• Rod contoured and connected to plate and screws
  4. Fusion preparation
• Decortication to bleeding bone of the arch of C1, posterior occiput, C2, and other fusion levels is completed using a high-speed burr
• Bone grafting is performed using local bone and autologous iliac crest

Question 225

What are the steps for a C1 Lateral Mass Screw?

Answer 225

1. Dissection is inferior to the posterior arch of C1
2. C2 nerve root is retracted caudally
3. Start point is at the inferior aspect of the posterior lateral mass in the midline
4. Starting hole is created with a 2.5mm burr then 2.5mm drill by handpower angled ~10° medial

Question 226

What are the steps for a C2 Pars/Pedicle Screw?

Answer 226

1. C2 Pars Screw [Operative Techniques in Spine Surgery; Wiesel 2016]
   * The starting point of the C2 pars screw is 2 mm superior and lateral to the inferior C2-C3 articulation
   * It is placed in a craniocaudal trajectory similar to the transarticular screw but does not need to be aimed as much cephalad
   * It is aimed 20 to 25 degrees medial
2. C2 pedicle screw [Operative Techniques in Spine Surgery; Wiesel 2016]

• The starting point of the C2 pedicle is in the midline of the C2-C3 facet joint, 3 to 5 mm cranial to the C2-C3 articulation
• The trajectory is 25 degrees of medial convergence and is aimed 25 degrees cephalad

Question 227

What are the steps for a Subaxial Lateral Mass screw?

Answer 227

1. The quadrilateral posterior surface of the lateral mass is clearly exposed
2. Roy Camille

• Start point center of the lateral mass
• Directed perpendicular to the posterior lateral mass and 10° lateral

3. Magerl

• Start point inferior and medial
• Directed 30° lateral and 15° cephalad
• This trajectory aims to exit lateral to the vertebral artery and superior to the exiting nerve root

Question 228

What are the steps for an Odontoid Screw?

Answer 228

1. Anaesthesia
   * Awake fiberoptic intubation
2. Positioning/setup

• Supine, bump under shoulders, bite block, halter traction
• Biplanar fluoroscopy

3. Approach
   * Anterior approach starting at level of C5/C6
4. Fixation

• An entry site on the anterior inferior edge of C2 is chosen and confirmed on AP and lateral fluoroscopy
  
  • One midline site for one screw
  • Two paramedian sites about 2 to 3 mm from the midline for two screws
• K-wire is placed into start point followed by inner and outer drill guide tubes over the K-wire
• Under biplanar fluoro the drill is passed through the C2 body, into the odontoid and penetrates the apical cortex
• Depth is measured off calibrated drill
• Inner guide is removed and tap is inserted
• A 4mm partially threaded lag screw is inserted and should engage the apical cortex
• Traction should be removed as screw is tightened
• A second screw can be inserted by the same technique if anatomy allows
  
  • Confirm stability under fluoro with flexion and extension of the head

Question 229

What are the steps to do an ACDF?

Answer 229

1. Supine
2. Approach
   * Standard Smith-Robinson at planned level
3. Confirm levels with fluoro
4. Perform discectomy from uncus to uncus as far posterior as the PLL

• Generally remove PLL to visualize cord
• The uncinates define the safe zone for the vertebral artery

5. Prepare endplates

• Thoroughly denuded of cartilage and decorticated
• Alternating use of the high-speed burr, curettes, and the pituitary rongeur (or rasp)

6. Perform anterior foraminotomy

• Alternating between microcurettes or a Kerrison and the burr, the foramen can be gently and progressively carved out laterally
• Foraminotomy is complete when a micro nerve hook or curette can easily be passed into the foramen anterior to the exiting root without resistance

7. Graft sizing and placement

• The final height of the graft can be determined after endplate preparation with sizers that accompany commercial grafts
• Prefer to use commercially prepared cortical allografts for ACDF

8. Select and fix anterior plate

• Once the graft has been placed, the size of the plate is then determined
• Optimal plate length is one that allows for the screws to be immediately adjacent to the endplates

Question 230

What are the steps to do an ACCF?

Answer 230

1. Supine
2. Approach
   * Standard Smith-Robinson at planned level
3. Confirm levels with fluoro
4. Perform discectomy from uncus to uncus as far posterior as the PLL (generally remove PLL to visualize cord)

• The uncinates define the safe zone for the vertebral artery
• Perform above and below level of planned corpectomy, corpectomy is completed inline

5. Endplate preparation
   * The endplates above and below the corpectomy should be thoroughly decorticated and denuded of all cartilaginous material
6. Graft selection
   * Allograft fibula or cages filled with local autograft remain popular choices
   
   • Autograft available from corpectomy
     * Autograft options include structural iliac crest or autologous fibula
7. Graft inserted and anterior plating