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Orthopedic Spine Review | Dr Hutaif Spine Surgery Revie -...

Orthopedic Board Review: Spondylolisthesis Diagnosis & Classification MCQs

23 Apr 2026 77 min read 116 Views
Illustration of oral questions spondylolisthesis - Dr. Mohammed Hutaif

Key Takeaway

For orthopedic board exams, mastering spondylolisthesis involves understanding its classification, particularly the Wiltse-Newman system. Focus on differentiating types like isthmic (e.g., in gymnasts with pars defects) from degenerative. Recognizing clinical presentations, imaging findings, and appropriate treatment pathways is crucial for successful diagnosis and question resolution.

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Question 1

A 14-year-old competitive gymnast presents with insidious onset low back pain exacerbated by extension and hyperextension activities. Physical examination reveals hamstring tightness and a palpable step-off at L5. AP and lateral radiographs of the lumbar spine show a defect in the pars interarticularis at L5 with an anterior translation of L5 on S1. Which of the following is the most appropriate classification for this condition?





Explanation

The patient's age, activity (gymnast), pars defect, and anterior translation are classic for an isthmic spondylolisthesis. Wiltse-Newman classification Type II isthmic is characterized by a lesion in the pars interarticularis. Given the insidious onset and high-impact repetitive extension activities, it's most likely a stress fracture (lytic) rather than an acute traumatic fracture (Type IV) or congenital dysplastic anomaly (Type I). Degenerative (Type III) is typically seen in older adults, and pathologic (Type V) is due to bone disease.

Question 2

Which of the following Meyerding grades of spondylolisthesis indicates a slip of 50-75% of the vertebral body's width?





Explanation

The Meyerding classification system grades spondylolisthesis based on the percentage of anterior displacement of the superior vertebral body over the inferior one. Grade I is 0-25%, Grade II is 25-50%, Grade III is 50-75%, Grade IV is 75-100%, and Grade V (spondyloptosis) is complete displacement (>100%). Therefore, 50-75% displacement corresponds to Grade III.

Question 3

A 55-year-old female presents with a long history of low back pain and bilateral leg pain, worse with standing and walking, relieved by sitting or leaning forward. Radiographs show L4-L5 degenerative spondylolisthesis (Grade I) with associated spinal stenosis. She has failed 6 months of comprehensive conservative management including physical therapy, NSAIDs, and epidural steroid injections. Neurological exam reveals mild quadriceps weakness (4+/5) bilaterally but no frank motor deficit. What is the most appropriate next step in management?





Explanation

For symptomatic degenerative spondylolisthesis with spinal stenosis that has failed conservative management, surgical intervention is often indicated. The Spine Patient Outcomes Research Trial (SPORT) demonstrated superior outcomes for surgical treatment compared to non-operative care in patients with degenerative spondylolisthesis and stenosis. While decompression alone can address stenosis, studies like SPORT have shown that adding fusion to decompression significantly improves outcomes and reduces reoperation rates for degenerative spondylolisthesis, especially in the presence of instability or significant back pain. Quadriceps weakness suggests L4 nerve root compression, making decompression necessary. Anterior fusion alone does not address the posterior decompression requirement. TLIF typically includes decompression. The best option combining decompression and stabilization is decompression with instrumented posterolateral fusion.

Question 4

Which type of spondylolisthesis is most commonly associated with a sacral spina bifida occulta and a trapezoidal L5 vertebral body?





Explanation

Type I, or Dysplastic Spondylolisthesis, is a congenital anomaly characterized by malformed sacral facets, an elongated pars, and a trapezoidal L5 vertebral body, often associated with sacral spina bifida occulta. This morphology leads to an inherent instability that predisposes to anterior slippage. The other types have different underlying etiologies.

Question 5

A 30-year-old male with chronic L5-S1 isthmic spondylolisthesis (Grade II) complains of persistent low back pain and bilateral S1 radiculopathy despite 9 months of conservative treatment. On examination, he has bilateral hamstring tightness and a positive straight leg raise test at 45 degrees. Which of the following imaging modalities is most crucial for evaluating potential nerve root compression and planning surgical decompression?





Explanation

While plain radiographs define the slip, and CT can better visualize bony stenosis, MRI is superior for evaluating soft tissue structures, including nerve roots, discs, and the spinal cord, and identifying nerve root compression by hypertrophic soft tissue, disc herniation, or foraminal stenosis, which is critical for surgical planning in patients with radiculopathy. EMG assesses nerve function but isn't an imaging modality for structural compression.

Question 6

What is the primary role of an oblique radiograph in the workup of spondylolisthesis?





Explanation

Oblique radiographs are specifically used to visualize the pars interarticularis, which appears as the 'neck' of the 'Scottie dog.' A defect or fracture in the pars ('collar on the Scottie dog') is indicative of an isthmic spondylolysis or spondylolisthesis. Other views (AP/Lateral) are better for alignment, slip percentage, and disc space evaluation.

Question 7

In a pediatric patient with spondylolysis (pars defect without slip) who is asymptomatic, what is the recommended management?





Explanation

For asymptomatic spondylolysis without slip, the primary recommendation is observation with activity as tolerated. Most pars defects remain stable and asymptomatic. Surgical intervention is reserved for symptomatic, failed conservative cases. Bracing or activity restriction might be considered for symptomatic spondylolysis to promote healing, but not for asymptomatic lesions. Physical therapy is more relevant for symptomatic individuals.

Question 8

A 68-year-old male with a history of hypertension and diabetes presents with progressively worsening low back pain and L4-L5 neurogenic claudication. He has a Grade I degenerative spondylolisthesis at L4-L5. His pain is 7/10 on the VAS. He has tried epidural steroid injections, NSAIDs, and physical therapy for 9 months with no sustained relief. What is the strongest indicator for surgical intervention in this patient?





Explanation

The strongest indicator for surgical intervention in symptomatic degenerative spondylolisthesis is the failure of a prolonged course of conservative management combined with persistent severe symptoms (pain, neurological deficits) impacting quality of life. While neurogenic claudication itself is a symptom, its persistence despite non-operative efforts is the key factor. The grade of slip alone isn't an indication for surgery, nor are comorbidities unless they contraindicate surgery. Age is a factor for surgical risk but not an indication for surgery.

Question 9

What is the most common neurological complication following reduction of a high-grade spondylolisthesis?





Explanation

The L5 nerve root is most vulnerable during the reduction of a high-grade L5-S1 spondylolisthesis. This is due to its course over the sacral ala and the potential for stretch injury during the reduction maneuver, especially with attempts to correct lumbosacral kyphosis. While other nerve injuries can occur, L5 radiculopathy/palsy is the most frequently reported neurological complication.

Question 10

Which of the following describes the anatomical defect in Type IIB isthmic spondylolisthesis?





Explanation

Wiltse-Newman Type II isthmic spondylolisthesis is subdivided: Type IIA is a lytic (stress) fracture of the pars, Type IIB is an elongated but intact pars (often a healed stress fracture with elongation), and Type IIC is an acute fracture of the pars. Therefore, Type IIB specifically refers to an elongated pars without a clear lytic defect.

Question 11

For a patient with symptomatic L5-S1 isthmic spondylolisthesis (Grade II) and significant L5 radiculopathy, what is the primary goal of posterior decompression?





Explanation

The primary goal of decompression in the setting of radiculopathy is to relieve the neural element compression. In L5-S1 isthmic spondylolisthesis, the exiting L5 nerve root can be compressed by the pars defect, pedicle, or scar tissue in the foramen, and the traversing S1 nerve root can be compressed by the slipped superior vertebral body or disc. While fusion stabilizes and can indirectly help, decompression specifically targets the neural impingement.

Question 12

What is the primary advantage of a Transforaminal Lumbar Interbody Fusion (TLIF) over a Posterior Lumbar Interbody Fusion (PLIF) for spondylolisthesis correction?





Explanation

TLIF offers a unilateral approach to the disc space, allowing for disc excision and cage placement through the foramen. This typically involves less retraction of the thecal sac and nerve roots compared to PLIF, which requires bilateral laminectomy and retraction, thereby generally carrying a lower risk of dural tear and nerve root injury. While both can restore lordosis and achieve fusion, the safety profile regarding dural injury is a key advantage of TLIF.

Question 13

A 10-year-old child presents with a painful L5-S1 spondylolysis. MRI shows no significant slip, but a high signal intensity within the pars defect on T2-weighted images. What does this finding suggest?





Explanation

High signal intensity (edema) on T2-weighted MRI within the pars defect of a child or adolescent with spondylolysis indicates an active, acute, or subacute stress reaction or fracture. This finding suggests a higher potential for healing with conservative management (e.g., bracing, activity restriction) compared to a chronic, non-edematous defect.

Question 14

Which factor is most strongly associated with progression of a low-grade (Grade I or II) spondylolisthesis in children?





Explanation

Sacral dome rounding (or dome-shaped sacrum) is a key morphological risk factor associated with the progression of spondylolisthesis, especially in the setting of Type I dysplastic slips, as it indicates a less stable articulation. While hamstring tightness is a symptom, and other factors may play minor roles, sacral morphology is a strong radiological predictor of progression.

Question 15

What is the primary rationale for using instrumented fusion over non-instrumented fusion for lumbar spondylolisthesis?





Explanation

Instrumented fusion, typically using pedicle screws and rods, provides immediate rigid internal fixation, which significantly enhances spinal stability, promotes higher fusion rates by minimizing motion at the fusion site, and facilitates early mobilization, potentially reducing the need for external bracing. It does not eliminate the need for bone graft, nor does it inherently reduce operative time or blood loss (often the opposite).

Question 16

A 40-year-old construction worker with chronic L4-L5 degenerative spondylolisthesis (Grade II) and bilateral L5 radiculopathy undergoes L4-L5 posterior decompression and instrumented fusion. Postoperatively, he develops increased bilateral foot drop and numbness in the lateral calves. What is the most likely cause?





Explanation

New or worsened foot drop and numbness in the lateral calves (consistent with L5 radiculopathy/palsy) immediately post-op following a decompression and fusion for spondylolisthesis, especially Grade II, strongly suggests an iatrogenic L5 nerve root injury. This can occur due to excessive retraction during decompression, direct trauma, or stretch injury during screw placement or reduction maneuvers. Epidural hematoma or persistent stenosis could cause symptoms, but an acute worsening immediately post-op points more to an iatrogenic event. Infection typically presents later and with systemic signs.

Question 17

Which of the following describes a 'high-grade' spondylolisthesis?





Explanation

High-grade spondylolisthesis refers to a slip of greater than 50% (Meyerding Grades III, IV, and V). These slips are often associated with more severe symptoms, lumbosacral kyphosis, and a higher risk of complications with surgical reduction compared to low-grade slips (Grades I and II).

Question 18

What is the primary indication for surgical reduction of a high-grade spondylolisthesis?





Explanation

While high-grade slips can cause mechanical pain and cosmetic issues, the primary indication for reduction (especially with its increased risks) is a progressive neurological deficit, such as worsening weakness or the development of cauda equina syndrome, where reduction may be necessary to decompress and stabilize the neural elements. In situ fusion is often preferred for pain or stable neurological symptoms due to the risks of reduction.

Question 19

In an adult patient with isthmic spondylolisthesis, which muscle group is characteristically tight and often contributes to sagittal imbalance and altered gait?





Explanation

Hamstring tightness is a common clinical finding in patients with spondylolisthesis, particularly in children and adolescents, but also in adults. It is thought to be a compensatory mechanism to maintain sagittal balance and prevent further anterior shear forces on the unstable segment, often leading to a 'pelvic tilt' or 'waddling' gait.

Question 20

A 16-year-old male presents with a painful L5-S1 Grade II isthmic spondylolisthesis and mild, non-progressive S1 radiculopathy. He has failed 6 months of physical therapy and bracing. Given his persistent pain and radiculopathy, which surgical option is generally considered the most appropriate initial treatment in this adolescent?





Explanation

For symptomatic Grade II isthmic spondylolisthesis with radiculopathy that has failed conservative management in adolescents, the standard of care is L5-S1 posterior decompression (if radicular symptoms are present) and instrumented posterolateral fusion. Fusion is necessary to stabilize the unstable segment and prevent further progression. Decompression alone without fusion is prone to failure and re-operation due to instability. Pars repair is typically for spondylolysis without significant slip. In situ fusion without decompression may not adequately relieve radiculopathy.

Question 21

What is the typical radiological feature that differentiates degenerative spondylolisthesis from isthmic spondylolisthesis?





Explanation

Degenerative spondylolisthesis (Wiltse-Newman Type III) is characterized by an intact pars interarticularis, with anterior slippage resulting from chronic instability due to degenerative changes in the facet joints and intervertebral disc. Isthmic spondylolisthesis (Type II) is defined by a defect in the pars. Type I (Dysplastic) can have a trapezoidal L5 and spina bifida. High-grade slips can occur in both types, though less common in Type III.

Question 22

Which of the following is considered the gold standard for diagnosing a pars interarticularis defect if plain radiographs are equivocal in a symptomatic patient?





Explanation

While SPECT/CT is very sensitive for identifying active pars lesions, a CT scan of the lumbar spine is considered the gold standard for clearly visualizing the bony anatomy of the pars interarticularis and definitively diagnosing a pars defect. MRI is excellent for soft tissue but less precise for fine bony detail. SPECT/CT shows metabolic activity but not always the defect itself with the same clarity as CT.

Question 23

In a patient undergoing surgery for L5-S1 high-grade spondylolisthesis, what intraoperative monitoring technique is most critical to prevent neurological injury during reduction maneuvers?





Explanation

Motor Evoked Potentials (MEPs) are crucial for monitoring the motor tracts of the spinal cord and nerve roots, especially during high-risk maneuvers like reduction of high-grade spondylolisthesis. Changes in MEPs can indicate impending motor nerve injury, allowing the surgeon to adjust the reduction. SSEPs monitor sensory tracts, and EMG monitors nerve root irritation but not directly the motor integrity of the spinal cord as effectively as MEPs.

Question 24

A 70-year-old female presents with severe back and leg pain, positive sagittal imbalance, and Grade III L4-L5 degenerative spondylolisthesis with severe stenosis. She is otherwise healthy. What is the most comprehensive surgical approach for this patient?





Explanation

For a Grade III degenerative spondylolisthesis with severe stenosis and sagittal imbalance in an otherwise healthy 70-year-old, a comprehensive stabilization and decompression is required. TLIF with decompression and pedicle screw fixation provides direct decompression of the neural elements, restores disc height, potentially corrects sagittal balance, and offers robust segmental stability with a high fusion rate. While circumferential fusion can be considered, TLIF often achieves similar goals with a single approach. Decompression alone leads to instability. Posterolateral fusion in situ may not address severe stenosis or kyphosis adequately. ALIF alone doesn't decompress posteriorly.

Question 25

What is the typical angle measured on a lateral radiograph to assess the severity of lumbosacral kyphosis associated with high-grade spondylolisthesis?





Explanation

The Lumbosacral Angle (also known as the Slip Angle or Dubousset's Angle) is specifically used to quantify lumbosacral kyphosis in spondylolisthesis. It is formed by the intersection of a line drawn along the inferior endplate of L5 and a line drawn along the superior endplate of S1. Increased kyphosis (a negative angle) is a sign of instability and often correlates with higher-grade slips. Other angles like LL, SS, PI, TPA are measures of overall sagittal balance but not specific to L5-S1 kyphosis due to slip.

Question 26

Which of the following conservative treatments has the strongest evidence for improving pain in pediatric spondylolysis with active pars defect?





Explanation

For pediatric spondylolysis with active pars lesions (e.g., confirmed by SPECT/CT or MRI edema) that are symptomatic, lumbar bracing combined with activity modification (restricting aggravating activities) has the strongest evidence for promoting healing and relieving pain. Complete bed rest is rarely indicated and detrimental. Opioids are inappropriate for chronic pediatric pain. Activity modification is key, not just stretching, and high-impact sports will hinder healing.

Question 27

In the context of degenerative spondylolisthesis, which level is most commonly affected?





Explanation

Degenerative spondylolisthesis most commonly occurs at the L4-L5 level. This is thought to be due to the orientation of the L4-L5 facet joints, which are more sagittally oriented and thus less resistant to anterior shear forces, combined with the greater mobility and stress at this segment.

Question 28

A patient with L5-S1 high-grade spondylolisthesis presents with progressive cauda equina syndrome. Which surgical approach is generally indicated for rapid decompression and stabilization?





Explanation

Progressive cauda equina syndrome is a surgical emergency. Urgent decompression of the compressed neural elements is paramount. For high-grade spondylolisthesis, this typically involves a posterior approach with decompression (e.g., laminectomy/foraminotomy) and instrumented fusion to provide immediate stability. While reduction carries risks, it might be necessary to adequately decompress in some severe cases. ALIF alone would not achieve rapid posterior decompression. Laminoplasty is for cervical spine. Conservative management is inappropriate for progressive cauda equina.

Question 29

What is the main concern with surgical reduction of high-grade spondylolisthesis in terms of achieving optimal spinal balance?





Explanation

A significant concern with aggressive reduction of high-grade spondylolisthesis, particularly in patients with compensatory hyperlordosis above the slip, is the potential for overcorrection of the lumbosacral kyphosis. This can lead to a 'flatback syndrome' or sagittal imbalance if the overall lumbar lordosis is excessively restored without considering the patient's global sagittal alignment. It's often more about restoring a balanced sagittal alignment than just maximal reduction of the slip.

Question 30

When is an isolated direct pars repair (e.g., Buck's technique, Scott wiring) considered in the management of spondylolysis?





Explanation

Isolated pars repair is typically reserved for young, active patients with symptomatic spondylolysis (a pars defect without significant anterior translation or only a very minimal Grade I slip) who have failed conservative treatment. The goal is to heal the pars defect and restore its integrity without fusing the segment. It is not indicated for significant spondylolisthesis or degenerative conditions where stability is the primary issue.

Question 31

Which anatomical structure is most commonly implicated in the compression of the L5 nerve root in L5-S1 isthmic spondylolisthesis?





Explanation

In L5-S1 isthmic spondylolisthesis, the L5 nerve root exits above the slipped L5 vertebral body. It can be compressed as it passes through the L5-S1 foramen, primarily by the pars interarticularis defect itself, the hypertrophic pseudarthrosis tissue at the defect, or the superior aspect of the S1 body or disc. While other structures can contribute to stenosis, the pars defect is specific to this type of spondylolisthesis at this level.

Question 32

What is the typical timeframe for conservative management of symptomatic spondylolisthesis before considering surgical intervention?





Explanation

For most cases of symptomatic spondylolisthesis (especially low-grade isthmic or degenerative), a trial of comprehensive conservative management, including physical therapy, activity modification, NSAIDs, and potentially epidural injections, for 6 months to 1 year is generally recommended before surgical intervention is considered. Exceptions are progressive neurological deficits or cauda equina syndrome, which require more urgent evaluation.

Question 33

A 12-year-old active child presents with an L5-S1 Grade II spondylolisthesis that has shown progression from Grade I over the past 6 months. He has moderate back pain but no neurological deficits. Conservative treatment has been initiated but the slip continues to progress. What is the most appropriate next step in management?





Explanation

In a child with a progressive spondylolisthesis (especially Grade II or higher) despite conservative management, surgical stabilization is indicated to prevent further slip and potential neurological complications. L5-S1 in situ posterolateral fusion is generally preferred for these cases. Aggressive reduction is associated with higher risks of neurological injury, and decompression alone would not address the instability or progression. Corticosteroids are not indicated.

Question 34

Which type of spondylolisthesis is most commonly associated with a 'vertical sacrum' or high sacral inclination?





Explanation

Type I (Dysplastic) spondylolisthesis is characterized by congenital anomalies that predispose to instability, including abnormal sacral morphology such as a more vertically oriented sacrum (high sacral inclination) and a domed sacrum, which reduce the sheer resistance and facilitate anterior slippage of L5 on S1.

Question 35

What is the main advantage of an Anterior Lumbar Interbody Fusion (ALIF) over a posterior approach for treating L5-S1 spondylolisthesis?





Explanation

An ALIF approach at L5-S1 allows for excellent access to the anterior column, enabling aggressive discectomy, release of the anterior longitudinal ligament, and placement of a large interbody cage. This is highly effective in restoring disc height, correcting L5-S1 lordosis, and indirectly decompressing the foramina. While it has advantages, it does not directly decompress posterior neural elements and requires an abdominal incision. Pseudarthrosis rates are comparable to other fusion types, and blood loss can vary.

Question 36

Which of the following is considered a relative contraindication for surgical reduction of a high-grade spondylolisthesis in adults?





Explanation

Long-standing, non-progressive neurological symptoms, especially if associated with significant dural scarring and adhesions (common in chronic high-grade slips), represent a relative contraindication to reduction. Attempts at reduction in such cases carry a significantly higher risk of neurological injury due to the adherent and tethered nerve roots/dura. In these situations, in situ fusion with adequate posterior decompression is often preferred. Other options listed are indications for surgery (pain, deficit, kyphosis) or less compelling (cosmetic).

Question 37

What is the primary objective of a 'Gaines procedure' (dome osteotomy) in the treatment of high-grade L5-S1 spondylolisthesis?





Explanation

The Gaines procedure (dome osteotomy) is a surgical technique for severe high-grade L5-S1 spondylolisthesis. It involves an S1 dome osteotomy (removal of a wedge of the S1 superior vertebral body) to effectively 'hinge' the L5 vertebral body posteriorly, allowing for correction of the lumbosacral kyphosis and safer reduction of the L5 on S1 without excessive stretch on the L5 nerve roots. It is a complex procedure aimed at correcting sagittal alignment and facilitating reduction.

Question 38

Which spinal deformity is commonly seen in patients with high-grade L5-S1 spondylolisthesis due to the slip and compensatory mechanisms?





Explanation

High-grade L5-S1 spondylolisthesis often leads to an abnormal sagittal alignment characterized by lumbosacral kyphosis, meaning the L5-S1 segment angles forward rather than maintaining the normal lordotic curve. This is often accompanied by compensatory hyperlordosis in the segments above the slip and pelvic retroversion to maintain overall sagittal balance.

Question 39

Which of the following is a common early complication specific to the anterior approach for L5-S1 spondylolisthesis fusion?





Explanation

Retrograde ejaculation is a well-known, albeit rare, complication specific to anterior lumbar approaches, particularly at L5-S1. It results from injury or disruption of the superior hypogastric plexus (autonomic nerves responsible for seminal vesicle and vas deferens contraction) during dissection anterior to the sacrum. Other listed complications are general surgical risks or specific to posterior approaches.

Question 40

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?





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 41

What is the primary biomechanical advantage of an interbody fusion cage (e.g., TLIF or ALIF cage) in treating spondylolisthesis?





Explanation

Interbody cages are critical for restoring anterior column support, which in turn helps restore disc height, opens the neuroforamina (indirect decompression), and contributes to the restoration of optimal sagittal balance (lordosis). This robust anterior column support shares load, promoting solid arthrodesis. It complements, rather than replaces, posterior instrumentation for stability, and it doesn't directly prevent hardware failure or provide immediate pain relief (fusion is a slower process).

Question 42

Which of the following describes Wiltse-Newman Type IV spondylolisthesis?





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 43

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





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 44

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?





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 45

In pediatric spondylolisthesis, which of the following is a recognized indication for surgical intervention?





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 46

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





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 47

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





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 48

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





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 49

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





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 50

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?





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 51

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





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 52

What radiographic finding indicates successful fusion following surgery for spondylolisthesis?





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 53

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?





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 54

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?





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 55

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





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 56

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





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 57

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?





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 58

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





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 59

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?





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 the current progressive neurological symptoms is 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 the current radicular 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 60

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





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.

Question 61

Which of the following describes the anatomical anomaly defining Wiltse-Newman Type V spondylolisthesis?





Explanation

Wiltse-Newman Type V, or Pathologic Spondylolisthesis, results from bone weakening due to generalized or localized bone disease, such as tumors (primary or metastatic), Paget's disease, or severe osteoporosis, which compromises the structural integrity of the vertebral segment and leads to slippage. Other options describe different types of spondylolisthesis.

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