AAOS & ABOS Spine MCQs Set 4: Trauma & Degenerative

Question 1

During the application of halo skeletal fixation, the most appropriate position for the placement of the anterior halo pins is approximately 1 cm above the superior orbital rim and

Explanation

Halo fixation is the most rigid form of cervical orthosis, but complications can arise from improper placement of the initial halo ring. A relatively safe zone for anterior pin placement is located 1 cm above the orbital rim and superior to the lateral two thirds of the orbit. This position avoids the supraorbital and supratrochlear nerves and arteries over the medial one third of the orbit. The more lateral positions in the temporal fossa have very thin bone and can interfere with the muscles of mastication. Posterior pin site locations are less critical; positioning on the posterolateral aspect of the skull, diagonal to the contralateral anterior pins, is generally desirable. Botte MJ, Byrne TP, Abrams RA, et al: Halo skeletal fixation: Techniques of application and prevention of complications. J Am Acad Orthop Surg 1996;4:44-53.

Question 2

Figures 28a and 28b show the sagittal and axial lumbar MRI scans of a 72-year-old man who reports dull aching back pain that spreads to his legs, calves, and buttocks. He has had the pain for several years and it is precipitated by standing and walking and relieved by sitting. His symptoms have been worsening over the past year and he notes that he is leaning forward while walking to help relieve his symptoms. He has had no treatment to date. What is his prognosis if he chooses to pursue nonsurgical management for this condition?

Explanation

The patient has lumbar spinal stenosis and the MRI scans reveal the pathology at L4-5, which is secondary to posterior disk bulging and hypertrophy and infolding of the ligamentum flavum, as well as degenerative facet arthrosis. The degree of spinal stenosis is moderate and his symptoms are positional in nature. Tadokoro and associates reported on a prospective study of 89 patients older than 70 years of age who underwent nonsurgical management for lumbar spinal stenosis. They found the prognosis to be relatively good with patients scoring at "excellent" or "good" for activities of daily living at final follow-up. However, they did note that patients with a complete block on myelography did not respond favorably to nonsurgical management. Amundsen and associates reported on a 10-year prospective study comparing surgical care to nonsurgical management. They concluded that, while the long-term results largely favored surgical treatment, more than half of the nonsurgically managed patients had a satisfactory outcome. They also concluded that a delay of surgery for some months did not worsen the prognosis. Therefore, their recommendation was for an initial primarily nonsurgical approach. Amundsen T, Weber H, Nordal HJ, et al: Lumbar spinal stenosis: Conservative or surgical management? A prospective 10-year study. Spine 2000;25:1424-1435. Hilibrand AS, Rand N: Degenerative lumbar stenosis: Diagnosis and management. J Am Acad Orthop Surg 1999;7:239-249.

Question 3

Which of the following vertebrae has the smallest pedicle isthmic width in a nondeformity patient?

Explanation

The smallest pedicle isthmic width is at L1, whereas T12 has the largest pedicle width in the upper lumbar and lower thoracic spine. Although smaller in diameter than T12, both T10 and T11 have larger pedicle widths than L1.

Question 4

Which of the following represents a contraindication for interspinous process decompression for the treatment of lumbar spinal stenosis?

Explanation

Kondrashov and associates noted stable good outcomes at 4 years in 14 of 18 patients treated with X-STOP interspinous process decompression as defined as an improvement over preoperative Oswestry scores of 15 points or more. Similar results were seen after 1 year in a European study by Siddiqui and associates. Exclusion and inclusion criteria for these studies varied somewhat, but cauda equina syndrome was the only exclusion criteria listed in both studies. All of the other choices did not represent exclusion criteria in either study. Kondrashov DG, Hannibal M, Hsu KY, et al: Interspinous process decompression with the X-STOP device for lumbar spinal stenosis: A 4-year follow-up study. J Spinal Disord Tech 2006;19:323-327.

Question 5

Which of the following statements about hoarseness due to vocal cord paralysis after anterior cervical diskectomy and fusion is most accurate?

Explanation

It has been traditionally taught that a left-sided approach to the anterior cervical spine is associated with a lower incidence of injury compared to the right-sided approach. This is due in part to the anatomic differences in the path the recurrent laryngeal nerve (RLN) takes on the right as compared to the left. Both nerves ascend in the tracheoesophageal groove after branching off the vagus nerve in the upper thorax. The left-sided RLN loops around the aortic arch and stays relatively medial as compared to the right-sided RLN which loops around the right subclavian artery and is somewhat more lateral at this point, and therefore is theoretically more vulnerable as it ascends toward the larynx before becoming protected in the tracheoesophageal groove. Furthermore, the variant of a nonrecurrent inferior laryngeal nerve branching directly off the vagus nerve at the level of the midcervical spine is much more common on the right than the left. Despite this reasoning, there has been no clinical evidence to suggest that laterality of approach for anterior cervical surgery makes any difference in the incidence of vocal cord paralysis. Furthermore, two recent studies have shown that the incidence of RLN injury and vocal cord paralysis is equal with either side of approach. Beutler WJ, Sweeney CA, Connolly PJ: Recurrent laryngeal nerve injury with anterior cervical spine surgery risk with laterality of surgical approach. Spine 2001;26:1337-1342.

Question 6

A 23-year-old man is involved in a motor vehicle accident. An AP radiograph is shown in Figure 29a, and axial and sagittal CT scans are shown in Figures 29b and 29c. Neurologic examination shows 1/5 strength of his quadriceps and iliopsoas on the right, with 1/5 quadriceps function on the left. Definitive treatment of his injury should consist of

Explanation

The imaging studies show a fracture-dislocation. Surgical treatment of this injury consists of a decompression reduction, stabilization, and fusion. A posterolateral decompression can also be performed as necessary. An isolated anterior procedure in this type of injury is contraindicated. The anterior longitudinal ligament is most likely intact; therefore, an anterior procedure further destabilizes the spine. Reduction by an anterior approach would also be difficult. Nonsurgical management of the neurologic injury in this patient is not indicated. Theiss SM: Thoracolumbar and lumbar spine trauma, in Stannard JP, Schmidt AH, Kregor PJ (eds): Surgical Treatment of Orthopaedic Trauma. New York, NY, Thieme, 2007, pp 179-207.

Question 7

Surgical treatment for symptomatic disk herniations is associated with which of the following?

Explanation

The recently published SPORT trial verifies that surgical treatment of symptomatic disk herniations is associated with early and sustained pain relief. The trial also verifies that nonsurgical management is associated with improved symptoms as well. Nerve root injury, recurrent herniation, and diskitis are known complications of surgery, but all are less common than described above.

Question 8

A 25-year-old man is unresponsive at the scene of a high-speed motor vehicle accident and remains obtunded. Initial evaluation in the emergency department reveals a left-sided femoral shaft fracture and a right-sided humeral shaft fracture. The cervical spine remains immobilized in a semi-rigid cervical collar, and the initial AP and lateral radiographs obtained in the emergency department are unremarkable. What is the most appropriate management at this time?

Explanation

Clearance of the cervical spine can be difficult in the obtunded or unresponsive patient. Various trauma series have been reported to detect up to 95% of cervical fractures but only when ideal imaging views have been obtained, which is not often possible in the unresponsive or uncooperative patient. Passively performed cervical flexion-extension under live fluoroscopy has been suggested but is not without inherent risk in the potentially unstable cervical spine. CT of the cervical spine has gained acceptance for the evaluation of these patients given the excellent evaluation of the osseous anatomy and for the common availability in most emergency departments. Sanchez and associates, using a protocol to evaluate for cervical spine injuries after blunt trauma, were able to detect 99% of cervical fractures with 100% specificity. Chiu WC, Haan JM, Cushing BM, et al: Ligamentous injuries of the cervical spine in unreliable blunt trauma patients: Incidence, evaluation, and outcome. J Trauma 2001;50:457-463. Sanchez B, Waxman K, Jones T, et al: Cervical spine clearance in blunt trauma: Evaluation of a computed tomography-based protocol. J Trauma 2005;59:179-183.

Question 9

A 55-year-old woman undergoes an anterior cervical diskectomy and fusion at C5-C6 through a left-sided approach. One year later, she requires an anterior cervical diskectomy and fusion on another level. Which of the following is considered a contraindication to performing a right-sided approach for the revision procedure?

Explanation

When attempting a revision anterior cervical approach from the side opposite the original approach, it is important to evaluate the function of the vocal cords. If this evaluation reveals dysfunction of the vocal cord on the side of the original approach, then an approach on the contralateral side should not be attempted. Injury to the stellate ganglion, which causes a Horner's syndrome, should not preclude an approach on the contralateral side. While the side of the symptomatology can influence the surgeon's choice as to the side of an anterior approach, it does not preclude a certain approach. When approaching the lower cervical spine from the right side, the recurrent laryngeal nerve can cross the surgical field and should be preserved. Excessive intraoperative pressure on the esophagus can increase the incidence of dysphagia, but its incidence is no different with either approach. Spivak JM, Connolly PJ (eds): Orthopaedic Knowledge Update: Spine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, pp 387-394.

Question 10

A 56-year-old woman sustained the fracture shown in Figures 30a and 30b in a motor vehicle accident. What mechanism is most likely responsible for the injury?

Explanation

The CT scans show a burst fracture that results from an axial load injury. The radiographic hallmark of a burst fracture is compression of the posterior cortex of the vertebral body with retropulsion of bone into the spinal canal. AP radiographs often show widening of the interpedicular distance with a fracture of the lamina. Theiss SM: Thoracolumbar and lumbar spine trauma, in Stannard JP, Schmidt AH, Kregor PJ (eds): Surgical Treatment of Orthopaedic Trauma. New York, NY, Thieme, 2007, pp 179-207.

Question 11

In providing culturally competent care to a Muslim woman with a cervical spine injury, which of the following most accurately describes the steps a male orthopaedist should take to respect her religious beliefs during his examination?

Explanation

In examining a traditional Muslim woman, a male physician should have another woman present, and the patient's husband, if possible. Only the affected limb or area needing examination should be exposed.

Question 12

Figure 31 shows the radiograph of a 64-year-old woman who is seen in the emergency department following a motor vehicle accident. She has no voluntary motor function in her distal upper extremities or lower extremities. She does not have a bulbocavernosus reflex. She has a blood pressure of 80/50 mm Hg with a pulse of 50/min. Her hypotension does not improve with initial fluid resuscitation. Further treatment of her hypotension should consist of

Explanation

The hallmark of neurogenic shock is hypotension without tachycardia. It is associated most commonly with high cervical spinal cord injuries and results from loss of function of the sympathetic nervous system. Because the peripheral vasculature is dilated due to loss of its sympathetic tone, continued rapid administration of fluid corrects the hypotension and can quickly lead to fluid overload and congestive heart failure. Therefore, neurogenic shock is best treated by the use of pressors. Cardioversion or administration of antibiotics or systemic steroids is not appropriate treatment for this patient's hypotension. Spivak JM, Connolly PJ (eds): Orthopaedic Knowledge Update: Spine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, pp 179-187.

Question 13

What is the typical axial plane transverse angulation of the thoracic pedicles?

Explanation

Thoracic pedicles typically are angled 25 degrees medially at T1 so the starting point is more lateral. T2 angles about 15 degrees, and then the pedicles average about 5 to 7 degrees down to T10. At T11 and 12, the angulation is minimal. Weinstein L: Pediatric Spine Principles and Practice. New York, NY, Raven Press, 1994, pp 1659-1681.

Question 14

What muscle is most often encountered during surgical approaches to C5-6?

Explanation

The omohyoid muscle crosses the surgical field from inferior lateral to anterior superior traveling from the scapula to the hyoid bone and may need to be transected. The posterior digastric crosses the field as well but higher near C3-4. The other muscles run longitudinally. Chang U, Lee MC, Kim DH: Anterior approach to the midcervical spine, in Kim DH, Henn JS, Vaccaro AR, et al (eds): Surgical Anatomy and Techniques to the Spine. Philadelphia, PA, Saunders Elsevier, 2006, pp 45-56.

Question 15

Which of the following lumbar disk components has the highest tensile modulus to resist torsional, axial, and tensile loads?

Explanation

The annulus fibrosis has a multilayer lamellar architecture mode of type I collagen fibers. Each successive layer is oriented at 30 degrees to the horizontal in the opposite direction, leading to a "criss-cross" type pattern. This composition allows the annulus, which has the highest tensile modulus, to resist torsional, axial, and tensile loads.

Question 16

When comparing the overall outcomes of surgical versus nonsurgical treatment of stable thoracolumbar burst fractures in patients without neurologic injury, 5 years following injury, the principle differences lie in

Explanation

When patients are compared at 5 years follow-up, there are no statistically significant differences between the two groups with respect to kyphosis, the degree of retropulsed bone resorption, pain and function levels, or the ability to return to work. Nonsurgical management of stable neurologically intact burst fractures has a very low incidence of complications. Wood K, Butterman G, Mehbod A, et al: Operative compared with nonoperative treatment of a thoracolumbar burst fracture without neurological deficit: A prospective, randomized study. J Bone Joint Surg Am 2003;85:773-781.

Question 17

A 42-year-old woman who has had an 18-month history of severe low back pain is referred to your office for surgical evaluation. She reports that the pain initially began with right lower extremity pain and management consisted of oral analgesics, nonsteroidal anti-inflammatory drugs, and muscle relaxants. She has seen a chiropractor as well as a pain management specialist and she is status-post epidural steroid injections. She has also completed exhaustive physical therapy, as she is a certified athletic trainer and runs a health fitness program at a community hospital. Currently, she denies lower extremity pain and her pain is isolated to her low back and is subjectively graded as 8/10, with 10 being the worst pain she has ever experienced. The pain is interfering with her activities of daily living and she is seeking definitive treatment. Figures 32a through 32c show current MRI scans. Based on the current available medical literature, what is the most appropriate treatment?

Explanation

The MRI scans reveal advanced degenerative disk disease at L5-S1. Nonsurgical management has failed to provide relief and the patient is quite debilitated as a result of her back pain. Fritzell and associates demonstrated that in a well-informed and selected group of patients with severe low back pain, lumbar fusion can diminish pain and decrease disability more efficiently than commonly used nonsurgical treatments. In a recent updated Cochrane Review of surgery for degenerative lumbar spondylosis, it was noted that while Fritzell and associates appeared to provide strong evidence in favor of fusion, a more recent trial by Brox and associates demonstrated no difference between those patients undergoing lumbar fusion compared to those receiving cognitive intervention and exercise. The Cochrane Review suggests that this may reflect a difference between the control groups. Fritzell and associates compared lumbar fusion to standard 1990s "usual care," whereas Brox and associates compared lumbar fusion to a "modern rehabilitation program." Bear in mind that this patient is a certified athletic trainer and runs a hospital health fitness department; therefore, at least for purposes of this question, it can be assumed that she has participated in a "modern rehabilitation program." The Cochrane Review goes on to state that preliminary results of three small trials of intradiskal electrotherapy suggest that it is ineffective and that preliminary data from three trials of disk arthroplasty do not permit firm conclusions. Gibson JN, Waddell G: Surgery for degenerative lumbar spondylosis: Updated Cochrane Review. Spine 2005;30:2312-2320. Fritzell P, Hagg O, Wessberg P, et al: 2001 Volvo Award Winner in Clinical Studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain: A multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group. Spine 2001;26:2521-2532.

Question 18

Figure 33 shows the MRI scan of a 55-year-old woman who has had a 6-week history of back and leg pain. Which of the following clinical scenarios is most consistent with the MRI scan findings at L4-L5?

Explanation

The MRI scan reveals a L4-L5 foraminal disk herniation originating from the L4-5 disk space that has migrated up into the foramen, compressing the left L4 nerve root. There is normal distribution of the roots in the cerebrospinal fluid, excluding arachnoiditis as a diagnosis, and disk herniation in this location would not result in cauda equina syndrome or myelopathy.

Question 19

Intradiskal electrothermal therapy (IDET) uses an intradiskal catheter to deliver controlled thermal energy to the inner periphery of the annulus fibrosis of a chronically painful intervertebral disk. Lumbar diskography is used diagnostically to identify the presumed pain generator to be targeted with IDET. Based on the medical literature, what can be said about the current status of IDET?

Explanation

Intradiskal electrothermal therapy (IDET) initial clinical results were reported in 2000. The early case series were quite encouraging with reported therapeutic success rates of 60% to 80%. Early enthusiasm was high as IDET provided a nonsurgical treatment option for an otherwise complex and difficult clinical entity, chronic diskogenic low back pain. The actual mechanism of action was not well understood, and while the theoretic explanation made good sense, it did not hold up under laboratory testing. Soon clinical results from the field did not meet the high expectations set by the developers of the technique. Since those early case studies, a few level I evidence studies have been conducted, one by Freeman and associates and one by Pauza and associates. These randomized, placebo-controlled trials demonstrated no significant benefit of IDET over the placebo. Freeman BJ, Fraser RD, Cain CM, et al: A randomized, double-blind, controlled trial: Intradiscal electrothermal therapy versus placebo for the treatment of chronic discogenic low back pain. Spine 2005;30:2369-2377. Pauza KJ, Howell S, Dreyfuss P, et al: A randomized, placebo-controlled trial of intradiscal electrothermal therapy for the treatment of discogenic low back pain. Spine J 2004;4:27-35.

Question 20

A 56-year-old mechanic has had pain in the hypothenar region of his dominant right hand for the past 6 months. He reports weakness in his grip and pain is worse with activity. Which of the following examination findings is most suggestive of a cervical etiology?

Explanation

Hypothenar atrophy is a nonspecific sign that can be seen in ulnar neuropathy, C8 radiculopathy, or even cervical myelopathy; however, the atrophy usually is not unilateral and includes other muscle groups. The Spurling test is an excellent method of eliciting cervical radicular pain but involves hyperextension and ipsilateral rotation of the cervical spine, resulting in nerve root compression by reducing the cross-sectional area of the ipsilateral neuroforamen. Tinel's sign at the levator scapulae, if present, is indicative of an upper cervical (C3 or C4) radiculopathy. A subluxable ulnar nerve at the cubital tunnel, while often asymptomatic, points toward cubital tunnel syndrome as an etiology for this patient's pain. The shoulder abduction relief (SAR) sign (relief of upper extremity pain with shoulder abduction) is virtually pathognomic of cervical radiculopathy because this maneuver results in relaxation of a compressed and/or inflamed cervical nerve root. The SAR sign is the converse analog of the straight leg raising sign in the lumbar examination for lumbar radiculopathy, as it relieves tension in the nerve root, thereby relieving symptoms. Ducker TB, Zeidman SM: Neurologic and functional evaluation, in Clark CR (ed): The Cervical Spine, ed 3. Philadelphia, PA, Lippincott Raven, 1998, pp 143-161. An HS: Clinical presentation of discogenic neck pain, radiculopathy, and myelopathy, in Clark CR (ed): The Cervical Spine, ed 3. Philadelphia, PA, Lippincott Raven, 1998, pp 755-764.

Question 21

A 35-year-old woman reports an 8-week history of neck pain radiating to her right upper extremity. She denies any history of trauma or provocative event. Examination reveals decreased pinprick sensation in her right middle finger, otherwise sensation is intact bilaterally. Finger flexors and interossei demonstrate 5/5 motor strength bilaterally. Finger extensors are 4/5 on the right and 5/5 on the left. The triceps reflex is 1+ on the right and 2+ on the left. The most likely diagnosis is a herniated nucleus pulposus at what level?

Explanation

The patient's neurologic examination is consistent with a C7 radiculopathy on the right side. In a patient with this symptom complex in the absence of trauma, a cervical disk herniation is the most common etiology for a C7 radiculopathy. There are eight cervical nerve roots and the C7 nerve exits at the C6-7 disk space and is most frequently impinged by a disk herniation at this level. Houten JK, Errico TJ: Cervical spondylotic myelopathy and radiculopathy: Natural history and clinical presentation, in Clark CR (ed): The Cervical Spine, ed 4. Philadelphia, PA, Lippincott Williams & Wilkins, 2005, pp 985-990.

Question 22

What is the most common nonanesthetic-related reversible cause of changes in intraoperative neurophysiologic monitoring data?

Explanation

Patient positioning that results in local nerve compression, plexus traction, or improper neck alignment is the most common nonanesthetic-related cause of changes in intraoperative neurophysiologic monitoring data during spinal surgery. Jones SC, Fernau R, Woeltjen BL: Use of somatosensory evoked potentials to detect peripheral ischemia and potential injury resulting from positioning of the surgical patient: Case reports and discussion. Spine J 2004;4:360-362.

Question 23

During a left-sided transforaminal lumbar interbody fusion at the L4-5 level, the surgeon notes a significant amount of bleeding that cannot be controlled while using a pituitary rongeur. What anatomic structure has been injured?

Explanation

The surgeon perforated the anterior longitudinal ligament and injured the common iliac artery. Bingol and associates described injuries to the vascular structures during lumbar disk surgery. The common iliac artery was most commonly affected and constituted 76.9% of injuries.

Question 24

Six weeks after onset, what is the most clearly accepted indication for surgical management for lumbar disk herniation?

Explanation

In the absence of a cauda equina syndrome or progressive weakness, the best indication for surgical management is refractory radicular pain. Surgical decision-making should not be based on the size of the herniation. Large extruded herniations tend to resolve more predictably than smaller herniations. Stable motor weakness and numbness resolve similarly in both surgical and nonsurgical management, although surgery hastens the process. When intractable radicular pain is the strict indication for surgery, surgical intervention provides substantial and more rapid pain relief than nonsurgical care. Rhee JM, Schaufele M, Abdu WA: Radiculopathy and the herniated lumbar disc: Controversies regarding pathophysiology and management. J Bone Joint Surg Am 2006;88:2070-2080.

Question 25

A 45-year-old woman has idiopathic scoliosis. Surgery is to include an anterior thoracic release through an open left thoracotomy. The thoracotomy will have what effect on the patient's pulmonary function postoperatively?

Explanation

A thoracotomy in an adult with idiopathic scoliosis causes a reduction in pulmonary function that often does not return to preoperative levels. What pulmonary function that does recover, recovers over many months. Long-term improvement in pulmonary function, compared to preoperative function, is rarely seen. This should be considered in planning surgical intervention in adults with scoliosis. Graham EJ, Lenke LG, Lowe TG, et al: Prospective pulmonary function evaluation following open thoracotomy for anterior spinal fusion in adolescent idiopathic scoliosis. Spine 2000;25:2319-2325.

Question 26

A 25-year-old obtunded male is brought to the trauma bay after a motor vehicle collision. CT shows a right-sided unilateral facet dislocation at C5-C6. What is the most appropriate next step in management?

Explanation

In an obtunded or unexaminable patient with a cervical facet dislocation, an MRI must be obtained prior to closed or open reduction to rule out a compressive disc herniation. This prevents potentially catastrophic iatrogenic spinal cord injury during reduction.

Question 27

In the evaluation of adult spinal deformity, achieving appropriate sagittal balance is critical. Which of the following formulas best describes the ideal relationship between pelvic incidence (PI) and lumbar lordosis (LL) to optimize outcomes?

Explanation

To achieve optimal sagittal balance in adult spinal deformity, the lumbar lordosis (LL) should match the pelvic incidence (PI) within 10 degrees. A mismatch of greater than 10 degrees strongly correlates with increased disability and adjacent segment disease.

Question 28

A 45-year-old man presents with acute right anterior thigh pain and weakness in knee extension. A representative MRI reveals a far lateral disc herniation at the L4-L5 level on the right.

Which nerve root is most likely compressed in this scenario?

Explanation

Far lateral (extraforaminal) disc herniations compress the exiting nerve root at the same level, unlike central or paracentral herniations which affect the traversing root. Therefore, a far lateral disc at L4-L5 compresses the exiting L4 nerve root.

Question 29

Which of the following morphological fracture patterns is assigned the highest point value in the Thoracolumbar Injury Classification and Severity (TLICS) system?

Explanation

In the TLICS system, morphology is scored as follows: compression (1), burst (2), translation/rotation (3), and distraction (4). Distraction morphology carries the highest point value as it implies severe instability.

Question 30

A 65-year-old female with a 20-year history of rheumatoid arthritis presents with progressive hand clumsiness. Flexion-extension cervical radiographs show an anterior atlantodens interval (ADI) of 11 mm. What is the most reliable radiographic predictor of impending neurologic deficit in this patient?

Explanation

In rheumatoid arthritis, the posterior atlantodens interval (PADI), also known as the space available for the cord (SAC), is the most reliable predictor of neurologic deficit. A PADI of less than 14 mm is associated with a high risk of neurologic compromise.

Question 31

A 72-year-old man with cervical spondylosis falls forward, striking his forehead. He presents with profound bilateral upper extremity weakness but retains moderate strength in his lower extremities. Which of the following is true regarding his condition?

Explanation

This presentation is classic for Central Cord Syndrome, which disproportionately affects upper extremities. It carries a favorable prognosis for functional ambulation compared to complete injuries, with hand recovery typically being the last to return.

Question 32

A 58-year-old man with advanced ankylosing spondylitis presents with severe neck pain following a ground-level fall. Neurological examination is intact. Plain radiographs of the cervical spine appear normal. What is the next most appropriate step in management?

Explanation

Patients with ankylosing spondylitis have highly rigid spines susceptible to highly unstable fractures even from low-energy trauma. If plain radiographs are normal or inconclusive, a CT scan is mandatory to rule out occult fractures, particularly at the cervicothoracic junction.

Question 33

A 30-year-old male dives into a shallow pool and sustains a C1 Jefferson fracture. Open-mouth odontoid radiographs reveal lateral displacement of the lateral masses. According to the Rule of Spence, rupture of the transverse ligament is highly suspected if the combined lateral mass overhang exceeds:

Explanation

The Rule of Spence dictates that a combined lateral mass overhang of C1 on C2 greater than 6.9 mm on an open-mouth AP radiograph suggests a ruptured transverse ligament. MRI is typically used in modern practice to confirm this ligamentous disruption.

Question 34

A 65-year-old man presents with bilateral hand weakness and numbness after a hyperextension injury. He is able to ambulate but struggles to button his shirt. What is the most likely anatomic location of the primary spinal cord injury?

Explanation

Central cord syndrome typically occurs after hyperextension injuries in stenotic cervical canals. The medial location of the cervical tracts in the corticospinal tract leads to disproportionate upper extremity weakness, particularly distal hand function.

Question 35

In adult spinal deformity surgery, achieving proper sagittal balance is highly correlated with improved Health-Related Quality of Life (HRQOL) outcomes. Which of the following radiographic targets is generally recommended?

Explanation

Favorable outcomes in adult spinal deformity are associated with an SVA < 5 cm, PT < 20 degrees, and a PI-LL mismatch of less than 10 degrees. These parameters optimize standing posture and minimize energy expenditure.

Question 36

A 24-year-old male is intubated and obtunded following a severe motor vehicle collision. Radiographs demonstrate a unilateral facet dislocation at C5-C6. What is the most appropriate next step prior to attempted surgical reduction?

Explanation

In an un-evaluable or obtunded patient with a cervical facet dislocation, an MRI must be obtained prior to reduction to rule out a concomitant disc herniation that could cause neurologic injury during reduction.

Question 37

A 65-year-old man presents with progressive clumsiness in his hands and difficulty walking. Examination reveals a positive Hoffman's sign and generalized hyperreflexia.

What is the most common gait abnormality seen in patients with this condition?

Explanation

The most common and often earliest gait abnormality in cervical spondylotic myelopathy is a broad-based, unsteady, and stiff (spastic) gait due to upper motor neuron dysfunction.

Question 38

In the Lenke classification of adolescent idiopathic scoliosis, a lumbar curve is considered a 'structural' minor curve if it bends out to what minimum Cobb angle on supine side-bending radiographs?

Explanation

In the Lenke classification, a minor curve is structural if it has a residual Cobb angle of 25 degrees or greater on supine lateral bending radiographs, or if there is kyphosis of at least +20 degrees.

Question 39

A 40-year-old male falls from a height and sustains an L1 burst fracture. He is neurologically intact.

Which of the following parameters is the strongest indication for operative stabilization over nonoperative management?

Explanation

Injury to the posterior ligamentous complex (PLC) indicates a highly unstable injury pattern (earning 3 points on the TLICS scale) and is a strong indication for surgical stabilization in thoracolumbar burst fractures.

Question 40

A 45-year-old man presents with right leg pain radiating to the dorsum of his foot and isolated weakness in great toe extension. Which nerve root is most likely compressed, and what is the typical associated reflex abnormality?

Explanation

Extensor hallucis longus (EHL) weakness and numbness over the dorsum of the foot indicate an L5 radiculopathy. The L5 nerve root does not have a reliable primary deep tendon reflex.

Question 41

In surgical planning for adult spinal deformity, achieving optimal spinopelvic harmony is critical. Which formula represents the ideal relationship between pelvic incidence (PI) and lumbar lordosis (LL)?

Explanation

For optimal spinopelvic harmony and improved functional outcomes, the lumbar lordosis (LL) should match the pelvic incidence (PI) within 10 degrees (PI = LL ± 10 degrees).

Question 42

A 78-year-old female presents with neck pain after a low-energy fall. CT reveals a Type II odontoid fracture with 2 mm of posterior displacement.

What is the most significant risk factor for nonunion if treated nonoperatively?

Explanation

The most significant risk factor for nonunion in Type II odontoid fractures is age over 50 years. Other factors include displacement > 5 mm, posterior displacement, and excessive angulation.

Question 43

Three years following an L4-L5 posterior lumbar interbody fusion (PLIF), a patient develops adjacent segment degeneration at L3-L4. Which biomechanical change at the adjacent segment is most directly responsible?

Explanation

Spinal fusion creates a rigid segment that significantly increases biomechanical stress, intradiscal pressure, and segmental mobility at the adjacent un-fused levels, accelerating degeneration.

Question 44

A 16-year-old female wearing a lap belt in an MVA sustains a flexion-distraction injury (Chance fracture) of L2.

Which of the following associated injuries must be aggressively ruled out?

Explanation

Chance fractures are highly associated with intra-abdominal injuries, particularly hollow viscus injuries (e.g., bowel perforations), which occur in up to 50% of cases due to extreme lap-belt compression.

Question 45

A 15-year-old boy presents with progressive mid-back pain. Radiographs show a thoracic kyphosis of 55 degrees. Which radiographic criteria is strictly required to diagnose Scheuermann's kyphosis?

Explanation

Sorensen's classic criteria for diagnosing Scheuermann's kyphosis require anterior wedging of at least 5 degrees in three or more consecutive vertebral bodies.

Question 46

A 78-year-old man falls and sustains a Type II odontoid fracture with 1 mm of displacement. He has a history of severe chronic obstructive pulmonary disease (COPD) and heart failure. He is neurologically intact. What is the most appropriate initial management?

Explanation

Elderly patients with Type II odontoid fractures have significantly higher mortality rates with halo vest immobilization. Given this patient's severe medical comorbidities and minimal fracture displacement, a rigid cervical collar is the safest and most appropriate initial management.

Question 47

A 65-year-old male presents with bilateral upper extremity weakness (hands > arms) and mild lower extremity weakness after a hyperextension injury. Which of the following is true regarding his prognosis?

Explanation

In central cord syndrome, the classic recovery pattern progresses from the lower extremities to the upper extremities, and from proximal to distal. Hand intrinsic function is the last to return and the least likely to fully recover.

Question 48

A 45-year-old male arrives intubated and sedated with a unilateral C6-C7 facet dislocation. What is the most appropriate next step prior to attempting reduction?

Explanation

In an unexaminable (intubated/sedated) patient with a cervical facet dislocation, an MRI is mandatory before attempting reduction to rule out a disc herniation that could cause iatrogenic spinal cord injury.

Question 49

What is the most common associated intra-abdominal injury in a pediatric patient with a flexion-distraction (Chance) fracture of the lumbar spine?

Explanation

Chance (flexion-distraction) fractures have a highly significant association (30-50%) with intra-abdominal injuries. The most commonly injured structures are hollow visceral organs, such as the bowel.

Question 50

A 14-year-old female with Adolescent Idiopathic Scoliosis has a right thoracic curve. She is Risser 0 and pre-menarchal. Her curve measures 35 degrees. What is the most appropriate treatment?

Explanation

TLSO bracing is indicated for skeletally immature patients (Risser 0-2) with progressive curves measuring between 25 and 40 degrees to halt curve progression.

Question 51

In planning for adult spinal deformity correction, which of the following radiographic relationships is the primary goal to achieve a well-balanced spine?

Explanation

A fundamental goal of adult spinal deformity surgery is to restore sagittal balance. This is best achieved by correcting the Lumbar Lordosis to within 9-10 degrees of the patient's fixed Pelvic Incidence.

Question 52

During the anterior approach to the lower cervical spine (C5-C7), which of the following structures is at greatest risk of injury when dissecting in the tracheoesophageal groove on the right side?

Explanation

The recurrent laryngeal nerve has a variable, aberrant course on the right side as it loops around the subclavian artery, placing it at higher risk during right-sided anterior lower cervical approaches.

Question 53

A 30-year-old male presents with severe right leg pain and weakness in big toe extension. MRI reveals a large paracentral disc herniation at L4-L5. Which nerve root is most likely affected?

Explanation

In the lumbar spine, a typical paracentral disc herniation at L4-L5 impinges the traversing L5 nerve root. This classically presents with weakness of the extensor hallucis longus (EHL).

Question 54

Which of the following is an absolute indication for surgical intervention in a patient with a traumatic thoracolumbar burst fracture?

Explanation

The development of a progressive neurologic deficit is an absolute indication for urgent surgical decompression and stabilization in the setting of a thoracolumbar burst fracture.

Question 55

A 60-year-old male with long-standing Ankylosing Spondylitis presents with neck pain after a minor fall. Initial plain radiographs of the cervical spine are unremarkable. What is the most appropriate next step in management?

Explanation

Patients with Ankylosing Spondylitis are at extremely high risk for highly unstable, occult cervical fractures even after minor trauma. A CT scan of the entire cervical spine is mandatory if plain films are negative.

Question 56

In evaluating an atlas (C1) ring fracture, lateral mass displacement on the open-mouth odontoid radiograph indicates a tear of the transverse atlantal ligament if the combined displacement exceeds what value?

Explanation

The Rule of Spence states that a combined lateral mass displacement of C1 on C2 greater than 6.9 mm (typically rounded to 7 mm) on an AP open-mouth radiograph indicates a rupture of the transverse atlantal ligament. This implies transverse instability requiring more rigid fixation or prolonged halo immobilization.

Question 57

A 25-year-old man presents with a unilateral C5-C6 facet dislocation and a C6 radiculopathy following a motor vehicle collision. He is awake, alert, and cooperative. What is the most appropriate initial management?

Explanation

In an awake, alert, and cooperative patient with a cervical facet dislocation, rapid closed reduction using awake cervical traction is indicated. An MRI is not required prior to closed reduction in a cooperative patient, as continuous neurologic monitoring during traction ensures safety.

Question 58

A 35-year-old woman falls from a height and sustains a T12 burst fracture. Imaging reveals splaying of the spinous processes and an MRI shows disruption of the posterior ligamentous complex. She is neurologically intact. What is her Thoracolumbar Injury Classification and Severity (TLICS) score?

Explanation

The TLICS score is based on morphology (burst = 2 points), posterior ligamentous complex integrity (disrupted = 3 points), and neurologic status (intact = 0 points). A total score of 5 points indicates that surgical stabilization is the recommended treatment.

Question 59

In planning a corrective surgery for adult spinal deformity, which of the following spinopelvic parameter relationships represents the primary goal to achieve optimal sagittal balance?

Explanation

A key goal in adult spinal deformity surgery is to restore the normal relationship between Pelvic Incidence (PI) and Lumbar Lordosis (LL). Matching PI and LL within 10 degrees (PI - LL < 10 degrees) minimizes compensatory mechanisms like increased pelvic tilt and improves clinical outcomes.

Question 60

A 45-year-old man presents with severe right leg pain. An MRI of the lumbar spine reveals a far lateral (extraforaminal) disc herniation on the right side at the L4-L5 level. Which nerve root is most likely compressed, and what clinical finding would be expected?

Explanation

In the lumbar spine, a far lateral (extraforaminal) disc herniation compresses the exiting nerve root at that level, which is L4 at L4-L5. An L4 radiculopathy classically presents with a diminished patellar reflex, weakness in knee extension, and anterior thigh numbness.

Question 61

Which of the following anatomical factors is most strongly associated with the development of degenerative spondylolisthesis at L4-L5?

Explanation

Sagittal orientation of the facet joints at L4-L5 reduces their ability to resist anterior shear forces, strongly predisposing individuals to degenerative spondylolisthesis. Normal facet joints at this level are typically more coronally oriented, which mechanically blocks anterior translation.

Question 62

A 40-year-old man presents to the emergency department with acute onset of severe back pain, saddle anesthesia, and urinary retention. Post-void residual volume is 400 mL. Emergent MRI confirms a massive L4-L5 disc herniation. To maximize the chance of full neurologic recovery, decompression should ideally be performed within what maximum timeframe from the onset of symptoms?

Explanation

Cauda equina syndrome is a surgical emergency. Decompression performed within 48 hours of symptom onset has been shown to significantly improve the likelihood of resolving bladder and motor dysfunction compared to delayed intervention.

Question 63

Which of the following factors is most predictive of nonunion following nonoperative management (halo immobilization) of a Type II odontoid fracture?

Explanation

High risk of nonunion in Type II odontoid fractures managed conservatively is associated with initial displacement greater than 5 mm, age > 50 years, and posterior displacement. These factors often necessitate surgical stabilization, such as an anterior odontoid screw or posterior C1-C2 fusion.

Question 64

A 65-year-old man undergoes a posterior cervical laminectomy and fusion from C3-C7 for severe cervical spondylotic myelopathy. On postoperative day 2, he develops isolated profound weakness of bilateral deltoids and biceps, but has no sensory changes and lower extremity function remains normal. What is the most likely etiology of this complication?

Explanation

C5 palsy is a known complication following posterior cervical decompression, occurring in up to 10% of cases. It is believed to be caused by posterior shifting (drift) of the spinal cord, leading to traction on the short, horizontally oriented C5 nerve roots.

Question 65

A 60-year-old man with a long-standing history of ankylosing spondylitis sustains a minor ground-level fall. He complains of severe neck pain but has no neurologic deficits. Plain radiographs of the cervical spine are difficult to interpret due to artifact and deformity, but appear unchanged from previous. What is the next best step in management?

Explanation

Patients with ankylosing spondylitis are at extremely high risk for highly unstable, transcortical fractures of the rigid spine even after minor trauma. Due to obscured anatomy on plain films, a CT scan of the cervical spine is mandatory to rule out an occult fracture.

Question 66

An 82-year-old male sustains a Type II odontoid fracture after a ground-level fall. He has multiple medical comorbidities. Which of the following management strategies carries the lowest treatment-related morbidity while still providing acceptable clinical outcomes, despite having the highest rate of nonunion?

Explanation

A rigid cervical collar is the preferred initial treatment for many elderly patients with Type II odontoid fractures who are poor surgical candidates. While it has a high nonunion rate, fibrous nonunions are generally well-tolerated, and it avoids the high morbidity and mortality associated with halo vest immobilization in the elderly.

Question 67

A 25-year-old male is involved in a high-speed motor vehicle collision while wearing a lap seatbelt. Radiographs demonstrate a flexion-distraction injury (Chance fracture) at L1. Which of the following is the most commonly associated concomitant injury?

Explanation

Chance fractures typically occur due to hyperflexion over a fulcrum (like a lap seatbelt), causing distraction of the posterior and middle columns. They are highly associated with intra-abdominal injuries, most notably hollow viscus injuries such as bowel perforations.

Question 68

A 65-year-old female presents with progressive difficulty manipulating buttons, frequent dropping of objects, and a broad-based gait. Physical examination reveals a positive Hoffmann sign and hyperreflexia in the lower extremities. MRI confirms severe spinal cord compression at C4-C5. What is the most appropriate next step in management?

Explanation

The patient is presenting with classic signs of cervical spondylotic myelopathy (CSM). Surgical decompression (such as ACDF) is indicated to halt the progression of neurologic decline, as conservative measures are ineffective for progressive myelopathy.

Question 69

During the surgical planning for an adult patient with severe sagittal imbalance, the surgeon evaluates the spinopelvic parameters. Which of the following formulas correctly describes the fixed anatomic relationship of the pelvis?

Explanation

Pelvic Incidence (PI) is a fixed morphologic parameter that does not change with positioning. It is the algebraic sum of the position-dependent parameters: Pelvic Tilt (PT) and Sacral Slope (SS).

Question 70

A 70-year-old male reports bilateral leg heaviness, pain, and paresthesias that worsen after walking 50 yards. He notes that the symptoms are significantly relieved when he leans forward on a shopping cart or walks uphill, but worsen when walking downhill. What is the most likely diagnosis?

Explanation

The symptoms describe classic neurogenic claudication caused by lumbar spinal stenosis. Flexion of the spine (leaning on a shopping cart, walking uphill) increases the cross-sectional area of the spinal canal, relieving symptoms, whereas extension (walking downhill) exacerbates them.

Question 71

A 55-year-old male with long-standing ankylosing spondylitis presents to the emergency department complaining of neck pain following a minor ground-level fall. He is neurologically intact. Plain radiographs of the cervical spine are interpreted as negative for acute fracture. What is the most appropriate next step?

Explanation

Patients with ankylosing spondylitis have a highly rigid, brittle spine and are at significant risk for unstable fractures and epidural hematomas even after minor trauma. Advanced imaging (CT or MRI) is mandatory because these fractures are frequently missed on plain radiographs.

Question 72

A 14-year-old female gymnast complains of insidious onset, activity-related low back pain. Radiographs demonstrate a Grade 1 isthmic spondylolisthesis at L5-S1 with an identifiable pars interarticularis defect. She has no neurologic deficits. What is the most appropriate initial management?

Explanation

Initial management for symptomatic, low-grade (Grade 1 or 2) isthmic spondylolisthesis in an adolescent is nonoperative. This includes a period of activity modification, physical therapy, and potentially bracing (TLSO) to allow symptoms to resolve.

Question 73

When utilizing the Thoracolumbar Injury Classification and Severity (TLICS) score to determine the indication for surgery in a thoracolumbar burst fracture, which of the following radiographic parameters is heavily weighted and strongly drives the recommendation toward surgical stabilization?

Explanation

In the TLICS system, disruption of the posterior ligamentous complex (PLC) assigns 3 points (if indeterminate, 2 points) and strongly pushes the score toward operative management. Degree of height loss and canal compromise are not directly scored in TLICS, distinguishing it from older classification systems.

Question 74

A 45-year-old male presents with severe radicular leg pain. MRI reveals a far lateral (extraforaminal) disc herniation at the L4-L5 level. Which nerve root is most likely compressed by this specific herniation?

Explanation

In the lumbar spine, a far lateral (extraforaminal) disc herniation impinges the exiting nerve root at that level. Therefore, a far lateral L4-L5 disc herniation will compress the exiting L4 nerve root.

Question 75

A 72-year-old male with known cervical spondylosis falls forward and strikes his chin, forcefully hyperextending his neck. He arrives at the ER with significant weakness in his upper extremities and relatively preserved motor function in his lower extremities. Which incomplete spinal cord syndrome has he developed?

Explanation

Central cord syndrome is typically caused by a hyperextension injury in an older patient with pre-existing cervical spondylosis. The pathognomonic presentation is motor weakness that is more severe in the upper extremities than in the lower extremities.

Question 76

Which of the following describes the accepted radiographic criteria established by Sorensen for the diagnosis of typical Scheuermann's kyphosis?

Explanation

Sorensen criteria for classic Scheuermann's kyphosis requires thoracic kyphosis greater than 40 degrees along with anterior wedging of at least 5 degrees in 3 or more consecutive vertebrae.

Question 77

A 60-year-old male of Japanese descent undergoes an anterior cervical corpectomy for progressive myelopathy caused by severe Ossification of the Posterior Longitudinal Ligament (OPLL). Which of the following is the most frequent intraoperative complication specifically associated with anterior resection of this pathology?

Explanation

OPLL frequently merges with and ossifies the underlying dura mater. Consequently, attempted anterior resection of the ossified mass has a notoriously high risk of dural tears and subsequent CSF leaks.

Question 78

A 28-year-old male presents with severe neck pain and C6 radiculopathy after a high-speed rollover collision. Lateral radiographs reveal approximately 25% anterior translation of the C5 vertebral body over C6. What is the most likely mechanism of this injury?

Explanation

Anterior translation of approximately 25% of the vertebral body width is characteristic of a unilateral facet dislocation. The mechanism of injury for a unilateral facet dislocation is typically flexion-distraction combined with a rotational force.

Question 79

A 60-year-old female with metastatic breast cancer presents with progressive back pain. The Spinal Instability Neoplastic Score (SINS) is utilized to evaluate her need for surgical stabilization. Which of the following factors is incorporated into the SINS calculation?

Explanation

The SINS criteria assess spinal stability in neoplastic disease based on 6 parameters: location of the lesion, pain characteristics, bone lesion type (lytic/blastic), radiographic spinal alignment, degree of vertebral body collapse, and posterolateral involvement of spinal elements.

AAOS Orthopedic MCQs (Set 1): Spine Disorders, Sports Medicine & Arthroplasty | 2026 Board Review

AAOS & ABOS Spine MCQs (Set 4): Trauma, Degenerative & Deformity | Board Prep

Key Takeaway

AAOS & ABOS Spine MCQs (Set 4): Trauma, Degenerative & Deformity | Board Prep

Chapter Index