This practice set contains high-yield board review questions covering key concepts in Thoracolumbar Spine & Deformity. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 401
Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast presents with persistent lower back and radicular leg pain. Imaging reveals an L5-S1 isthmic spondylolisthesis with 60% anterior translation of L5 on S1 (Meyerding Grade III). She has failed non-operative management, and surgical reduction with instrumented fusion is planned. Which nerve root is at the highest risk of iatrogenic traction injury during the reduction maneuver?
Correct Answer & Explanation
. L5
Explanation
During the surgical reduction of a high-grade L5-S1 spondylolisthesis, the L5 nerve root is at the highest risk for traction injury. As L5 is pulled posteriorly and superiorly to align with S1, the L5 nerve root becomes stretched over the sacral ala.
Question 402
Topic: Thoracolumbar Spine & Deformity
A 15-year-old female gymnast complains of chronic lower back pain. Lateral lumbar radiographs reveal an isthmic spondylolisthesis at L5-S1 with 65% anterior translation of L5 on S1. According to the Meyerding classification, what grade is this slip?
Correct Answer & Explanation
. Grade III
Explanation
The Meyerding classification grades spondylolisthesis based on the percentage of anterior translation of the superior vertebral body over the inferior one. Grade I: 0-25%; Grade II: 26-50%; Grade III: 51-75%; Grade IV: 76-100%; Grade V: >100% (Spondyloptosis). A 65% slip falls into the Grade III category.
Question 403
Topic: Thoracolumbar Spine & Deformity
A 14-year-old female gymnast complains of chronic, activity-related low back pain. Radiographs reveal a Grade II spondylolisthesis at L5-S1. If this is an isthmic spondylolisthesis, what is the primary anatomic etiology of the slippage?
Correct Answer & Explanation
. A bilateral defect or stress fracture in the pars interarticularis
Explanation
Isthmic spondylolisthesis (Wiltse Type II) is caused by a defect (spondylolysis), elongation, or acute fracture in the pars interarticularis. This is common in adolescent athletes involved in repetitive lumbar hyperextension (e.g., gymnasts, fast bowlers). Dysplastic spondylolisthesis (Wiltse Type I) is due to congenital anomalies of the upper sacrum or the arch of L5 (facet joint dysplasia).
Question 404
Topic: Thoracolumbar Spine & Deformity
A 16-year-old gymnast complains of chronic low back pain exacerbated by extension. Radiographs and subsequent MRI show a unilateral pars interarticularis defect at L5 without evidence of spondylolisthesis.
She has failed 6 months of structured conservative management including bracing and physical therapy. She strongly wishes to return to competitive gymnastics. What is the most appropriate surgical intervention?
Correct Answer & Explanation
. Direct surgical repair of the pars interarticularis (e.g., pedicle screw-hook construct)
Explanation
In young, active patients (like athletes) with symptomatic spondylolysis (pars defect) who fail nonoperative treatment and do not have a significant spondylolisthesis, direct pars repair is the procedure of choice. Techniques include the Buck procedure (direct lag screw), Scott wiring, or a pedicle screw-laminar hook construct. This preserves the motion segment and allows a higher rate of return to sports compared to fusion.
Question 405
Topic: Thoracolumbar Spine & Deformity
A 65-year-old female presents with neurogenic claudication and lower back pain. Radiographs reveal a grade I L4-L5 degenerative spondylolisthesis. Which of the following anatomical features is most characteristic of degenerative spondylolisthesis compared to isthmic spondylolisthesis?
Correct Answer & Explanation
. Sagittal orientation of the facet joints
Explanation
Degenerative spondylolisthesis most commonly occurs at L4-L5 and is associated with a more sagittal orientation of the facet joints, which allows for anterior translation as the disc and joints degenerate without a pars defect. Isthmic spondylolisthesis involves a pars interarticularis defect, most commonly occurs at L5-S1, and is often associated with higher pelvic incidence.
Question 406
Topic: Thoracolumbar Spine & Deformity
A 32-year-old female falls from a height. CT of the lumbar spine reveals an L1 burst fracture. There is splaying of the spinous processes on the AP radiograph. MRI confirms disruption of the posterior ligamentous complex (PLC). Neurological examination is completely normal. According to the Thoracolumbar Injury Classification and Severity (TLICS) score, what is her total score and the recommended management?
Correct Answer & Explanation
. Score 5; operative management.
Explanation
TLICS scoring involves three categories: Morphology: Burst fracture = 2 points. Neurology: Intact = 0 points. Posterior Ligamentous Complex (PLC): Disrupted = 3 points. Total score = 5 points. A score > 4 indicates operative management is strongly recommended.
Question 407
Topic: Thoracolumbar Spine & Deformity
In the radiographic evaluation of adult spinal deformity, pelvic parameters are critical for restoring sagittal balance. Which of the following equations accurately defines the geometric relationship between pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS)?
Correct Answer & Explanation
. PI = PT + SS
Explanation
Pelvic incidence (PI) is a fixed anatomical morphological parameter unique to each individual after skeletal maturity. It dictates the orientation of the pelvis and is geometrically equal to the sum of the pelvic tilt (PT) and the sacral slope (SS): PI = PT + SS. A patient's required lumbar lordosis is typically matched to their PI (LL = PI ± 9 degrees).
Question 408
Topic: Thoracolumbar Spine & Deformity
A 40-year-old construction worker falls from a scaffolding, sustaining an L1 burst fracture. He is neurologically intact. According to the Thoracolumbar Injury Classification and Severity (TLICS) score, which of the following findings would unequivocally push his score to 5 or higher, thereby strongly favoring operative intervention?
Correct Answer & Explanation
. Disruption of the posterior ligamentous complex (PLC)
Explanation
The TLICS scoring system aids in deciding whether a thoracolumbar fracture requires surgery. It is based on three categories: injury morphology, neurological status, and integrity of the posterior ligamentous complex (PLC). A burst fracture (morphology) gives 2 points. Intact neuro status gives 0 points. A confirmed disruption of the PLC adds 3 points. Thus, 2 + 0 + 3 = 5 points. A score of 4 can be treated conservatively or operatively (surgeon's choice), while a score greater than 4 strongly dictates operative intervention. Neither loss of height alone nor the degree of canal compromise automatically mandates surgery without neuro deficits or PLC injury.
Question 409
Topic: Thoracolumbar Spine & Deformity
In the evaluation of a traumatic spine injury using the Thoracolumbar Injury Classification and Severity (TLICS) score, which of the following mechanisms of injury is assigned the highest number of points?
Correct Answer & Explanation
. Distraction
Explanation
The TLICS score assigns points based on morphology/mechanism: Compression (1 point), Burst (2 points), Translation/Rotation (3 points), and Distraction (4 points). Therefore, a distraction mechanism yields the highest point value in this category, reflecting the severe instability typical of these injuries (e.g., flexion-distraction/Chance fractures).
Question 410
Topic: Thoracolumbar Spine & Deformity
A 65-year-old female presents with progressive back pain and increasing truncal imbalance. Her sagittal balance parameters show a Sagittal Vertical Axis (SVA) of +10 cm, Pelvic Incidence (PI) of 60 degrees, Lumbar Lordosis (LL) of -30 degrees, and Pelvic Tilt (PT) of 35 degrees. She has failed extensive conservative management.
Based on these radiographic parameters, what is the most appropriate surgical goal to restore optimal sagittal alignment?
Correct Answer & Explanation
. Match LL to PI (PI-LL < 10 degrees).
Explanation
The patient presents with significant sagittal malalignment, characterized by a large positive SVA (+10 cm), increased Pelvic Tilt (35 degrees), and a substantial mismatch between Pelvic Incidence (PI) and Lumbar Lordosis (LL) (PI-LL = 60 - 30 = 30 degrees). For adult spinal deformity, a key surgical goal for optimal sagittal balance is to achieve an LL that is closely matched to the PI, specifically aiming for a PI-LL mismatch of < 10 degrees. This ensures that the spine can efficiently balance the trunk over the pelvis. While an SVA < 5 cm is generally desired, and reducing pelvic tilt is part of overall correction, the PI-LL mismatch is a primary driver of sagittal malalignment and a critical parameter for surgical planning. Simply increasing LL to > 60 degrees without considering PI is insufficient. Reducing SVA by 15 cm is a consequence of proper PI-LL correction, not the primary strategic goal for planning.
Question 411
Topic: Thoracolumbar Spine & Deformity
A 68-year-old male with a history of L3-S1 instrumented fusion presents with increasing back pain, progressive stooping posture, and difficulty ambulating. Clinical examination reveals a positive sagittal imbalance. A standing lateral spinopelvic radiograph is shown below.
Which radiographic parameter is MOST strongly correlated with functional outcome and satisfaction following surgical correction of adult spinal deformity with sagittal imbalance?
Correct Answer & Explanation
. Pelvic Incidence minus Lumbar Lordosis (PI-LL) mismatch
Explanation
The Pelvic Incidence minus Lumbar Lordosis (PI-LL) mismatch is considered one of the most critical radiographic parameters correlating with functional outcome and patient satisfaction after adult spinal deformity correction. A mismatch of >10 degrees is generally considered pathologic and a primary driver for sagittal imbalance, requiring surgical correction. While Sagittal Vertical Axis (SVA) is also a crucial measure of global balance, the PI-LL mismatch directly reflects the patient's inherent pelvic morphology relative to their lumbar lordosis requirement, which is key for a stable and energy-efficient posture. Reducing this mismatch to <10 degrees is a primary surgical goal. Sacral Slope and Pelvic Tilt are components of Pelvic Incidence and change with posture, but PI-LL mismatch integrates the relationship between the pelvis and the lumbar spine.
Question 412
Topic: Thoracolumbar Spine & Deformity
A 22-year-old female presents with chronic right hip pain and a diagnosis of symptomatic hip dysplasia. An AP pelvis radiograph is shown. She is scheduled for a Bernese periacetabular osteotomy (PAO). Which intraoperative maneuver is critical for optimizing hip joint coverage and load distribution while minimizing impingement?
Correct Answer & Explanation
. Anterior and lateral rotation of the acetabular fragment.
Explanation
During a Bernese periacetabular osteotomy (PAO), the acetabular fragment is mobilized and repositioned. The critical maneuver involves anterior and lateral rotation of the acetabular fragment. This movement effectively increases anterior and lateral coverage of the femoral head, correcting the underlying dysplasia. This leads to increased contact area, reduced peak stresses, and improved load distribution across the articular cartilage, while carefully avoiding impingement with the femoral neck. Medialization of the acetabulum also occurs as a secondary effect of this rotation, further improving joint mechanics.
Question 413
Topic: Thoracolumbar Spine & Deformity
A 68-year-old male presents with worsening back pain and progressive difficulty maintaining an upright posture. Clinical examination reveals a positive sagittal imbalance. Lateral standing radiographs are obtained, revealing the following spinal alignment parameters:
Pelvic incidence (PI) = 60°, Pelvic tilt (PT) = 30°, Sacral slope (SS) = 30°, Sagittal vertical axis (SVA) = +10 cm. Based on these findings, which of the following statements regarding his sagittal alignment is MOST accurate?
Correct Answer & Explanation
. His pelvic tilt indicates a compensatory mechanism for a positive sagittal balance.
Explanation
The image provided depicts a lateral view of the spine, emphasizing sagittal alignment. A positive sagittal imbalance (SVA > 5cm) is often compensated for by retroversion of the pelvis, leading to an increased pelvic tilt (normal < 20-25°) and a decreased sacral slope (normal > 35-40°). In this patient, SVA of +10 cm confirms a positive sagittal imbalance. A PI of 60° is within the normal range (45-60°), although higher PI values are associated with a greater lordosis requirement. His PT of 30° is indeed increased, representing a compensatory mechanism where the pelvis rotates posteriorly to try and bring the trunk center of gravity back over the feet. His SS of 30° is decreased, also consistent with pelvic retroversion. Surgical goals for sagittal deformity often involve decreasing PT and SVA, and increasing SS and lumbar lordosis, ideally matching lumbar lordosis to PI - 10°.Rationale for options:A. His PI (60°) is within the high-normal range, not abnormally low.B. An increased PT (30°) is a classic compensatory mechanism for positive sagittal balance, attempting to shift the center of gravity posteriorly. This is the correct statement.C. A decreased sacral slope (30°) is indicative of pelvic retroversion, which is a sign ofdecompensatedorcompensatingsagittal alignment, not a well-compensated one. A large sacral slope typically indicates a more upright pelvis and better compensation, if paired with appropriate lumbar lordosis.D. SVA of +10 cm is significantly positive (normal is generally < 5 cm), indicating a significant sagittal imbalance, not normal limits.E. Surgical correction typically aims todecreasepelvic tilt andincreasesacral slope to improve global sagittal alignment, but the statement 'decrease pelvic tilt and increase sacral slope' is part of the correction strategy, whereas the initial question asks for the most accurate statementregarding his current alignment. The current PT indicates compensation.
Question 414
Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast presents with persistent lower back pain. Radiographs demonstrate an isthmic spondylolisthesis at L5-S1. If this patient's slip progresses to a high-grade slip (>50%), which of the following spinopelvic parameters is most likely to be significantly elevated as a compensatory mechanism to maintain sagittal balance?
Correct Answer & Explanation
. Pelvic tilt
Explanation
In high-grade isthmic spondylolisthesis, patients compensate for the anterior shift of the center of gravity by retroverting the pelvis. This retroversion is measured as an increase in Pelvic Tilt (PT).
Question 415
Topic: Thoracolumbar Spine & Deformity
A 68-year-old male presents with incapacitating low back pain and significant postural changes. Standing X-rays reveal a severe thoracolumbar kyphoscoliosis with a positive sagittal vertical axis (SVA) of +10 cm and a pelvic incidence (PI) of 60 degrees. The patient has undergone prior L3-S1 fusion. Revision surgery is planned. Considering modern spinopelvic parameters, what is the most critical sagittal parameter to restore for optimal long-term outcomes and pain relief in this patient?
Correct Answer & Explanation
. Sagittal Vertical Axis (SVA) less than 5 cm
Explanation
For adult spinal deformity, particularly with significant positive sagittal vertical axis (SVA), restoring SVA to less than 5 cm is considered the most critical goal for improving pain and functional outcomes. While aligning Lumbar Lordosis (LL) with Pelvic Incidence (PI) (LL ≈ PI ± 9 degrees) and maintaining a Pelvic Tilt (PT) <20-25 degrees are vital components for achieving overall sagittal balance, a persistently positive SVA is independently correlated with worse outcomes and significantly higher disability. The global balance is ultimately reflected by SVA, which quantifies the deviation of the plumb line from the sacrum.
Question 416
Topic: Thoracolumbar Spine & Deformity
In an isthmic spondylolisthesis (Wiltse Type II) at L5-S1, the primary pathology is a defect in the pars interarticularis. Which exiting nerve root is most commonly compressed, and where does the compression typically occur?
Correct Answer & Explanation
. L5 root in the neuroforamen
Explanation
In L5-S1 isthmic spondylolisthesis, the L5 pars defect results in an accumulation of fibrocartilaginous tissue (the pars hook or Gill nodule). This hypertrophic tissue, combined with the anterior translation of the L5 vertebral body relative to the posterior elements, typically compresses the exiting L5 nerve root within the neuroforamen.
Question 417
Topic: Thoracolumbar Spine & Deformity
A spinal surgeon is evaluating a 45-year-old patient for an isthmic spondylolisthesis at L5-S1. Radiographic measurements reveal a Pelvic Incidence (PI) of 60 degrees and a Pelvic Tilt (PT) of 25 degrees. Based on the established geometric relationship of spinopelvic parameters, what is the patient's Sacral Slope (SS)?
Correct Answer & Explanation
. 35 degrees
Explanation
The fundamental formula relating pelvic parameters is: Pelvic Incidence (PI) = Pelvic Tilt (PT) + Sacral Slope (SS). Since PI (60) = PT (25) + SS, the Sacral Slope is calculated as 60 - 25 = 35 degrees.
Question 418
Topic: Thoracolumbar Spine & Deformity
A 35-year-old male sustains an L1 burst fracture. He is neurologically intact. MRI demonstrates an intact posterior ligamentous complex (PLC). According to the Thoracolumbar Injury Classification and Severity (TLICS) score, what is his total score and recommended treatment?
Correct Answer & Explanation
. Score 2; Non-operative management
Explanation
The TLICS score assigns points based on morphology, neurologic status, and PLC integrity. Morphology: Burst fracture = 2 points. Neurologic status: Intact = 0 points. PLC: Intact = 0 points. Total score = 2. A TLICS score of <= 3 indicates non-operative management (e.g., TLSO brace). A score of 4 is indeterminate, and >= 5 indicates operative management.
Question 419
Topic: Thoracolumbar Spine & Deformity
A 40-year-old man falls from a height of 10 feet and sustains an L1 burst fracture. He is neurologically intact (ASIA E). MRI confirms that the posterior ligamentous complex (PLC) is intact. According to the Thoracolumbar Injury Classification and Severity Score (TLICS), what is his score and the recommended management?
Correct Answer & Explanation
. Score 2, suggesting non-operative management
Explanation
The TLICS system assigns points based on morphology, neurologic status, and PLC integrity. A burst fracture (morphology) gets 2 points. Intact neurologic status gets 0 points. Intact PLC gets 0 points. Total score = 2. A score of 3 or less suggests non-operative management. A score of 4 is indeterminate, and 5 or more suggests surgery.
Question 420
Topic: Thoracolumbar Spine & Deformity
A 14-year-old female gymnast presents with an insidious onset of lower back pain. Radiographs demonstrate a grade II L5-S1 spondylolisthesis, and oblique views reveal an obvious defect in the pars interarticularis. According to the Wiltse classification of spondylolisthesis, into which category does this patient fall?
Correct Answer & Explanation
. Type II (Isthmic)
Explanation
The Wiltse classification defines Type II as Isthmic, which involves a defect or lesion in the pars interarticularis. Subtype IIA is a stress fracture of the pars (most common in young athletes like gymnasts). Type I is dysplastic (congenital abnormalities of the upper sacrum or L5 arch). Type III is degenerative. Type IV is traumatic (fracture in areas other than the pars). Type V is pathologic.
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