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1. General Principles & Basic Science MCQs

Practice Set 26 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 501

Topic: 1. General Principles & Basic Science

At which age do patients most commonly present with dysplasia epiphysialis hemimelia (DEH):

. Birth
. Between early childhood and early teen years
. Early adulthood
. Middle age
. Older than 60 years

Correct Answer & Explanation

. Between early childhood and early teen years

Explanation

Most cases of DEH occur in patients between early childhood and early teen years. Dysplasia epiphysialis hemimelia does not present at birth.C orrect Answer: Between early childhood and early teen years

Question 502

Topic: 1. General Principles & Basic Science

Which of the following measurements reflects the mean lateral distal femoral joint angle with respect to the mechanical axis:

. 90°
. 87°
. 84°
. 81°
. 78°

Correct Answer & Explanation

. 87°

Explanation

The lateral distal femoral angle with respect to the mechanical axis is 87°.

Question 503

Topic: 1. General Principles & Basic Science
Which of the following symptoms is not characteristic of McCune-Albright syndrome?
. Café-au-lait spots with irregular borders
. Café-au-lait spots with smooth borders
. Precocious puberty
. Diabetes mellitus
. Hyperthyroidism

Correct Answer & Explanation

. Café-au-lait spots with irregular borders

Explanation

The café-au-lait spots associated with McCune-Albright syndrome are described as 'coast of Maine' spots because they have irregular borders. The café-au-lait spots associated with neurofibromatosis are described as 'coast of California' spots because they have smooth borders.

Question 504

Topic: 1. General Principles & Basic Science

A 24-month-old girl presents with bilateral lower extremity bowing. Which of the following radiographic measurements is most predictive of infantile Blount disease rather than physiologic bowing?

. Metaphyseal-diaphyseal angle greater than 16 degrees
. Mechanical axis falling in the medial quadrant of the knee
. Tibiofemoral angle of 10 degrees varus
. Medial proximal tibial angle of 85 degrees
. Posterior distal femoral angle of 80 degrees

Correct Answer & Explanation

. Metaphyseal-diaphyseal angle greater than 16 degrees

Explanation

A metaphyseal-diaphyseal angle (Drennan angle) greater than 16 degrees on an AP radiograph strongly suggests infantile Blount disease. Angles less than 10 degrees are typically physiologic, while 10-16 degrees represent a gray zone requiring observation.

Question 505

Topic: Surgical Anatomy & Approaches



A 6-year-old falls on an outstretched hand, sustaining a completely displaced supracondylar humerus fracture. If the distal fragment is displaced posteromedially, which neurovascular structure is at highest risk of injury?

. Anterior interosseous nerve
. Radial nerve
. Ulnar nerve
. Musculocutaneous nerve
. Axillary nerve

Correct Answer & Explanation

. Radial nerve

Explanation

In a posteromedially displaced supracondylar fracture, the proximal fragment spikes anterolaterally, putting the radial nerve at the greatest risk of tethering or injury.

Question 506

Topic: Infection, Pharmacology & VTE

A 4-year-old child presents with a limp, refusal to bear weight, and a temperature of 38.6°C. WBC is 13,000/mm3, and ESR is 45 mm/hr. According to the Kocher criteria, what is the probability that this child has septic arthritis of the hip?

. Less than 10%
. Approximately 40%
. Approximately 93%
. Greater than 99%
. 100%

Correct Answer & Explanation

. Approximately 93%

Explanation

The child meets 3 of the 4 Kocher criteria (fever >38.5°C, non-weight bearing, WBC >12k, ESR >40). The probability of septic arthritis with 3 positive predictors is approximately 93%.

Question 507

Topic: Infection, Pharmacology & VTE

A 5-year-old boy presents with a 2-day history of a right-sided limp and mild hip pain. He is afebrile with normal inflammatory markers. Ultrasound shows a small effusion in the right hip. He had an upper respiratory infection a week ago. What is the most appropriate management?

. Urgent joint aspiration
. Intravenous antibiotics
. Non-steroidal anti-inflammatory drugs (NSAIDs) and observation
. Hip spica casting
. Surgical irrigation and debridement

Correct Answer & Explanation

. Non-steroidal anti-inflammatory drugs (NSAIDs) and observation

Explanation

The clinical picture of mild hip pain, normal inflammatory markers, afebrile status, and recent URI strongly suggests transient synovitis. This is a self-limiting condition best treated with NSAIDs, rest, and supportive care.

Question 508

Topic: 1. General Principles & Basic Science
Which of the following designations best describes this radiograph (Slide):
. Herring antibody
. Herring body
. Stulberg 4
. Catterall 1
. 30% epiphyseal extrusion

Correct Answer & Explanation

. Herring antibody

Explanation

This patient has Herring body involvement of the hip. As a result, this patient has less than a 50% loss of lateral column height and is in the early fragmentation phase. This patient has a Catterall involvement of at least 3. The Stulberg classification is used to rate a patient's hip after it has healed.

Question 509

Topic: 1. General Principles & Basic Science
In which muscle does Ely's test detect spasticity or contracture:
. Biceps femoris
. Rectus femoris
. Gastrocnemius
. Soleus
. Semimembranosus

Correct Answer & Explanation

. Rectus femoris

Explanation

Ely's test is performed while the patient is prone and his or her hip is at maximal extension. Ely's test is positive if flexion of the patient's knee causes the patient's hip to flex. A positive Ely's test indicates spasticity or contracture of the rectus femoris.

Question 510

Topic: 1. General Principles & Basic Science
Staheli's test is designed to detect hip flexion contracture. Which of the following tests also detects hip flexion contracture:
. Silfvers test
. Ober's test
. Thomas test
. Jack's test
. Trendelenburg's test

Correct Answer & Explanation

. Thomas test

Explanation

Staheli's test and the Thomas test are designed to detect hip flexion contracture. Staheli's test is performed with a patient in the prone position. The lumbar lordosis is eliminated by flexing a patient's hips, and then gradually extending the affected hip. The Thomas test is performed with a patient in the supine position. The lumbar lordosis is minimized by flexing a patient's hips forward, allowing the affected hip to go into extension.

Question 511

Topic: 1. General Principles & Basic Science

A 6-year-old boy presents with torticollis and neck stiffness 2 weeks after undergoing a tonsillectomy. Radiographs show atlantoaxial rotatory subluxation. What is the most appropriate initial management?

. Immediate C1-C2 posterior fusion
. Rigid cervical collar and antibiotics
. Soft collar and observation
. Halotraction
. Cervical halter traction and anti-inflammatory medications

Correct Answer & Explanation

. Cervical halter traction and anti-inflammatory medications

Explanation

This is Grisel syndrome. The initial treatment for atlantoaxial rotatory subluxation present for less than 1 month involves admission, cervical halter traction, muscle relaxants, and anti-inflammatory medications.

Question 512

Topic: 1. General Principles & Basic Science

A newborn is evaluated for a short, webbed neck and limited cervical range of motion. Radiographs show multiple fused cervical vertebrae. Which organ system requires routine screening in this patient?

. Gastrointestinal
. Renal
. Endocrine
. Pulmonary
. Hematologic

Correct Answer & Explanation

. Renal

Explanation

Klippel-Feil syndrome is associated with renal anomalies in about 30% of cases, necessitating a screening renal ultrasound. Cardiovascular and hearing abnormalities are also common.

Question 513

Topic: Infection, Pharmacology & VTE

A 7-year-old girl presents with torticollis and neck pain 1 week after a severe viral pharyngitis. Her head is tilted to the right and rotated to the left. Dynamic CT confirms atlantoaxial rotatory subluxation (Grisel's syndrome). What is the most appropriate initial treatment?

. Occipitocervical fusion
. Hard cervical collar alone
. Halter traction and NSAIDs/muscle relaxants
. Open reduction and internal fixation
. Translaminar screw fixation

Correct Answer & Explanation

. Halter traction and NSAIDs/muscle relaxants

Explanation

Grisel's syndrome is non-traumatic AARS secondary to retropharyngeal inflammation. Initial treatment involves soft tissue relaxation, anti-inflammatories, and halter traction, followed by cervical bracing once the subluxation is reduced.

Question 514

Topic: 1. General Principles & Basic Science

A 5-year-old boy presents to the emergency department after a minor fall. Lateral cervical radiographs reveal a 3 mm anterior displacement of C2 on C3. Which of the following radiographic methods is best used to differentiate physiologic pseudosubluxation from true pathologic subluxation?

. Powers ratio
. Wackenheim's line
. Swischuk's line
. McGregor's line
. Chamberlain's line

Correct Answer & Explanation

. Swischuk's line

Explanation

Swischuk's line is drawn from the anterior aspect of the posterior arch of C1 to the anterior aspect of the posterior arch of C3. In physiologic pseudosubluxation, the anterior aspect of the posterior arch of C2 should be within 1.5 to 2 mm of this line.

Question 515

Topic: Biology, Genetics & Bone Healing
The mother of a 4-month-old boy brings him to a physician to be evaluated for a swollen leg. The most likely diagnosis is:
. Rickets
. Osteogenesis imperfecta (OI)
. Scurvy
. Nonaccidental injury
. Caffey's disease

Correct Answer & Explanation

. Nonaccidental injury

Explanation

This radiograph shows two fractures in different stages of healing. Note the old femur fracture at the top of the field. No evidence of decreased cortical thickness, diaphyseal thinning, or bowing suggests OI. The physis of the distal femur and proximal femur show no signs of rickets. The presence of fractures rather than periosteal reaction make Caffey's disease unlikely. The fractures in scurvy are more commonly located in the physis. The diagnosis of nonaccidental injury should be made only after performing a thorough patient history and physical.

Question 516

Topic: 1. General Principles & Basic Science

Which of the following is not a contraindication to the repair of a spondylolytic defect:

. Age older than 35 years
. Slip greater than 25%
. Disk degeneration at the same level
. Bilateral pars defect
. Minimal symptoms

Correct Answer & Explanation

. Age older than 35 years

Explanation

Repair of a spondylolytic defect is usually a successful procedure for relieving symptoms. Repair is not indicated in patients older than 35 years of age. Repair should not be done if there is a significant slip over a grade 1 at most or if the patient has minimal, tolerable symptoms or has symptoms complicated by a degenerative disk at the same level.

Question 517

Topic: 1. General Principles & Basic Science

Most cases of L5 spondylolysis develop in patients by:

. Birth
. Age 3 years
. Age 6 years
. Age 9 years
. Age 12 years

Correct Answer & Explanation

. Age 6 years

Explanation

A study was conducted to monitor the development of L5 spondylolysis in patients from birth to 6 years of age. The study showed that no cases of L5 spondylolysis were present at birth in any of the patients. The majority of the patients developed L5 spondylolysis by the time they had reached 6 years of age. A 45-year follow-up study showed that none of the 30 patients had more than a 40% slip and that only 1 patient required fusion.

Question 518

Topic: 1. General Principles & Basic Science
Which of the following is not a feature of Klippel-Trénaunay-Weber syndrome?
. Varicose veins
. Cutaneous nevus
. Increased length of the involved limb
. Increased width of the involved limb
. Seizure disorder

Correct Answer & Explanation

. Seizure disorder

Explanation

Klippel-Trénaunay-Weber syndrome is a constellation of varicose veins, cutaneous nevus, and an increase in the length or width of the involved limb. Seizure disorder is a feature of von Hippel-Lindau disease.

Question 519

Topic: 1. General Principles & Basic Science

Which ligamentous structure is characteristically thickened and contracted in Scheuermann's disease, acting as a major anterior tether against curve correction?

. Anterior longitudinal ligament (ALL)
. Posterior longitudinal ligament (PLL)
. Ligamentum flavum
. Interspinous ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Anterior longitudinal ligament (ALL)

Explanation

The anterior longitudinal ligament (ALL) becomes significantly thickened and contracted in Scheuermann's disease, contributing to the rigidity of the kyphotic deformity.

Question 520

Topic: Biology, Genetics & Bone Healing

A 15-year-old male presents with cosmetic concerns regarding his back. A lateral radiograph is shown. Which histologic abnormality at the vertebral endplate is considered the primary etiology for the characteristic findings seen in this condition?

. Abnormal enchondral ossification with disorganized cartilage matrix
. Proliferation of woven bone in the primary spongiosa
. Defective intramembranous ossification of the vertebral bodies
. Excessive osteoclastic resorption due to hyperparathyroidism
. Loss of proteoglycans primarily in the nucleus pulposus

Correct Answer & Explanation

. Abnormal enchondral ossification with disorganized cartilage matrix

Explanation

The image demonstrates Scheuermann's kyphosis with anterior wedging and Schmorl nodes. The primary histologic defect is abnormal enchondral ossification of the vertebral endplates, leading to weakened cartilage and subsequent herniation of the disc material.

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