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Spine
General Knowledge
Intervertebral Disk
| 1. | What two changes occur in the vascular supply to the disk with aging? | 1. | Vessels begin disappearing after the age of 10 years Endplates ossify |
| 2. | What is the source of nutrients to the disk? | 2. | Diffusion through endplates |
| 3. | What two external factors decrease endplate permeability? | 3. | Smoking Vibration |
| 4. | What factors increase permeability? | 4. | Exercise |
| 5. | How does aging affect the disk’s collagen content? | 5. | Decreased collagen content |
| 6. | How does aging affect the disk’s fibril diameter? | 6. | Increased fibril diameter and variability |
| 7. | How does aging affect the disk’s noncollagenous protein? | 7. | Increased noncollagenous protein |
| 8. | How does aging affect the disk’s pH? | 8. | Decreased pH |
| 9. | Magnetic resonance imaging (MRI): what are the rates of false-positive (asymptomatic) findings for patients <40 years old, >40 years old, and >60 years old? | 9. | <40 years old: 25% >40 years old: 60% >60 years old: 90% |
Biomechanics
| 10. | What is the function of the anterior column and the posterior column? | 10. | Anterior column: support Posterior column: tension band |
| 11. | An anteriorly placed graft is loaded in which two directions and unloaded in which two directions? | 11. | Loaded in compression, flexion Unloaded in extension, traction |
| 12. | What effect does an anterior plate have on the axis of rotation? | 12. | Moves axis of rotation anteriorly |
| 13. | … on the graft in extension? | 13. | Loads graft in extension |
| 14. | … on the graft in flexion? | 14. | Unloads graft in flexion |
| 15. | What is the definition of terminal bending? | 15. | Moments at ends of a long construct |
| 16. | How can terminal bending be prevented? | 16. | With intermediate fixation points |
| 17. | How much lumbar torsional resistance is provided by facets, disk, and ligaments? | 17. | Facets: 40% Disk: 40% Ligaments: 20% |
| 18. | After a flexion-distraction injury, what is the status of the anterior longitudinal ligament (ALL) and the posterior longitudinal ligament (PLL disrupted)? | 18. | ALL intact PLL out |
| 19. | Which approach is biomechanically superior in this situation? | 19. | Posteriorly based fusions are superior to anteriorly based fusions |
Anatomy
| 20. | How are the cervical spine facets oriented in the sagittal plane? | 20. | Cervical: 45 degrees in the sagittal plane |
| 21. | Compare with thoracic and lumbar facet orientation. | 21. | Thoracic: vertical in sagittal plane (essentially in the coronal plane) Lumbar: sagittally aligned |
| 22. | The sinuvertebral nerve originates from which structure? | 22. | Sympathetic chain |
| 23. | What structures and elements does it supply? | 23. | Supplies structures within the spinal canal Supplies posterior elements |
| 24. | What other neurologic structure also innervates the posterior elements? | 24. | Primary dorsal ramus also contributes to innervation |
| 25. | Pattern of innervation example: the L3 nerve root innervates which facets? | 25. | L3 innervates the L3-4 facets |
| 26. | At which level is the pedicle diameter the smallest? | 26. | T5 |
| 27. | What is the furcal nerve? What is its clinical significance? | 27. | Peripheral nerve often originating from L4 nerve root Can result in variable L4 dermatomal distribution |
Infections and Malignancies
| 28. | Infection versus malignancy: which generally destroys the disk? | 28. | Infection destroys the disk early Malignancy usually skips the disk |
| 29. | Compare with the effect of tuberculosis on the disk. | 29. | Tb skips the disk early, but may involve the disk late |
| 30. | What are the earliest plain radiographic findings of infection? | 30. | Disk space narrowing at 7 to 10 days |
| 31. | What is the natural history of disk space infection? | 31. | Spontaneous arthrodesis |
| 32. | What are the two usual treatment for osteomyelitis? | 32. | Intravenous antibiotics Brace |
| 33. | What are the three operative indications? | 33. | Failure of conservative treatment Progressive neurologic deficit Instability (e.g., fracture) |
| 34. | What are the two negative prognostic factors for infection? | 34. | Increased age More cephalad involvement |
| 35. | What is the MRI appearance of malignancy on T1 and T2 sequences? | 35. | T1: low T2: high |
| 36. | What three tumors classically involve the posterior elements? | 36. | ABC (aneurysmal bone cyst) Osteoid osteoma/osteoblastoma Osteochondroma |
Cervical Spine
General Knowledge
| 37. | Cervical spondylosis is most common at which two levels? | 37. | C5–6 C6–7 |
| 38. | Degenerative cervical spondylolisthesis is most common at which two levels? | 38. | C3–4 C4–5 |
| 39. | What are the most common levels of cervical trauma in the young? | 39. | C4 to C7 |
| 40. | What are the most common levels of cervical trauma in the elderly? | 40. | C1, C2 |
| 41. | What is Spurling’s test? What is its clinical significance? | 41. | Rotation, lateral bend, vertical compression of neck To identify cervical radiculopathy |
| 42. | What arm position classically relieves the symptoms of cervical radiculopathy? | 42. | Symptoms improve with the arm overhead |
| 43. | What is the ideal therapy regimen for radiculopathy? What percentage of patients improve? | 43. | Isometric exercises 75% improve |
| 44. | What is the finger escape test? What is its clinical significance? | 44. | Spontaneous small finger abduction secondary to weak intrinsics Indicative of myelopathy |
| 45. | In what two ways does cervical myelopathy generally progress? | 45. | Long quiescent periods Stepwise deterioration |
| 46. | What is Lhermittes sign? | 46. | Lightning sensation in arms with neck flexion |
| 47. | What does the C4 nerve root innervate? | 47. | Scapular muscles |
| 48. | What three roots correspond to reflexes within the upper extremities? | 48. | C5: biceps C6: brachioradialis C7: triceps |
| 49. | What is the significance of a hypoactive brachioradialis (BR) reflex? | 49. | Hypoactive BR reflex = lower motor neuron involvement (radiculopathy) |
| 50. | What is the significance of an inverted radial reflex (IRR)? | 50. | IRR: hypoactive BR reflex + concurrent finger flexion Upper motor neuron involvement (myelopathy) |
| 51. | What is Power’s ratio used for? What is its critical value? | 51. | Anterior atlanto-occipital (AO) dissociation BC/AO >1: abnormal |
| 52. | What is the definition of Torg’s ratio? What is its clinical significance? | 52. | Canal width divided by vertebral body width For the identification of congenital stenosis |
| 53. | Compare normal and critical values of Torg’s ratio? | 53. | Normal is 1.0 Critical value is <0.8 |
| 54. | What three arteries contribute to the spinal cord blood supply? | 54. | Anterior spinal artery (two thirds from vertebral artery) Two dorsal spinal arteries (one third from posterior inferior cerebellar artery [PICA]) |
| 55. | The watershed area of the cervical spinal cord is at which levels? | 55. | C5 to C7 |
| 56. | What are the two classic symptoms of calcified disk disease in a child? | 56. | Neck pain Torticollis |
| 57. | What is the treatment of choice? | 57. | Observation |
| 58. | What is the prognosis? | 58. | Likely to go on to spontaneous resolution |
Radiographic Evaluation
| 59. | What is the most common reason for a missed cervical spine injury? | 59. | Inadequate visualization of involved levels |
| 60. | At which two levels are injuries most often missed? | 60. | Cervicothoracic junction Atlantooccipital junction |
| 61. | In an awake, alert patient without neck symptoms, what is required for C-spine clearance? | 61. | Clinical exam only No films required |
| 62. | Compare with a patient with neck pain or neurologic deficits. | 62. | Three views of cervical spine with or without computed tomography (CT) |
| 63. | What is the normal atlantodens interval (ADI) in adults and in children? | 63. | Adults: <3.5 mm Children: <4.0 mm |
| 64. | What are the normal and unstable values of a lateral mass overhang on an open mouth view? What is its clinical significance? | 64. | Normal = 0 mm overhang Unstable = >6.9 mm Relevant for Jefferson fracture |
| 65. | What are the two White/Panjabi instability criteria for subaxial C-spine on flexion-extension films? | 65. | Sagittal translation >3.5 mm or 20% Sagittal rotation >20 degrees |
| 66. | … on resting films? | 66. | Sagittal translation >3.5 mm or 20% Relative sagittal angulation >11 degrees |
| 67. | On a pediatric lateral C-spine film, what is the normal C2 retropharyngeal space? Retrotracheal space? | 67. | <6 mm retropharyngeal <14 mm retrotracheal |
| 68. | What level is most commonly involved in pseudosubluxation? What is its significance? | 68. | C2 on C3 May be a normal finding in children |
| 69. | What is the key radiographic landmark when evaluating for pseudosubluxation? | 69. | Check spinolaminar line |
Surgical Anatomy: Atlas/Axis
| 70. | What percentage of space is occupied by the cord? What makes up the remainder? | 70. | 33% cord 33% dens 33% empty (cerebrospinal fluid [CSF], fat) Steele’s rule of thirds |
| 71. | What percentage of head rotation occurs at C1–2? | 71. | 50% |
| 72. | The arterial arcade around the odontoid process is supplied by which two vessels? | 72. | Vertebral artery External carotid artery |
Surgical Anatomy: Anterior Approach
| 73. | What are the anterior landmarks for levels C3, C4, C5, and C6? | 73. | C3: hyoid C4, C5: thyroid C6: cricoid |
| 74. | The carotid tubercle is at which level? | 74. | C6 |
| 75. | What is the C7-T1 landmark? | 75. | Sternal notch |
| 76. | With an anterior cervical discectomy and fusion (ACDF), what is the first muscle encountered? What is the innervation? | 76. | Platysma Facial nerve (cranial nerve [CN] VII) |
| 77. | With an ACDF, the interval for dissection lies between what two anatomical areas? | 77. | Carotid sheath Trachea |
| 78. | What are the four contents of the carotid sheath? | 78. | Internal carotid artery (ICA) Common carotid artery (CCA) Internal jugular vein (IJV) CN X (vagus) |
| 79. | What artery lies at the proximal extent of exposure? What is to be done with it? | 79. | Superior thyroid artery It may be sacrificed |
| 80. | Where is the omohyoid muscle encountered? How should it be retracted? | 80. | Encountered on the medial side of the carotid sheath within pretracheal tissue Retract medially, may divide if necessary |
| 81. | What are the origin, insertion, innervation, and function of the omohyoid muscle? | 81. | Origin: scapula Insertion: hyoid bone Innervation: ansa cervicalis (C1 to C3) Function: depress hyoid bone and larynx |
| 82. | More proximal approaches put which nerve at risk? What is its clinical significance? | 82. | Superior laryngeal nerve Responsible for high note phonation |
| 83. | Classically, there is increased recurrent laryngeal nerve risk with which approach? Why? | 83. | Right-sided approach More variable on right (left goes around the aortic arch) |
| 84. | In which interval does the recurrent laryngeal nerve ascend? | 84. | Tracheoesophageal interval |
| 85. | What do recent data indicate about the side of approach and recurrent laryngeal nerve injury rate? | 85. | Right- and left-sided approaches have equivalent injury rates |
| 86. | What approach places the thoracic duct at risk? What is the treatment if the duct is injured? | 86. | Left-sided approach If injured, ligate proximally and distally |
| 87. | Horner’s syndrome is a risk at which level? Why? | 87. | C7-T1 Because of the inferior cervical ganglion |
| 88. | Vocal cord paralysis may also occur by which other mechanism? How can this be prevented? | 88. | Compression of larynx between retractor and endotracheal (ET) tube Prevention: deflate ET tube after retractors are placed, allow tube to re-centralize |
| 89. | What does “SLAC Line” refer to? | 89. | The five capital letters in the acronym refer to the following structures (anterior to posterior): Sympathetic chain Longus coli Artery (vertebral) Cervical nerve root Lateral mass |
| 90. | What is the preferred proximal cervical approach for a singer? | 90. | Anterior retropharyngeal approach |
Surgical Anatomy: Posterior Approach
| 91. | What is the key posterior triangle for the posterior approach? | 91. | Suboccipital triangle |
| 92. | What two structures does this triangle contain? | 92. | Vertebral artery C1 nerve |
| 93. | What is the most superficial structure? | 93. | Greater occipital nerve (C2) |
| 94. | What is the size of the safe zone relative to the C1 spinous process? | 94. | 1.5 to 2 cm lateral from C1 spinous process to vertebral artery |
| 95. | With a posterior approach, which way should the nerve root be retracted? | 95. | Elevate root superiorly |
| 96. | What nerve root is at the highest risk for traction injury? Why? | 96. | C5 at highest risk Straightest take-off |
| 97. | What is the best way to approach ossification of the posterior longitudinal ligament (OPLL)? What is the preferred surgical technique for decompression? | 97. | Posterior Laminoplasty |
| 98. | What preoperative sagittal plane requirement is necessary for laminoplasty success? | 98. | Cervical lordosis |
| 99. | What is the principal complication of laminoplasty? | 99. | Decreased cervical range of motion (ROM) by 50 to 62% |
| 100. | The lateral mass includes which two structures? | 100. | Pedicle Ipsilateral lamina |
Outcomes and Surgical Decision Making
| 101. | For a one-level ACDF, compare outcomes associated with allograft versus autograft use. | 101. | Equivalent outcomes |
| 102. | What two clinical conditions are the exceptions? | 102. | Multiple levels Smokers |
| 103. | In performing a multiple-level ACDF, what should one consider preoperatively? | 103. | Strut graft Plate Adjunct posterior fusion |
| 104. | For smokers, is allograft or autograft preferred for one level? What about for two levels? | 104. | One level: always autograft Two levels: autograft strut |
| 105. | A posterior approach should generally be included with anterior surgeries in excess of ________. | 105. | Two corpectomies |
| 106. | What are reported ACDF pseudarthrosis rates for one level? | 106. | 12% |
| 107. | What are reported ACDF pseudarthrosis rates for multiple levels? | 107. | 30% |
| 108. | What is the significance of the Hillibrand study? | 108. | 25% of ACDF patients required an additional procedure within 10 years for adjacent-level disease |
| 109. | What is the principal factor in determining adjacent-level degeneration? | 109. | Preoperative adjacent-level status |
| 110. | What is the treatment if the lateral femoral cutaneous nerve (LFCN) is cut with graft harvest? | 110. | Allow it to retract into the pelvis |
| 111. | What percentage of patients develop long-term pain at the graft site? | 111. | 25% |
| 112. | For the elderly patient, is an ACDF or a posterior approach generally better tolerated? | 112. | Posterior approach |
| 113. | Increased risk of dysphagia and respiratory compromise occur with which four factors? | 113. | Increased number of levels Increased operative time Increased blood loss More proximal level of surgery |
| 114. | What complication is unique to an posterior approach? | 114. | Air embolism |
| 115. | When performing a multilevel posterior laminectomy, what else should one do? Why? | 115. | Instrumented fusion To prevent postoperative kyphosis |
Rheumatoid Arthritis
| 116. | What is the order of relative frequency of the three rheumatoid-related disorders within the cervical spine? | 116. | 1: C1–2 instability |
| 2: basilar invagination | |||
| 3: subaxial subluxation |
Atlantoaxial Instability
| 117. | What are the criteria for atlantoaxial instability in the adult and in the child? | 117. | Adult: >3 mm motion Child: >4 mm motion |
| 118. | What is the significance if >7 mm motion is seen at C1–2? | 118. | Alar ligaments also disrupted Contraindication to elective orthopaedic surgery |
| 119. | A posterior atlanto-dens interval (PADI) smaller than ________ is an indication for surgery. | 119. | 14 mm |
| 120. | What are the expected surgical outcomes if PADI is 10 to 14 mm or <10 mm? | 120. | 10 to 14 mm: can expect neurologic improvement postoperatively <10 mm: stabilize; improvement unlikely |
| 121. | What is the critical PADI value in flexed position? | 121. | Surgery indicated if <6 mm in flexion |
| 122. | What are the two additional operative indications at C1–2? | 122. | >10 mm motion Myelopathy |
| 123. | What four surgical options are appropriate if C1–2 subluxation is reducible? | 123. | Gallie technique Brooks technique Transarticular screws Harms technique |
| 124. | What three surgical options are appropriate if subluxation is irreducible? What is the key step to all three? | 124. | Posterior decompression with occiput-C2 fusion Posterior decompression with C1–2 transarticular screws Harms technique Key step with all interventions: decompression! |
| 125. | What is the expected long-term consequence without surgery for instability? | 125. | On average, patients die within 8 years |
| 126. | What are the three criteria that indicate that surgery is less likely to be successful? What is the Ranawat category? | 126. | Objective weakness Upper motor neuron (UMN) signs Nonambulatory Ranawat IIIB |
| 127. | Upon which two factors is the Nurick classification of myelopathy based? | 127. | Gait Ambulatory function |
Basilar Invagination
| 128. | What anatomic line lies at the base of the foramen magnum? What is its clinical significance? | 128. | McRae’s line across the base of the foramen magnum Odontoid should always be below this line (if not, then invagination is present) |
| 129. | What is the most important operative indication for invagination? | 129. | Neurologic compromise |
Other indications include …
| 130. | … Migration in excess of? | 130. | >5 mm |
| 131. | … Cervicomedullary angle (CMA)? | 131. | <135 degrees |
| 132. | … Ranawat measurement? | 132. | <13 mm |
| 133. | … McRae’s line? | 133. | Odontoid proximal to McRae’s line |
| 134. | What two surgical options are appropriate for basilar invagination? | 134. | Occiput to C2 fusion Transoral odontoid resection |
| 135. | What are the only two current indications for a transoral approach? | 135. | Cranial nerve deficits (brainstem compromise) Solid posterior C1–2 fusion with persistent anterior cord compromise |
| 136. | What are the two classic symptoms of atlantoaxial arthritis? What is the treatment? | 136. | Headache Rotational pain Treatment: posterior C1–2 fusion |
Subaxial Subluxation
| 137. | What are the criteria for instability: (________ mm, ________ degrees)? | 137. | >3.5 mm or 20% translation >11 degrees (static film) >20 degrees (flexion-extension films) |
| 138. | Which gender is most commonly affected? What are the other three primary risk factors? | 138. | Male History steroid use RF+ Nodules |
| 139. | An increased risk of neurologic compromise exists with what two radiographic criteria? | 139. | Subluxation >4 mm Cervical height index >2 |
| 140. | What is the treatment of choice? | 140. | Posterior fusion and wiring |
Surgical Techniques
Fusion to Occiput
| 141. | Where is the skull thickest? | 141. | External occipital protuberance |
| 142. | What structures are at risk with screws? | 142. | Venous sinuses |
Comparison of Posterior Fusion Techniques
| 143. | What is the Gallie technique? | 143. | Spinous process wiring with midline graft |
| 144. | How much relative resistance does the Gallie provide versus flexion, extension, and rotation? | 144. | Good versus flexion Not good versus extension and rotation |
| 145. | Gallie should not be used in what situation? | 145. | Posteriorly displaced odontoid fracture |
| 146. | What is the Brooks technique? | 146. | Posterior wiring with bilateral grafts |
| 147. | How much relative resistance does the Brooks provide versus flexion, extension, and rotation? | 147. | Good versus flexion Better versus extension and rotation |
| 148. | With either the Gallie or Brooks, what must be applied postoperatively? | 148. | Halo vest |
| 149. | How effective are C1–2 transarticular screws against flexion, extension, and rotation? | 149. | Best versus flex, extension, and rotation |
| 150. | How can the vertebral artery be injured with a transarticular screw? | 150. | Screw too caudally directed |
| 151. | How can the occiput-C1 joint be injured? | 151. | Screw too cephalad |
| 152. | How can the hypoglossal nerve (CN XII) be injured? | 152. | Screw too long: too anterior to lateral mass |
| 153. | What are the two functions of the hypoglossal nerve? | 153. | Innervates muscles of tongue Contributes to strap muscle innervation via ansa cervicalis |
| 154. | If considering transarticular screws, which study must be obtained preoperatively? | 154. | Preoperative thin-cut CT scan |
| 155. | What percentage of patients have anatomy that precludes C1–2 screws? | 155. | 15% |
| 156. | If an iatrogenic injury to one vertebral artery occurs, what is the next step? | 156. | Sublaminar wires and graft (Gallie/ Brooks type) |
Vertebral Artery Injury
| 157. | Vertebral artery injury may be seen in association with trauma at what location? | 157. | Facet joint injury |
| 158. | How can it be injured intraoperatively? | 158. | Lateral bone removal with burr |
| 159. | If a vertebral artery stroke occurs, what is the name of the resultant syndrome? What are its four features? | 159. | Wallenberg syndrome Nystagmus Diplopia Dysphagia Pain, temperature loss |
| 160. | What is the path of the vertebral artery? Above C1? | 160. | C6 foramen transversarium to C1 Up and medially through arcuate foramen above C1 |
| 161. | What goes through the C7 foramen transversarium? | 161. | Accessory vein |
Thoracic Spine
General Knowledge
| 162. | Thoracic disk disease is most common at which levels? | 162. | T8 to T12 (especially T11-T12) |
| 163. | What is the classic mechanism of injury resulting in thoracic disk herniation (herniated nucleus pulposus [HNP])? | 163. | Torsion + bend |
| 164. | An HNP is most likely to be symptomatic in what two situations? | 164. | Scheuermann’s disease Calcified disk |
| 165. | What are the two indications for surgery? | 165. | Myelopathy Pain with magnetic resonance (MR) correlation |
| 166. | What are the two surgical options? | 166. | Open/thoracoscopic (anterior) Costotransversectomy (posterior) |
| 167. | What is the disadvantage of a posterior approach? | 167. | Decreased midline access from the posterior |
| 168. | If the HNP is calcified, there is an increased risk of what surgical complication? | 168. | Dural tear |
| 169. |
