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1. General Principles & Basic Science MCQs

Practice Set 102 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 2021

Topic: Surgical Anatomy & Approaches

During a deltopectoral approach for a complex proximal humerus fracture, the surgeon identifies the cephalic vein within the deltopectoral groove. According to the comprehensive guide, what is the preferred management strategy for the cephalic vein, and why?

. Ligation, to prevent kinking and improve exposure.
. Lateral retraction with the deltoid, to protect the pectoralis major.
. Medial retraction with the pectoralis major, to protect the axillary nerve and avoid kinking.
. Splitting the vein longitudinally, to maintain partial venous return.
. Dissection and transposition to a subcutaneous pocket, to ensure full preservation.

Correct Answer & Explanation

. Medial retraction with the pectoralis major, to protect the axillary nerve and avoid kinking.

Explanation

Correct Answer: CExplanation:The case states: "TheCephalic Vein... is typically identified early, carefully dissected free from its surrounding areolar tissue, and gently mobilized.Preferred Management:The cephalic vein is typically retracted medially along with the pectoralis major muscle. This minimizes the risk of injury from retractors against the deltoid and protects the axillary nerve (which lies laterally) and prevents kinking or compression of the vein against the deltoid."A. Ligation, to prevent kinking and improve exposure:While ligation can improve exposure, it is explicitly stated as an option only if retraction is inadequate or the vein is compromised, and should be avoided if possible to mitigate post-operative venous congestion and swelling. It is not the preferred strategy.B. Lateral retraction with the deltoid, to protect the pectoralis major:Lateral retraction is generally discouraged because it places the vein at risk of injury from retractors against the deltoid and potentially obscures the axillary nerve, which lies laterally.D. Splitting the vein longitudinally, to maintain partial venous return:This is not a recognized or safe surgical technique for managing the cephalic vein in this approach and would likely lead to significant bleeding and thrombosis.E. Dissection and transposition to a subcutaneous pocket, to ensure full preservation:While preservation is desired, transposition to a subcutaneous pocket is an overly complex and unnecessary maneuver for the cephalic vein in this context. Simple medial retraction is sufficient for preservation.

Question 2022

Topic: Surgical Anatomy & Approaches

A surgeon is performing a deltopectoral approach. After incising the clavipectoral fascia and retracting the conjoined tendon medially, they are preparing to expose the subscapularis. Which nerve is most vulnerable to injury with excessive or forceful medial retraction of the conjoined tendon?

. Axillary nerve
. Suprascapular nerve
. Long thoracic nerve
. Musculocutaneous nerve
. Dorsal scapular nerve

Correct Answer & Explanation

. Musculocutaneous nerve

Explanation

Correct Answer: DExplanation:The case states: "TheMusculocutaneous Nerve (C5-C7): This nerve typically enters the deep surface of the coracobrachialis muscle approximately 5-8 cm distal to the coracoid tip. Excessive or unmindful medial retraction or division of the conjoined tendon risks injury to this nerve." The conjoined tendon is formed by the short head of the biceps and coracobrachialis, and the musculocutaneous nerve innervates the coracobrachialis and then the biceps.A. Axillary nerve:While the axillary nerve is highly vulnerable in the deltopectoral approach, its primary risk is during inferior capsular release, humeral head resection, or fracture fixation around the surgical neck, not directly from medial retraction of the conjoined tendon itself. The axillary neurovascular bundle (which includes the axillary artery, vein, and brachial plexus cords) is deep and medial to the conjoined tendon, and at risk withextrememedial retraction, but the musculocutaneous nerve iswithinor immediately adjacent to the conjoined tendon.B. Suprascapular nerve:This nerve is located more posteriorly, passing through the suprascapular notch, and is not typically at risk during an anterior deltopectoral approach unless there is extensive posterior dissection or specific superior glenoid pathology.C. Long thoracic nerve:This nerve innervates the serratus anterior and courses along the lateral chest wall. It is not typically at risk during a deltopectoral approach.E. Dorsal scapular nerve:This nerve innervates the rhomboids and levator scapulae and is located more posteriorly, not in the field of the deltopectoral approach.

Question 2023

Topic: Surgical Anatomy & Approaches

A 45-year-old male undergoes open reduction and internal fixation of a 3-part proximal humerus fracture via a standard deltopectoral approach. Which of the following best describes the internervous plane utilized during the superficial dissection?

. Deltoid (axillary nerve) and Pectoralis major (medial and lateral pectoral nerves)
. Deltoid (axillary nerve) and Biceps brachii (musculocutaneous nerve)
. Pectoralis major (medial/lateral pectoral nerves) and Pectoralis minor (medial pectoral nerve)
. Coracobrachialis (musculocutaneous nerve) and Short head of the biceps (musculocutaneous nerve)
. Subscapularis (upper/lower subscapular nerves) and Infraspinatus (suprascapular nerve)

Correct Answer & Explanation

. Deltoid (axillary nerve) and Pectoralis major (medial and lateral pectoral nerves)

Explanation

The deltopectoral approach utilizes the internervous plane between the deltoid (axillary nerve) and pectoralis major (medial and lateral pectoral nerves). This true internervous plane allows for safe anterior exposure of the proximal humerus.

Question 2024

Topic: Surgical Anatomy & Approaches

A surgeon is performing an open rotator cuff repair via a lateral deltoid-splitting approach. To avoid iatrogenic injury to the axillary nerve, the distal extent of the deltoid split should not exceed what distance from the lateral edge of the acromion?

. 2 cm
. 5 cm
. 7 cm
. 9 cm
. 11 cm

Correct Answer & Explanation

. 5 cm

Explanation

The axillary nerve runs transversely across the deep surface of the deltoid approximately 5 cm (range 4-7 cm) distal to the lateral edge of the acromion. Extending the deltoid split beyond 5 cm puts the nerve at significant risk.

Question 2025

Topic: Surgical Anatomy & Approaches

A 65-year-old female undergoes total hip arthroplasty via an anterolateral (Watson-Jones) approach. Which two muscles define the primary intermuscular interval utilized in this approach?

. Tensor fasciae latae and Gluteus medius
. Tensor fasciae latae and Sartorius
. Gluteus medius and Gluteus minimus
. Gluteus medius and Vastus lateralis
. Sartorius and Rectus femoris

Correct Answer & Explanation

. Tensor fasciae latae and Gluteus medius

Explanation

The Watson-Jones approach exploits the intermuscular interval between the tensor fasciae latae and the gluteus medius. This is not a true internervous plane, as both muscles are innervated by the superior gluteal nerve.

Question 2026

Topic: Surgical Anatomy & Approaches

During the ilioinguinal approach for an anterior column acetabular fracture, three specific surgical windows are developed. Which structures define the medial and lateral borders of the middle window?

. Iliopectineal fascia and iliopsoas
. External iliac vessels and iliopsoas/femoral nerve
. External iliac vessels and spermatic cord
. Spermatic cord and rectus abdominis
. Femoral nerve and lateral femoral cutaneous nerve

Correct Answer & Explanation

. External iliac vessels and iliopsoas/femoral nerve

Explanation

The middle window of the ilioinguinal approach is bordered medially by the external iliac vessels and laterally by the iliopsoas muscle and femoral nerve. Access to the pelvic brim and quadrilateral plate is achieved through this interval.

Question 2027

Topic: Surgical Anatomy & Approaches

A surgeon utilizes the modified Stoppa approach for an anterior acetabular fracture. Severe bleeding occurs over the superior pubic ramus during dissection. This is most likely due to injury to the "corona mortis," which is an anastomosis between which two vascular systems?

. External iliac (or inferior epigastric) and Internal iliac (obturator)
. Common iliac and Femoral
. Internal pudendal and Inferior epigastric
. Superior gluteal and Obturator
. Internal iliac and External pudendal

Correct Answer & Explanation

. External iliac (or inferior epigastric) and Internal iliac (obturator)

Explanation

The corona mortis is a vascular anastomosis between the obturator vessels (from the internal iliac system) and the inferior epigastric vessels (from the external iliac system). It crosses the superior pubic ramus and is highly vulnerable during anterior intrapelvic approaches.

Question 2028

Topic: Surgical Anatomy & Approaches

A surgeon is utilizing the deltopectoral approach for a total shoulder arthroplasty. The cephalic vein is identified within the internervous plane. To minimize bleeding and preserve venous drainage from the deltoid, what is the standard recommended handling of the cephalic vein?

. Ligate the vein in all cases to improve exposure
. Retract the vein medially with the pectoralis major
. Retract the vein laterally with the deltoid
. Divide the vein superiorly and retract it inferiorly
. Leave the vein undissected within the superficial fascia

Correct Answer & Explanation

. Retract the vein laterally with the deltoid

Explanation

The cephalic vein is typically retracted laterally with the deltoid to preserve its major venous tributaries, which predominantly drain the deltoid muscle. Medial retraction risks tearing these delicate branches.

Question 2029

Topic: Surgical Anatomy & Approaches

During a lateral deltoid-splitting approach for a proximal humerus fracture, the surgeon must avoid propagating the split too far distally. What is the maximum safe distance from the lateral edge of the acromion to prevent injury to the axillary nerve?

. 1-2 cm
. 3-4 cm
. 5-7 cm
. 8-10 cm
. 11-13 cm

Correct Answer & Explanation

. 5-7 cm

Explanation

The axillary nerve courses horizontally along the deep surface of the deltoid approximately 5 to 7 cm distal to the lateral edge of the acromion. Extending the deltoid split beyond this distance risks denervating the anterior deltoid.

Question 2030

Topic: Surgical Anatomy & Approaches

During a Watson-Jones (anterolateral) approach to the hip for a femoral neck fracture, the surgical interval is developed between the tensor fasciae latae and the gluteus medius. Why is this technically considered an intermuscular rather than a true internervous plane?

. Both muscles are innervated by the femoral nerve.
. Both muscles are innervated by the superior gluteal nerve.
. The tensor fasciae latae is innervated by the superior gluteal nerve and gluteus medius by the inferior gluteal nerve.
. Both muscles are innervated by the inferior gluteal nerve.
. The plane does not cross any major motor nerve branches.

Correct Answer & Explanation

. Both muscles are innervated by the superior gluteal nerve.

Explanation

The Watson-Jones approach develops the plane between the tensor fasciae latae and the gluteus medius. It is considered an intermuscular plane because both muscles are innervated by the superior gluteal nerve.

Question 2031

Topic: Surgical Anatomy & Approaches

During a deltopectoral approach for a total shoulder arthroplasty, the conjoint tendon is retracted medially. At what approximate distance distal to the tip of the coracoid process does the musculocutaneous nerve typically enter the coracobrachialis?

. 1 to 3 cm
. 3 to 8 cm
. 8 to 12 cm
. 12 to 15 cm
. Greater than 15 cm

Correct Answer & Explanation

. 3 to 8 cm

Explanation

The musculocutaneous nerve typically penetrates the coracobrachialis 5 to 8 cm distal to the coracoid process. Vigorous medial retraction of the conjoint tendon risks neuropraxia to this nerve.

Question 2032

Topic: Surgical Anatomy & Approaches

A patient undergoes a Kocher-Langenbeck approach for a posterior wall acetabular fracture. Postoperatively, the patient demonstrates an asymmetric foot drop and absent sensation over the anterolateral leg and dorsum of the foot, with intact plantar sensation. Which portion of the sciatic nerve was most likely injured during retraction?

. Tibial division
. Common peroneal division
. Sciatic nerve trunk proximal to division
. Sural nerve
. Deep peroneal nerve selectively

Correct Answer & Explanation

. Common peroneal division

Explanation

The common peroneal division of the sciatic nerve is located laterally and is relatively tethered at the fibular head, making it highly susceptible to stretch injury during posterior acetabular surgery. This injury presents with foot drop and sensory loss over the anterolateral leg and dorsal foot.

Question 2033

Topic: Physiology & Rehabilitation

The direct lateral (Hardinge) approach to the hip requires splitting the gluteus medius and vastus lateralis. To avoid denervation of the anterior portion of the abductor mechanism, the proximal split in the gluteus medius should safely not extend beyond what distance from the tip of the greater trochanter?

. 1 cm
. 3 cm
. 5 cm
. 8 cm
. 10 cm

Correct Answer & Explanation

. 5 cm

Explanation

The superior gluteal nerve traverses the gluteus medius approximately 3 to 5 cm proximal to the tip of the greater trochanter. Extending the split beyond 5 cm places the nerve at significant risk, which can lead to postoperative Trendelenburg gait.

Question 2034

Topic: Surgical Anatomy & Approaches

A surgeon performs a deltoid-splitting anterolateral approach for plate fixation of a proximal humerus fracture. To prevent denervation of the anterior deltoid, the distal split must not exceed what distance from the lateral edge of the acromion?

. 2 cm
. 5 cm
. 8 cm
. 10 cm
. 12 cm

Correct Answer & Explanation

. 5 cm

Explanation

The axillary nerve crosses the humerus approximately 5 to 7 cm distal to the lateral edge of the acromion. Splitting the deltoid further than 5 cm distally risks transection of the axillary nerve, compromising deltoid function.

Question 2035

Topic: 1. General Principles & Basic Science

Following the diagnosis of a pseudotumour in a 52-year-old woman with a painful MOM hip resurfacing, the examiner asks about risk factors. Which of the following combinations of patient characteristics and implant features would represent the highest risk for developing a pseudotumour, according to the case?

. Male patient, age 45, large component size, no hip dysplasia.
. Female patient, age 38, small component size, history of hip dysplasia.
. Female patient, age 55, large component size, no specific implant design.
. Male patient, age 30, small component size, no history of hip dysplasia.
. Female patient, age 42, average component size, history of inflammatory arthritis.

Correct Answer & Explanation

. Female patient, age 38, small component size, history of hip dysplasia.

Explanation

Correct Answer: BThe case explicitly lists significant risk factors for the development of pseudotumour: 'female sex, age less than 40 years, small component size, hip dysplasia and specific implant designs (ASR).'Option B includes female sex, age 38 (less than 40), small component size, and history of hip dysplasia. This combination aligns perfectly with multiple high-risk factors mentioned in the case.Option A includes male sex and age 45 (not less than 40), which are not high-risk factors according to the case.Option C includes age 55 (not less than 40) and large component size, which are not high-risk factors.Option D includes male sex, which is not a risk factor, and while age 30 and small component size are risk factors, the combination in B is stronger due to the inclusion of female sex and hip dysplasia.Option E includes female sex, but age 42 is not less than 40, and 'average component size' is not specified as a risk factor (small component size is). Inflammatory arthritis is listed as a factor for higher revision rates for hip resurfacing in general, but not specifically for pseudotumour development in the risk factor list.

Question 2036

Topic: Biology, Genetics & Bone Healing

The examiner asks about contraindications for hip resurfacing. Based on the detailed list provided by the candidate, which of the following patient profiles would be an absolute contraindication for hip resurfacing?

. A 40-year-old male with a BMI of 32 kg/m2and mild femoral head cysts.
. A 50-year-old female with a BMI of 30 kg/m2and a history of metal hypersensitivity.
. A 35-year-old male with a BMI of 28 kg/m2and a narrow femoral neck.
. A 60-year-old male with severe osteoporosis and insufficient bone stock in the femoral head.
. A 45-year-old female of childbearing age with no other risk factors.

Correct Answer & Explanation

. A 60-year-old male with severe osteoporosis and insufficient bone stock in the femoral head.

Explanation

Correct Answer: DThe candidate lists several contraindications for resurfacing: 'These include severe osteoporosis, insufficient bone stock in the femoral head, large cysts at the femoral neck or head, a narrow femoral neck, notching of the femoral neck and severe obesity (BMI > 35 kg/m2). Other contraindications include a history of chronic renal disease, metal hypersensitivity, those with anatomical abnormalities in the acetabulum or proximal femur and certainly caution in women of childbearing age.'Option D, 'A 60-year-old male with severe osteoporosis and insufficient bone stock in the femoral head,' combines two absolute contraindications explicitly stated: 'severe osteoporosis' and 'insufficient bone stock in the femoral head.'Option A: BMI of 32 is not > 35 (severe obesity). Mild femoral head cysts are not listed as an absolute contraindication, though large cysts are.Option B: While metal hypersensitivity is a contraindication, the question asks for anabsolutecontraindication from the list. This is a strong contraindication, but D combines two distinct, severe bone-related contraindications.Option C: A narrow femoral neck is a contraindication, but this option only lists one. Option D lists two severe, bone-related contraindications.Option E: 'Caution in women of childbearing age' is mentioned, but the candidate clarifies that most surgeons believe women should not be excluded, although the examiner notes a trend to avoid in all females. It's not presented as anabsolutecontraindication in the same vein as severe osteoporosis or insufficient bone stock.

Question 2037

Topic: 1. General Principles & Basic Science

After successful revision surgery for the pseudotumour, the patient's postoperative radiograph is shown below. The examiner notes that the patient was kept non-weightbearing for 6 weeks due to an extensive anterior wall defect in the acetabulum. This specific post-operative instruction primarily aims to prevent which of the following complications?

. Deep vein thrombosis (DVT).
. Heterotopic ossification.
. Acetabular component loosening or migration.
. Periprosthetic joint infection.
. Femoral nerve palsy.

Correct Answer & Explanation

. Acetabular component loosening or migration.

Explanation

Correct Answer: CThe case states: 'We kept her non-weightbearing for 6 weeks as there was quite an extensive anterior wall defect in the acetabulum.' An acetabular wall defect compromises the structural integrity and initial stability of the acetabular component. Non-weightbearing protects the bone-implant interface during early healing and osseointegration, thereby preventing excessive stress that could lead to micromotion, loosening, or migration of the acetabular component.Option A (DVT) is a general surgical complication, but non-weightbearing is not its primary prevention strategy; anticoagulation and early mobilization (when permitted) are.Option B (Heterotopic ossification) is a known complication of hip surgery, but non-weightbearing does not directly prevent it. Prophylaxis typically involves NSAIDs or radiation.Option D (Periprosthetic joint infection) is a serious complication, but non-weightbearing is not a direct preventative measure. Strict aseptic technique and prophylactic antibiotics are key.Option E (Femoral nerve palsy) is a potential nerve injury during surgery, but non-weightbearing is not a preventative measure for this complication.

Question 2038

Topic: Biology, Genetics & Bone Healing

A 68-year-old woman presents with an 18-month history of left hip pain and difficulty walking. An anteroposterior radiograph of the pelvis is obtained:

Based on the radiographic findings, which of the following is the MOST characteristic feature of Paget's disease in this image?

. A. Joint space narrowing and subchondral cysts indicative of severe osteoarthritis.
. B. Diffuse osteopenia with cortical thinning consistent with senile osteoporosis.
. C. Coarsened trabecular pattern, thickened cortex, and increased bone density in the left hemipelvis and proximal femur.
. D. Multiple well-defined lytic lesions throughout the pelvis and femur, suggesting metastatic disease.
. E. Bilateral symmetrical sacroiliac joint fusion and squaring of vertebral bodies.

Correct Answer & Explanation

. C. Coarsened trabecular pattern, thickened cortex, and increased bone density in the left hemipelvis and proximal femur.

Explanation

Correct Answer: CThe radiograph demonstrates classic features of Paget's disease, including a coarsened trabecular pattern, thickened left cortex, and increased density (sclerosis) of the left hip compared with the right side. Both iliopectineal (Brim sign) and ilioischiatic lines are thickened, and there is sclerosis involving the left pelvis (ileum, ischium, and pubic rami), left femur, and lower lumbar spine. These findings are highly suspicious of Paget's disease, which is characterized by disorganized bone turnover leading to biomechanically weak, enlarged, and sclerotic bone.Option A describes features of osteoarthritis, which may coexist but are not the primary findings of Paget's disease itself. Option B describes osteoporosis, which is characterized by decreased bone density, the opposite of what is seen in the sclerotic phase of Paget's. Option D describes lytic lesions, which can be seen in the early lytic phase of Paget's (e.g., osteoporosis circumscripta in the skull or 'candle flame' sign in long bones), but the predominant features in this image are sclerotic. Multiple lytic lesions are also characteristic of other conditions like multiple myeloma or metastatic disease, which are differential diagnoses but do not match the overall pattern. Option E describes features of ankylosing spondylitis, which is unrelated to the findings in this case.

Question 2039

Topic: Biology, Genetics & Bone Healing

A 60-year-old patient with Paget's disease of the tibia presents with new onset anterior bowing and localized pain. Radiographs show a transverse fissure on the convex anterior surface of the tibia. This finding is best characterized as:

. A. A typical Looser zone, indicative of osteomalacia.
. B. A 'candle flame' sign, representing advancing lysis.
. C. A stress fracture, common in pagetic bone due to its biomechanical weakness.
. D. A pathological fracture secondary to malignant transformation.
. E. A 'picture-frame' vertebral body, a characteristic spinal finding.

Correct Answer & Explanation

. C. A stress fracture, common in pagetic bone due to its biomechanical weakness.

Explanation

Correct Answer: CThe case states that in Paget's disease, 'Fine cracks may appear (stress fractures) which resemble Looser zones but occur on the convex bone surface.' The tibia developing an anterior curvature is also mentioned as a deformity that may result in fracture. The description of a transverse fissure on the convex anterior surface of the tibia in a patient with anterior bowing is highly consistent with a stress fracture in pagetic bone, which is biomechanically weak and prone to deformity and fracture.Option A is incorrect because while they resemble Looser zones, the case explicitly differentiates them, stating they occur on the convex bone surface in Paget's, unlike Looser zones which are typically associated with osteomalacia and occur on the concave (compression) side. Option B, the 'candle flame' or 'blade of grass' sign, represents a wedge- or V-shaped pattern of advancing lysis in the diaphysis of long bones, characteristic of the lytic phase, not a stress fracture. Option D, while malignant transformation is a complication, a stress fracture is a more common and direct consequence of the altered bone mechanics in Paget's, and the description does not suggest the aggressive destruction seen with sarcoma. Option E, a 'picture-frame' vertebral body, is a radiographic feature of spinal Paget's, not a tibial finding.

Question 2040

Topic: Biology, Genetics & Bone Healing

A 55-year-old male with Paget's disease is being evaluated for hip pain. His alkaline phosphatase (AlkPhos) level is significantly elevated. The orthopedic surgeon is concerned about the potential for increased intraoperative bleeding during a planned total hip arthroplasty (THA). What is the MOST appropriate preoperative measure to mitigate this risk?

. A. Administer prophylactic antibiotics immediately prior to surgery.
. B. Initiate a course of non-steroidal anti-inflammatory drugs (NSAIDs) to reduce inflammation.
. C. Refer to a rheumatologist for Pamidronate injection to reduce bone vascularity.
. D. Perform a diagnostic local anesthetic injection to confirm joint pain etiology.
. E. Schedule the surgery without specific blood management, as bleeding risk is minimal.

Correct Answer & Explanation

. C. Refer to a rheumatologist for Pamidronate injection to reduce bone vascularity.

Explanation

Correct Answer: CThe case explicitly states that 'Patients with very high AlkPhos levels are thought to be at higher risk of bleeding and heterotrophic ossification formation.' It also mentions that if Paget's disease is active, a referral for Pamidronate (a bisphosphonate) injection is indicated. Pamidronate is described as a 'potent inhibitor of osteoclastic activity, and hence bone resorption. This reduces bone vascularity and bleeding and possibly the incidence of heterotopic ossification.' Therefore, referring for Pamidronate is the most appropriate measure to reduce the risk of excessive bleeding due to increased bone vascularity in active Paget's disease.Option A, prophylactic antibiotics, are standard for THA but do not address the specific bleeding risk associated with active Paget's. Option B, NSAIDs, are not indicated for reducing surgical bleeding; in fact, some can increase bleeding risk. Option D, a diagnostic local anesthetic injection, is important for differentiating joint pain from bone pain or referred pain, but it does not directly mitigate the risk of intraoperative bleeding from hypervascular pagetic bone. Option E is incorrect, as the case clearly highlights the tendency for excessive bleeding as a significant technical issue in THA for Paget's disease, necessitating specific blood management strategies.

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