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1. General Principles & Basic Science MCQs

Practice Set 203 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 4041

Topic: 1. General Principles & Basic Science

When planning a corrective osteotomy for a diaphyseal angular deformity, placing the osteotomy and the hinge exactly at the Center of Rotation of Angulation (CORA) will mathematically result in:

. Pure angulation correction without secondary translation
. Angulation correction with deliberate translation
. Translation without angulation
. Significant shortening of the anatomic axis
. Lengthening of the anatomic axis beyond the osteotomy gap

Correct Answer & Explanation

. Pure angulation correction without secondary translation

Explanation

According to the rules of osteotomy planning (Paley's rules), when the osteotomy and the mechanical hinge are both placed at the CORA, the deformity corrects with pure angulation and no secondary translation.

Question 4042

Topic: 1. General Principles & Basic Science
A posterolateral approach to the tibial plafond proceeds between what two muscles?
. Peroneus longus and brevis
. Peroneus longus and flexor hallucis longus
. Peroneus brevis and flexor hallucis longus
. Peroneus brevis and flexor digitorum longus
. Flexor hallucis longus and flexor digitorum longus

Correct Answer & Explanation

. Peroneus brevis and flexor hallucis longus

Explanation

A posterolateral approach to the posterior malleolus proceeds between the lateral and deep posterior compartments. Distally, the peroneus brevis muscle lies most medially within the lateral compartment, and the flexor hallucis longus lies most laterally in the deep posterior compartment.

Question 4043

Topic: 1. General Principles & Basic Science

-Figures 7a through 7c are the radiograph and MRI scans of a 72-year-old woman who has had back and leg pain for 3 months. Her pain is worse with prolonged walking and relieved with bending forward.Examination reveals normal strength and sensation in her legs with intact pedal pulses. She has persistent pain despite physical therapy, medications, and epidural injections. What is the most appropriate treatment option?

. Laminectomy
. Laminectomy and instrumented fusion
. Laminectomy and uninstrumented fusion
. Endovascular aortic bypass
. Anterior lumbar interbody fusion

Correct Answer & Explanation

. Laminectomy

Explanation

Question 4044

Topic: 1. General Principles & Basic Science

A 65-year-old female presents with intractable lateral hip pain and weakness in hip abduction. MRI confirms a severe abductor tendon tear. Anatomically, the gluteus minimus tendon primarily inserts onto which specific facet of the greater trochanter?

. Anterior facet
. Lateral facet
. Posterior facet
. Superoposterior facet
. Medial facet

Correct Answer & Explanation

. Anterior facet

Explanation

The greater trochanter has distinct anatomical facets for tendon insertions. The gluteus minimus tendon inserts primarily onto the anterior facet. The gluteus medius tendon has a broader footprint, inserting onto the lateral and superoposterior facets. Knowledge of these footprints is critical for accurate MRI interpretation and surgical repair of abductor tears.

Question 4045

Topic: 1. General Principles & Basic Science

A 21-year-old male sustains a bucket-handle tear of the medial meniscus. The tear is located in the peripheral red-white zone. The surgeon elects to perform an arthroscopic repair using an inside-out technique for the posterior horn. During the passage of the sutures through the posterior medial joint capsule, which anatomic structure is at greatest risk of iatrogenic injury?

. Popliteal artery
. Common peroneal nerve
. Saphenous nerve (sartorial branch)
. Tibial nerve
. Obturator nerve

Correct Answer & Explanation

. Saphenous nerve (sartorial branch)

Explanation

During an inside-out repair of the medial meniscus, the needles are passed from inside the joint to a posterior medial incision. The structure at greatest risk during a posteromedial approach/needle passage is the sartorial branch of the saphenous nerve, which runs posteromedial to the sartorius. The popliteal artery and tibial nerve are at risk if needles are passed too centrally/posteriorly. The common peroneal nerve is at risk during a posterolateral inside-out repair for the lateral meniscus.

Question 4046

Topic: 1. General Principles & Basic Science

When comparing the open tibial inlay technique to the arthroscopic transtibial tunnel technique for posterior cruciate ligament (PCL) reconstruction, biomechanical and clinical outcome studies have demonstrated which of the following?

. The tibial inlay technique provides significantly better clinical outcome scores.
. The transtibial technique has a significantly higher rate of graft failure due to the 'killer turn'.
. The tibial inlay technique requires a technically easier surgical approach without patient repositioning.
. There is no significant difference in clinical outcomes or AP stability between the two techniques.
. The transtibial technique provides superior restoration of normal knee kinematics.

Correct Answer & Explanation

. The tibial inlay technique provides significantly better clinical outcome scores.

Explanation

While the tibial inlay technique was designed to avoid the 'killer turn' (the acute angle of the graft at the posterior tibial aperture) seen in the transtibial technique, systematic reviews and meta-analyses have shown no significant differences in clinical outcomes, functional scores, or anteroposterior stability between the two techniques.

Question 4047

Topic: 1. General Principles & Basic Science

A 32-year-old female in her third trimester of pregnancy presents with the insidious onset of severe left groin pain. She has no history of trauma. Radiographs show focal, severe osteopenia of the left femoral head and neck with a preserved joint space. MRI reveals diffuse bone marrow edema in the femoral head and neck without subchondral collapse.

What is the most likely diagnosis and appropriate initial management?

. Avascular necrosis; immediate core decompression
. Septic arthritis; emergent surgical irrigation and debridement
. Transient osteoporosis of the hip; protected weight-bearing and observation
. Femoral neck stress fracture; prophylactic internal fixation
. Chondrolysis; high-dose nonsteroidal anti-inflammatory drugs

Correct Answer & Explanation

. Avascular necrosis; immediate core decompression

Explanation

Transient osteoporosis of the hip classically affects women in the third trimester of pregnancy and middle-aged men. It presents with severe pain and diffuse marrow edema on MRI without focal necrosis or collapse. It is a self-limiting condition managed with protected weight-bearing to prevent a completion fracture.

Question 4048

Topic: 1. General Principles & Basic Science

A 42-year-old male undergoes a medial opening-wedge high tibial osteotomy (HTO) for medial compartment osteoarthritis with a varus deformity. During the procedure, the osteotomy gap is opened equally at the anterior and posterior cortex with a rectangular distractor. What is the most likely consequence of this maneuver on the sagittal profile of the proximal tibia?

. It significantly decreases the posterior tibial slope
. It significantly increases the posterior tibial slope
. It has no effect on the posterior tibial slope
. It causes immediate patella alta
. It shifts the mechanical axis strictly posteriorly

Correct Answer & Explanation

. It significantly increases the posterior tibial slope

Explanation

Because the proximal tibia is triangular in cross-section (narrower anteriorly than posteriorly), opening an osteotomy gap equally from anterior to posterior results in a relatively greater angular opening anteriorly. This geometrically leads to an unintended increase in the posterior tibial slope. To preserve the slope, the gap must typically be opened approximately half as much anteriorly as posteriorly.

Question 4049

Topic: 1. General Principles & Basic Science

A 6-year-old girl is evaluated for a painless "snapping" sensation in her lateral knee with extension. MRI confirms a Wrisberg-variant discoid lateral meniscus. By definition, this specific meniscal variant lacks which of the following normal posterior stabilizing attachments?

. Anterior horn of the lateral meniscus
. Transverse meniscal ligament
. Meniscofemoral ligament of Humphry
. Coronary (meniscotibial) ligaments
. Posterior cruciate ligament

Correct Answer & Explanation

. Anterior horn of the lateral meniscus

Explanation

The Wrisberg-variant of a discoid lateral meniscus lacks the normal posterior coronary (meniscotibial) ligament attachments. Its only posterior tether is the meniscofemoral ligament of Wrisberg, leading to hypermobility and the classic 'snapping knee' phenomenon.

Question 4050

Topic: Biology, Genetics & Bone Healing
Which of the following has been shown to have similar biochemical and clinical characteristics as iliac crest autograft?
. Femoral intramedullary reaming contents
. BMP-2
. BMP-7 with collagen matrix carrier
. Hydroxyapatite cement
. Platelet rich plasma with allograft cancellous bone carrier

Correct Answer & Explanation

. Femoral intramedullary reaming contents

Explanation

In multiple studies, femoral intramedullary reaming debris has been shown to have similar biochemical characteristics as iliac crest autograft. Intramedullary reaming products have osteogenic potential with viable cells while BMPs are osteoinductive cytokines. Hoegel et al found that the reamings had alkaline phosphatase activity, indicating living osteoblasts. The amount of activity was independent of the reamer sizes and reamer design. Frolke et al concluded that reaming debris supports callus building (healing) as much as conventional iliac crest bone grafting in an animal fracture gap model.

Question 4051

Topic: 1. General Principles & Basic Science

Compared with myodesis, osteomyoplasty offers which of the following advantages in transtibial amputation?

. Enhanced end-bearing
. Early prosthetic fitting
. Immediate weight bearing
. Fibular abduction
. Decreased surgical morbidity

Correct Answer & Explanation

. Enhanced end-bearing

Explanation

Osteomyoplasty in transtibial amputation, originally described by Ertl in 1949, features creation of a bone bridge between the distal tibia and fibula, which istheorized to enhance bony stability and increase end-bearing of the residual limb, and may enhance patient-perceived functional outcomes relative to myodesis. Fibular abduction is a known complication of traditional myodesis techniques, and is believed to represent syndesmotic instability. Osteomyoplasty requires additional surgical time and increased surgical morbidity, and because the success of the procedure is dependent on achieving bony union, early prosthetic fitting and immediate weight bearing are typically contraindicated.

Question 4052

Topic: Surgical Anatomy & Approaches

Figure 99 shows a dorsal approach for a midfoot arthrodesis following a Lisfranc injury in a 43-year-old woman. The base of the second metatarsal is labeled with the letter B. The interval used to create this exposure is

. an internervous plane between muscles innervated by the deep and superficial peroneal nerves.
. an internervous plane between muscles innervated by the deep peroneal and the medial plantar nerves.
. an interval between the extensor digitorum longus and the extensor digitorum brevis.
. not an internervous plane.

Correct Answer & Explanation

. not an internervous plane.

Explanation

DISCUSSIONThe interval shown is between the extensor hallucis longus (left) and the extensor hallucis brevis (right), which is not an internervous plane because both are innervated by the deep peroneal nerve. The neurovascular bundle is under the extensor hallucis brevis muscle. Bothmuscles are innervated by branches of the deep peroneal nerve. The superficial peroneal

Question 4053

Topic: Biology, Genetics & Bone Healing
What does Dual Energy X-ray Absorptiometry (DEXA) testing, as a technique, measure?
. Bone mineral content and soft-tissue composition
. Qualitative value of core bone mineral content
. Differentiation of trabecular and cortical bone content
. Core bone mineral density unchanged by osteoarthritis at or around the site
. Bone mineral content and density without need for cross-sectional dimension

Correct Answer & Explanation

. Bone mineral content and soft-tissue composition

Explanation

DEXA can provide data on bone mineral content and soft-tissue composition, and requires cross-sectional dimension for accuracy. DEXA provides a quantitative, not qualitative, measurement of bone mineral content and is incapable of differentiating between trabecular and cortical bone. Osteoarthritis falsely elevates the values, especially in the AP spinal analysis.

Question 4054

Topic: 1. General Principles & Basic Science
Which of the following procedures is included in third-generation cement technique?
. Addition of antibiotic to the cement
. Monomer chilling to increase working time and lower viscosity
. Porosity reduction through centrifugation and/or vacuum mixing
. Use of a cemented, polished, tapered stem
. Placement of a plastic tube distally to allow fluid to escape

Correct Answer & Explanation

. Porosity reduction through centrifugation and/or vacuum mixing

Explanation

DISCUSSION: The so-called third-generation cement technique adds porosity reduction techniques, centralization devices, and surface modifications to the femoral component. The surgeon must be aware of the meaning of the various generations of cement technique when interpreting the results presented at meetings and in the literature. REFERENCES: Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 181-193. Maloney WJ, Hartford JM: The cemented femoral component, in Callaghan JJ, Rosenberg AG, Rubash HE (eds): The Adult Hip. Philadelphia, PA, Lippincott-Raven, 1998, vol 2, pp 959-979.

Question 4055

Topic: Biomechanics & Biomaterials

An opening wedge high tibial osteotomy (HTO) is planned for a 45-year-old male laborer with isolated medial compartment osteoarthritis and varus malalignment. What is a common unintended consequence on the sagittal plane biomechanics of the knee if the osteotomy gap is opened equally anteriorly and posteriorly?

. Decreased posterior tibial slope
. Increased posterior tibial slope
. Anterior translation of the tibia relative to the femur in extension
. Increased patellofemoral tracking laterally
. Decreased tension on the posterior cruciate ligament

Correct Answer & Explanation

. Decreased posterior tibial slope

Explanation

During a medial opening wedge HTO, opening the osteotomy gap equally anteriorly and posteriorly typically leads to an unintended increase in the posterior tibial slope. This occurs because the proximal tibia is triangular, being narrower anteriorly than posteriorly. To maintain the native sagittal slope, the anterior opening gap must be approximately half the size of the posterior gap. An increased posterior slope can inadvertently increase anterior tibial translation and stress the ACL.

Question 4056

Topic: 1. General Principles & Basic Science

A surgeon is performing a medial opening wedge high tibial osteotomy (HTO) to treat medial compartment osteoarthritis in a varus knee. To avoid unintentionally increasing the posterior tibial slope (creating a "flexion osteotomy"), what must the ratio of the anterior osteotomy gap to the posterior osteotomy gap approximately be?

. 1:1
. 2:1
. 1:2
. 1:3
. 3:1

Correct Answer & Explanation

. 1:1

Explanation

Because the proximal tibia is triangular, opening the osteotomy equally anteriorly and posteriorly will inadvertently increase the posterior tibial slope. To maintain the native sagittal slope, the anterior gap should be approximately one-half the size of the posterior gap (1:2 ratio).

Question 4057

Topic: 1. General Principles & Basic Science

A 45-year-old female experiences a sudden "pop" in the back of her knee while ascending stairs, followed by mild effusion and posteromedial pain. MRI reveals a posterior root tear of the medial meniscus with 3 mm of meniscal extrusion. What is the most significant biomechanical consequence of leaving this tear untreated?

. Increased anterior tibial translation
. Loss of hoop stresses leading to peak contact pressures similar to a total meniscectomy
. Rapid development of patellofemoral osteoarthritis
. Chronic posterior subluxation of the tibia
. Increased valgus laxity in full extension

Correct Answer & Explanation

. Loss of hoop stresses leading to peak contact pressures similar to a total meniscectomy

Explanation

A posterior root tear of the medial meniscus disrupts the circumferential hoop stresses, rendering the meniscus functionally incompetent. Biomechanically, this results in increased peak compartment contact pressures equivalent to those seen after a total meniscectomy, rapidly leading to osteoarthritis.

Question 4058

Topic: Infection, Pharmacology & VTE

A 25-year-old male sustains an anterior knee dislocation after a motorcycle accident. The knee is reduced in the emergency department. The patient has palpable, symmetric 2+ dorsalis pedis and posterior tibial pulses. However, the ankle-brachial index (ABI) is measured at 0.85. What is the most appropriate next step in management?

. Discharge with a knee immobilizer and close follow-up
. Perform a CT angiogram of the lower extremity
. Immediate surgical exploration of the popliteal fossa
. Obtain a venous duplex ultrasound to rule out DVT
. Repeat ABI measurement in 24 hours

Correct Answer & Explanation

. Perform a CT angiogram of the lower extremity

Explanation

In the setting of a knee dislocation, palpable pulses do not definitively rule out an intimal flap tear of the popliteal artery. An ABI less than 0.9 is highly sensitive for vascular injury and mandates advanced imaging, such as a CT angiogram.

Question 4059

Topic: 1. General Principles & Basic Science

During the surgical repair of a chronic, complete rupture of the pectoralis major muscle, the surgeon must mobilize and anatomically repair the sternal and clavicular heads to their footprint on the humerus. What is the correct anatomical relationship of the clavicular head relative to the sternal head at their humeral insertion?

. The clavicular head inserts posterior (deep) and proximal to the sternal head
. The clavicular head inserts anterior (superficial) and distal to the sternal head
. The clavicular head inserts posterior (deep) and distal to the sternal head
. The clavicular head inserts directly medial to the sternal head
. The clavicular head inserts anterior (superficial) and proximal to the sternal head

Correct Answer & Explanation

. The clavicular head inserts anterior (superficial) and distal to the sternal head

Explanation

At the humeral insertion, the pectoralis major tendon undergoes a 180-degree twist. The clavicular head descends directly to insert anteriorly (superficially) and distally on the lateral lip of the bicipital groove. The sternal head twists such that its lower fibers become superior and insert posteriorly (deep) and proximal to the clavicular head.

Question 4060

Topic: 1. General Principles & Basic Science

Historically, it was taught that the anterior circumflex humeral artery provides the primary blood supply to the humeral head via its arcuate branch. However, modern quantitative studies (e.g., Hettrich et al.) have demonstrated that the principal blood supply to the humeral head is actually provided by which vessel?

. Thoracoacromial artery
. Anterior circumflex humeral artery
. Posterior circumflex humeral artery
. Suprascapular artery
. Circumflex scapular artery

Correct Answer & Explanation

. Posterior circumflex humeral artery

Explanation

Classic anatomic teaching held that the anterior circumflex humeral artery (ACHA) was the dominant blood supply to the humeral head. However, landmark modern cadaveric studies using gadolinium MRI quantification (Hettrich et al., JBJS 2010) demonstrated that the posterior circumflex humeral artery (PCHA) provides 64% of the blood supply to the humeral head, making it the dominant vessel.

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