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6. Spine MCQs

Practice Set 337 of 379

This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 6721

Topic: Thoracolumbar Spine & Deformity

A 25-year-old male with chronic L5-S1 isthmic spondylolisthesis (Grade II) complains of persistent mechanical back pain after 1 year of conservative treatment. He has no neurological deficits. Which surgical procedure is most appropriate given his symptoms?

. L5-S1 decompression alone
. L5-S1 posterolateral fusion in situ
. L4-L5 fusion
. Isolated pars repair
. Aggressive reduction and circumferential fusion

Correct Answer & Explanation

. L5-S1 posterolateral fusion in situ

Explanation

For mechanical back pain associated with a stable (non-progressive) Grade II isthmic spondylolisthesis without neurological deficit, the primary goal is stabilization. L5-S1 posterolateral fusion in situ (without attempting reduction unless very specific indications are present) is a well-established and effective procedure that provides stability and high fusion rates while avoiding the risks associated with reduction or unnecessary decompression. Decompression alone does not address mechanical pain from instability. Isolated pars repair is for spondylolysis without slip. Fusion at L4-L5 is incorrect.

Question 6722

Topic: Thoracolumbar Spine & Deformity
Which of the following describes Wiltse-Newman Type IV spondylolisthesis?
. Degenerative changes of facet joints
. Stress fracture of the pars interarticularis
. Pathologic bone disease
. Acute fracture of the neural arch other than the pars
. Congenital malformation of the sacrum

Correct Answer & Explanation

. Acute fracture of the neural arch other than the pars

Explanation

Wiltse-Newman Type IV is 'Traumatic' spondylolisthesis, which results from an acute fracture in the neural arch other than the pars interarticularis. This differentiates it from Type II isthmic (pars defect) and Type I dysplastic (congenital malformation). Degenerative (Type III) and pathologic (Type V) are distinct etiologies.

Question 6723

Topic: Thoracolumbar Spine & Deformity

What imaging characteristic on MRI helps differentiate an active pars stress reaction (pre-spondylolysis) from a chronic non-union?

. Sclerosis around the defect
. Vertebral body height loss
. Presence of high signal intensity (edema) within and around the pars on T2-weighted images
. Disc dehydration at the affected level
. Endplate changes

Correct Answer & Explanation

. Presence of high signal intensity (edema) within and around the pars on T2-weighted images

Explanation

High signal intensity (edema) on T2-weighted MRI within and around the pars interarticularis is indicative of an active stress reaction or acute/subacute fracture. This suggests ongoing bone healing activity and a potential for successful non-operative management. Chronic non-unions or pseudarthroses typically show no or minimal edema, often appearing sclerotic or with fatty infiltration.

Question 6724

Topic: 6. Spine

For patients with degenerative spondylolisthesis and associated lumbar spinal stenosis, what finding has been shown to be an independent risk factor for needing revision surgery after decompression alone?

. Presence of diabetes mellitus
. Multilevel stenosis
. Preoperative low back pain
. Presence of a concomitant disc herniation
. Postoperative residual slip

Correct Answer & Explanation

. Preoperative low back pain

Explanation

Studies, particularly the SPORT trial, have shown that patients with degenerative spondylolisthesis who undergo decompression alone have higher rates of reoperation (often for persistent or recurrent instability/pain) if they had significant preoperative low back pain in addition to leg pain. This highlights the importance of addressing the instability with fusion in these patients. While other factors might influence outcomes, preoperative back pain in this context is a strong predictor of failure for decompression alone.

Question 6725

Topic: Thoracolumbar Spine & Deformity
In pediatric spondylolisthesis, which of the following is a recognized indication for surgical intervention?
. Asymptomatic Grade I slip, stable over time
. Grade I slip with mild, intermittent back pain responsive to conservative care
. Progressive neurological deficit or high-grade slip with significant lumbosacral kyphosis
. Any radiographic evidence of slip progression, regardless of symptoms
. Adolescent age group

Correct Answer & Explanation

. Progressive neurological deficit or high-grade slip with significant lumbosacral kyphosis

Explanation

Indications for surgery in pediatric spondylolisthesis include progressive neurological deficit, high-grade slips (often Grade III or higher, especially with lumbosacral kyphosis), or persistent, intractable pain despite adequate conservative management, particularly if the slip is progressive. Asymptomatic or mildly symptomatic, stable low-grade slips are typically managed conservatively. Radiographic progression without symptoms is not an absolute indication unless it becomes a high-grade slip.

Question 6726

Topic: 6. Spine

What is the primary risk associated with attempting to reduce a high-grade spondylolisthesis by aggressively restoring sagittal alignment?

. Increased blood loss
. Pedicle screw pullout
. Dural tear
. Neurological deficit (e.g., L5 nerve root stretch injury or cauda equina syndrome)
. Increased risk of deep surgical site infection

Correct Answer & Explanation

. Neurological deficit (e.g., L5 nerve root stretch injury or cauda equina syndrome)

Explanation

Aggressive reduction of high-grade spondylolisthesis, particularly in chronic cases where neural elements may be tethered and scarred, carries a significant risk of neurological injury due to stretch on the nerve roots (most commonly L5) or even the cauda equina. This is the most feared complication and often guides the decision towards in situ fusion or more controlled reduction techniques.

Question 6727

Topic: Thoracolumbar Spine & Deformity

Which surgical technique specifically involves resecting the L5 vertebral body to achieve reduction and decompression in severe L5-S1 spondylolisthesis?

. Posterolateral fusion
. Transforaminal lumbar interbody fusion (TLIF)
. Anterior lumbar interbody fusion (ALIF)
. Vertebrectomy (e.g., L5 vertebrectomy with reconstruction)
. Direct pars repair

Correct Answer & Explanation

. Vertebrectomy (e.g., L5 vertebrectomy with reconstruction)

Explanation

A vertebrectomy, specifically L5 vertebrectomy with reconstruction, is a highly aggressive and complex procedure reserved for the most severe cases of L5-S1 spondylolisthesis (e.g., spondyloptosis with severe neurological compromise or sagittal imbalance) where conventional reduction and fusion techniques are insufficient. It allows for complete decompression and significant reduction, but carries substantial risks. Other listed options are less aggressive fusion or repair techniques.

Question 6728

Topic: Thoracolumbar Spine & Deformity

What is a major contributing factor to the 'pelvic tilt' or 'waddling' gait often observed in patients with high-grade spondylolisthesis?

. Quadriceps weakness
. Abdominal muscle atrophy
. Gluteus medius insufficiency
. Compensatory hamstring tightness
. Shortened iliopsoas muscle

Correct Answer & Explanation

. Compensatory hamstring tightness

Explanation

Compensatory hamstring tightness is a very common finding in high-grade spondylolisthesis. It serves as a protective mechanism to limit pelvic rotation and prevent further anterior shear forces. This tightness often leads to a flexed-hip, flexed-knee gait pattern, sometimes described as a 'pelvic tilt' or 'waddling' gait.

Question 6729

Topic: Thoracolumbar Spine & Deformity

What is the significance of the 'chevron sign' on a lateral lumbar radiograph in the context of spondylolisthesis?

. Indicates disc space infection
. Signifies sacralization of L5
. Suggests high-grade spondylolisthesis with sagittal plane deformity
. Points to a pars interarticularis fracture
. Identifies a herniated nucleus pulposus

Correct Answer & Explanation

. Suggests high-grade spondylolisthesis with sagittal plane deformity

Explanation

The 'chevron sign' is a radiological finding on a lateral lumbar radiograph in patients with severe L5-S1 spondylolisthesis. It refers to the appearance of the L5 vertebral body superimposed on the S1 vertebral body, creating a 'V' or 'chevron' shape due to the significant anterior displacement and often associated lumbosacral kyphosis. It is a marker of high-grade slip and severe sagittal deformity.

Question 6730

Topic: 6. Spine

A 40-year-old male with symptomatic L5-S1 isthmic spondylolisthesis (Grade II) and L5 radiculopathy undergoes L5-S1 posterior decompression and instrumented fusion. Postoperatively, he develops fever, increasing back pain, and elevated inflammatory markers. A wound aspirate grows Staphylococcus aureus. What is the most appropriate initial management?

. Immediate hardware removal
. Long-term oral antibiotics alone
. Irrigation and debridement with retention of hardware and targeted IV antibiotics
. Observation and repeat cultures in 1 week
. Physical therapy to improve wound healing

Correct Answer & Explanation

. Irrigation and debridement with retention of hardware and targeted IV antibiotics

Explanation

In the setting of an acute postoperative surgical site infection following spinal fusion with instrumentation, particularly with a virulent organism like S. aureus, the most appropriate initial management is surgical irrigation and debridement. The goal is to eradicate the infection while attempting to retain the hardware if stability is achieved and the infection can be controlled with targeted intravenous antibiotics. Early hardware removal can compromise fusion. Long-term oral antibiotics alone are insufficient for acute deep infections with hardware.

Question 6731

Topic: 6. Spine

Which of the following is a common long-term complication associated with solid L5-S1 fusion for spondylolisthesis?

. Cauda equina syndrome
. Neurological deficit at L5
. Adjacent segment disease (ASD)
. Recurrence of the slip
. Vertebral artery injury

Correct Answer & Explanation

. Adjacent segment disease (ASD)

Explanation

Adjacent segment disease (ASD) is a well-recognized long-term complication following spinal fusion. By fusing a mobile segment, increased stress and motion are transferred to the adjacent unfused segments, which can accelerate degenerative changes and lead to symptoms (e.g., pain, radiculopathy, stenosis) at those levels. Cauda equina and L5 nerve injury are more often acute, perioperative complications. Recurrence of slip should not happen with a solid fusion.

Question 6732

Topic: Thoracolumbar Spine & Deformity

What radiographic finding indicates successful fusion following surgery for spondylolisthesis?

. Absence of pain
. Return to full activity
. Bridging bone formation across the fused segment (trabecular continuity) on plain radiographs or CT
. Hardware integrity without loosening
. Restoration of normal lumbar lordosis

Correct Answer & Explanation

. Bridging bone formation across the fused segment (trabecular continuity) on plain radiographs or CT

Explanation

Radiographic evidence of successful fusion (arthrodesis) is typically demonstrated by the presence of solid bridging bone formation (trabecular continuity) between the fused vertebral segments, seen on plain radiographs or, more definitively, on a CT scan. While pain relief and return to activity are clinical goals, they do not directly confirm fusion. Hardware integrity is necessary for stability but doesn't confirm biological fusion. Restoration of lordosis is an alignment goal, not a fusion confirmation.

Question 6733

Topic: 6. Spine

A 60-year-old female presents with low back pain and bilateral S1 radiculopathy. Radiographs show L5-S1 Grade II degenerative spondylolisthesis and MRI confirms severe central canal and foraminal stenosis. She has multiple comorbidities making posterior open surgery high risk. What minimally invasive approach might be considered?

. L5-S1 laminectomy without fusion
. Direct pars repair
. Oblique Lumbar Interbody Fusion (OLIF) at L5-S1
. Posterolateral fusion without instrumentation
. Microdiscectomy alone

Correct Answer & Explanation

. Oblique Lumbar Interbody Fusion (OLIF) at L5-S1

Explanation

For L5-S1 degenerative spondylolisthesis with stenosis, especially in a high-risk patient, Oblique Lumbar Interbody Fusion (OLIF) is a minimally invasive technique that accesses the disc space through a retroperitoneal oblique corridor, avoiding major abdominal vessels and posterior muscle dissection. This allows for interbody cage placement to restore disc height, achieve indirect decompression, and provide anterior column support. It's often combined with percutaneous posterior instrumentation. Laminectomy alone is prone to instability. Pars repair is for isthmic spondylolysis. Posterolateral fusion without instrumentation has lower fusion rates. Microdiscectomy alone doesn't address the instability or stenosis adequately.

Question 6734

Topic: Thoracolumbar Spine & Deformity

In the context of adult low-grade isthmic spondylolisthesis, what is the significance of significant low back pain (in the absence of neurological deficit) failing conservative management?

. It suggests a high likelihood of concurrent infection.
. It is generally managed by continued pain medication without surgery.
. It is a primary indication for surgical fusion to address mechanical instability.
. It requires immediate aggressive surgical reduction.
. It indicates the need for psychological counseling as the sole intervention.

Correct Answer & Explanation

. It is a primary indication for surgical fusion to address mechanical instability.

Explanation

For adult low-grade isthmic spondylolisthesis, if significant mechanical low back pain persists and profoundly impacts quality of life despite a thorough and prolonged course of conservative management, surgical fusion (typically an in situ posterolateral fusion) is a primary indication. The pain is often attributed to the inherent instability at the slipped segment. While psychological factors can play a role, intractable mechanical pain is a legitimate surgical indication. Immediate aggressive reduction is rarely indicated for low-grade slips without neurological deficit.

Question 6735

Topic: Thoracolumbar Spine & Deformity

Which of the following is NOT a common goal of conservative management for spondylolisthesis?

. Pain relief
. Improvement in functional capacity
. Promotion of natural fusion
. Strengthening of core musculature
. Education on activity modification

Correct Answer & Explanation

. Promotion of natural fusion

Explanation

Conservative management for spondylolisthesis aims to alleviate pain, improve function, strengthen the core, and educate on appropriate activity modification. However, it does not promote 'natural fusion' of the vertebral segments. Fusion is a surgical outcome. While some pars defects might heal with bracing, natural fusion of the entire segment is not an expected outcome of conservative care for spondylolisthesis.

Question 6736

Topic: Thoracolumbar Spine & Deformity

Which sacral morphological parameter is most strongly correlated with an increased risk of spondylolisthesis progression?

. Pelvic Tilt (PT)
. Sacral Slope (SS)
. Pelvic Incidence (PI)
. Lumbosacral Angle (LSA)
. Vertebral Endplate Angle (VEA)

Correct Answer & Explanation

. Pelvic Incidence (PI)

Explanation

Pelvic Incidence (PI) is a fixed anatomical parameter that defines the orientation of the sacrum relative to the hip axis. A higher pelvic incidence is associated with increased shear forces at the lumbosacral junction, predisposing individuals to a higher risk of developing and progressing spondylolisthesis, especially high-grade slips. It is a key factor in sagittal balance and pathology.

Question 6737

Topic: 6. Spine

A patient with L4-L5 degenerative spondylolisthesis presents with progressive unilateral L5 radiculopathy due to severe foraminal stenosis. They have failed conservative treatment. What surgical technique would most effectively decompress the L5 nerve root in the foramen and stabilize the segment?

. L4-L5 anterior lumbar interbody fusion (ALIF) only
. L4-L5 posterolateral fusion without decompression
. L4-L5 laminectomy and bilateral foraminotomy without fusion
. L4-L5 Transforaminal Lumbar Interbody Fusion (TLIF)
. L4-L5 posterior osteotomy only

Correct Answer & Explanation

. L4-L5 Transforaminal Lumbar Interbody Fusion (TLIF)

Explanation

Transforaminal Lumbar Interbody Fusion (TLIF) is an excellent choice for unilateral radiculopathy caused by foraminal stenosis in degenerative spondylolisthesis. It allows for direct decompression of the L5 nerve root through a unilateral approach, followed by disc space preparation and interbody cage placement. The cage helps restore disc height and indirectly decompress the foramen, while the pedicle screw fixation provides immediate stability. ALIF doesn't directly decompress the foramen posteriorly. Laminectomy/foraminotomy alone leaves instability. Posterolateral fusion without decompression doesn't relieve neural compression. Posterior osteotomy alone isn't a complete solution.

Question 6738

Topic: Thoracolumbar Spine & Deformity

What is the role of dynamic flexion-extension radiographs in the evaluation of spondylolisthesis?

. To measure the exact percentage of slip in the static position.
. To assess overall sagittal balance.
. To quantify the amount of instability or segmental motion at the affected level.
. To visualize the pars interarticularis defect.
. To evaluate disc height.

Correct Answer & Explanation

. To quantify the amount of instability or segmental motion at the affected level.

Explanation

Dynamic flexion-extension radiographs are critical for assessing segmental instability. By comparing the amount of slip or angular motion between the flexion and extension views, surgeons can determine if there is excessive pathological motion, which can be an important factor in deciding whether to add fusion to a decompression procedure for degenerative spondylolisthesis, or in evaluating stability in isthmic slips.

Question 6739

Topic: 6. Spine

In an adult patient with a long-standing, stable Grade I L5-S1 isthmic spondylolisthesis presenting with progressive L5 radiculopathy due to a large central disc herniation at L4-L5, what is the most appropriate initial surgical management for the radiculopathy?

. L5-S1 decompression and fusion
. L4-L5 microdiscectomy and fusion
. L4-L5 microdiscectomy alone
. L5-S1 aggressive reduction and fusion
. Conservative management of the disc herniation

Correct Answer & Explanation

. L4-L5 microdiscectomy alone

Explanation

This patient has a symptomatic disc herniation at L4-L5, which is causing the L5 radiculopathy, despite having an incidental L5-S1 spondylolisthesis. The primary problem causing thecurrent progressive neurological symptomsis the L4-L5 disc herniation. Therefore, the most appropriate initial surgical management is L4-L5 microdiscectomy alone to address the symptomatic lesion. The L5-S1 spondylolisthesis is stable and not the source of thecurrentradicular pain. Fusion at L4-L5 might be considered later if instability develops, but not initially for a disc herniation. Aggressive reduction of L5-S1 is inappropriate. Conservative management has failed.

Question 6740

Topic: Thoracolumbar Spine & Deformity

What is the recommended approach for a pediatric patient with an asymptomatic L5-S1 spondylolisthesis (Grade II) that is not progressing?

. Surgical fusion to prevent future symptoms
. Activity restriction and bracing for 12 months
. Regular observation with periodic clinical and radiographic evaluation
. MRI every 6 months to monitor for neural compression
. Physical therapy focusing on hamstring stretching

Correct Answer & Explanation

. Regular observation with periodic clinical and radiographic evaluation

Explanation

For asymptomatic, non-progressive spondylolisthesis in children, regular observation with periodic clinical and radiographic evaluation is the recommended approach. Many such slips remain stable and asymptomatic throughout life. Surgical intervention is reserved for symptomatic or progressive slips. Bracing/activity restriction is for symptomatic or active pars defects, not necessarily for asymptomatic stable slips. MRI every 6 months is excessive and unnecessary. Hamstring stretching is for symptomatic tightness, not a prophylactic measure for asymptomatic slips.

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