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 4761
Topic: Cervical Spine
During the late cocking and early acceleration phases of throwing, which specific component of the ulnar collateral ligament (UCL) complex of the elbow serves as the primary restraint to valgus stress?
Correct Answer & Explanation
. Anterior band of the anterior bundle
Explanation
The anterior bundle of the UCL is the primary restraint to valgus stress at the elbow. It is further divided into the anterior and posterior bands. The anterior band is tight in extension and serves as the primary restraint to valgus stress throughout the critical degrees of flexion seen during the acceleration phase of throwing.
Question 4762
Topic: Cervical Spine
A 21-year-old collegiate baseball pitcher is undergoing an ulnar collateral ligament (UCL) reconstruction utilizing an autograft.
Which native anatomical structure is the primary restraint to valgus stress at the elbow during the late cocking and early acceleration phases of throwing?
Correct Answer & Explanation
. Anterior bundle of the UCL
Explanation
The anterior bundle of the ulnar collateral ligament (UCL) is the primary restraint to valgus stress at the elbow, particularly between 30 and 120 degrees of flexion, which corresponds to the late cocking and early acceleration phases of throwing. The posterior bundle is a secondary restraint, and the transverse ligament provides no significant stability.
Question 4763
Topic: Cervical Spine
A 22-year-old collegiate baseball pitcher reports insidious onset of medial elbow pain and decreased pitching velocity. Physical examination reveals pain with the moving valgus stress test. An MRI confirms a high-grade partial tear of the ulnar collateral ligament (UCL). Which specific anatomic structure is the primary restraint to valgus stress at the elbow during the late cocking and early acceleration phases of throwing?
Correct Answer & Explanation
. Anterior bundle of the UCL
Explanation
The ulnar collateral ligament (UCL) complex of the elbow consists of the anterior bundle, posterior bundle, and transverse ligament. The anterior bundle is the primary restraint to valgus stress at the elbow from 30 to 120 degrees of flexion, which perfectly correlates with the elbow position during the late cocking and early acceleration phases of the throwing motion. The posterior bundle provides restraint in deep flexion, and the transverse ligament contributes little to no valgus stability.
Question 4764
Topic: 6. Spine
A 7-year-old girl with Down syndrome wishes to participate in Special Olympics gymnastics. She is completely asymptomatic, has no history of neck pain or weakness, and her neurologic examination is normal. Based on the American Academy of Pediatrics (AAP) guidelines, what is the recommendation regarding pre-participation cervical spine screening?
Correct Answer & Explanation
. Screening radiographs are not recommended for asymptomatic individuals
Explanation
The American Academy of Pediatrics (AAP) revised its guidelines, stating that routine cervical spine radiographs in asymptomatic children with Down syndrome are not indicated prior to sports participation, as they have poor predictive value for catastrophic spinal cord injury. Targeted radiographic screening is recommended only for patients with symptomatic neck pain, radiculopathy, or myelopathy.
Question 4765
Topic: 6. Spine
A 10-year-old boy with spinal muscular atrophy (SMA) type II presents with a progressive, collapsing thoracolumbar neuromuscular scoliosis measuring 85 degrees. He is non-ambulatory, has pelvic obliquity, and his forced vital capacity (FVC) is 40% of predicted. He underwent placement of magnetically controlled growing rods at age 5, which have now reached their maximum excursion. What is the most definitive surgical option at this stage?
Correct Answer & Explanation
. Definitive posterior spinal fusion from the upper thoracic spine to the pelvis
Explanation
This patient has reached the stage where his growth-friendly instrumentation (magnetic rods) has 'graduated' or 'maxed out.' In a 10-year-old with a severe, progressive collapsing neuromuscular scoliosis (like in SMA) and pelvic obliquity, sufficient spinal length has usually been achieved. The definitive and standard management upon graduation from a growing construct is a definitive posterior spinal fusion (PSF). For non-ambulatory patients with neuromuscular scoliosis and pelvic obliquity, the fusion typically extends from the upper thoracic spine down to the pelvis to restore sitting balance, correct the pelvic obliquity, and provide a stable spine for pulmonary function and wheelchair seating.
Question 4766
Topic: Thoracolumbar Spine & Deformity
A 14-year-old male athlete presents with lower back pain and notably tight hamstrings. A lateral lumbar radiograph reveals a grade II isthmic spondylolisthesis at L5-S1.
He has failed 6 months of nonoperative management, including bracing, physical therapy, and activity modification. What is the most appropriate surgical treatment?
Correct Answer & Explanation
. L5-S1 in situ posterolateral arthrodesis
Explanation
For pediatric and adolescent patients with symptomatic low-grade (Grade I or II) isthmic spondylolisthesis who fail comprehensive conservative management, L5-S1 in situ posterolateral arthrodesis is the surgical standard of care. Pars repairs (e.g., Buck or Scott wiring) are generally reserved for young patients with a pars defect but minimal or no slip (typically L1-L4, not L5-S1). Laminectomy alone is contraindicated in children as it promotes instability and further slippage.
Question 4767
Topic: 6. Spine
A 3-year-old girl is diagnosed with infantile idiopathic scoliosis. Radiographs reveal a primary left thoracic curve of 35 degrees. The rib-vertebra angle difference (RVAD) of Mehta is measured at 25 degrees. What is the most appropriate initial management for this patient to control deformity progression?
Correct Answer & Explanation
. Serial elongation-derotation-flexion (EDF) Mehta casting
Explanation
Infantile idiopathic scoliosis with a curve > 30 degrees and an RVAD > 20 degrees has a high likelihood of rapid progression. Serial elongation-derotation-flexion (EDF) casting, also known as Mehta casting, is the gold standard initial management for progressive early-onset scoliosis in this age group. It has been shown to effectively control curve progression, allow for pulmonary development, and in some cases, completely resolve the deformity. Bracing is less effective in controlling severe rotation in infantile progressive curves.
Question 4768
Topic: 6. Spine
A 14-year-old female gymnast complains of lower back pain that worsens with extension and twisting movements. Physical examination reveals tight hamstrings and pain elicited on the single-leg hyperextension test (Stork test). Standing AP and lateral radiographs of the lumbar spine show no distinct abnormalities. If advanced imaging is to be ordered to confirm an acute pars interarticularis stress reaction, which imaging modality is highly sensitive and best avoids ionizing radiation?
Correct Answer & Explanation
. Magnetic Resonance Imaging (MRI) of the lumbar spine
Explanation
Magnetic Resonance Imaging (MRI) of the lumbar spine, specifically utilizing T2-weighted and STIR sequences, is highly sensitive for detecting bone marrow edema indicative of an acute pars stress reaction (early spondylolysis). Unlike SPECT scans or CT scans, MRI has the significant advantage of not exposing the pediatric patient to ionizing radiation, making it the preferred advanced imaging modality for evaluating suspected acute pars pathology in young athletes when plain radiographs are negative.
Question 4769
Topic: Thoracolumbar Spine & Deformity
A 14-year-old female gymnast presents with persistent lower back pain. Radiographs reveal an isthmic spondylolisthesis at L5-S1 with a slip of 60% (Meyerding Grade III). She has failed 6 months of nonoperative management. What is the most appropriate surgical intervention?
Correct Answer & Explanation
. L5-S1 in situ posterolateral fusion
Explanation
For symptomatic high-grade (>50% slip) isthmic spondylolisthesis that fails conservative care, L5-S1 in situ posterolateral fusion (typically with instrumentation) is the standard treatment to prevent further progression.
Question 4770
Topic: 6. Spine
A 2-year-old child with achondroplasia presents with hypotonia, developmental delay, and central sleep apnea. Which of the following is the most critical screening study to obtain to determine the cause of these symptoms?
Correct Answer & Explanation
. MRI of the craniovertebral junction
Explanation
Children with achondroplasia are at high risk for foramen magnum stenosis, which can cause cervicomedullary compression leading to central sleep apnea, hypotonia, and sudden death. MRI of the craniovertebral junction is the imaging modality of choice to assess this.
Question 4771
Topic: 6. Spine
A 65-year-old man with ankylosing spondylitis and a completely fused lumbosacral spine is scheduled for a primary total hip arthroplasty (THA). How does this patient's spinopelvic stiffness alter the targeted functional safe zone for acetabular cup positioning compared to a patient with normal spinal mobility?
Correct Answer & Explanation
. The cup should be placed in increased anteversion to compensate for the lack of posterior pelvic tilt during sitting.
Explanation
A stiff spine prevents the normal posterior pelvic tilt that occurs during sitting, which naturally increases functional acetabular anteversion. To prevent anterior impingement and posterior dislocation when sitting, the cup may require increased anteversion.
Question 4772
Topic: 6. Spine
A 65-year-old man is scheduled to undergo a total hip arthroplasty (THA). Preoperative radiographs reveal spontaneous fusion of the lumbar spine from L2 to S1 secondary to diffuse idiopathic skeletal hyperostosis. How does this spinal stiffness affect acetabular dynamics and dislocation risk during the transition from standing to sitting?
Correct Answer & Explanation
. Acetabular anteversion changes minimally, predisposing to posterior dislocation.
Explanation
In a patient with a stiff spine, the pelvis cannot appropriately tilt posteriorly when transitioning from standing to sitting. Consequently, acetabular anteversion changes minimally (fails to increase), leading to anterior impingement and a high risk of posterior dislocation.
Question 4773
Topic: 6. Spine
A 70-year-old man is scheduled for a THA. He has a history of a rigid multilevel lumbar spinal fusion from L2 to the sacrum. How should acetabular cup placement be adjusted to minimize the risk of posterior dislocation during sitting?
Correct Answer & Explanation
. Increase cup anteversion and inclination
Explanation
Patients with a lumbosacral fusion have a stiff spine (spinopelvic stiffness) and lack the normal increase in posterior pelvic tilt during sitting. To prevent anterior impingement and subsequent posterior dislocation during flexion, the acetabular cup should be placed with increased anteversion and inclination.
Question 4774
Topic: 6. Spine
A 72-year-old woman is scheduled for a total hip arthroplasty (THA) for severe right hip osteoarthritis. She has a history of a multi-level lumbar spinal fusion from L2 to S1. How does this spinal pathology significantly alter her spinopelvic kinematics during the transition from standing to sitting?
Correct Answer & Explanation
. The pelvis fails to tilt posteriorly adequately, requiring more hip flexion and increasing the risk of anterior impingement and posterior dislocation.
Explanation
In a healthy spine, transitioning from standing to sitting is accompanied by posterior pelvic tilt, which increases functional acetabular anteversion and allows the femur to flex without impinging on the anterior acetabular rim. Patients with a stiff lumbar spine (e.g., from multilevel fusion) cannot achieve this normal posterior pelvic tilt. Consequently, the acetabulum fails to 'open up' anteriorly. To achieve a seated position, the patient requires excessive hip flexion, which leads to anterior impingement between the femur and the anterior rim of the acetabulum. This impingement acts as a fulcrum, predisposing the hip to posterior dislocation.
Question 4775
Topic: 6. Spine
A 68-year-old man with a history of a long spinal fusion from T10 to the pelvis is planned for a total hip arthroplasty. How does his spinal pathology alter the target placement of his acetabular component compared to a patient with normal spinopelvic mobility?
Correct Answer & Explanation
. The cup requires more anteversion and more abduction.
Explanation
Patients with spinopelvic stiffness (e.g., prior lumbopelvic fusion) cannot undergo normal posterior pelvic tilt during hip flexion. To prevent anterior bony impingement and subsequent posterior dislocation during sitting, the acetabular component must be placed in greater anteversion and abduction.
Question 4776
Topic: 6. Spine
A 68-year-old woman is undergoing a primary total hip arthroplasty. She has a prior spinal fusion from L2 to the pelvis. Preoperative standing and sitting lateral radiographs show no change in her pelvic tilt. To minimize the risk of posterior dislocation, how should the acetabular component be positioned compared to a patient with normal spino-pelvic mobility?
Correct Answer & Explanation
. Increased anteversion
Explanation
In a patient with a stiff spino-pelvic segment (fusion to pelvis), the pelvis fails to retrovert during sitting. This requires the acetabular component to be placed in increased anteversion to clear the femur and prevent posterior dislocation during hip flexion.
Question 4777
Topic: 6. Spine
A 55-year-old man with ankylosing spondylitis and a fused lumbar spine is undergoing THA. Preoperative standing and sitting lateral spinopelvic radiographs show less than 10 degrees of change in pelvic tilt between positions. How should the acetabular component positioning be adjusted to minimize dislocation risk?
Correct Answer & Explanation
. Target increased anteversion and slightly increased inclination
Explanation
In a stiff spine, the pelvis fails to retrovert during sitting, leaving the acetabulum relatively under-anteverted and increasing the risk of anterior impingement and posterior dislocation. The cup should be placed in more anteversion to accommodate sitting.
Question 4778
Topic: 6. Spine
A 72-year-old man with previous lumbar fusion from L2 to S1 is scheduled for a total hip arthroplasty. Flexion-extension seating radiographs demonstrate less than 10 degrees of change in his pelvic tilt. To minimize the risk of posterior dislocation, how should the acetabular component be positioned compared to a patient with normal spinopelvic mechanics?
Correct Answer & Explanation
. Increased anteversion and increased inclination
Explanation
Patients with a stiff spine cannot increase pelvic tilt when sitting, requiring the cup to be placed in greater anteversion and inclination to accommodate hip flexion. This prevents anterior impingement and subsequent posterior dislocation.
Question 4779
Topic: 6. Spine
A 70-year-old female with a history of a solid multi-level lumbar spine fusion (L2-S1) presents for right THA for primary osteoarthritis. What modification regarding acetabular component positioning should be considered to minimize the risk of dislocation, compared to a patient with a normal mobile lumbar spine?
Correct Answer & Explanation
. Increase the anteversion of the acetabular component
Explanation
Patients with a fused or stiff lumbar spine fail to increase their pelvic tilt when transitioning from standing to sitting. Normally, posterior pelvic tilt during sitting increases functional acetabular anteversion, preventing anterior impingement and posterior dislocation. Because these patients have reduced spinopelvic mobility, the acetabular component should be placed in slightly more anteversion than the standard 'safe zone' to compensate for the lack of functional anteversion during sitting.
Question 4780
Topic: 6. Spine
A 72-year-old male is undergoing primary total hip arthroplasty (THA). Preoperative standing and sitting lateral radiographs reveal a fused lumbar spine from L2 to the sacrum, with no change in pelvic tilt between positions. Which of the following adjustments to the acetabular component position is recommended to minimize the risk of posterior dislocation when the patient sits?
Correct Answer & Explanation
. Increase both anteversion and inclination
Explanation
In a patient with a stiff lumbar spine, the pelvis fails to roll posteriorly (retrovert) when transitioning from standing to sitting. Normally, this posterior pelvic tilt dynamically increases functional acetabular anteversion, allowing clearance for hip flexion. A stiff spine removes this compensatory mechanism, significantly increasing the risk of anterior impingement and subsequent posterior dislocation during sitting. To compensate, the surgeon should implant the cup with increased anteversion and inclination (while remaining within safe zones) to mimic the missing dynamic clearance.
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