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Thoracolumbar Spine & Deformity MCQs

Practice Set 36 of 49

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 701

Topic: Thoracolumbar Spine & Deformity
A 68-year-old woman with a prior L3-S1 fusion presents with severe back pain, a stooped posture, and an inability to stand up straight. Standing full-length radiographs show a pelvic incidence (PI) of 60 degrees, lumbar lordosis (LL) of 20 degrees, pelvic tilt (PT) of 35 degrees, and a sagittal vertical axis (SVA) of +12 cm. Revision corrective spinal osteotomy is planned. To optimize sagittal balance, what is the minimum lumbar lordosis (LL) that should be targeted during the reconstruction?
. 20 degrees
. 30 degrees
. 50 degrees
. 70 degrees
. 80 degrees

Correct Answer & Explanation

. 50 degrees

Explanation

For optimal sagittal alignment in adult spinal deformity, the lumbar lordosis (LL) should be matched to the patient's fixed pelvic incidence (PI). The recognized formula is PI - LL ≤ 10 degrees. With a PI of 60 degrees, the targeted LL should be at least 50 degrees (preferably closer to 60) to restore sagittal balance, reduce the compensatory high pelvic tilt, and bring the SVA under 5 cm.

Question 702

Topic: Thoracolumbar Spine & Deformity

A 14-year-old girl presents with severe low back pain and significant hamstring tightness. She stands with a characteristic 'pelvic waddle' gait. Lateral radiographs demonstrate a Grade 4 dysplastic isthmic spondylolisthesis at L5-S1 with a high slip angle. Nonoperative management has failed. Surgical planning includes an L4-to-pelvis posterior instrumented fusion with partial reduction of the L5 vertebral body. Which nerve root is at the highest risk of injury during the reduction maneuver?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L5

Explanation

Reduction of a high-grade dysplastic or isthmic spondylolisthesis at L5-S1 carries a well-documented risk of neurologic injury. The L5 exiting nerve root is at the highest risk. As the displaced L5 vertebral body is reduced (pulled posteriorly and translated cranially), the L5 nerve root is stretched tightly across the anterior sacral ala.

Question 703

Topic: Thoracolumbar Spine & Deformity

A 35-year-old construction worker falls from a height of 15 feet and sustains a T12 burst fracture. On examination, he is neurologically intact with 5/5 motor strength and normal bowel/bladder function. Upright radiographs show 25 degrees of local kyphosis, and CT shows 40% canal compromise. An MRI reveals that the posterior ligamentous complex (PLC) is completely intact. What is the most appropriate management?

. Short-segment posterior spinal fusion
. Anterior corpectomy and strut grafting
. Thoracolumbosacral orthosis (TLSO) bracing
. Balloon kyphoplasty
. Laminectomy alone

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) bracing

Explanation

For neurologically intact patients with a thoracolumbar burst fracture and an intact posterior ligamentous complex (TLICS score <= 3), nonoperative management with a TLSO or hyperextension brace is the standard of care. Surgical stabilization is typically indicated if there is a progressive neurologic deficit, definite PLC injury (indicating instability), or severe progressive kyphotic collapse. Laminectomy alone is strictly contraindicated as it further destabilizes the fracture.

Question 704

Topic: Thoracolumbar Spine & Deformity

A 65-year-old woman presents with severe low back pain and an inability to stand up straight, reporting progressive fatigue when walking. Radiographs reveal a degenerative lumbar scoliosis with marked sagittal imbalance. Her measured pelvic incidence (PI) is 65 degrees. For an optimal postoperative functional outcome in sagittal alignment, her lumbar lordosis (LL) should be surgically restored to approximately:

. 25 degrees
. 45 degrees
. 65 degrees
. 85 degrees
. 105 degrees

Correct Answer & Explanation

. 65 degrees

Explanation

The primary goal of sagittal realignment in adult spinal deformity surgery is to achieve a lumbar lordosis (LL) that is proportional to the patient's fixed pelvic incidence (PI). The widely accepted Schwab-SRS classification dictates that the target LL should be within 10 degrees of the PI (PI - LL = <10 degrees). Therefore, for a PI of 65 degrees, restoring the LL to approximately 65 degrees provides the most physiologic standing posture and minimizes adjacent segment stress.

Question 705

Topic: Thoracolumbar Spine & Deformity

A 62-year-old female presents with severe low back pain and difficulty standing upright. She constantly leans forward to walk. Standing full-length scoliosis radiographs show a pelvic incidence (PI) of 65 degrees, lumbar lordosis (LL) of 30 degrees, and a sagittal vertical axis (SVA) of +12 cm. If surgical intervention is planned, which of the following sagittal alignment goals is most critical to achieve optimal clinical outcomes and reduce the risk of adjacent segment disease?

. Correction of the pelvic incidence to less than 50 degrees
. Restoring the lumbar lordosis to match the pelvic incidence within 10 degrees
. Increasing the sagittal vertical axis to +15 cm
. Decreasing pelvic tilt to greater than 30 degrees
. Creating a flat back by performing multiple Smith-Petersen osteotomies

Correct Answer & Explanation

. Restoring the lumbar lordosis to match the pelvic incidence within 10 degrees

Explanation

In adult spinal deformity, restoring sagittal balance is the most critical factor for a good clinical outcome. A key parameter is the mismatch between pelvic incidence (PI) and lumbar lordosis (LL). The goal of surgical correction is to restore the LL to within 10 degrees of the PI (PI - LL < 10 degrees). Pelvic incidence is a fixed morphological parameter and cannot be changed surgically.

Question 706

Topic: Thoracolumbar Spine & Deformity

A 15-year-old boy is brought by his parents for evaluation of a 'hunchback' posture. He reports mild achy pain in the mid-back after playing sports. Standing lateral radiographs demonstrate a thoracic kyphosis of 65 degrees. According to Sorensen's criteria, which of the following radiographic findings is required to confirm the diagnosis of Scheuermann's disease?

. Anterior wedging of at least 5 degrees in three or more sequential vertebrae
. A Cobb angle of greater than 45 degrees with normal vertebral morphology
. Defect in the pars interarticularis at L5
. Lateral curvature of the spine greater than 10 degrees
. Spondylolisthesis of L4 on L5

Correct Answer & Explanation

. Anterior wedging of at least 5 degrees in three or more sequential vertebrae

Explanation

Sorensen's criteria define classic Scheuermann's disease radiographically as a structural thoracic kyphosis > 40 degrees with anterior wedging of at least 5 degrees in 3 or more consecutive vertebral bodies. While Schmorl's nodes and irregular endplates are often present, sequential wedging is the definitive diagnostic criterion.

Question 707

Topic: Thoracolumbar Spine & Deformity
A 13-year-old female competitive gymnast presents with progressive low back pain and bilateral radicular symptoms radiating to the posterior thighs. Examination reveals a palpable 'step-off' at the lumbosacral junction, a crouched gait, and severe hamstring tightness. Standing lateral radiographs reveal a Meyerding Grade III isthmic spondylolisthesis at L5-S1 with a slip angle of 45 degrees. What is the most appropriate definitive management?
. Thoracolumbosacral orthosis (TLSO) bracing for 6 months followed by core strengthening
. Pars interarticularis repair using pedicle screws and a laminar hook (Morscher technique)
. In situ posterolateral fusion from L5 to S1 without instrumentation
. Posterior spinal decompression, reduction of the slip, and L5-S1 instrumented fusion
. Anterior lumbar interbody fusion (ALIF) alone

Correct Answer & Explanation

. Posterior spinal decompression, reduction of the slip, and L5-S1 instrumented fusion

Explanation

The patient has a high-grade (Meyerding Grade III, >50% slip) isthmic spondylolisthesis with a high slip angle, clinical deformity, and neurologic symptoms. High-grade slips with radicular symptoms and sagittal imbalance in adolescents mandate surgical intervention. The contemporary standard involves posterior spinal decompression (to relieve the L5 roots), partial or complete reduction of the slip (to restore sagittal balance), and instrumented fusion (L5-S1 or L4-S1 depending on the specific anatomy). Pars repair is reserved for low-grade slips (Grade I) without disc degeneration. In situ fusion in the setting of a high slip angle carries an unacceptable risk of pseudarthrosis and progressive deformity.

Question 708

Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast presents with chronic lower back pain that radiates to her posterior thighs. Radiographs reveal a grade III L5-S1 isthmic spondylolisthesis. She has failed 6 months of conservative management. What is the most appropriate surgical treatment?
. Pars interarticularis repair with a compression screw
. L5-S1 posterior lateral in situ fusion
. L5 laminectomy without fusion
. L5-S1 anterior lumbar interbody fusion alone
. L4-L5 posterior spinal fusion

Correct Answer & Explanation

. L5-S1 posterior lateral in situ fusion

Explanation

High-grade (Grade III or IV) or symptomatic slipped dysplastic spondylolisthesis failing non-operative care requires surgical stabilization. L5-S1 posterolateral fusion (with or without instrumentation/reduction) is the standard treatment.

Question 709

Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast presents with chronic lower back pain and severe hamstring tightness. Radiographs reveal an L5-S1 isthmic spondylolisthesis with 60% anterior translation of L5 on S1 (Grade III). Nonoperative management has failed over 6 months. What is the most appropriate surgical intervention?
. Direct pars repair (e.g., Scott wiring or pedicle screw hook construct)
. L5-S1 posterolateral fusion in situ
. L4-S1 posterolateral fusion in situ
. L5-S1 posterior lumbar interbody fusion with complete reduction
. Anterior lumbar interbody fusion at L5-S1 only

Correct Answer & Explanation

. L4-S1 posterolateral fusion in situ

Explanation

For high-grade (Grade III or higher) isthmic spondylolisthesis in children, an L4-S1 fusion spanning the slip and the adjacent segment is recommended to prevent progression and reduce the high risk of pseudarthrosis. In situ posterolateral fusion is safe and has an excellent track record compared to aggressive reduction.

Question 710

Topic: Thoracolumbar Spine & Deformity

A 14-year-old female presents with severe back pain and radiating bilateral leg pain. Radiographs reveal an L5-S1 isthmic spondylolisthesis with an 80% slip (Meyerding Grade IV) and a high slip angle. She has failed conservative management. What is the recommended surgical approach?

. Pars repair alone
. L5-S1 posterior in situ fusion without decompression
. L4-S1 posterior decompression and instrumented fusion
. Anterior lumbar interbody fusion (ALIF) alone
. Total disc replacement at L5-S1

Correct Answer & Explanation

. L4-S1 posterior decompression and instrumented fusion

Explanation

High-grade spondylolisthesis (>50% slip) with radicular symptoms and failure of conservative management is best treated with posterior decompression and instrumented fusion. Pars repair is reserved for low-grade slips without nerve root compression.

Question 711

Topic: Thoracolumbar Spine & Deformity

A 6-month-old boy is diagnosed with infantile idiopathic scoliosis. A radiograph reveals a left-sided thoracic curve of 35 degrees. Which of the following parameters is the most important radiographic predictor of curve progression in this patient?

. Apical vertebral rotation of grade 1
. Rib-vertebral angle difference (RVAD) greater than 20 degrees
. Presence of a compensatory lumbar curve
. Cobb angle magnitude alone
. Risser sign

Correct Answer & Explanation

. Rib-vertebral angle difference (RVAD) greater than 20 degrees

Explanation

The Rib-vertebral angle difference (RVAD), or Mehta's angle, is the most reliable predictor of progression in infantile idiopathic scoliosis. An RVAD greater than 20 degrees strongly indicates a high likelihood of progressive deformity requiring intervention.

Question 712

Topic: Thoracolumbar Spine & Deformity

A 14-year-old male gymnast reports 6 weeks of localized low back pain that worsens with lumbar extension. Neurologic exam is normal. Oblique radiographs show a radiolucency at the pars interarticularis of L5, and a SPECT scan shows intense focal uptake. Initial management should consist of:

. Immediate surgical pars repair
. In situ L5-S1 posterolateral fusion
. Epidural steroid injection
. Activity restriction and antilordotic bracing
. Lumbar microdiscectomy

Correct Answer & Explanation

. Activity restriction and antilordotic bracing

Explanation

Acute or stress-reactive spondylolysis (indicated by positive SPECT or MRI bone edema) is initially managed nonoperatively with activity modification, core stabilization therapy, and often an antilordotic brace until symptoms resolve.

Question 713

Topic: Thoracolumbar Spine & Deformity

A 14-year-old male gymnast presents with persistent lower back pain exacerbated by extension. Radiographs and an MRI confirm a bilateral L5 pars interarticularis defect with a Grade I spondylolisthesis. The pain has not improved after 6 months of rest, bracing, and physical therapy. What is the most appropriate surgical treatment?

. L5-S1 posterior spinal fusion with instrumentation
. Direct pars defect repair with pedicle screws and laminar hooks
. L5 laminectomy
. Anterior lumbar interbody fusion
. S1 nerve root decompression

Correct Answer & Explanation

. L5-S1 posterior spinal fusion with instrumentation

Explanation

In a patient with spondylolisthesis (even Grade I) that fails non-operative management, a posterolateral in situ fusion (L5-S1) is the procedure of choice. Direct pars repair is generally reserved for patients with a pars defect (spondylolysis) without any spondylolisthesis (slip).

Question 714

Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast is diagnosed with an L5-S1 isthmic spondylolisthesis with a 60 percent slip (Grade III). She reports persistent mechanical back pain and L5 radiculopathy despite 6 months of rest and therapy. What is the most appropriate surgical management?
. Continued rigid bracing for 6 additional months
. Pars interarticularis defect repair (Buck procedure)
. L5-S1 in situ posterolateral fusion
. L4-L5-S1 wide laminectomy without fusion
. Epidural steroid injections alone

Correct Answer & Explanation

. L5-S1 in situ posterolateral fusion

Explanation

High-grade spondylolisthesis (greater than 50 percent slip) with refractory symptoms is generally managed with an in situ posterolateral fusion, often with decompression if radicular symptoms are profound. Pars repair is reserved for Grade 0 or I slips.

Question 715

Topic: Thoracolumbar Spine & Deformity

A 65-year-old woman is evaluated for a total hip arthroplasty. She has a history of L3-S1 lumbar fusion. Sitting and standing lateral radiographs show a change in pelvic tilt of 5 degrees. How should the acetabular cup be positioned compared to a patient with normal spinopelvic mobility?

. Increased anteversion and increased inclination
. Decreased anteversion and decreased inclination
. Decreased anteversion and increased inclination
. Increased anteversion and normal inclination
. Normal positioning as fusion does not affect cup dynamics

Correct Answer & Explanation

. Increased anteversion and increased inclination

Explanation

A stiff lumbar spine (change in pelvic tilt <10 degrees) prevents normal posterior pelvic rollback during sitting. This increases the risk of anterior impingement and posterior dislocation; therefore, the cup should be placed in increased anteversion and inclination.

Question 716

Topic: Thoracolumbar Spine & Deformity

A patient is scheduled for a THA. Preoperative standing and sitting lateral spinopelvic radiographs demonstrate a stiff lumbar spine with less than 10 degrees of pelvic tilt change between standing and sitting. How does this condition affect acetabular component positioning?

. The cup should be placed in less anteversion to prevent anterior dislocation in standing.
. The cup must be placed in a patient-specific safe zone with increased anteversion to accommodate the lack of posterior pelvic tilt in sitting.
. A dual mobility bearing is absolutely contraindicated due to restricted pelvic motion.
. The cup should be placed in more retroversion to improve posterior coverage.
. Standard Lewinnek safe zone parameters (40 degrees inclination, 15 degrees anteversion) remain optimal.

Correct Answer & Explanation

. The cup must be placed in a patient-specific safe zone with increased anteversion to accommodate the lack of posterior pelvic tilt in sitting.

Explanation

A stiff spinopelvic junction prevents the normal posterior pelvic tilt required to accommodate hip flexion when sitting, increasing the risk of anterior impingement and posterior dislocation. The acetabular component typically requires higher anteversion and inclination to compensate for this stiffness.

Question 717

Topic: Thoracolumbar Spine & Deformity

A 35-year-old woman is involved in a high-speed collision. CT of the thoracolumbar spine demonstrates an L1 burst fracture with a fracture of the posterior elements.

Her neurologic examination is normal. The TLICS score is calculated as 5 (Morphology=2; PLC=3; Neuro=0). What is the recommended management?

. TLSO brace for 12 weeks
. Hyperextension casting
. Surgical stabilization
. Observation with serial radiographs
. Immediate physical therapy

Correct Answer & Explanation

. Surgical stabilization

Explanation

The Thoracolumbar Injury Classification and Severity (TLICS) score dictates treatment pathways. A score of 5 or greater indicates an unstable injury pattern that mandates surgical stabilization.

Question 718

Topic: Thoracolumbar Spine & Deformity

In the surgical evaluation and reconstruction of adult degenerative scoliosis, achieving proper sagittal balance is highly correlated with improved clinical outcomes. Which of the following spinopelvic parameters is the primary target?

. Pelvic Incidence (PI) minus Lumbar Lordosis (LL) < 10 degrees
. Pelvic Tilt (PT) > 25 degrees
. Sagittal Vertical Axis (SVA) > 5 cm
. Thoracic Kyphosis > 60 degrees
. Sacral Slope < 10 degrees

Correct Answer & Explanation

. Pelvic Incidence (PI) minus Lumbar Lordosis (LL) < 10 degrees

Explanation

Restoration of optimal sagittal balance is critical in adult spinal deformity surgery. A PI-LL mismatch of less than 10 degrees is the widely accepted target to minimize postoperative disability and prevent implant failure.

Question 719

Topic: Thoracolumbar Spine & Deformity

A 22-year-old man is a restrained backseat passenger (lap belt only) in a motor vehicle collision. He sustains a flexion-distraction injury to his lumbar spine (Chance fracture). Which associated injury must be most actively excluded during his trauma workup?

. Aortic dissection
. Intra-abdominal hollow viscus injury
. Diaphragmatic rupture
. Splenic laceration
. Renal artery thrombosis

Correct Answer & Explanation

. Intra-abdominal hollow viscus injury

Explanation

Chance fractures (flexion-distraction injuries) are classically associated with lap-belt use and carry a very high incidence (up to 50%) of concomitant intra-abdominal injuries, particularly hollow viscus (bowel) perforations.

Question 720

Topic: Thoracolumbar Spine & Deformity

A

35-year-old man is diagnosed with an unstable T12 thoracolumbar burst fracture with MRI-confirmed posterior ligamentous complex (PLC) disruption. He is neurologically intact. Based on the Thoracolumbar Injury Classification and Severity (TLICS) score, what is his point value and the recommended treatment?

. 3 points, non-operative
. 4 points, operative or non-operative
. 5 points, operative
. 6 points, operative
. 7 points, operative

Correct Answer & Explanation

. 5 points, operative

Explanation

The TLICS score is 5: burst fracture morphology (2 points), posterior ligamentous complex injury (3 points), and intact neurology (0 points). A score of 5 or higher is a definitive indication for operative management.

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