Question 1

Which of the following regions of the spine is normally straight:

Explanation

The normal range of thoracic kyphosis is 20° to 50°. The mean in normal adults is 35°. The normal range of lumbar lordosis is 40° to 80°. The mean in normal adults is approximately 60°. The spine is usually straight in the sagittal plane between T10 and L2. The majority of lumbar lordosis occurs between L4 and S1.

Question 2

The endplates and pedicles of which of the following vertebra are normally parallel to the ground in a standing individual:

Explanation

The alignment of the spine is important in normal upright posture. There is a normal degree of lordosis in the cervical and lumbar spines and a moderate degree of kyphosis in the thoracic spine. The head, spine, and pelvis are connected and balanced. If the spine is out of balance, then a deformity can develop causing fatigue of the paraspinal muscles. The normal sagittal alignment in the upright patient is as follows: Plumb line The sagittal plumb line falls from the odontoid process through the C 7-T1 intervertebral disk and then anterior to the thoracic spine. The plumb line then crosses the spine at the T12-L1 intervertebral disk, and then travels posterior to the spine. The plumb line crosses at the posterior corner of the S1 vertebra. The endplates and pedicles of the L3 vertebra are normally parallel to the ground.

Question 3

Which of the following is true regarding the alignment of the spine with aging:

Explanation

The normal range of thoracic kyphosis is 20° to 50°. The mean in normal adults is 35°. The normal range of lumbar lordosis is 40° to 80°. The mean in normal adults is approximately 60°. The spine is usually straight in the sagittal plane between T10 and L2. The majority of lumbar lordosis occurs between L4 and S1. With aging, due to changes in the intervertebral disks, thoracic kyphosis increases and lumbar lordosis increases. There is loss of height of the intervertebral disks.

Question 4

In reference to the normal sagittal vertical axis (sagittal plumb line), the axis normally falls from the odontoid process through the C 7-T1 intervertebral disk and anterior to the thoracic vertebra. This normal axis crosses the spinal column at which of the following levels before crossing the spinal column at the posterior superior border of the S1 vertebral body:

Explanation

The alignment of the spine is important in normal upright posture. There is a normal degree of lordosis in the cervical and lumbar spines and a moderate degree of kyphosis in the thoracic spine. The head, spine, and pelvis are connected and balanced. If the spine is out of balance, then a deformity can develop causing fatigue of the paraspinal muscles. The normal sagittal alignment in an upright patient is as follows: Plumb line The sagittal plumb line falls from the odontoid process through the C 7-T1 intervertebral disk and then anterior to the thoracic spine. The plumb line then crosses the spine at the T12-L1 intervertebral disk, and then travels posterior to the spine. The plumb line crosses at the posterior corner of the S1 vertebra The endplates and pedicles of the L3 vertebra are normally parallel to the ground.

Question 5

The vertebral artery on the right side of the body arises from the subclavian artery and enters the lateral mass foramen of which of the following cervical vertebra (the first one it enters) before ascending to the brain:

Explanation

The vertebral artery arises from the subclavian artery on the right side of the body and the aortic arch on the left side. The vertebral artery enters the lateral mass foramen of the sixth cervical vertebra before ascending to the brain.

Question 6

To avoid damages to the vertebral arteries when exposing the posterior aspect of the first cervical vertebra, dissection should be limited to __ mm from the midline on the superior aspect of C 1 and ___ mm from the midline on the posterior aspect of C 1.

Explanation

One must be careful not to damage the vertebral artery when exposing the posterior and superior aspect of the C1 vertebra. It is especially important when using a Cobb elevator or an electrocautery not to dissect too far from the midline. The vertebral artery lies close to the midline. On the superior aspect, the groove for the vertebral artery lies 8 mm to12 mm from the midline. On the posterior aspect of the vertebral body, the vertebral artery lies 12 mm to 23 mm from the midline.

Question 7

Which of the following levels most significantly contributes to the blood supply of the cervical spinal cord:

Explanation

The major blood supply to the cervical spinal cord comes from the anterior spinal artery, which arises from the deep cervical artery. This vessel most commonly accompanies the left C 6 spinal nerve.

Question 8

Patients with Brown-SÃ©quard syndrome usually presents with:

Explanation

Brown-S aquard Syndrome usually results from hemisection of the spinal cord, which is often a result of trauma (eg, penetrating stab wounds). Clinical presentation usually consists of: Ipsilateral paralysis Loss of ipsilateral vibration and touch sensation Loss of contralateral pain and temperature sensation

Question 9

Central cord syndrome is typically due to:

Explanation

Central cord syndrome is the most common incomplete spinal cord lesion and is usually seen in patients with preexisting cervical spondylosis who then sustain a hyperextension injury to the cervical spine. This mechanism causes compression of the cord by osteophytes anteriorly and the infolded ligamentum flavum posteriorly with resulting injury to the central gray matter. The clinical presentation is variable but usually consists of: Greater loss of motor neurons to the upper extremities than the lower extremities often resulting in profound weakness in the arms and hands, and some weakness in the legs and feet Variable sensory loss Patients with central cord syndrome have variable return of function but are usually left with some degree of residual deficit and spasticity.

Question 10

Patients with anterior cord syndrome usually presents with:

Explanation

Anterior cord syndrome is due to injury of the anterior elements of the spinal cord, which is usually due to a space-occupying lesion anterior to the cord such as vertebral body fracture fragments, a herniated disk, or a hematoma. The clinical presentation consists of: Complete motor paralysis (loss of anterior corticospinal tract) Loss of pain/temperature sensation (loss of lateral and anterior spinothalamic tracts) Preservation of vibration sensation/proprioception and light touch sensation (preservation of dorsal columns) In less severe cases, some motor function is preserved through the lateral corticospinal pathways. Prognosis is generally poor and in patients with absence of sacral sensation (pin prick/temperature) after 24 hours following injury, recovery is seen in 10% of patients.

Question 11

A patient with cauda equina syndrome and the full spectrum of symptons presents with:

Explanation

Cauda equina syndrome is a severe neurologic disorder that results from an injury to the neural elements within the thecal sac between the conus medullaris and the lumbosacral nerve roots (ie, cauda equina or "horse's tail"). Cauda equina syndrome usually occurs as a result of lumbar disk herniation with compression of the cauda equina and requires urgent surgical decompression. Clinical presentation includes: Severe low back pain Bilateral or unilateral sciatica Saddle anesthesia Motor or sensory deficit Bladder and bowel vesicular involvement (classically leading to urinary retention) With a complete lesion, a loss of bulbocavernosus reflex, anal wink, and reflexes in the lower extremities

Question 12

Which of the following descriptions applies to the sacroiliac joint:

Explanation

Sacroiliac joint pathology accounts for 15% of lower back pain, and the sacroiliac joint is one of the most common sites of referred pain. Patients with sacroiliac joint pathology commonly experience pain above the posterior buttock and seldom have focal neurological deficits. Physical examination tests are poor predictors of sacroiliac joint pathology.

Question 13

Which of the following statements is true regarding the sacroiliac joint:

Explanation

The sacroiliac joint is the largest axial joint in the body. The anterior capsule is thin and weaker than the posterior capsule. The posterior supporting structures are strong and are comprised of a tough interosseous ligament, a long posterior sacroiliac ligament, and strong sacrotuberous, sacrospinous ligaments. Joint innervation usually occurs anteriorly in the S2 ventral rami. Compared with the lumbosacral spine, the sacroiliac joint can better withstand medial forces, but is weaker in axial compression and in axial torsion. Nutation (backward rotation of less than 4° and 1.6 mm rotation of the ilium on the sacrum) is the most common motion in the sacroiliac joint. Increased motion of the sacroiliac joint occurs only with sectioning of the interosseous ligaments.

Question 14

Osteochondromatosis is a hereditary genetic disorder that is:

Explanation

Osteochondromatosis (also known as hereditary multiple exostoses) is a genetic disorder that is autosomal dominant with incomplete penetrance in women. The genetic defect occurs on the EXT1, EXT2, and EXT 3 genes located on chromosome 8q24.

Question 15

Osteochondromatosis is a hereditary genetic disorder that is caused by:

Explanation

Osteochondromatosis (also known as hereditary multiple exostoses) is a genetic disorder that is autosomal dominant with incomplete penetrance in women. The genetic defect occurs on the EXT1, EXT2, and EXT 3 genes located on chromosome 8q24. Mutation in the fibrillin-1 gene is seen in patients with Marfan syndrome. Translocation between chromosomes 9 and 22 is seen in myxoid chondrosarcoma. Mutation in the g-fos gene is seen in patients with Ollierâ s disease. Translocation between chromosomes 11 and 22 is present in patientâ s with Ewings tumor.

Question 16

Osteochondromas in the spine most commonly occur in:

Explanation

Osteochondromas most commonly occur in the appendicular skeleton but can also occur in the spine (<5% of cases). When present in the spine, solitary osteochondromas have a predilection for the cervical spine. They can, however, also occur in the thoracic and lumbar spine. Sacral involvement is rare.

Question 17

When an osteoid osteoma occurs in the spine, it can involve all of the following except:

Explanation

When an osteoid osteoma occurs in the spine, involvement of the posterior elements of the vertebra is typical and includes: Lamina Pedicles Transverse processes Facets Rib heads adjacent to thoracic vertebrae

Question 18

Typical histologic features of an osteoid osteoma include all of the following except:

Explanation

The histologic features of an osteoid osteoma include the following: Nidus composed of haphazardly arranged network of osteoid trabeculae Varying degrees of mineralization with greatest mineralization in the center of the lesion Loose fibrovascular connective tissue between trabeculae Osteoblasts rimming the trabeculae Vascularized spindle cell stroma

Question 19

Treatment of a vertebral osteoid osteoma includes all of the following except:

Explanation

Treatment of osteoid osteomas in the spine include the following: Aspirin/salicylates/NSAIDs Administered for up to 2 years Successful in up to 50% cases Radiofrequency ablation (RFA) Usually computed tomography-guided Clinical success rates as high as 97% have been reported with 1 to 2 treatments Surgical excision of the nidus/curettage Necessary when aspirin/salicylates/NSAIDs cannot be tolerated for long periods of time and RFA is not possible or unsuccessful Can usually be accomplished through a posterior approach En-bloc resection or a more radical procedure play no role in management

Question 20

Typical symptoms of a spinal osteoblastoma include all of the following except:

Explanation

The most common symptoms of spinal osteoblastomas include: Pain Usually the first and most common presenting symptom Night pain is not as common as it is with osteoid osteomas Night pain is not as common as it is with osteoid osteomas Painful scoliosis Torticollis Stiffness Radicular symptoms usually due to mass effect

Question 21

Which of the following equations correctly defines the relationship between spinopelvic parameters?

Explanation

Pelvic incidence (PI) is a fixed morphological parameter defined as the sum of pelvic tilt (PT) and sacral slope (SS). Therefore, PI = PT + SS.

Question 22

In a normal, asymptomatic adult, the C7 plumb line (Sagittal Vertical Axis) should fall within what distance relative to the posterior superior corner of the S1 endplate?

Explanation

A normal sagittal vertical axis (SVA) is considered balanced when the C7 plumb line falls within 5 cm of the posterior superior corner of the sacrum. Values greater than 5 cm anteriorly indicate positive sagittal imbalance.

Question 23

Which of the following spinopelvic parameters is considered a fixed morphological parameter that does not change with posture after skeletal maturity?

Explanation

Pelvic incidence is a fixed anatomical parameter dictated by the morphology of the pelvis. It remains constant regardless of posture, unlike pelvic tilt and sacral slope which act as dynamic compensatory parameters.

Question 24

When planning surgical correction for adult spinal deformity, the generally accepted target for lumbar lordosis (LL) relative to pelvic incidence (PI) is:

Explanation

For optimal sagittal balance, the lumbar lordosis should be matched to the patient's pelvic incidence. The widely accepted target for correction is to have PI minus LL be less than or equal to 10 degrees.

Question 25

As a patient develops positive sagittal imbalance due to age-related degenerative loss of lumbar lordosis, which of the following compensatory mechanisms initially occurs at the pelvis?

Explanation

To compensate for a loss of lumbar lordosis and an anterior shift of the sagittal vertical axis, the pelvis retroverts. This pelvic retroversion results in an increased pelvic tilt and a reciprocally decreased sacral slope.

Question 26

A 65-year-old patient requires a corrective osteotomy for a rigid flatback deformity. Approximately how much sagittal correction can be expected from a single-level pedicle subtraction osteotomy (PSO)?

Explanation

A pedicle subtraction osteotomy (PSO) is a three-column, closing-wedge osteotomy hinged at the anterior cortex. It typically provides 30 to 35 degrees of lordosis correction per treated level.

Question 27

A patient with ankylosing spondylitis presents with severe cervicothoracic kyphosis. Surgical correction is planned. What is the optimal target for the chin-brow vertical angle (CBVA) to ensure appropriate forward gaze?

Explanation

The chin-brow vertical angle (CBVA) evaluates horizontal gaze and functional vision. An angle between 10 and 20 degrees is generally considered optimal to allow patients to see straight ahead and walk safely.

Question 28

In the evaluation of cervical sagittal balance, the T1 slope is most analogous to which parameter in the lumbar spinopelvic evaluation?

Explanation

The T1 slope acts as the foundational parameter for the cervical spine, dictating the magnitude of required cervical lordosis to maintain balance. It is highly analogous to pelvic incidence in the lumbar spine.

Question 29

Proximal junctional kyphosis (PJK) after long-segment spinal fusion is typically defined as a proximal junctional sagittal Cobb angle of at least 10 degrees and a change from the preoperative measurement of at least:

Explanation

Proximal junctional kyphosis is defined as a proximal junctional angle greater than 10 degrees. Furthermore, it requires an abnormal increase of at least 10 degrees compared to preoperative standing measurements.

Question 30

In the standard measurement of lumbar lordosis using the Cobb angle method on a standing lateral radiograph, which anatomical landmarks are most commonly utilized?

Explanation

Global lumbar lordosis is standardly measured as the Cobb angle between the superior endplate of L1 and the superior endplate of S1. The majority of this lordosis normally occurs distally between L4 and S1.

Question 31

Which of the following spinopelvic parameter profiles is most characteristically associated with a high risk of progression in L5-S1 isthmic spondylolisthesis?

Explanation

High pelvic incidence forces a correspondingly high sacral slope, which exponentially increases anterior shear forces at the L5-S1 junction. This specific profile is strongly associated with the development and progression of isthmic spondylolisthesis.

Question 32

When pelvic retroversion is exhausted in a patient with severe positive sagittal malalignment, what is the next typical compensatory mechanism involving the lower extremities?

Explanation

When the pelvis can no longer retrovert to compensate for an anterior sagittal shift, the patient will typically resort to hip extension and knee flexion. This crouching stance helps physically shift the center of gravity posteriorly over the feet.

Question 33

The T1 Pelvic Angle (TPA) is a measure of global sagittal alignment. It is defined as the angle between a line from the center of the femoral heads to the center of the S1 endplate, and a line from the femoral heads to the:

Explanation

The T1 Pelvic Angle (TPA) is constructed by drawing a line from the femoral heads to the center of the T1 body and another to the center of the S1 superior endplate. A TPA greater than 14 degrees indicates significant sagittal deformity.

Question 34

A 45-year-old female presents with a rigid, focal, angular kyphotic deformity of 65 degrees following an old burst fracture. To achieve optimal correction, which of the following osteotomies is most indicated?

Explanation

Vertebral Column Resection (VCR) is a three-column osteotomy involving complete removal of the vertebral body and posterior elements. It is indicated for rigid, focal, and severe coronal or sagittal deformities exceeding 40 degrees where a PSO would be insufficient.

Question 35

In a healthy adult with normal sagittal alignment, which vertebra typically represents the apex of thoracic kyphosis?

Explanation

The normal thoracic kyphosis spans from T1 to T12. The structural apex of this curve is typically located around T6 or T7.

Question 36

Cervical sagittal vertical axis (cSVA) is used to assess cervical spinal alignment. It is measured as the horizontal distance between the C2 plumb line and the:

Explanation

The cervical SVA is measured as the horizontal distance from the C2 plumb line to the posterior superior corner of the C7 endplate. Normal values are generally less than 4 cm, with higher values correlating with disability.

Question 37

A surgeon plans to perform a Smith-Petersen osteotomy (SPO) to correct a sagittal deformity. Which of the following is a strict prerequisite for an SPO to effectively induce lordosis?

Explanation

An SPO relies on hinging through the posterior column while the anterior column acts as an opening wedge. Therefore, a mobile anterior disc space is an absolute prerequisite for the osteotomy to close posteriorly and successfully achieve lordosis.

Question 38

In an individual standing upright, if the pelvic incidence is 50 degrees and the pelvic tilt is 15 degrees, what is the orientation of the sacral endplate relative to the horizontal plane?

Explanation

The sacral slope (SS) is defined as the angle of the sacral endplate relative to the horizontal plane. Since Pelvic Incidence = Pelvic Tilt + Sacral Slope, the SS must be 35 degrees (50 - 15 = 35).

Question 39

Which of the following is considered the normal range for cervical lordosis (measured from C2 to C7) in asymptomatic adults?

Explanation

Normal cervical lordosis measured from C2 to C7 generally ranges from 20 to 40 degrees. The subaxial spine (C3-C7) works in tandem with the upper cervical spine to maintain a horizontal gaze and global alignment.

Question 40

According to the Roussouly classification of sagittal alignment, a Type 1 spine is typically characterized by which of the following features?

Explanation

In the Roussouly classification, Type 1 is characterized by a low sacral slope (less than 35 degrees) and a low pelvic incidence. The lumbar lordosis is notably short and concentrated distally, coupled with a prominent thoracolumbar kyphosis.

Question 41

A 65-year-old woman presents with progressive low back pain and leaning forward while walking. Radiographs reveal a pelvic incidence (PI) of 60 degrees. Which of the following formulas correctly defines the relationship between pelvic incidence, pelvic tilt (PT), and sacral slope (SS)?

Explanation

Pelvic incidence is a fixed morphological parameter defined as the sum of pelvic tilt and sacral slope (PI = PT + SS). It dictates the required lumbar lordosis for a patient to achieve sagittal balance.

Question 42

In surgical planning for an adult patient with severe sagittal imbalance, the surgeon calculates the patient's pelvic incidence (PI) to be 55 degrees. To achieve optimal postoperative sagittal alignment and minimize the risk of adjacent segment disease, the target lumbar lordosis (LL) should be:

Explanation

For optimal sagittal balance, the lumbar lordosis (LL) should match the pelvic incidence (PI) within 10 degrees (PI - LL < 10 degrees). Therefore, a PI of 55 degrees requires an LL of approximately 45 to 65 degrees.

Question 43

Which of the following compensatory mechanisms occurs FIRST in a patient developing progressive positive sagittal spinal imbalance?

Explanation

The initial compensatory mechanism for positive sagittal imbalance is pelvic retroversion, which increases pelvic tilt (PT) and decreases sacral slope (SS). As the deformity worsens and pelvic compensation is exhausted, knee flexion and hip extension occur.

Question 44

A 40-year-old male with iatrogenic flatback syndrome requires surgical correction. The surgeon plans a Pedicle Subtraction Osteotomy (PSO) at L3. Approximately how many degrees of sagittal correction can be expected from a single-level standard PSO?

Explanation

A pedicle subtraction osteotomy (PSO) is a three-column closing wedge osteotomy that typically provides 30 to 40 degrees of sagittal correction at a single level. In contrast, a Smith-Petersen Osteotomy (SPO) yields about 10 degrees per level.

Question 45

Which of the following radiographic parameters is considered a rigid, position-independent morphological feature of the pelvis that does NOT change with patient posture?

Explanation

Pelvic incidence (PI) is an anatomical parameter fixed at skeletal maturity and does not change with posture. Pelvic tilt, sacral slope, and SVA are dynamic parameters that alter with the patient's positional compensatory mechanisms.

Question 46

During surgical correction of a fixed severe cervicothoracic kyphosis in a patient with Ankylosing Spondylitis, the primary goal is to optimize the patient's horizontal gaze. Which of the following targets for the Chin-Brow Vertical Angle (CBVA) is associated with the best functional outcome?

Explanation

The Chin-Brow Vertical Angle (CBVA) correlates with horizontal gaze and quality of life in ankylosing spondylitis. The optimal postoperative target is typically between 10 and 20 degrees of flexion to allow for safe ambulation and forward viewing.

Question 47

A 15-year-old girl with Adolescent Idiopathic Scoliosis (AIS) presents for evaluation. In addition to coronal deformity, which of the following is the characteristic sagittal profile seen in the thoracic spine of patients with typical right thoracic AIS?

Explanation

Adolescent Idiopathic Scoliosis (AIS) is typically a lordoscoliosis, characterized by a relative hypokyphosis or true lordosis in the thoracic spine. This is primarily due to anterior spinal overgrowth relative to the posterior elements.

Question 48

Which of the following spinopelvic profiles is most classically associated with the development and progression of high-grade isthmic spondylolisthesis (e.g., L5-S1) in an adolescent?

Explanation

High pelvic incidence (PI) is a primary predisposing factor for the development and progression of isthmic spondylolisthesis. A higher PI requires a higher sacral slope and compensatory lumbar lordosis, increasing the shear forces across the L5-S1 pars interarticularis.

Question 49

A patient develops Proximal Junctional Kyphosis (PJK) following a T10 to pelvis posterior spinal fusion. Which of the following factors most significantly increases the risk of developing PJK?

Explanation

Over-correction of sagittal alignment, specifically excessive lumbar lordosis and shifting the SVA too far posteriorly, significantly increases mechanical stress at the proximal junction, leading to PJK. Extensive disruption of the posterior tension band is also a major risk factor.

Question 50

In an asymptomatic adult with a normal spine, the C7 plumb line (Sagittal Vertical Axis) should ideally fall within what distance relative to the posterior superior corner of the S1 endplate?

Explanation

In a normally aligned spine, the C7 plumb line should fall within 5 cm (anteriorly or posteriorly) of the posterior superior corner of the S1 endplate. Values greater than 5 cm anteriorly define positive sagittal imbalance.

Question 51

A 70-year-old male presents with severe leaning forward. You measure his T1 Pelvic Angle (T1PA). Which of the following best describes the advantage of using T1PA over Sagittal Vertical Axis (SVA) in assessing global spinal alignment?

Explanation

The T1 Pelvic Angle (T1PA) is the angle between a line from the femoral heads to T1 and a line from the femoral heads to the S1 endplate. Unlike SVA, it is an angular measure that is not affected by pelvic retroversion or knee flexion compensations.

Question 52

A normal aging spine typically undergoes which of the following combined sagittal plane changes over time?

Explanation

With normal aging, disc degeneration and loss of anterior column height lead to a decrease in lumbar lordosis and an increase in thoracic kyphosis. This progression often shifts the global alignment toward a positive sagittal vertical axis.

Question 53

When evaluating cervical spine sagittal balance, the Cervical Sagittal Vertical Axis (cSVA) is typically measured as the distance between the C2 plumb line and the:

Explanation

The cervical SVA (cSVA) is defined as the horizontal distance from a plumb line dropped from the centroid of C2 to the posterior superior corner of the C7 vertebral body. A normal cSVA is generally less than 4 cm.

Question 54

A 16-year-old male is evaluated for hyperkyphosis. Radiographs reveal anterior wedging of 6 degrees at T7, T8, and T9. What is the most likely diagnosis based on Sorensen's criteria?

Explanation

Sorensen's criteria for Scheuermann's kyphosis require the presence of at least 5 degrees of anterior wedging in at least three adjacent vertebrae. Additional findings often include Schmorl's nodes and irregular endplates.

Question 55

During multi-level posterior spinal fusion for degenerative scoliosis, Smith-Petersen Osteotomies (SPOs) are performed. Which spinal column(s) is/are shortened and lengthened during an SPO?

Explanation

A Smith-Petersen Osteotomy (SPO) involves resection of the posterior ligaments and facet joints. Upon closure, it shortens the posterior column and lengthens the anterior column by hinging on the posterior annulus/ligamentum flavum.

Question 56

A 68-year-old female undergoes a T10 to pelvis fusion. Postoperatively, she develops a 'flatback deformity'. Which of the following consequences is most likely a direct result of this specific iatrogenic deformity?

Explanation

Flatback syndrome results from a loss of normal lumbar lordosis, causing an anterior shift in the center of gravity (positive SVA). Patients experience severe paraspinal muscle fatigue and pain as they constantly recruit these muscles to maintain an upright posture.

Question 57

Which of the following describes the mathematical relationship between pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS)?

Explanation

Pelvic incidence is a fixed morphological parameter determined by the equation PI = PT + SS. As an individual changes position, PT and SS vary inversely to maintain a constant PI.

Question 58

In an aging patient developing progressive sagittal imbalance (positive sagittal vertical axis), which of the following is the primary initial compensatory mechanism at the pelvis?

Explanation

To compensate for a positive sagittal vertical axis (forward leaning), the body retroverts the pelvis, which increases pelvic tilt (PT) and decreases sacral slope (SS). Knee flexion and cervical hyperlordosis are secondary compensations.

Question 59

According to the SRS-Schwab adult spinal deformity classification, an ideal post-operative alignment goal for the relationship between Pelvic Incidence (PI) and Lumbar Lordosis (LL) is:

Explanation

The SRS-Schwab criteria recommend a post-operative PI-LL mismatch of less than 10 degrees to achieve optimal sagittal balance and reduce adjacent segment disease. Other targets include a PT < 20 degrees and SVA < 50 mm.

Question 60

In a normal standing adult with balanced sagittal alignment, which vertebra typically has its endplates perfectly parallel to the floor?

Explanation

In normal sagittal alignment, L3 is typically the apex of the lumbar lordosis curve or the vertebra positioned with its endplates most horizontal (parallel) to the ground.

Question 61

Which parameter in the cervical spine is considered the morphological equivalent of pelvic incidence and remains constant regardless of patient positioning?

Explanation

The Thoracic Inlet Angle (TIA) is a fixed anatomical parameter defined as the sum of T1 slope and Neck Tilt (TIA = T1S + NT). It dictates the amount of cervical lordosis required for horizontal gaze.

Question 62

Sorensen's criteria for the radiographic diagnosis of Scheuermann's disease requires anterior wedging of at least 5 degrees in how many consecutive vertebrae?

Explanation

Scheuermann's kyphosis is classically defined by Sorensen criteria, which require anterior wedging of 5 degrees or more in at least three adjacent vertebrae. It typically involves rigid thoracic hyperkyphosis and Schmorl's nodes.

Question 63

Which pelvic parameter is typically significantly elevated in patients with high-grade dysplastic spondylolisthesis compared to the normal population?

Explanation

A high Pelvic Incidence (PI) increases shear forces at the lumbosacral junction and is strongly associated with the development and progression of isthmic and dysplastic spondylolisthesis.

Question 64

Which of the following congenital spinal anomalies has the highest risk of rapid curve progression?

Explanation

A unilateral unsegmented bar with a contralateral fully segmented hemivertebra has the worst prognosis for progression. It represents a combination of restricted growth on one side and accelerated asymmetric growth on the other.

Question 65

A 65-year-old female undergoes T10-pelvis fusion for adult spinal deformity. Six months later, she develops Proximal Junctional Kyphosis (PJK). By definition, the proximal junctional sagittal angle must be at least:

Explanation

PJK is classically defined as a proximal junctional angle >10 degrees that is also at least 10 degrees greater than the preoperative measurement. It most commonly occurs at the uppermost instrumented vertebra (UIV) and UIV+2.

Question 66

A patient with ankylosing spondylitis requires a pedicle subtraction osteotomy (PSO) for severe chin-on-chest deformity. A single-level lumbar PSO typically provides approximately how many degrees of sagittal correction?

Explanation

A pedicle subtraction osteotomy (PSO) is a three-column wedge osteotomy hinged at the anterior longitudinal ligament. It typically yields about 30 to 35 degrees of lordotic correction per level.

Question 67

In the Lenke classification for adolescent idiopathic scoliosis, a lumbar modifier of "B" indicates that the Center Sacral Vertical Line (CSVL) falls:

Explanation

In the Lenke classification, a "B" modifier means the CSVL falls between the medial aspect of the concave pedicle and the lateral margin of the apical lumbar vertebral body. "A" is between the pedicles, and "C" is entirely medial to the body.

Question 68

Which Risser stage corresponds to complete ossification and fusion of the iliac apophysis to the ilium, indicating skeletal maturity?

Explanation

Risser 5 indicates complete capping and fusion of the iliac apophysis to the ilium, signaling the end of spinal growth. Risser 1-4 correspond to the progressive lateral-to-medial ossification of the apophysis.

Question 69

With normal aging, which of the following sequences best represents the typical cascade of sagittal spinal alignment changes?

Explanation

Aging typically causes disc degeneration and loss of lumbar lordosis, leading to a positive (forward) sagittal vertical axis (SVA). The body compensates sequentially via pelvic retroversion (increased PT), hip extension, and finally knee flexion.

Question 70

The Sagittal Vertical Axis (SVA) is a key metric in evaluating global spinal alignment. It is measured as the horizontal distance between a plumb line dropped from the center of C7 and which anatomical landmark?

Explanation

The SVA is measured as the horizontal offset between the C7 plumb line and the posterior superior corner of the S1 endplate. A normal SVA is considered to be less than 50 mm.

Question 71

When a healthy individual transitions from a standing to a seated position, how do the pelvic parameters normally adjust?

Explanation

During sitting, the pelvis undergoes retroversion to accommodate hip flexion and maintain trunk balance. This results in an increased pelvic tilt (PT) and a correspondingly decreased sacral slope (SS), while pelvic incidence (PI) remains constant.

Question 72

Which region of the normal adult spine typically acts as a transition zone and is generally considered straight (zero degrees) in the sagittal plane?

Explanation

The thoracolumbar junction (typically T10-L2) is a transitional zone between the kyphotic thoracic spine and the lordotic lumbar spine. It is normally straight (0 degrees) in the sagittal plane.

Question 73

On an anteroposterior (AP) radiograph of the lumbar spine, the pedicles of which vertebra are normally most widely separated?

Explanation

The interpedicular distance normally increases steadily from L1 to L5. The L5 pedicles are the widest apart, accommodating the expanded size of the thecal sac and nerve roots exiting the lumbosacral junction.

Question 74

In evaluating coronal balance on full-length standing spine radiographs, the Central Sacral Vertical Line (CSVL) is drawn vertically from which starting point?

Explanation

The CSVL is a vertical reference line drawn straight upward from the exact center (bisection) of the S1 superior endplate. Coronal decompensation is measured as the horizontal distance from the C7 plumb line to this CSVL.

Question 75

In the functional spinal unit of the normal lumbar spine, where is the instantaneous axis of rotation (IAR) located during flexion-extension?

Explanation

During flexion and extension of the lumbar spine, the instantaneous axis of rotation (IAR) normally lies within the posterior third of the intervertebral disc. Pathological translation occurs when this axis shifts due to instability.

Question 76

According to the Meyerding grading system for spondylolisthesis, a slip of 60% of the superior vertebral body over the inferior vertebral body is classified as:

Explanation

The Meyerding classification grades slip percentage as follows: Grade 1 (0-25%), Grade 2 (26-50%), Grade 3 (51-75%), Grade 4 (76-100%), and Spondyloptosis (>100%). A 60% slip falls into Grade 3.

Question 77

What is the fundamental mathematical relationship between Pelvic Incidence (PI), Pelvic Tilt (PT), and Sacral Slope (SS) in spino-pelvic alignment?

Explanation

Pelvic incidence is a fixed morphological parameter defined as the sum of pelvic tilt and sacral slope (PI = PT + SS). It dictates the required lumbar lordosis for optimal sagittal balance.

Question 78

When surgically correcting adult spinal deformity, which of the following postoperative spino-pelvic parameters is associated with the best health-related quality of life (HRQOL) scores according to the SRS-Schwab criteria?

Explanation

The SRS-Schwab criteria for optimal HRQOL outcomes include a Sagittal Vertical Axis (SVA) < 5 cm, Pelvic Tilt (PT) < 20 degrees, and a PI-LL mismatch of < 10 degrees.

Question 79

In a normal healthy adult, what percentage of the total lumbar lordosis is typically distributed between the L4 and S1 segments?

Explanation

Approximately two-thirds (66%) of total lumbar lordosis is concentrated in the lower lumbar spine between L4 and S1. This anatomic fact is critical when planning interbody fusions to restore normal sagittal contours.

Question 80

A patient with rigid positive sagittal imbalance requires 30 degrees of lordotic correction at a single level. Which of the following techniques is most appropriate to achieve this exact degree of correction?

Explanation

A Pedicle Subtraction Osteotomy (PSO) is a three-column, closing wedge osteotomy that typically provides 30 to 35 degrees of sagittal correction at a single level. In contrast, an SPO provides approximately 10 degrees per level.

Question 81

A 65-year-old patient presents with a progressive positive sagittal vertical axis (SVA). Which of the following represents the body's initial primary compensatory mechanism to maintain horizontal gaze and standing balance?

Explanation

The initial compensatory mechanism for a positive SVA is pelvic retroversion, which manifests radiographically as an increased Pelvic Tilt (PT). As this mechanism exhausts, patients subsequently resort to knee flexion and hip extension.

Question 82

Which of the following parameters is used to assess the spino-pelvic equivalent for the cervical spine, helping to determine the ideal cervical lordosis and risk of adjacent segment disease?

Explanation

T1 slope acts similarly to pelvic incidence for the cervical spine. A mismatch of T1 Slope minus Cervical Lordosis (T1S - CL) greater than 15-20 degrees correlates with poor clinical outcomes and increased neck disability.

Question 83

What is the classic Sorensen radiographic criteria for diagnosing Scheuermann's kyphosis?

Explanation

The Sorensen criteria define Scheuermann's disease as anterior wedging of greater than 5 degrees in at least three consecutive vertebrae. It is often accompanied by Schmorl's nodes and irregular vertebral endplates.

Question 84

In patients with developmental L5-S1 high-grade spondylolisthesis, which spino-pelvic parameter is characteristically significantly elevated compared to the normal population?

Explanation

Patients with isthmic or dysplastic spondylolisthesis characteristically have a high Pelvic Incidence (PI). A higher PI leads to greater sacral slope and higher shear forces at the lumbosacral junction, predisposing to slip progression.

Question 85

A patient with Ankylosing Spondylitis is undergoing preoperative planning for a lumbar osteotomy to correct severe fixed kyphosis. Which of the following clinical measurements is most critical for determining the required degree of correction to restore horizontal gaze?

Explanation

The Chin-Brow Vertical Angle (CBVA) is essential in assessing horizontal gaze in rigid cervicothoracic or thoracolumbar deformities. The surgical goal is typically to restore the CBVA to between +10 degrees and -10 degrees.

Question 86

In a healthy, sagittally balanced adult, the C7 plumb line should fall within what structure on a standing lateral radiograph?

Explanation

The normal Sagittal Vertical Axis (SVA), measured by dropping a plumb line from the center of the C7 vertebral body, should pass within +/- 2 cm of the posterior superior corner of the S1 endplate.

Question 87

When treating an adolescent with a Lenke 1A curve, fusing down to the stable vertebra is historically considered. How is the stable vertebra defined on a standing PA radiograph?

Explanation

The stable vertebra is defined as the most proximal (caudal to the curve) vertebra that is substantially bisected by the Central Sacral Vertical Line (CSVL). Identifying it helps determine the Lowest Instrumented Vertebra (LIV).

Question 88

A 13-year-old female presents with a 25-degree right thoracic scoliosis curve. Radiographs show ossification over the lateral 50% of the iliac apophysis, but it has not reached the medial half. What is her Risser grade?

Explanation

Risser 2 indicates ossification of 25% to 50% of the iliac apophysis. Risser 1 is 0-25%, Risser 3 is 50-75%, Risser 4 is 75-100% (without fusion), and Risser 5 is complete fusion of the apophysis to the ilium.

Question 89

Which of the following is considered a significant risk factor for the development of Proximal Junctional Kyphosis (PJK) following long posterior spinal fusion for adult deformity?

Explanation

Risk factors for PJK include overcorrection of sagittal alignment, older age, high body mass index, and disruption of the posterior ligamentous complex at the Upper Instrumented Vertebra (UIV).

Question 90

A 14-year-old gymnast complains of lower back pain aggravated by extension. Plain radiographs are negative. Which imaging modality has historically been considered the gold standard for detecting an acute, metabolically active pars interarticularis stress fracture?

Explanation

A SPECT scan (Single Photon Emission Computed Tomography) is highly sensitive for detecting metabolically active pars stress reactions. While MRI is increasingly preferred to avoid radiation, SPECT remains the classic gold standard for confirming metabolic activity.

Question 91

A 72-year-old female with adult spinal deformity requires a long segment fusion. Her DEXA scan reveals a T-score of -3.2. To maximize pedicle screw pull-out strength, which surgical modification is most effective?

Explanation

Undertapping the pedicle by 1 mm compared to the screw diameter significantly increases pullout strength in osteoporotic bone. Maximizing screw diameter, length, and utilizing cement augmentation are also highly effective strategies.

Question 92

What is the formula for the target Lumbar Lordosis (LL) based on Pelvic Incidence (PI) to minimize the risk of adjacent segment disease and sagittal imbalance?

Explanation

To maintain harmonious sagittal balance and reduce the risk of adjacent segment breakdown, the target lumbar lordosis should ideally be within 10 degrees of the patient's fixed pelvic incidence (PI - LL ≤ 10 degrees).

Question 93

In evaluating a patient with cervical myelopathy, the C2-C7 Sagittal Vertical Axis (SVA) is measured. A value greater than which of the following thresholds is most strongly correlated with poor clinical outcomes and increased neck pain?

Explanation

A C2-C7 SVA greater than 4 cm (40 mm) indicates severe cervical sagittal imbalance. It is strongly correlated with increased neck disability index (NDI) scores and poor surgical outcomes.

Question 94

When performing a long fusion to the sacrum for adult deformity, S2-alar-iliac (S2AI) screws are commonly used. What is the primary biomechanical and technical advantage of S2AI screws compared to traditional iliac screws?

Explanation

The primary advantage of S2AI screws is that their starting point is in-line with the S1 and lumbar pedicle screws, minimizing the need for complex rod contouring or bulky offset connectors.

Question 95

Which of the following vertebral anomalies carries the highest risk of rapid curve progression in congenital scoliosis?

Explanation

A unilateral unsegmented bar combined with a contralateral fully segmented hemivertebra at the same level possesses the greatest growth potential asymmetry. This anomaly leads to extremely rapid curve progression requiring early surgical intervention.

Question 96

Which of the following is true regarding the normal anatomical alignment of the thoracic spine?

Explanation

Normal thoracic kyphosis ranges from 20 to 50 degrees (measured as the Cobb angle from T2 to T12) with its apex typically located between the T6 and T8 levels. Unlike lumbar lordosis, thoracic kyphosis naturally increases with age.

Orthopedic Prometric MCQs - Chapter 3 Part 1

Orthopedic Prometric MCQs - Chapter 3 Part 33

Orthopedic Prometric MCQs - Chapter 3 Part 33

Chapter Index