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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 13 of 326

This practice set contains high-yield board review questions covering key concepts in 3. Adult Reconstruction (Hip & Knee). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 241

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male with a history of essential hypertension undergoes an elective total knee arthroplasty. On post-operative day 0, his blood pressure is persistently 190/100 mmHg despite adequate pain control. He is alert, oriented, and denies chest pain or shortness of breath. His urine output is 50 mL/hr. What is the most appropriate initial management strategy?

. Administer IV Labetalol 10 mg over 2 minutes
. Start oral Nifedipine extended-release 30 mg
. Increase IV fluid rate to 200 mL/hr of 0.9% Normal Saline
. Obtain STAT ECG and cardiac enzymes
. Reassure the patient and monitor blood pressure hourly

Correct Answer & Explanation

. Administer IV Labetalol 10 mg over 2 minutes

Explanation

Correct Answer: AAcute post-operative hypertension (BP >180/110 or >160/90 with risk factors/symptoms) requires prompt management to prevent complications such as myocardial ischemia, stroke, or surgical site hematoma. IV Labetalol is an excellent first-line agent for rapid blood pressure control in this setting, as it offers both alpha and beta-adrenergic blockade, reducing systemic vascular resistance and heart rate. Oral Nifedipine is typically used for less acute control. Increasing IV fluids would likely exacerbate hypertension in an euvolemic patient. While an ECG and enzymes are important if symptoms suggestive of cardiac ischemia were present, they are not the immediate management for asymptomatic hypertension. Reassurance is insufficient for such elevated blood pressure.

Question 242

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female undergoes a total hip arthroplasty. On post-operative day 1, she develops new-onset confusion, headache, and nausea. Labs reveal a serum sodium (Na+) of 122 mEq/L, serum osmolality of 250 mOsm/kg, and urine osmolality of 480 mOsm/kg. She has received 4 liters of D5 0.45% Normal Saline intravenously since surgery. Her physical exam is notable for euvolemia. What is the most likely cause of her hyponatremia?

. Cerebral Salt Wasting (CSW)
. Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
. Hypovolemic hyponatremia due to renal losses
. Hyperglycemic pseudohyponatremia
. Primary polydipsia

Correct Answer & Explanation

. Syndrome of Inappropriate Antidiuretic Hormone (SIADH)

Explanation

Correct Answer: BThis patient's presentation with euvolemic hyponatremia (Na+ 122 mEq/L), inappropriately concentrated urine (urine osmolality 480 mOsm/kg, which is >100 mOsm/kg in the setting of hyponatremia), and a relatively low serum osmolality (250 mOsm/kg) in the post-operative setting is highly suggestive of SIADH. Surgical stress, pain, and certain medications (e.g., opioids) can all stimulate ADH release. The administration of hypotonic fluids (D5 0.45% NS) further exacerbates the condition. CSW typically presents with hypovolemia. Hypovolemic hyponatremia would show signs of dehydration. Hyperglycemic pseudohyponatremia would be accompanied by significant hyperglycemia. Primary polydipsia would result in dilute urine (urine osmolality <100 mOsm/kg).

Question 243

Topic: 3. Adult Reconstruction (Hip & Knee)

During total knee arthroplasty under spinal anesthesia, a 75-year-old patient's blood pressure drops to 70/40 mmHg. Heart rate is 50 bpm. The patient is well-hydrated preoperatively. What is the most appropriate initial pharmacologic intervention?

. IV Epinephrine
. IV Phenylephrine
. IV Norepinephrine
. IV Atropine
. IV Labetalol

Correct Answer & Explanation

. IV Phenylephrine

Explanation

Correct Answer: BSpinal anesthesia often causes hypotension and bradycardia due to sympathetic blockade. Phenylephrine, a pure alpha-1 adrenergic agonist, causes peripheral vasoconstriction, effectively raising blood pressure without significantly increasing heart rate (which is already low). Epinephrine and Norepinephrine are potent vasopressors and inotropes, typically reserved for more profound or refractory shock. Atropine is useful for bradycardia but does not directly address the hypotension due to vasodilation. Labetalol would worsen both hypotension and bradycardia.

Question 244

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old female with a known history of severe rheumatoid arthritis and chronic steroid use is scheduled for a total wrist arthroplasty. Her baseline blood pressure is 110/70 mmHg. What is a critical perioperative consideration regarding her steroid regimen?

. Discontinue steroids immediately to reduce infection risk
. Decrease steroid dose by half on the day of surgery
. Administer a 'stress dose' of corticosteroids perioperatively
. Switch from oral to inhaled corticosteroids
. Monitor for hyperglycemia only

Correct Answer & Explanation

. Administer a 'stress dose' of corticosteroids perioperatively

Explanation

Correct Answer: CPatients on chronic corticosteroid therapy (especially at doses equivalent to prednisone >5 mg/day for >3 weeks) are at risk of adrenal insufficiency during surgical stress. The hypothalamic-pituitary-adrenal (HPA) axis can be suppressed, preventing an adequate endogenous cortisol response. Therefore, a 'stress dose' of corticosteroids (e.g., hydrocortisone) is crucial perioperatively to prevent adrenal crisis, which can manifest as hypotension, hypoglycemia, and shock. Discontinuing or decreasing the dose without replacement would be dangerous. Switching to inhaled steroids is irrelevant for systemic stress response. Monitoring for hyperglycemia is important but secondary to preventing adrenal crisis.

Question 245

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male post-op total hip arthroplasty develops delirium and his serum sodium is 160 mEq/L. He is hypovolemic with a urine output of 180 mL/hr, urine osmolality 150 mOsm/kg. His blood glucose is 120 mg/dL. What is the appropriate rate of sodium correction for this hypernatremia?

. Rapidly correct to normal within 6 hours
. Aim for a decrease of 10-12 mEq/L over the first 24 hours
. Aim for a decrease of 20-24 mEq/L over the first 24 hours
. No correction needed if the patient is asymptomatic
. Correct with D5W at 500 mL/hr until Na+ is normalized

Correct Answer & Explanation

. Aim for a decrease of 10-12 mEq/L over the first 24 hours

Explanation

Correct Answer: BCorrection of hypernatremia should be gradual to prevent cerebral edema. A rapid decrease in serum sodium can cause water to shift into brain cells, leading to cerebral edema, seizures, and neurological damage. The general recommendation is to decrease serum sodium by no more than 10-12 mEq/L over the first 24 hours, and then by 18 mEq/L per 48 hours, or 0.5 mEq/L/hour. Rapid correction within 6 hours or by 20-24 mEq/L in 24 hours is too aggressive. The patient is symptomatic (delirium), requiring correction. Correcting with D5W at 500 mL/hr is too rapid and does not account for the gradual nature of correction.

Question 246

Topic: Total Hip Arthroplasty (THA)

A 62-year-old male undergoes a total hip arthroplasty (THA) via a direct anterior approach. Postoperatively, he complains of numbness and burning pain over the lateral aspect of his thigh. Physical examination reveals diminished sensation in this distribution. Motor strength is intact. Which of the following nerves was most likely injured during the procedure?

. Sciatic nerve
. Femoral nerve
. Lateral femoral cutaneous nerve
. Obturator nerve
. Superior gluteal nerve

Correct Answer & Explanation

. Lateral femoral cutaneous nerve

Explanation

Correct Answer: CThe patient's symptoms of numbness and burning pain over the lateral aspect of the thigh, without motor weakness, are classic for meralgia paresthetica, which is caused by compression or injury to the lateral femoral cutaneous nerve (LFCN). The direct anterior approach (DAA) to the hip is known to have a higher risk of LFCN injury due to the nerve's superficial course and its proximity to the surgical incision and retractors. While the DAA is associated with a lower dislocation rate and potentially faster recovery, this specific nerve injury is a recognized complication. The sciatic nerve (A) injury would typically cause weakness in the posterior thigh and leg muscles, and sensory loss in the posterior leg and foot. The femoral nerve (B) injury would cause weakness in hip flexion and knee extension, and sensory loss over the anterior thigh. The obturator nerve (D) injury would cause weakness in hip adduction and sensory loss over the medial thigh. The superior gluteal nerve (E) injury would cause weakness in hip abduction (Trendelenburg gait).

Question 247

Topic: 3. Adult Reconstruction (Hip & Knee)
A 6-year-old boy presents with a 3-month history of a painless limp and mild right hip pain, worse with activity. Physical examination reveals limited internal rotation and abduction of the right hip. Radiographs show flattening and increased density of the right femoral epiphysis. What is the most appropriate initial management strategy for this condition?
. Bracing or casting to achieve hip containment
. Immediate surgical core decompression
. Non-weight bearing and observation
. Total hip arthroplasty
. Anti-inflammatory medications and physical therapy

Correct Answer & Explanation

. Bracing or casting to achieve hip containment

Explanation

This clinical presentation and radiographic findings are classic for Legg-Calvรฉ-Perthes disease (LCPD), which is avascular necrosis of the femoral head in children. The goal of treatment for LCPD, especially in a 6-year-old with significant involvement, is to contain the femoral head within the acetabulum to maintain its spherical shape during the revascularization and healing phases. This 'containment' can be achieved non-operatively with bracing (e.g., Scottish Rite brace, Petrie cast) or operatively with osteotomies (femoral or pelvic) if non-operative measures fail or are not suitable. Observation alone is typically reserved for very young children (under 6) with minimal involvement. Core decompression is for adult avascular necrosis. Total hip arthroplasty is a salvage procedure for end-stage arthritis, not initial management for LCPD. Anti-inflammatory medications and physical therapy are adjunctive for symptom management but do not address the underlying pathology or prevent deformity.

Question 248

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female with a well-fixed cementless total hip arthroplasty (THA) from 10 years ago falls and sustains a periprosthetic femur fracture. Radiographs show a spiral fracture extending from just below the lesser trochanter down the femoral shaft, with the femoral stem intact and stable within the proximal fragment. There is no evidence of stem loosening. According to the Vancouver classification, which type of fracture does this represent, and what is the most appropriate management?

. Type A, non-operative management with protected weight-bearing.
. Type B1, open reduction and internal fixation (ORIF) with plates and screws.
. Type B2, revision THA with a longer, often cemented, stem.
. Type B3, revision THA with extensive bone grafting or modular stem.
. Type C, ORIF with plates and screws.

Correct Answer & Explanation

. Type B1, open reduction and internal fixation (ORIF) with plates and screws.

Explanation

Correct Answer: BThe Vancouver classification is used for periprosthetic femur fractures around a THA stem. The fracture described is a spiral fracture below the lesser trochanter, with the femoral stem intact and stable within the proximal fragment, and no evidence of stem loosening. This fits the criteria for a Vancouver Type B1 fracture. Type B1 fractures are characterized by a fracture around or just below the stem, with a well-fixed stem. The most appropriate management for a Vancouver Type B1 fracture is open reduction and internal fixation (ORIF) using plates and screws (e.g., locking plates, cables) to stabilize the fracture while retaining the well-fixed stem. Type A fractures (A) are trochanteric fractures, typically managed with ORIF. Type B2 (C) fractures involve a loose stem, requiring stem revision. Type B3 (D) fractures involve a loose stem with significant bone loss, requiring extensive revision and often allograft. Type C fractures (E) are distal to the stem, managed with ORIF, but the description places the fracture around the stem.

Question 249

Topic: 3. Adult Reconstruction (Hip & Knee)

An 80-year-old patient undergoing rehabilitation after a total hip arthroplasty develops new onset of localized lower abdominal pain and tenderness at a previous laparoscopic cholecystectomy incision site. She reports being able to pass gas but has some difficulty with defecation. Examination reveals a subtle, firm, tender lump. Given her age and recent surgery, an occult Richter hernia should be considered. What imaging modality would be most sensitive for initial diagnosis?

. Plain abdominal radiography
. Abdominal ultrasound
. CT scan of the abdomen and pelvis with intravenous contrast
. Magnetic Resonance Imaging (MRI)
. Barium enema

Correct Answer & Explanation

. CT scan of the abdomen and pelvis with intravenous contrast

Explanation

Correct Answer: CA CT scan of the abdomen and pelvis with intravenous contrast is the most sensitive and specific imaging modality for diagnosing a Richter hernia. It can clearly visualize the incarcerated bowel segment, assess for mural thickening, fat stranding, and signs of ischemia (lack of enhancement, pneumatosis), and rule out other causes of abdominal pain. Plain abdominal radiographs are poor for soft tissue detail and often normal in Richter hernias without complete obstruction. Ultrasound can be helpful but is operator-dependent and may miss deeper or subtle hernias. MRI is also highly detailed but generally less available for acute emergencies and offers no significant advantage over CT for initial diagnosis. A barium enema is for colon evaluation and not suitable for acute small bowel pathology like a Richter hernia.

Question 250

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female undergoes a total hip arthroplasty utilizing a ceramic-on-ceramic bearing surface. At her 2-year follow-up, she complains of a loud, audible squeaking sound from her hip during normal gait. Which of the following factors is most strongly associated with this phenomenon?

. Acetabular component placed in relative retroversion
. Femoral stem subsidence of 2 mm
. Use of a 28 mm femoral head
. Acetabular component placed in excessive anteversion and inclination
. Patient body mass index greater than 40

Correct Answer & Explanation

. Acetabular component placed in excessive anteversion and inclination

Explanation

Squeaking in ceramic-on-ceramic THA is most often associated with edge loading due to component malposition, specifically excessive acetabular cup inclination and anteversion. This abnormal contact mechanics leads to stripe wear and loss of normal fluid film lubrication.

Question 251

Topic: 3. Adult Reconstruction (Hip & Knee)
A 25-year-old male sustains a high-energy Pauwels type III femoral neck fracture. To minimize the risk of avascular necrosis, surgical fixation should respect the primary blood supply to the femoral head. Which of the following vessels provides the majority of the blood supply to the adult femoral head?
. Medial femoral circumflex artery
. Inferior gluteal artery
. Lateral femoral circumflex artery
. Artery of the ligamentum teres
. Superior gluteal artery

Correct Answer & Explanation

. Medial femoral circumflex artery

Explanation

The medial femoral circumflex artery (MFCA) is the predominant blood supply to the adult femoral head. It gives rise to the lateral epiphyseal artery, which enters the capsule posteriorly to perfuse the femoral head.

Question 252

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old active female undergoes a primary total hip arthroplasty. To minimize wear, a ceramic-on-ceramic bearing surface is chosen. Which of the following is a recognized complication specifically associated with this bearing surface?

. Trunnionosis
. Audible squeaking during ambulation
. Adverse local tissue reaction (ALTR) from metal ions
. Polyethylene osteolysis
. Spontaneous head dissociation

Correct Answer & Explanation

. Audible squeaking during ambulation

Explanation

Ceramic-on-ceramic bearing surfaces are known for low wear rates but carry specific risks, including ceramic fracture and audible squeaking. Squeaking is often associated with component malposition, such as edge loading.

Question 253

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female undergoes a total knee arthroplasty for severe valgus osteoarthritis. The surgeon plans a sequential lateral soft tissue release. Which of the following structures is the primary restraint to valgus instability when the knee is in 90 degrees of flexion?

. Iliotibial band
. Lateral collateral ligament (LCL)
. Popliteus tendon
. Posterolateral capsule
. Lateral head of the gastrocnemius

Correct Answer & Explanation

. Lateral collateral ligament (LCL)

Explanation

The lateral collateral ligament (LCL) is the primary restraint to valgus stress when the knee is flexed. The iliotibial band acts as a secondary restraint, more so in extension.

Question 254

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female presents with recurrent posterior dislocations following a primary total hip arthroplasty performed via a posterior approach. Radiographs demonstrate that the acetabular component is in 25 degrees of abduction and 0 degrees of anteversion. Which of the following is the most appropriate surgical management?

. Revision of the femoral component to increase offset
. Conversion to a constrained acetabular liner
. Revision of the acetabular component to increase anteversion
. Advancement of the greater trochanter
. Application of an abduction brace for 6 weeks

Correct Answer & Explanation

. Revision of the acetabular component to increase anteversion

Explanation

The acetabular component is retroverted (0 degrees of anteversion), which strongly predisposes the hip to posterior dislocation. The most appropriate treatment is revision of the acetabular shell to correct the version to 15-20 degrees of anteversion.

Question 255

Topic: 3. Adult Reconstruction (Hip & Knee)

A 22-year-old male sustains a displaced, completely off-ended femoral neck fracture in a high-speed motor vehicle collision. He is hemodynamically stable. What is the most critical factor in minimizing his risk of avascular necrosis (AVN) and nonunion?

. Anatomic reduction and stable internal fixation
. Urgent hemiarthroplasty
. Use of a sliding hip screw instead of cannulated screws
. Total hip arthroplasty
. Delaying surgery for 48 hours to allow capsular decompression

Correct Answer & Explanation

. Anatomic reduction and stable internal fixation

Explanation

In young patients with displaced femoral neck fractures, head-preserving surgery is indicated. The quality of the anatomic reduction and the stability of the fixation are the most critical factors in preventing AVN and nonunion.

Question 256

Topic: 3. Adult Reconstruction (Hip & Knee)

A 30-year-old snowboarder sustains a displaced talar neck fracture treated with open reduction and internal fixation. At his 8-week follow-up, an AP mortise radiograph of the ankle shows a linear subchondral radiolucency in the dome of the talus. What does this radiographic finding indicate?

. Imminent talar body collapse
. Infection of the talar dome
. Viable talar body with a low likelihood of avascular necrosis
. Complete avascular necrosis of the talar body
. Nonunion of the talar neck

Correct Answer & Explanation

. Viable talar body with a low likelihood of avascular necrosis

Explanation

This finding is Hawkins' sign, representing subchondral osteopenia secondary to hyperemia. It indicates intact vascularity to the talar body, making avascular necrosis highly unlikely.

Question 257

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old male presents after a high-energy fall, sustaining a posterior wall acetabular fracture with a congruent reduction after closed hip dislocation. Post-reduction radiographs show no incarcerated fragments. Which of the following is the most appropriate management strategy?

. Immediate open reduction internal fixation (ORIF) of the posterior wall.
. Skeletal traction for 6 weeks followed by progressive mobilization.
. Non-weight bearing with protected range of motion, closely monitoring for instability.
. Hip arthroplasty due to high risk of avascular necrosis.
. Repeat CT scan in 24 hours to reassess stability.

Correct Answer & Explanation

. Non-weight bearing with protected range of motion, closely monitoring for instability.

Explanation

Correct Answer: CFor isolated posterior wall acetabular fractures that are congruent and stable after closed reduction of a hip dislocation, non-operative management with protected weight-bearing and restricted range of motion is a recognized option. Instability is typically assessed with stress radiographs or dynamic fluoroscopy after reduction. If stable, close monitoring for secondary displacement or late instability is crucial. Surgical indications usually include persistent instability, incarcerated fragments, or significant displacement. Immediate ORIF is typically reserved for unstable fractures or those with incarcerated fragments. Skeletal traction is less commonly used for these stable fracture patterns. Hip arthroplasty is not indicated primarily for this injury pattern without pre-existing arthritis or severe head damage. A CT scan is usually performed initially to assess the fracture pattern and rule out incarcerated fragments, but repeating it in 24 hours without clinical change is not the primary management.

Question 258

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old male sustains a displaced femoral neck fracture. He has a history of severe COPD, home oxygen dependence, and minimal daily ambulation. What is the most appropriate surgical treatment?

. In situ pinning with cannulated screws
. Total hip arthroplasty
. Bipolar hemiarthroplasty
. Unipolar hemiarthroplasty
. Proximal femoral nail

Correct Answer & Explanation

. Unipolar hemiarthroplasty

Explanation

Unipolar or bipolar hemiarthroplasty is indicated for displaced femoral neck fractures in elderly, low-demand patients. Unipolar is highly appropriate here given his minimal ambulation and severe medical issues, minimizing surgical time and dislocation risk.

Question 259

Topic: 3. Adult Reconstruction (Hip & Knee)

In total hip arthroplasty, which bearing surface combination historically had the highest rate of component fracture but the lowest volumetric wear?

. Cobalt-chromium on highly cross-linked polyethylene
. Ceramic on ceramic
. Ceramic on highly cross-linked polyethylene
. Oxinium on cross-linked polyethylene
. Cobalt-chromium on conventional polyethylene

Correct Answer & Explanation

. Ceramic on ceramic

Explanation

Ceramic-on-ceramic bearings offer the lowest volumetric wear rates but are associated with the risk of catastrophic component fracture and squeaking. Modern highly cross-linked polyethylene has drastically reduced wear rates while maintaining toughness.

Question 260

Topic: 3. Adult Reconstruction (Hip & Knee)

During a posterior-stabilized total knee arthroplasty, early cam-post engagement in flexion is noted. Which of the following is the most likely technical error causing this phenomenon?

. Oversizing the femoral component
. Undersizing the femoral component
. Excessive posterior slope of the tibial tray
. Insufficient posterior slope of the tibial tray
. Internal rotation of the tibial component

Correct Answer & Explanation

. Insufficient posterior slope of the tibial tray

Explanation

Insufficient posterior slope (or an anteriorly sloped tibial cut) moves the post relatively anteriorly, causing it to engage the femoral cam too early in flexion. This limits maximal flexion and increases stress on the polyethylene post.

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