Question 1

Advantages of minimally invasive lumbar interbody fusion over traditional open interbody fusion include:

Explanation

Minimally invasive lumbar interbody fusion involves less muscle dissection and trauma than traditional open approaches. The surgical exposure is more limited, though, and there is no evidence to date of minimally invasive techniques providing better fusion rates or lowered risk of nerve root injury.

Question 2

Which of the following instruments are of value to a surgeon when performing minimally invasive lumbar fusions:

Explanation

All of the above instruments are of value to a surgeon when performing minimally invasive lumbar fusion.

Question 3

Which of the following statements is true regarding minimally invasive posterior lumbar interbody fusion:

Explanation

Intraoperative fluoroscopy or radiography is vital for the proper identification of lumbar level and vertebral structures in minimally invasive posterior lumbar interbody fusions. While endoscopic assistance has been well described as a method of minimally invasive fusion, it is not vital to this technique. There is no evidence to date of increased risk of nerve root injury with minimally invasive techniques, and it is possible to internally fixate the lumbar segment with pedicle screws through minimally invasive techniques.

Question 4

Which of the following is not a described technique of minimally invasive anterior lumbar interbody fusion:

Explanation

All of the above are well-described techniques of minimally invasive anterior lumbar interbody fusion.

Question 5

Which of the following statements is false regarding minimally invasive transperitoneal anterior lumbar interbody fusion:

Explanation

Due to the potential risk of injury to the aorta and its bifurcation, which occurs at the L4 level, this procedure is difficult and may be impossible to perform above the L4 level. Retroperitoneal approaches allow access to more superior lumbar levels due to the more lateral trajectory taken to avoid the aorta and its bifurcation.

Question 6

All of the following are elements of the lateral mass of cervical spinal segments except:

Explanation

The lateral mass of the cervical spinal segments includes the inferior and superior articulating processes, the transverse foramen, and the transverse process. The spinous process is not an element of the lateral mass.

Question 7

To avoid vertebral artery injury during cervical lateral mass screw placement, it is best to:

Explanation

To avoid injury to the vertebral artery when placing lateral mass screws, it is best to avoid placing the screw in the medial portion of the lateral mass, where the vertebral body is most likely to be found.

Question 8

Which of the following is/are potential complications associated with posterior cervical decompression and placement of lateral mass screws:

Explanation

All of the above are potential complications associated with posterior cervical decompression and placement of lateral mass screws.

Question 9

Which of the following statements is true regarding the C 2 lateral mass:

Explanation

The vertebral artery assumes a more lateral position at the C 2 level; therefore, screw placement at this level should follow a medial trajectory to avoid injury to the vertebral artery.

Question 10

The technique for C1-C 2 lateral mass fixation may involve:

Explanation

The C 1 and C 2 levels have unique anatomies that require variation in lateral mass screw fixation technique. Removing the C1 arch assists in proper placement of the C 1 screws via a lateral trajectory. The C 2 pedicle is large, and pedicle screws arecommonly placed at this level to avoid vertebral artery injury in the small lateral masses. C 1 lateral mass screws follow the long axis of the C 1 lateral mass as visualized on pre-operative C T scanning.

Question 11

Which of the following conditions is not associated with cervical fractures:

Explanation

Rheumatoid arthritis, ankylosing spondylitis, and os odontoideum have been associated with fractures as part of their presentation or etiology. Os odontoideum is most likely an old nonunion fracture or injury to vascular supply of the developing odontoid process. However, one has to differentiate true os odontoideum from the more common ossiculum terminale, which describes the nonunion of the apex at the secondary ossification center and is not a fracture.

Question 12

Which of the following pathogens is not typically implicated in diskitis:

Explanation

The gram-positive cocci are typical opportunistic pathogens that are capable of causing infection in the vertebral disk space. Most commonly they seed via the hematogenous route but local translocation has also been implicated. Unless a patient has been hospitalized for a while and iatrogenesis is ruled out, Pseudomonas species usually do not cause diskitis.

Question 13

Which imaging modality is usually the least sensitive in diagnosing discitis:

Explanation

The least helpful modality in diagnosing early discitis is the plain radiograph. Fluoroscopy does not give insight into the state of the intervertebral disk. It can suggest loss of disk height or involvement of the vertebral bone but will not reveal infection limited to the disk. The CT scan is useful because of its excellent resolution of bony structures and associated changes secondary to disk infection. MRI is the best modality to characterize the soft tissues in the cervical spine.

Question 14

Potts disease is most commonly treated by:

Explanation

The treatment of tuberculous involvement of the spine is rarely surgical. Most commonly, the spine remains stable and fusion is not necessary. However, orthosis in combination with long-term antibiotic therapy is the key for successful treatment. A collar is sufficient to provide enough stability and comfort for the lesion to heal.

Question 15

Which of the following is characteristic of patients with Klippel-Feil syndrome:

Explanation

Klippel-Feil syndrome is a rare disorder characterized by the congenital fusion of any two of the seven cervical vertebrae. The cause is a failure in the early segmentation during fetal development. The fused segments show absence of intervertebral joints. Associated abnormalities may include scoliosis; spina bifida; anomalies of the kidneys and ribs; and other midline anomalies.

Question 16

A burst fracture results in failure of the:

Explanation

A burst fracture by definition is failure of the anterior and middle columns due to axial loading, which often leads to instability and neurologic impairment.

Question 17

What type of fracture is presented in the radiograph (Slide):

Explanation

Clearly seen in this radiograph is a fracture along the anterior/inferior vertebral body, which is a characteristic of a teardrop fracture.

Question 18

What type of fracture is presented in the radiograph (Slide):

Explanation

Orthopedic Prometric Exam Chapter 3 Image

Clearly seen in this radiograph is a fracture along the anterior/inferior vertebral body, which is a characteristic of a teardrop fracture.

Question 19

Which of the following may be used as treatment options for bilateral facet dislocations:

Explanation

All of the choices are used in the treatment of bilateral jumped facets, often in combination or sequence.

Question 20

Which of the following fracture types is the most stable fracture:

Explanation

The avulsion of part or all of the spinous process that occurs after a violent flexion motion is a one-column injury. The injury is a stable fracture treated by external orthosis, which rarely results in neurologic impairment. The other answer choices may be considered stable in some instances, but none of them are stable all of the time.

Question 21

Which of the following strictly defines the boundaries of Kambin's working triangle utilized in transforaminal endoscopic and minimally invasive spine procedures?

Explanation

Kambin's triangle is bound anteriorly by the exiting nerve root, inferiorly by the superior endplate of the inferior vertebral body, and posteriorly by the superior articular process of the inferior vertebra. It serves as a safe corridor for transforaminal access to the disc space.

Question 22

A key theoretical advantage of the paramedian Wiltse approach used in minimally invasive lumbar fusion, as opposed to the traditional midline open approach, is the preservation of which of the following structures?

Explanation

The Wiltse approach uses the natural cleavage plane between the multifidus and longissimus muscles. This minimizes devascularization and denervation of the multifidus by preserving the medial branch of the dorsal ramus.

Question 23

A 55-year-old female undergoes a minimally invasive lateral lumbar interbody fusion (LLIF) at L4-L5. Postoperatively, she demonstrates weakness in hip flexion and knee extension, along with anterior thigh numbness. Which of the following structures was most likely injured during the retractor docking phase?

Explanation

The femoral nerve (L2-L4) lies within the posterior aspect of the psoas muscle at the L4-L5 level. Prolonged retraction or direct injury during the transpsoas approach can lead to iatrogenic femoral nerve palsy, presenting with quadriceps weakness and anterior thigh numbness.

Question 24

Cortical bone trajectory (CBT) pedicle screws are increasingly used in minimally invasive lumbar fusions. Which of the following best describes the starting point and trajectory of a CBT screw compared to a traditional pedicle screw?

Explanation

CBT screws are inserted with a medial-to-lateral and caudad-to-cephalad trajectory, starting at the junction of the pars interarticularis and superior articular process. This maximizes engagement with high-density cortical bone, increasing pullout strength.

Question 25

Which of the following statements is true regarding radiation exposure to the surgical team during minimally invasive (MIS) lumbar fusions compared to traditional open procedures?

Explanation

Because MIS techniques rely heavily on fluoroscopy for anatomical orientation, percutaneous screw placement, and retractor docking, they are associated with significantly higher radiation exposure to the surgical team compared to open procedures, especially during the learning curve.

Question 26

A 62-year-old male presents with neurogenic claudication and L5-S1 isthmic spondylolisthesis. Why is a standard lateral lumbar interbody fusion (LLIF) approach generally contraindicated at this specific level?

Explanation

The standard transpsoas lateral approach (LLIF) is generally contraindicated at L5-S1 due to the anatomical obstruction caused by the iliac crest, which prevents direct orthogonal access to the disc space. ALIF or TLIF are preferred alternatives.

Question 27

During a single-level minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) using a non-expandable tubular retractor, a small incidental durotomy occurs. The surgeon assesses the tear to be 2 mm. What is the most appropriate management strategy?

Explanation

Small dural tears (<3 mm) in MIS tubular approaches are difficult to primarily suture due to limited visualization and working space. They can often be successfully managed with onlay synthetic dural substitutes, fibrin glue, and meticulous watertight closure of the fascia.

Question 28

When comparing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) to anterior lumbar interbody fusion (ALIF), which of the following is a recognized limitation of the MIS TLIF approach?

Explanation

While MIS TLIF reduces soft tissue injury and blood loss, it is generally less effective than ALIF at restoring large degrees of segmental lordosis and correcting global sagittal imbalance.

Question 29

Review the provided imaging.

In managing a patient with symptomatic L4-L5 degenerative spondylolisthesis, which of the following is a proven advantage of utilizing a minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) over an open approach?

Explanation

Extensive literature comparing MIS TLIF to open TLIF for degenerative spondylolisthesis demonstrates that MIS approaches lead to less intraoperative blood loss, decreased postoperative narcotic consumption, and a shorter hospital length of stay. Long-term fusion rates and ASD incidence remain similar.

Question 30

Based on the intraoperative fluoroscopy image,

when placing percutaneous pedicle screws, what is the most common direction of cortical breach that risks injury to the exiting nerve root?

Explanation

An inferior breach of the pedicle puts the exiting nerve root at risk as it exits the foramen directly caudal to the pedicle. Conversely, a medial breach risks injury to the traversing nerve root and dura.

Question 31

During the placement of percutaneous pedicle screws for a minimally invasive fusion, the surgeon inadvertently advances the Jamshidi guidewire too far anteriorly. Which of the following complications is most likely to occur as a direct result of an anterior vertebral body breach at the L4 level?

Explanation

At the L4 level, the bifurcation of the aorta and inferior vena cava into the common iliac vessels occurs just anterior to the vertebral body. An anterior guidewire breach carries a catastrophic risk of injuring these major vascular structures.

Question 32

The use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has been associated with which of the following specific postoperative complications?

Explanation

The use of rhBMP-2 in the posterior or transforaminal lumbar space has a well-documented risk of causing postoperative radiculitis, seroma formation, and ectopic bone growth leading to neuroforaminal stenosis.

Question 33

Which of the following is the most appropriate indication for utilizing an interlaminar endoscopic approach rather than a transforaminal endoscopic approach for a lumbar discectomy?

Explanation

The interlaminar approach is preferred at L5-S1 because the wide interlaminar window allows excellent access, while the transforaminal approach is often obstructed at this level by a high-riding iliac crest and large L5 transverse process.

Question 34

During a lateral lumbar interbody fusion (LLIF) at L4-L5, which of the following intraoperative neuromonitoring modalities is most critical to prevent lumbar plexus injury during dilation and retractor placement?

Explanation

Triggered EMG (tEMG) is critical during the transpsoas approach to map the proximity of the lumbar plexus to the dilators and retractor blades. sEMG detects spontaneous nerve irritation during retraction.

Question 35

During a percutaneous transforaminal endoscopic discectomy or MIS approach, the surgeon accesses the disc space via Kambin's triangle. Which of the following structures forms the medial (posterior) boundary of this working zone?

Explanation

Kambin's triangle is an anatomical corridor bounded anteriorly/laterally by the exiting nerve root, inferiorly by the superior endplate of the caudal vertebra, and medially/posteriorly by the traversing nerve root and thecal sac.

Question 36

The Wiltse paraspinal approach is frequently utilized in minimally invasive lumbar surgeries to minimize muscle morbidity. This approach utilizes an internervous and intermuscular plane between which of the following muscle groups?

Explanation

The Wiltse approach splits the fascia to access the natural cleavage plane between the multifidus (medially) and the longissimus (laterally). This avoids denervation of the multifidus, which is supplied by the medial branch of the dorsal ramus.

Question 37

When establishing the operative corridor for a minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) using a tubular retractor system, what is the primary initial bony docking point?

Explanation

In an MIS TLIF, the tubular retractor is typically docked directly over the facet complex (specifically the junction of the pars and the facet joint). This allows direct access for a unilateral facetectomy to expose the intervertebral disc and neuroforamen.

Question 38

Cortical bone trajectory (CBT) screws have gained popularity in minimally invasive lumbar fusions. Which of the following best describes the entry point and trajectory of a CBT pedicle screw compared to a traditional pedicle screw?

Explanation

The CBT screw entry point is in the pars interarticularis, starting medially and aiming laterally and cephalad. This maximizes contact with higher-density cortical bone, increasing pullout strength.

Question 39

A surgeon is performing a lateral lumbar interbody fusion (LLIF/XLIF). At which of the following operative levels is the patient at the highest risk for postoperative lumbar plexus injury or severe psoas weakness?

Explanation

The lumbar plexus courses more anteriorly within the psoas muscle as it descends the lumbar spine. Consequently, the L4-L5 level carries the highest risk for iatrogenic plexus injury during a transpsoas lateral approach.

Question 40

A 55-year-old patient undergoes an uncomplicated L4-L5 MIS TLIF for right-sided radiculopathy. Postoperatively, the patient develops severe new-onset left-sided (contralateral) radicular leg pain. What is the most likely intraoperative cause of this complication?

Explanation

Over-distraction of the intervertebral space with a large cage during a unilateral MIS TLIF can cause indirect compression or traction on the contralateral traversing nerve root, leading to new-onset contralateral radiculopathy.

Question 41

Oblique lumbar interbody fusion (OLIF) was developed as an alternative to the transpsoas lateral approach (LLIF). What is the primary anatomical advantage of OLIF over LLIF?

Explanation

OLIF approaches the lumbar spine through an oblique corridor anterior to the psoas muscle. This largely avoids the lumbar plexus, reducing the risk of postoperative psoas weakness and groin numbness associated with LLIF.

Question 42

Histological studies comparing multifidus muscle integrity after open versus minimally invasive lumbar fusion demonstrate significantly less muscle atrophy in the MIS group. What is the primary mechanism of multifidus injury prevented by the MIS tubular approach?

Explanation

Traditional open midline approaches require prolonged static retraction of the paraspinal muscles, causing elevated intramuscular pressure and subsequent ischemic necrosis. MIS tubular retractors split the muscle fibers and significantly reduce this ischemic burden.

Question 43

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is frequently used off-label as a bone graft extender in MIS TLIF procedures. Which of the following is a recognized complication specifically associated with its use in the posterior lumbar spine?

Explanation

When used in posterior or transforaminal approaches, rhBMP-2 leakage near neural elements can cause a robust localized inflammatory response resulting in severe postoperative radiculitis, as well as the risk of ectopic heterotopic ossification.

Question 44

The image demonstrates interbody cage subsidence. Which of the following technical errors most significantly increases the risk of cage subsidence following an MIS TLIF?

Explanation

Aggressive endplate scraping that violates the subchondral bone structurally weakens the vertebral endplate, drastically increasing the risk of the interbody cage subsiding into the vertebral body.

Question 45

Minimally invasive spine surgery heavily relies on intraoperative fluoroscopy, increasing radiation exposure to the surgeon. According to the inverse square law, stepping back 1 meter from the C-arm during exposure reduces the radiation dose by approximately what factor compared to standing 0.5 meters away?

Explanation

The inverse square law states that radiation exposure is inversely proportional to the square of the distance from the source. Doubling the distance (e.g., 0.5m to 1m) reduces the radiation exposure to one-fourth.

Question 46

During a single-level MIS TLIF using a 22 mm tubular retractor, an incidental durotomy occurs with visible cerebrospinal fluid leak. Primary suture repair is technically impossible due to limited visualization. What is the most appropriate next step in management?

Explanation

In minimally invasive tubular surgery, conversion to open is rarely mandatory for small unrepairable durotomies. Application of a dural overlay (patch/sealant) and watertight fascial closure is an accepted and effective management strategy.

Question 47

Computer-assisted navigation with intraoperative CT (O-arm) is increasingly used for percutaneous pedicle screw placement in MISS. What intraoperative maneuver is most likely to cause a "registration error" resulting in inaccurate screw navigation?

Explanation

Navigation systems rely on the fixed spatial relationship between the reference frame and the bony anatomy. Any manipulation (distraction, translation, or decompression) that alters the alignment of the vertebrae after the spin will compromise navigational accuracy.

Question 48

For a patient with an L5-S1 isthmic spondylolisthesis and significant loss of segmental lordosis, an Anterior Lumbar Interbody Fusion (ALIF) may be preferred over an MIS TLIF. What is the primary biomechanical advantage of ALIF at this specific level?

Explanation

ALIF at L5-S1 allows for the placement of a large, highly lordotic cage and release of the anterior longitudinal ligament (ALL), providing far superior restoration of segmental lordosis compared to a posterior/transforaminal approach.

Question 49

A patient presents with pseudoarthrosis one year after an L4-L5 MIS TLIF. Given the constraints of minimally invasive approaches, what is the most common technical etiology for pseudarthrosis in this specific procedure?

Explanation

The most common technical cause of pseudoarthrosis in MIS TLIF is incomplete disc removal and inadequate endplate preparation, as the limited "keyhole" visualization can make thorough contralateral disc space preparation challenging.

Question 50

During the placement of percutaneous pedicle screws, a Kirschner wire (K-wire) is impacted into the pedicle. What is the most devastating complication associated with poor K-wire control during this step?

Explanation

Loss of K-wire control during tapping or screw placement can lead to ventral migration through the anterior vertebral body cortex, risking catastrophic injury to the great vessels (aorta/vena cava) or bowel.

Question 51

Biomechanical studies comparing Cortical Bone Trajectory (CBT) screws to traditional pedicle screws demonstrate which of the following characteristics?

Explanation

By engaging the higher-density cortical bone of the pars and pedicle, CBT screws demonstrate higher insertional torque and superior pullout strength, making them highly advantageous in osteoporotic patients.

Question 52

Which of the following clinical scenarios represents a relative contraindication to a minimally invasive transforaminal lumbar interbody fusion (MIS TLIF)?

Explanation

While MIS TLIF is excellent for single-level degenerative disease, severe fixed sagittal deformity requiring major 3-column osteotomies (like PSO) necessitates extensive bilateral exposure and is best treated with an open approach.

Question 53

When counseling a patient on the long-term outcomes of minimally invasive vs open lumbar fusion, what does current literature indicate regarding the incidence of symptomatic adjacent segment disease (ASD) at 5 years?

Explanation

Long-term comparative studies and randomized trials show that while MIS techniques reduce immediate postoperative pain and blood loss, the long-term incidence of symptomatic adjacent segment disease remains statistically similar to open fusion.

Question 54

A surgeon plans a unilateral MIS TLIF with unilateral percutaneous pedicle screw fixation for a patient with a paracentral disc herniation. Compared to a bilateral pedicle screw construct, the unilateral construct is significantly weaker in resisting which force?

Explanation

Biomechanical studies consistently demonstrate that while unilateral pedicle screw fixation provides adequate stability for flexion/extension, it offers significantly less resistance to axial rotation (torsional stability) compared to bilateral constructs.

Question 55

Compared to traditional open transforaminal lumbar interbody fusion (TLIF), minimally invasive (MIS) TLIF is most consistently associated with which of the following?

Explanation

MIS TLIF relies heavily on fluoroscopy for localization and hardware placement, leading to significantly higher radiation exposure to the surgeon. Fusion rates, infection rates, blood loss, and hospital stays are generally equal or better compared to open TLIF.

Question 56

During a minimally invasive TLIF using a tubular retractor system, the initial docking site for the first dilator is typically the:

Explanation

The tubular retractor is typically docked on the pars interarticularis and the ipsilateral facet joint complex. This provides direct access for the facetectomy and subsequent transforaminal approach to the disc space.

Question 57

Which of the following approaches utilizes the interval between the multifidus and longissimus muscles?

Explanation

The Wiltse approach is a muscle-splitting paramedian approach utilizing the natural cleavage plane between the multifidus (medially) and longissimus (laterally) muscles. It is widely used in minimally invasive posterior spinal surgeries.

Question 58

Which of the following is a recognized absolute contraindication for a transpsoas extreme lateral interbody fusion (XLIF)?

Explanation

The L5-S1 level is generally a contraindication for the transpsoas lateral approach due to the obstruction by the iliac crest and the anterior position of the lumbar plexus at this level. An anterior (ALIF) or posterior (TLIF/PLIF) approach is preferred for L5-S1.

Question 59

During a lateral transpsoas interbody fusion at L4-L5, the patient develops immediate postoperative ipsilateral hip flexion weakness and anterior thigh numbness. What is the most likely cause?

Explanation

The lumbar plexus lies within the posterior aspect of the psoas major muscle. The transpsoas approach puts the lumbar plexus (specifically the femoral nerve components) at risk, causing temporary or permanent anterior thigh numbness and iliopsoas weakness.

Question 60

In cortical bone trajectory (CBT) pedicle screws used for minimally invasive fusions, the screw trajectory is typically described as:

Explanation

CBT screws are inserted with a medial to lateral and caudad to cephalad trajectory. This maximizes thread purchase in high-density cortical bone, increasing pullout strength, especially in osteoporotic bone.

Question 61

A key mechanism by which minimally invasive lateral lumbar interbody fusion (LLIF) achieves indirect decompression of the neural foramina is through:

Explanation

Indirect decompression in LLIF relies on placing a large interbody graft to restore disc space height. This distracts the neural foramen and tensions the posterior longitudinal ligament and ligamentum flavum, effectively unbuckling them from the spinal canal.

Question 62

Review the clinical image.

When performing a percutaneous transforaminal endoscopic discectomy, instruments are passed through Kambin's triangle. Which of the following defines the medial border of Kambin's triangle?

Explanation

Kambin's triangle is a safe working zone for transforaminal endoscopic access. Its hypotenuse is the exiting nerve root, the base is the superior endplate of the inferior vertebral body, and the medial border (or height) is the traversing nerve root/dura.

Question 63

The use of continuous free-running electromyography (EMG) is considered standard of care in the transpsoas lateral lumbar approach to avoid injury to which structure?

Explanation

Directional EMG monitoring is critical during the transpsoas approach to map the lumbar plexus within the psoas muscle. It helps the surgeon identify the safe zone (usually the anterior third of the psoas) to place the retractor.

Question 64

Compared to traditional open TLIF, studies evaluating muscle parameters post-MIS TLIF consistently demonstrate:

Explanation

MIS TLIF utilizes muscle-splitting approaches (like the Wiltse approach or tubular dilators) that minimize stripping of the multifidus from its bony attachments. This significantly decreases postoperative multifidus atrophy, fatty infiltration, and denervation compared to open approaches.

Question 65

A major disadvantage of the minimally invasive posterior lumbar interbody fusion (MIS PLIF) approach compared to MIS TLIF is:

Explanation

MIS PLIF requires bilateral laminotomies and significant medial retraction of the thecal sac and traversing nerve roots to insert the interbody cages. This increases the risk of dural tears and neurologic injury compared to the unilateral transforaminal approach of MIS TLIF.

Question 66

During a minimally invasive unilateral TLIF with bilateral decompression (over-the-top technique), the surgeon undercuts the spinous process to decompress the contralateral side. Which structure must be preserved to prevent iatrogenic instability?

Explanation

The over-the-top technique allows bilateral decompression through a unilateral tubular approach by undercutting the spinous process and contralateral lamina. It is crucial to preserve the contralateral facet joint to avoid creating iatrogenic instability.

Question 67

Review the radiograph of a MIS stabilization construct.

To ensure proper placement of percutaneous pedicle screws, a true anteroposterior (AP) fluoroscopic image is essential. What confirms a true AP view of a lumbar vertebra?

Explanation

A true AP fluoroscopic image is achieved when the spinous process is exactly equidistant from both pedicles and the superior and inferior endplates appear as sharp, single lines (parallel). This ensures accurate medial-lateral trajectory during percutaneous screw placement.

Question 68

When performing an anterior lumbar interbody fusion (ALIF) at L4-L5, the surgeon encounters massive venous bleeding from a large vessel situated directly anterior to the L4-L5 disc space. Which vessel is most likely injured?

Explanation

The left common iliac vein courses directly anterior to the L4-L5 disc space before joining the right common iliac vein to form the inferior vena cava. It is at highest risk during exposure for an L4-L5 ALIF.

Question 69

Retrograde ejaculation is a known complication of anterior lumbar interbody fusion (ALIF). This is caused by injury to the:

Explanation

Retrograde ejaculation occurs due to injury to the superior hypogastric plexus (sympathetic nerves), which lies anterior to the lower lumbar vertebrae and L5-S1 disc space. Careful blunt dissection and avoiding electrocautery over the disc space minimizes this risk.

Question 70

In a patient undergoing MIS TLIF for a degenerative spondylolisthesis, which of the following is an advantage of placing a banana-shaped interbody cage anteriorly in the disc space?

Explanation

Placing an interbody cage in the anterior third of the disc space acts as a fulcrum to increase segmental lordosis when posterior compression is applied. This helps restore sagittal balance, which is a key goal in degenerative spine surgery.

Question 71

Compared to an open Transforaminal Lumbar Interbody Fusion (TLIF), a minimally invasive (MIS) TLIF is characteristically associated with which of the following?

Explanation

MIS TLIF provides lower estimated intraoperative blood loss, shorter hospital stays, and less muscle damage compared to open TLIF. Long-term fusion rates and clinical outcomes are generally equivalent, while radiation exposure and the learning curve are increased.

Question 72

When performing a minimally invasive posterior lumbar approach using tubular retractors via a paramedian incision, the surgeon typically utilizes the natural intermuscular plane (Wiltse plane) located between the:

Explanation

The Wiltse paraspinal approach utilizes the avascular cleavage plane between the multifidus (medial) and longissimus (lateral) muscles. This minimizes denervation and ischemic injury to the paraspinal musculature.

Question 73

A major established disadvantage of minimally invasive spine surgery (MISS) techniques when compared to traditional open posterior techniques is:

Explanation

Because MISS relies heavily on fluoroscopy or navigation for localization and instrument placement due to limited direct vision, radiation exposure to the surgeon and OR staff is significantly increased. Postoperative pain, SSI, and blood loss are typically reduced.

Question 74

During the placement of a percutaneous pedicle screw for an MIS TLIF, what is the ideal starting point for the Jamshidi needle on the true anteroposterior (AP) fluoroscopic view before advancing into the pedicle?

Explanation

To ensure an in-to-in trajectory without violating the medial pedicle wall early, the starting point on the AP view is at the lateral border of the pedicle (3 o'clock for right, 9 o'clock for left). The needle should not cross the medial border until it has passed the posterior vertebral body wall on the lateral view.

Question 75

Which of the following neural structures is at the greatest risk of iatrogenic injury during the annulotomy and disc preparation phase of a minimally invasive transforaminal lumbar interbody fusion (MIS TLIF)?

Explanation

The MIS TLIF approach utilizes Kambin's triangle. The exiting nerve root forms the anterior/lateral boundary of this triangle and is highly vulnerable to injury from retractor placement and aggressive disc preparation.

Question 76

What is the most common clinically significant complication uniquely associated with the placement of percutaneous pedicle screws compared to open pedicle screw placement?

Explanation

Percutaneous screws carry a significantly higher risk of violating the cranial adjacent facet joint (up to 30% in some series) if the starting point is too cephalad or medial, which can accelerate adjacent segment disease.

Question 77

When performing an "over-the-top" bilateral decompression for central canal stenosis through a unilateral minimally invasive tubular approach, which critical stabilizing structure is intentionally preserved?

Explanation

The over-the-top technique allows the surgeon to undercut the spinous process and reach the contralateral recess while completely preserving the midline tension band (interspinous and supraspinous ligaments), maintaining biomechanical stability.

Question 78

Regarding the learning curve for minimally invasive lumbar fusion (MIS TLIF), literature demonstrates that during a surgeon's early experience, there is a statistically higher incidence of which of the following complications?

Explanation

The steep learning curve of MIS TLIF is associated with increased operative times, higher radiation exposure, and an increased incidence of technical complications like incidental durotomies and cage malposition/subsidence.

Question 79

In Cortical Bone Trajectory (CBT) screw fixation, often utilized in minimally invasive lumbar surgeries, the pedicle screw path is fundamentally directed:

Explanation

CBT screws maximize cortical bone contact by starting medially at the pars interarticularis and directed laterally and cephalad. This trajectory allows for a smaller midline incision and increased pullout strength.

Question 80

A 60-year-old male undergoes a minimally invasive extreme lateral interbody fusion (XLIF) at L4-L5. Postoperatively, he presents with profound weakness in hip flexion and knee extension, along with anterior thigh numbness. Which structure was most likely injured?

Explanation

The lateral transpsoas approach (XLIF/DLIF) risks injury to the lumbar plexus, which lies within the posterior third of the psoas major muscle. This risk is highest at the L4-L5 level.

Question 81

Which of the following is considered an absolute or strong relative contraindication for a minimally invasive direct lateral transpsoas lumbar interbody fusion (LLIF/XLIF)?

Explanation

The direct lateral transpsoas approach is generally contraindicated at L5-S1 due to obstruction by the iliac crest and the anterior position of the lumbar plexus and major iliac vessels at this level.

Question 82

A surgeon uses fluoroscopy to place percutaneous screws

. Which strategy is most effective at reducing radiation exposure specifically to the surgeon's hands?

Explanation

Hand-away techniques (using long instruments) and keeping hands out of the primary beam are the most effective ways to reduce extremity exposure. Standing on the side of the detector (not the tube) also reduces scatter.

Question 83

During a minimally invasive tubular decompression, an incidental durotomy occurs

. What is the most appropriate initial management step?

Explanation

Incidental durotomies during MIS procedures can often be managed through the tube using specialized MIS suturing instruments, dural patches, or sealants. Conversion to an open approach is reserved for large, unmanageable tears.

Question 84

Compared to the traditional open posterior lumbar interbody fusion (PLIF), the minimally invasive (MIS) PLIF or TLIF approach is primarily associated with:

Explanation

MIS techniques use serial dilation which splits, rather than strips and crushes, the paraspinal muscles. This drastically reduces multifidus atrophy and ischemic necrosis seen in open prolonged retractor placement.

Question 85

During an endoscopic transforaminal lumbar discectomy, accessing the L5-S1 disc space is often technically limited or prevented by which anatomical structure?

Explanation

A high iliac crest frequently obstructs the lateral trajectory required for a transforaminal endoscopic approach to L5-S1. Therefore, an interlaminar endoscopic approach is often preferred at this level.

Question 86

In an MIS TLIF, endplate preparation can be challenging due to the limited visual corridor. Inadequate endplate preparation is most strongly associated with which postoperative complication?

Explanation

Thorough removal of the cartilaginous endplate down to bleeding subchondral bone is essential for fusion. Inadequate preparation due to limited visualization in MIS TLIF leads to non-union (pseudoarthrosis).

Question 87

When comparing long-term follow-up (e.g., 2 to 5 years) between patients who underwent MIS TLIF versus Open TLIF, the literature generally shows equivalence in:

Explanation

While MIS TLIF provides short-term benefits (shorter hospital stay, less immediate pain, lower muscle enzymes), long-term clinical outcomes (ODI, VAS) and fusion rates are statistically equivalent to open TLIF.

Question 88

The use of expandable interbody cages in MIS TLIF has gained popularity. A theoretical biomechanical advantage of an expandable cage over a static cage inserted through a small tubular retractor is:

Explanation

Expandable cages can be inserted in a collapsed state through a minimal neural retraction corridor (small annulotomy) and then expanded to provide greater height restoration, lordosis, and footprint contact.

Question 89

What is the primary indication for the utilization of continuous intraoperative neuromonitoring (EMG) during a minimally invasive direct lateral interbody fusion (XLIF)?

Explanation

The transpsoas approach places the lumbar plexus at risk. Directional EMG mapping is mandatory to navigate safely through the psoas major muscle and avoid damaging the plexus nerves.

Question 90

A 45-year-old morbidly obese patient requires an L4-L5 fusion for a mobile grade 1 spondylolisthesis. A primary advantage of selecting an MIS tubular approach over a standard open approach in this specific patient population is:

Explanation

MIS spine surgery drastically reduces the incidence of deep surgical site infections compared to open surgery. This is particularly beneficial in obese patients, where large open incisions create massive dead space in poorly vascularized adipose tissue.

Orthopedic Prometric MCQs - Chapter 3 Part 1

Orthopedic Prometric MCQs - Chapter 3 Part 35

Orthopedic Prometric MCQs - Chapter 3 Part 35

Chapter Index