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1. General Principles & Basic Science MCQs

Practice Set 14 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 261

Topic: 1. General Principles & Basic Science
The term Schmorl's nodule refers to:
. A giant synovial cyst
. An enlarged paravertebral lymph node
. A pathologic dorsal root ganglion
. Superior or inferior displacement of an intervertebral disk
. Anterior displacement of an intervertebral disk

Correct Answer & Explanation

. Superior or inferior displacement of an intervertebral disk

Explanation

Superior and inferior displacements into the vertebral body are known as Schmorl's nodules.

Question 262

Topic: 1. General Principles & Basic Science

A far lateral herniated nucleus pulposus at the L4-L5 level would lead to signs and symptoms of which nerve root on the affected side:

. L3
. L4
. L5
. S1
. None of the above

Correct Answer & Explanation

. L4

Explanation

A far lateral herniated nucleus pulposus, which is less common, can lead to compression of the nerve root that has already exited the supra-adjacent foramen. Therefore, a far lateral L4-L5 herniated nucleus pulposus leads to L4 nerve root compression.

Question 263

Topic: 1. General Principles & Basic Science

A sequestered disk herniation refers to:

. Bulging of the nucleus through a weakened annulus
. Rupture of the nucleus through the annulus
. Rupture of the nucleus through the annulus and the posterior longitudinal ligament
. Rupture of the nucleus through the posterior longitudinal ligament
. Separation of a herniated fragment from the disk

Correct Answer & Explanation

. Separation of a herniated fragment from the disk

Explanation

A sequestered herniation is a separation of a herniated fragment from the disk from which it came.

Question 264

Topic: 1. General Principles & Basic Science
Which of the following statements is true regarding the natural history of a herniated lumbar disk?
. The natural history of a herniated lumbar disk is usually consistent with approximately 90% spontaneous resolution without intervention by 3 months' follow-up.
. Surgical intervention is often required for definitive and long-term treatment.
. Despite aggressive surgical correction, permanent neurological deficits are common.
. Surgical diskectomy is a contraindication in patients with neurologic deficit.
. The natural history of lumbar disk herniations has not been studied.

Correct Answer & Explanation

. The natural history of a herniated lumbar disk is usually consistent with approximately 90% spontaneous resolution without intervention by 3 months' follow-up.

Explanation

A period of rest is prescribed for 1 to 2 days with supports under the knees and neck to minimize root tension. Also, nonsteroidal anti-inflammatory drugs are used. Prolonged bed rest is no longer advocated because it can lead to deconditioning of compensatory musculature. Ambulation is begun as tolerated after the first few days of an acute event. More than one-half of patients who initially present with low back pain recover within 1 week and more than 90% of patients recover in 1 to 3 months. Physical therapy is started as tolerated.

Question 265

Topic: 1. General Principles & Basic Science

Long-term follow-up studies of surgical versus conservative treatment of herniated lumbar disks indicate:

. Conservative management yields better long-term outcome.
. Surgical intervention has better long-term results.
. No statistically significant difference in outcome is noted despite the type of treatment used.
. No long-term data are available.
. None of the above

Correct Answer & Explanation

. No statistically significant difference in outcome is noted despite the type of treatment used.

Explanation

The prognosis of herniated lumbar disks is generally good regardless of treatment. Patients operated on for proven disk herniations improved more rapidly than patients treated nonoperatively. However, within 4 to 5 years, the outcomes begin to approximate each other.

Question 266

Topic: Biology, Genetics & Bone Healing

A 28-year-old woman presents with severe sacral pain. Imaging shows a large, eccentric, purely lytic 'soap-bubble' lesion destroying the S1 and S2 vertebral bodies. Biopsy reveals multinucleated giant cells interspersed with mononuclear stromal cells. Which systemic medication targets the primary pathophysiology of this tumor?

. Imatinib
. Methotrexate
. Denosumab
. Doxorubicin
. Bevacizumab

Correct Answer & Explanation

. Denosumab

Explanation

Giant cell tumors of the bone express RANKL by the neoplastic stromal cells, which recruits osteoclast-like giant cells. Denosumab, a monoclonal antibody against RANKL, is an effective targeted therapy to shrink these tumors.

Question 267

Topic: Biology, Genetics & Bone Healing

A 40-year-old male presents with mechanical back pain and is found to have an expansile, osteolytic lesion isolated to the posterior elements of L4. Biopsy shows blood-filled spaces separated by septa containing giant cells and woven bone. During surgical treatment (curettage), massive bleeding is encountered. The most effective non-surgical adjunct to reduce recurrence of this specific lesion is:

. Postoperative local radiation therapy
. Preoperative selective arterial embolization
. Systemic administration of bisphosphonates
. Intravenous administration of denosumab
. Chemotherapy with ifosfamide and doxorubicin

Correct Answer & Explanation

. Preoperative selective arterial embolization

Explanation

The diagnosis is an aneurysmal bone cyst (ABC). Due to its highly vascular nature and risk of significant intraoperative blood loss, preoperative selective arterial embolization is a crucial adjunct that also helps decrease local recurrence rates.

Question 268

Topic: 1. General Principles & Basic Science

A 40-year-old male presents with bowel and bladder dysfunction. MRI shows a large, destructive midline sacral mass. Histology reveals physaliferous cells in a myxoid background. Which of the following represents the optimal management?

. Curettage and cementation
. En bloc wide resection
. Primary fractionated radiotherapy
. Systemic chemotherapy alone
. Intralesional debulking followed by radiation

Correct Answer & Explanation

. En bloc wide resection

Explanation

The clinical and histologic features (physaliferous cells) confirm a sacral chordoma. Chordomas are locally aggressive and relatively radioresistant, making en bloc wide surgical resection the only chance for potential long-term cure.

Question 269

Topic: Biology, Genetics & Bone Healing

A 30-year-old female presents with sacral pain. Imaging shows a lytic, expansile mass in the S1-S2 vertebral bodies. Biopsy demonstrates mononuclear cells and multinucleated giant cells. Which of the following targeted medical therapies is often used preoperatively to facilitate surgical resection by inducing an osteosclerotic shell?

. Imatinib
. Denosumab
. Zoledronic acid
. Rituximab
. Bevacizumab

Correct Answer & Explanation

. Denosumab

Explanation

Denosumab is a monoclonal antibody against RANKL used in giant cell tumors of bone. It inhibits osteoclast-like giant cells, arresting tumor growth and forming a peripheral sclerotic rim that facilitates intralesional curettage or en bloc resection.

Question 270

Topic: Biology, Genetics & Bone Healing

A 35-year-old man presents with back pain and a large expansile lytic lesion in the L4 vertebral body extending into the pedicle. Biopsy reveals multinucleated giant cells in a stroma of mononuclear cells. If the tumor is deemed unresectable due to neurovascular involvement, the best pharmacologic treatment is:

. Imatinib
. Zoledronic acid
. Denosumab
. Doxorubicin
. Methotrexate

Correct Answer & Explanation

. Denosumab

Explanation

This patient has a giant cell tumor (GCT) of the spine. Denosumab, a RANKL inhibitor, is highly effective for unresectable GCTs by inhibiting osteoclast-like giant cells and causing tumor ossification.

Question 271

Topic: 1. General Principles & Basic Science

A patient with neurofibromatosis type 1 (NF1) presents with a rapidly progressive, sharp, short-segment thoracic kyphoscoliosis. Which of the following MRI findings is strongly associated with this dystrophic curve pattern?

. Syrinx formation
. Dural ectasia
. Tethered cord
. Diastematomyelia
. Lipomyelomeningocele

Correct Answer & Explanation

. Dural ectasia

Explanation

Dystrophic kyphoscoliosis in NF1 is characterized by a sharp, short-segment curve. Classic associated findings include dural ectasia, penciling of the ribs, enlarged neural foramina, and vertebral scalloping.

Question 272

Topic: 1. General Principles & Basic Science

A 30-year-old female presents with slowly progressive lower back pain and saddle anesthesia. MRI reveals a large, well-circumscribed, homogeneously enhancing mass primarily involving the filum terminale. Histology shows ependymal cells arranged around blood vessels. Which variant is most likely?

. Anaplastic ependymoma
. Subependymoma
. Myxopapillary ependymoma
. Clear cell ependymoma
. Tanycytic ependymoma

Correct Answer & Explanation

. Myxopapillary ependymoma

Explanation

Myxopapillary ependymomas are a distinct subtype that almost exclusively arise in the conus medullaris and filum terminale region. They are slow-growing and demonstrate perivascular pseudorosettes histologically.

Question 273

Topic: Biology, Genetics & Bone Healing

Which of the following populations is most at risk for compression fractures of the spine:

. Middle-aged black women
. Elderly caucasian men
. Menopausal females of Inuit (Alaskan native) descent
. Elderly fair-skinned women of northern European descent
. Heavy laborers

Correct Answer & Explanation

. Elderly fair-skinned women of northern European descent

Explanation

Osteoporosis is an age-related decrease in bone mass usually associated with a loss of estrogen in postmenopausal women. Sedentary, thin white women of northern European descent are most severely affected. In addition, smoking, heavy drinking, and certain pharmacological agents, such as phenytoin, increase the severity of the disease. Women who breastfed their infants or those with low vitamin D or calcium diets are also at increased risk.

Question 274

Topic: Biology, Genetics & Bone Healing

Following an osteoporotic compression fracture, the risk of sustaining another compression fracture at a different level is increased by:

. 2 times
. 5 times
. 8 times
. 10 times
. 15 times

Correct Answer & Explanation

. 5 times

Explanation

Osteoporosis is a systemic disease affecting more than 24 million Americans. Osteoporosis results in progressive bone mineral loss and concurrent changes in bony architecture, which leave the spinal column vulnerable to compression fractures, often after minimal or no trauma. There are an estimated 700,000 osteoporotic vertebral compression fractures (VC Fs) in the United States each year, of which more than one third become chronically painful. Approximately 85% of VC Fs are due to primary osteoporosis and the remainder due to secondary osteoporosis or malignancies. These VC Fs lead to progressive sagittal spine deformity and changes in spinal biomechanics and are believed to contribute to a fivefold increased risk of further fracture by virtue of force transmission to weak vertebrae above or below. Whether the fracture is painful or not, the spinal deformity caused by two or more fractures dramatically impacts health, daily living, and medical costs through loss of lung capacity, loss of appetite, reduced mobility, chronic pain, and/or clinical depression.

Question 275

Topic: 1. General Principles & Basic Science

The following are all purported benefits of percutaneous intraosseous methylmethacrylate injection (vertebroplasty) for the treatment of osteoporotic compression fractures except:

. Decreased stiffness of the segment, distributing stress at adjacent levels
. Rapid pain relief
. Prevention of further compression fractures by restoring sagittal alignment
. Faster return to ambulation
. Increased mobility leading to prevention of further osteoporosis

Correct Answer & Explanation

. Decreased stiffness of the segment, distributing stress at adjacent levels

Explanation

Traditional treatment for patients with osteoporotic vertebral compression fractures (VC Fs) includes bed rest, analgesics, and bracing. This type of medical management does not restore spinal alignment, and the lack of mobility increases the rate of demineralization. Because of the inherent risks and invasive nature, surgical treatment of osteoporotic VCFs has been limited to patients with concurrent spinal instability or neurologic compromise. Reconstruction with structural bone graft and instrumentation may be performed from an anterior or posterior approach; however, the success of these techniques is limited by a patients poor bone quality and general medical condition. Augmentation of VC Fs with polymethylmethacrylate (PMMA), "vertebroplasty," involves the forced injection of low viscosity PMMA cement into the closed space of the collapsed vertebral body. Although vertebroplasty is currently being used successfully for pain relief in VC Fs, this technique does not restore the height of the collapsed vertebral body.

Question 276

Topic: 1. General Principles & Basic Science

The sagittal plumb line should fall:

. Anterior to the C 4 vertebral body
. Through the L3-L4 intervertebral disk
. Posterior to the anterosuperior corner of S1
. Through the T11 intervertebral disk
. Anterior to the S1 body

Correct Answer & Explanation

. Posterior to the anterosuperior corner of S1

Explanation

Radiographic assessment of the sagittal balance is usually made with a patient standing, with his or her arms flexed forward 90° and supported on a bar. Radiographic assessment is recorded on a 36-inch cassette. Several reference points regarding this technique have appeared in the literature. These points include a plumb line through the center of the C 7 vertebral body, passing 35 mm to 56 mm posterior to the anterosuperior border of S1.

Question 277

Topic: Infection, Pharmacology & VTE

Which of the following represents an absolute contraindication to performing a percutaneous vertebroplasty for a painful osteoporotic compression fracture?

. Asymptomatic adjacent level fracture
. Presence of an intravertebral vacuum cleft
. Active osteomyelitis or discitis at the target level
. Failure of conservative management after 6 weeks
. Patient age greater than 85 years

Correct Answer & Explanation

. Active osteomyelitis or discitis at the target level

Explanation

Active infection such as osteomyelitis, discitis, or systemic bacteremia is an absolute contraindication to percutaneous cement augmentation due to the high risk of abscess formation and failure of eradication.

Question 278

Topic: 1. General Principles & Basic Science

Compared to vertebroplasty, balloon kyphoplasty generally offers which of the following biomechanical or procedural advantages?

. Shorter total operative time per level
. Use of higher injection pressures for cement delivery
. Lower risk of symptomatic cement extravasation
. Elimination of the need for fluoroscopic guidance
. Superior long-term overall survival rates

Correct Answer & Explanation

. Lower risk of symptomatic cement extravasation

Explanation

Balloon kyphoplasty creates a low-pressure cavity within the vertebral body, allowing for the injection of higher viscosity cement. This technique significantly lowers the risk of cement extravasation compared to the high-pressure injection used in vertebroplasty.

Question 279

Topic: Biomechanics & Biomaterials

What is the most common serious systemic complication associated with the injection of polymethylmethacrylate (PMMA) during vertebroplasty?

. Fat embolism syndrome
. Pulmonary cement embolism
. Acute myocardial infarction
. Ischemic stroke
. Spinal epidural hematoma

Correct Answer & Explanation

. Pulmonary cement embolism

Explanation

Pulmonary cement embolism occurs when PMMA leaks into the paravertebral venous plexus and migrates to the lungs. While often asymptomatic, it can cause acute respiratory distress and requires careful fluoroscopic monitoring during cement injection.

Question 280

Topic: 1. General Principles & Basic Science

In an elderly patient with severe osteoporosis requiring posterior spinal instrumentation for instability, which technique is most effective for maximizing pedicle screw pullout strength?

. Using a shorter pedicle screw
. Undertapping the pedicle by 2 mm
. Polymethylmethacrylate (PMMA) screw augmentation
. Using a partially threaded cancellous screw
. Decreasing the screw diameter to preserve cortical bone

Correct Answer & Explanation

. Polymethylmethacrylate (PMMA) screw augmentation

Explanation

PMMA augmentation of fenestrated pedicle screws significantly increases the screw-bone interface strength. This is the most effective biomechanical method to prevent screw pullout in severely osteoporotic bone.

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