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 261
Topic: Thoracolumbar Spine & Deformity
Which of the following anatomic and biomechanical changes is most directly responsible for the development of degenerative (Wiltse Type III) spondylolisthesis?
Correct Answer & Explanation
. Sagittal orientation of the facet joints
Explanation
Degenerative spondylolisthesis is most commonly associated with a sagittal orientation of the lumbar facet joints. This anatomic variant provides less resistance to anterior shear forces, leading to progressive slipping.
Question 262
Topic: Thoracolumbar Spine & Deformity
A 10-year-old female gymnast is diagnosed with a Grade II L5-S1 isthmic spondylolisthesis. Which of the following is the most significant radiographic risk factor for further anterior progression of her slip?
Correct Answer & Explanation
. Slip angle greater than 45 degrees
Explanation
A high slip angle (typically greater than 45-50 degrees) is a strong radiographic predictor of slip progression in pediatric isthmic spondylolisthesis. Young age (prior to the adolescent growth spurt) and female gender are also significant risk factors.
Question 263
Topic: Thoracolumbar Spine & Deformity
A 19-year-old college football lineman presents with chronic mechanical low back pain. Radiographs show a Grade I L5-S1 isthmic spondylolisthesis. Which diagnostic test is most useful to confirm that the pars defect is the primary source of his pain prior to performing a direct pars repair?
Correct Answer & Explanation
. Fluoroscopically guided pars intra-articular/defect injection
Explanation
A fluoroscopically guided injection of local anesthetic into the pars defect can help isolate the defect as the primary pain generator. A positive response supports the decision for a direct pars repair in young patients without significant disc degeneration.
Question 264
Topic: Thoracolumbar Spine & Deformity
Which of the following anatomic factors has been most strongly correlated with the development of degenerative spondylolisthesis at the L4-L5 level?
Correct Answer & Explanation
. Sagittal orientation of the facet joints
Explanation
Sagittal orientation of the L4-L5 facet joints (sagittal tropism) is a primary anatomic risk factor for degenerative spondylolisthesis. This orientation provides less resistance to anterior shear forces, leading to progressive slip.
Question 265
Topic: Thoracolumbar Spine & Deformity
A 16-year-old high school football lineman complains of chronic low back pain. Radiographs demonstrate an isthmic spondylolisthesis. Advanced imaging reveals an elongated, but intact, pars interarticularis without a frank fracture. According to the Wiltse classification, which subtype does this represent?
Correct Answer & Explanation
. Type IIB
Explanation
Wiltse Type II isthmic spondylolisthesis is divided into three subtypes: IIA (lytic/stress fracture), IIB (elongated but intact pars due to healed repeated microfractures), and IIC (acute pars fracture). Type IIB correctly describes an elongated, intact pars.
Question 266
Topic: Thoracolumbar Spine & Deformity
A 12-year-old female undergoes surgical reduction and instrumented fusion for a Meyerding Grade IV isthmic spondylolisthesis at L5-S1. Postoperatively, she exhibits new-onset weakness in foot dorsiflexion and great toe extension. Which nerve root is most commonly injured during the reduction maneuver for a high-grade slip?
Correct Answer & Explanation
. L5
Explanation
The L5 nerve root is at the highest risk for stretch injury during the surgical reduction of a high-grade L5-S1 spondylolisthesis. This is due to the tethering of the nerve as it exits the L5-S1 foramen during the restoration of disc height and slip reduction.
Question 267
Topic: Thoracolumbar Spine & Deformity
In the evaluation of spinopelvic parameters for a patient with adult spinal deformity and spondylolisthesis, which of the following equations accurately defines Pelvic Incidence (PI)?
Correct Answer & Explanation
. PI = Pelvic Tilt (PT) + Sacral Slope (SS)
Explanation
Pelvic incidence (PI) is a fixed morphologic parameter defined as the sum of Pelvic Tilt (PT) and Sacral Slope (SS). Therefore, PI = PT + SS.
Question 268
Topic: Thoracolumbar Spine & Deformity
During a wide lumbar laminectomy and medial facetectomy for severe central and lateral recess stenosis at L4-L5, excessive resection of the pars interarticularis can lead to iatrogenic spondylolisthesis. Biomechanical instability is most likely to occur if the bilateral pars resection exceeds what percentage?
Correct Answer & Explanation
. 50%
Explanation
Resection of more than 50% of the bilateral pars interarticularis (or facet joint complexes) significantly compromises the biomechanical stability of the lumbar segment, increasing the risk of iatrogenic postoperative spondylolisthesis.
Question 269
Topic: Thoracolumbar Spine & Deformity
Dysplastic (Wiltse Type I) spondylolisthesis is characterized by congenital abnormalities of the upper sacrum or the neural arch of L5. Which of the following associated findings is most highly correlated with this specific subtype?
Correct Answer & Explanation
. Spina bifida occulta and a trapezoidal L5 vertebral body
Explanation
Dysplastic spondylolisthesis is highly associated with spina bifida occulta (deficient posterior elements) and a trapezoidal shape of the L5 vertebral body. It occurs secondary to congenital deficiency of the facet joints and posterior arch.
Question 270
Topic: Thoracolumbar Spine & Deformity
According to the Wiltse classification, Type IV (Traumatic) spondylolisthesis is characterized by an acute fracture involving which specific anatomical structure?
Correct Answer & Explanation
. Any part of the posterior arch other than the pars interarticularis
Explanation
Wiltse Type IV (Traumatic) spondylolisthesis occurs secondary to an acute fracture in a portion of the posterior arch OTHER than the pars interarticularis (e.g., pedicle, lamina, or facet). A fracture strictly through the pars is classified as Type II (Isthmic).
Question 271
Topic: Thoracolumbar Spine & Deformity
A 20-year-old collegiate gymnast complains of isolated, persistent mechanical low back pain. Radiographs and CT show a bilateral L5 pars defect without spondylolisthesis. After 9 months of conservative care, surgery is considered. Which diagnostic test is most appropriate to confirm that the pars defects are the primary pain generators before performing a direct pars repair?
Correct Answer & Explanation
. Bilateral pars interarticularis local anesthetic injections
Explanation
In a patient with a pars defect and no slip, isolated bilateral pars interarticularis injections with local anesthetic can confirm the defect as the primary pain generator. Significant temporary pain relief validates the indication for a direct pars repair rather than a fusion.
Question 272
Topic: Thoracolumbar Spine & Deformity
A 16-year-old gymnast complains of chronic low back pain. Radiographs show a Grade II L5-S1 isthmic spondylolisthesis. If the patient develops radicular symptoms, which nerve root is most commonly affected due to foraminal compression?
Correct Answer & Explanation
. L5
Explanation
In an L5-S1 isthmic spondylolisthesis, the slip occurs through the pars interarticularis. The exiting L5 nerve root is most commonly compressed within the neural foramen by the fibrocartilaginous mass at the pars defect.
Question 273
Topic: Thoracolumbar Spine & Deformity
A 15-year-old elite gymnast presents with mechanical low back pain. Radiographs demonstrate a Grade 1 isthmic spondylolisthesis at L5-S1. She is neurologically intact. What is the most appropriate initial management?
Correct Answer & Explanation
. Activity modification, core strengthening, and physical therapy
Explanation
For low-grade isthmic spondylolisthesis in adolescents without neurologic deficits, initial management should be nonoperative. This includes a temporary cessation of hyperextension activities, bracing if acutely symptomatic, and core-strengthening physical therapy.
Question 274
Topic: Thoracolumbar Spine & Deformity
When planning for percutaneous iliosacral screw fixation, which of the following is a classic radiographic hallmark of sacral dysmorphism?
Correct Answer & Explanation
. Acute sacral alar slope
Explanation
Radiographic signs of sacral dysmorphism include an acute (steep) alar slope, residual intervertebral discs, non-circular neural foramina, an elevated upper sacrum, and the presence of mammillary bodies.
Question 275
Topic: Thoracolumbar Spine & Deformity
In the radiographic evaluation of adult spinal deformity, which of the following spinopelvic parameters is most highly correlated with poor health-related quality of life (HRQOL) scores and serves as a primary target during surgical correction?
Correct Answer & Explanation
. Sagittal vertical axis (SVA)
Explanation
Sagittal vertical axis (SVA) measures global sagittal alignment and is one of the strongest radiographic predictors of pain and disability in adult spinal deformity. Restoration of neutral sagittal alignment is a primary surgical goal.
Question 276
Topic: Thoracolumbar Spine & Deformity
A 30-year-old male falls from a height of 15 feet, sustaining a T12 burst fracture. He is neurologically intact. Which of the following radiographic findings is most specifically indicative of a posterior ligamentous complex (PLC) injury, necessitating surgical stabilization?
Correct Answer & Explanation
. Widening of the interspinous distance on the AP radiograph
Explanation
Widening of the interspinous distance (splaying of the spinous processes) on an AP radiograph strongly indicates disruption of the posterior ligamentous complex (PLC). A disrupted PLC implies significant biomechanical instability requiring surgical stabilization.
Question 277
Topic: Thoracolumbar Spine & Deformity
An 18-month-old infant is diagnosed with an infantile idiopathic scoliosis measuring 28 degrees. The curve is progressive. Based on the case information, what is the most appropriate initial non-surgical management strategy for this patient?
Correct Answer & Explanation
. Application of serial plaster jackets (localizer casts).
Explanation
Correct Answer: DThe case states under 'Early-onset scoliosis' that 'Patients that present with an idiopathic scoliosis below the age of 3 (infantile scoliosis) have the most heterogeneous prognosis... Treatment is problematic and prolonged. The most common forms of treatment are serial plaster jackets (localizer casts), subsequently bracing and eventually growing rods.'Option A is incorrectbecause immediate surgical fusion, especially with growing rods, is typically reserved for curves that fail to respond to conservative measures or are extremely severe and progressive, not as an initial treatment for an 18-month-old with a 28-degree curve, even if progressive. Growing rods are a later stage treatment.Option B is incorrectbecause while a significant number of infantile curves (80-90%)canresolve, the question states the curve isprogressive. For progressive curves, active intervention is needed, not just observation. The text specifically mentions treatment for those that 'do not resolve'.Option C is incorrectbecause while bracing is a treatment option, the text specifically lists 'serial plaster jackets (localizer casts)' as themost common initial form of treatmentfor infantile idiopathic scoliosis, followed by bracing.Option E is incorrectbecause physical therapy alone is not an effective treatment for correcting or preventing the progression of structural scoliosis in an infant.
Question 278
Topic: Thoracolumbar Spine & Deformity
A 15-year-old boy presents with a 30-degree left thoracic scoliosis, severe localized back pain, and abnormal abdominal reflexes. His family history is negative for scoliosis. Based on the case information, which of these findings is considered an 'atypical feature' that warrants further investigation beyond standard scoliosis workup?
Correct Answer & Explanation
. The left thoracic curve, severe pain, and abnormal abdominal reflexes.
Explanation
Correct Answer: CThe case states under 'Pattern recognition' that 'Atypical features indicate possible underlying pathology (e.g. left-sided curves, severe pain, rapid progression and short angular deformities.)' Additionally, under 'Neurological examination', it notes that 'abnormal abdominal reflexes are most commonly associated with intraspinal anomalies.' Therefore, the combination of a left thoracic curve, severe pain, and abnormal abdominal reflexes are all significant atypical features strongly suggesting an underlying intraspinal anomaly or other pathology, necessitating further investigation such as an MRI.Option A is incorrectbecause a 30-degree curve is moderate, but the magnitude itself is not an atypical feature that suggests underlying pathology. It's thecombinationof other factors that makes it atypical.Option B is incorrectbecause while AIS is more prevalent in females (5.4:1 for curves >20 degrees), male gender alone is not considered an 'atypical feature' indicating underlying pathology in the same way as a left-sided curve or severe pain. It simply means it's less common for males to develop AIS.Option D is incorrectbecause adolescent onset (10-maturity) is the most common age group for idiopathic scoliosis, so this is a typical, not atypical, feature.Option E is incorrectbecause while there is a genetic tendency for scoliosis (20% have an affected family member), the absence of a family history does not rule out idiopathic scoliosis and is not considered an 'atypical feature' indicating underlying pathology.
Question 279
Topic: Thoracolumbar Spine & Deformity
A 16-year-old gymnast complains of chronic low back pain worsening with extension. Radiographs confirm a Grade 2 isthmic spondylolisthesis at L5-S1. She has failed 6 months of physical therapy and bracing. What is the most appropriate surgical treatment?
Correct Answer & Explanation
. L5-S1 posterior spinal fusion
Explanation
Symptomatic Grade 1 or 2 isthmic spondylolisthesis in adolescents failing conservative care is best treated with a single-level in situ posterior or transforaminal lumbar interbody fusion (L5-S1). Direct pars repair is reserved for minimal slip (Grade 0/1) usually above L5.
Question 280
Topic: Thoracolumbar Spine & Deformity
A 15-year-old male presents with an increased thoracic kyphosis measuring 65 degrees. To meet the radiographic Sorensen criteria for classical Scheuermann's disease, there must be anterior wedging of at least 5 degrees in a minimum of how many consecutive vertebrae?
Correct Answer & Explanation
. 3
Explanation
The classic Sorensen criteria for Scheuermann's kyphosis require the presence of anterior wedging of 5 degrees or more in at least 3 consecutive thoracic vertebrae.
Test Yourself
Switch to an interactive, timed exam simulation to truly master this topic.