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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 254 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 5061

Topic: 3. Adult Reconstruction (Hip & Knee)

When performing a surgical dislocation of the hip, the medial femoral circumflex artery (MFCA) must be protected to prevent avascular necrosis of the femoral head. Which of the following best describes the anatomic course of the deep branch of the MFCA?

. It runs posterior to the quadratus femoris and anterior to the piriformis.
. It runs anterior (deep) to the quadratus femoris and posterior to the obturator externus tendon.
. It runs superior to the superior gemellus and deep to the gluteus medius.
. It runs deep to the pectineus and anterior to the adductor longus.
. It courses directly through the ligamentum teres.

Correct Answer & Explanation

. It runs posterior to the quadratus femoris and anterior to the piriformis.

Explanation

The deep branch of the MFCA runs posteriorly, passing anterior (deep) to the quadratus femoris and posterior to the obturator externus tendon. It then crosses the superior gemellus to branch into the critical retinacular vessels that supply the femoral head.

Question 5062

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient complains of medial knee and leg pain following a medial unicompartmental knee arthroplasty. Entrapment or iatrogenic injury of the saphenous nerve is suspected. Anatomically, how does the saphenous nerve exit the adductor (Hunter's) canal?

. Through the adductor hiatus along with the superficial femoral artery.
. By piercing the anterior wall (vastoadductor membrane) of the canal.
. By passing deep to the semimembranosus tendon.
. By branching directly from the obturator nerve within the canal.
. By crossing superficially over the sartorius muscle proximally.

Correct Answer & Explanation

. Through the adductor hiatus along with the superficial femoral artery.

Explanation

The adductor canal contains the superficial femoral artery, femoral vein, saphenous nerve, and the nerve to the vastus medialis. The saphenous nerve exits the canal by piercing the vastoadductor membrane (the roof of the canal) beneath the sartorius muscle, rather than passing through the adductor hiatus with the femoral vessels.

Question 5063

Topic: 3. Adult Reconstruction (Hip & Knee)

During a posterior approach to the hip (Moore/Southern) for an elective arthroplasty, preserving the deep branch of the medial circumflex femoral artery (MCFA) is critical if avoiding avascular necrosis is desired (e.g., in tumor or trauma, or preserving anatomy). Which of the following short external rotators anatomically protects the MCFA when left intact?

. Piriformis
. Superior gemellus
. Obturator externus
. Quadratus femoris
. Gluteus maximus

Correct Answer & Explanation

. Piriformis

Explanation

The deep branch of the medial circumflex femoral artery (MCFA) represents the primary blood supply to the femoral head. It passes deep to the quadratus femoris and runs along the inferior border of the obturator externus. Thus, preserving the obturator externus tendon safely shields the MCFA from injury during the posterior approach.

Question 5064

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total hip arthroplasty, a screw is inadvertently placed outside the safe zone in the anterosuperior quadrant of the acetabulum. Which of the following structures is at the highest risk of injury?

. External iliac artery and vein
. Obturator nerve and vessels
. Sciatic nerve
. Internal pudendal artery
. Superior gluteal nerve

Correct Answer & Explanation

. External iliac artery and vein

Explanation

According to Wasielewski's quadrants, the anterosuperior quadrant of the acetabulum places the external iliac artery and vein at high risk of injury from screw penetration. The anteroinferior quadrant endangers the obturator nerve and vessels. The posterosuperior quadrant is considered the 'safe zone,' while the posteroinferior quadrant endangers the sciatic nerve and internal pudendal vessels.

Question 5065

Topic: 3. Adult Reconstruction (Hip & Knee)

During a posterior approach to the hip for total hip arthroplasty, the surgeon must take care not to injure the primary blood supply to the femoral head. Anatomically, where does the deep branch of the medial femoral circumflex artery (MFCA) course in relation to the short external rotators?

. Anterior to the superior gemellus and inferior to the piriformis tendon.
. Posterior to the quadratus femoris and anterior to the gluteus maximus.
. Anterior to the quadratus femoris and inferior to the obturator internus.
. Posterior to the obturator externus tendon and anterior to the inferior gemellus.
. Between the piriformis and the superior gemellus tendons.

Correct Answer & Explanation

. Anterior to the superior gemellus and inferior to the piriformis tendon.

Explanation

The deep branch of the MFCA courses posterior to the obturator externus tendon and anterior to the inferior gemellus and quadratus femoris. Protecting the obturator externus during a posterior approach helps shield this critical vessel from iatrogenic injury.

Question 5066

Topic: Total Hip Arthroplasty (THA)

During a direct lateral (Hardinge) approach to the hip, the anterior third of the gluteus medius is split to gain access to the joint. Splitting the muscle too proximally risks denervating the remaining anterior portion of the muscle. What is the accepted safe zone for splitting the gluteus medius proximal to the tip of the greater trochanter to avoid injuring the superior gluteal nerve?

. 1 to 2 cm
. 3 to 5 cm
. 6 to 8 cm
. 9 to 11 cm
. 12 to 14 cm

Correct Answer & Explanation

. 1 to 2 cm

Explanation

The superior gluteal nerve courses approximately 3 to 5 cm proximal to the tip of the greater trochanter. Limiting the proximal split of the gluteus medius to less than 3 cm minimizes the risk of iatrogenic denervation.

Question 5067

Topic: 3. Adult Reconstruction (Hip & Knee)
A 22-year-old female sustains a high-energy Pauwels type III femoral neck fracture. To maximize biomechanical stability, what is the preferred fixation construct?
. Three parallel cancellous screws placed in an inverted triangle
. A sliding hip screw (SHS) with a derotation screw
. Two parallel cancellous screws
. Hemiarthroplasty
. Cementless total hip arthroplasty

Correct Answer & Explanation

. A sliding hip screw (SHS) with a derotation screw

Explanation

Pauwels type III fractures are highly unstable due to significant vertical shear forces. A fixed-angle device like a sliding hip screw provides superior biomechanical stability compared to multiple cancellous screws in these vertical fracture patterns.

Question 5068

Topic: 3. Adult Reconstruction (Hip & Knee)

A 50-year-old concert pianist presents with severe, debilitating pain and progressive instability at the base of her right thumb, significantly impacting her ability to play. Radiographs, as shown, confirm Eaton-Littler Stage IV carpometacarpal (CMC) joint arthritis with subluxation and severe joint space narrowing. Conservative management, including injections and splinting, has failed. Maintaining excellent pinch strength and range of motion is paramount for her profession.

Which surgical intervention is most appropriate for this patient?

. CMC joint arthrodesis
. Trapezial excision alone
. Ligament reconstruction and tendon interposition (LRTI) arthroplasty
. Osteotomy of the first metacarpal
. Implantation of a silicone arthroplasty

Correct Answer & Explanation

. CMC joint arthrodesis

Explanation

For advanced thumb CMC arthritis (Eaton-Littler Stage IV) in a demanding patient like a concert pianist where motion and strength are critical, ligament reconstruction and tendon interposition (LRTI) arthroplasty is generally considered the gold standard. This procedure involves excision of the trapezium (trapeziectomy) to remove the arthritic joint, followed by reconstruction of the basal thumb ligaments and interposition of a rolled-up portion of the flexor carpi radialis (FCR) tendon. This technique aims to maintain a pain-free, stable, and mobile joint. Arthrodesis provides stability but sacrifices motion, which is unacceptable for a pianist. Trapezial excision alone may lead to shortening and instability. Silicone arthroplasty has fallen out of favor due to potential complications like synovitis and loosening. Osteotomy is typically for early-stage arthritis or deformities.

Question 5069

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old active male undergoes a total hip arthroplasty using a ceramic-on-ceramic bearing. Two years later, he presents with a 'squeaking' sound coming from the hip with deep flexion activities. Radiographs show well-fixed components. What is the most likely etiology of this phenomenon?

. Edge loading due to component malposition
. Fracture of the ceramic liner
. Impingement of the iliopsoas tendon
. Trunnionosis at the head-neck junction
. Infection with gas-forming organisms

Correct Answer & Explanation

. Edge loading due to component malposition

Explanation

Squeaking in ceramic-on-ceramic total hip arthroplasty is most commonly associated with edge loading of the bearing surface. This can occur due to component malposition, specifically cup retroversion, steep inclination, or loss of fluid film lubrication. While liner fracture can cause a catastrophic failure and acute pain, squeaking in an asymptomatic, well-fixed hip usually correlates with edge loading.

Question 5070

Topic: 3. Adult Reconstruction (Hip & Knee)

During a posterior-stabilized total knee arthroplasty, the surgeon assesses the gaps with trial components. The knee has a symmetric extension gap that accepts a 10 mm spacer block perfectly. In flexion, the gap is asymmetric, being tight medially and loose laterally. Which of the following is the most appropriate next step in management?

. Externally rotate the femoral component
. Internally rotate the femoral component
. Release the medial collateral ligament (MCL)
. Resect more posterior medial femoral condyle
. Upsize the femoral component

Correct Answer & Explanation

. Externally rotate the femoral component

Explanation

In TKA, an asymmetric flexion gap that is tight medially and loose laterally with a symmetric extension gap is indicative of an internally rotated femoral component. To correct this, the femoral component should be externally rotated. External rotation of the femoral component moves the posterior medial condyle more anteriorly (decreasing the medial flexion gap tension) and the posterior lateral condyle more posteriorly (tightening the lateral flexion gap), thereby balancing the flexion space.

Question 5071

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the 2018 Evidence-Based Validated Definition for Periprosthetic Joint Infection, which of the following findings is considered a 'Major Criterion' sufficient for a definitive diagnosis of periprosthetic joint infection (PJI)?

. Positive alpha-defensin test
. Sinus tract communicating with the joint
. Elevated synovial fluid polymorphonuclear percentage (PMN%) > 80%
. Elevated serum C-reactive protein (CRP) > 10 mg/L
. A single positive intraoperative tissue culture

Correct Answer & Explanation

. Positive alpha-defensin test

Explanation

According to the 2018 ICM/MSIS criteria for PJI, there are two major criteria, either of which is definitive for infection: 1) Two positive periprosthetic cultures with phenotypically identical organisms, or 2) A sinus tract communicating with the joint. Alpha-defensin, elevated synovial PMN%, and elevated CRP are all minor criteria that contribute to a scoring system. A single positive tissue culture is also a minor criterion, except in cases of highly virulent organisms where it might strongly suspect infection, but formally it is minor.

Question 5072

Topic: Total Knee Arthroplasty (TKA)

A 55-year-old male presents with isolated medial compartment osteoarthritis of the right knee. He is being evaluated for a medial unicompartmental knee arthroplasty (UKA). Which of the following physical examination or radiographic findings is an absolute contraindication to a medial UKA?

. Chondrocalcinosis in the lateral compartment
. A flexion contracture of 10 degrees
. Absent anterior cruciate ligament (ACL) with subjective instability
. Body Mass Index (BMI) of 34 kg/m2
. Patellofemoral osteoarthritis isolated to the medial facet

Correct Answer & Explanation

. Chondrocalcinosis in the lateral compartment

Explanation

An intact ACL is generally considered a prerequisite for a standard medial UKA. An absent ACL with subjective instability or anterior subluxation of the tibia on a lateral radiograph is a contraindication because it leads to eccentric wear of the UKA components and early failure. A BMI < 35, mild patellofemoral arthritis (especially medial facet or asymptomatic), and a flexion contracture up to 15 degrees are generally acceptable. Chondrocalcinosis is no longer considered an absolute contraindication if the lateral cartilage is otherwise intact.

Question 5073

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female falls and sustains a periprosthetic femur fracture around her cementless total hip arthroplasty. Radiographs reveal a fracture extending just distal to the tip of the stem. The stem is radiographically loose, but there is excellent proximal and distal bone stock. According to the Vancouver classification, what is the fracture type and the recommended surgical treatment?

. Vancouver A; non-operative management with touch-down weight bearing
. Vancouver B1; open reduction and internal fixation with a lateral locking plate and cables
. Vancouver B2; revision to a long, fully porous or fluted tapered stem that bypasses the fracture
. Vancouver B3; open reduction internal fixation and proximal femoral replacement
. Vancouver C; open reduction and internal fixation

Correct Answer & Explanation

. Vancouver A; non-operative management with touch-down weight bearing

Explanation

The fracture is around or just distal to the stem (Type B). The stem is loose, but bone stock is good, which makes it a Vancouver B2 fracture. The gold standard treatment for a Vancouver B2 fracture is revision of the femoral component to a long stem (often cementless fluted tapered or fully porous) that bypasses the fracture by at least 2 cortical diameters, along with fracture fixation (e.g., cerclage cables) if necessary. Vancouver B1 involves a well-fixed stem (treated with ORIF). Vancouver B3 involves a loose stem with poor bone stock (often treated with proximal femoral replacement).

Question 5074

Topic: 3. Adult Reconstruction (Hip & Knee)
During a revision total hip arthroplasty, you encounter severe acetabular bone loss. Preoperative radiographs demonstrate up and in migration of the cup past Kohler's line, superior migration of 4 cm, and intraoperatively you note destruction of >60% of the acetabular rim, with independent movement of the superior and inferior hemipelvis. What is the most appropriate reconstructive option?
. Jumbo hemispherical multi-hole cementless cup
. Standard cementless cup with structural allograft
. Impaction bone grafting with a cemented polyethylene cup
. Custom triflange acetabular component or cup-cage construct
. Cementless cup with a high hip center

Correct Answer & Explanation

. Custom triflange acetabular component or cup-cage construct

Explanation

The description represents a Paprosky Type 3B defect with pelvic discontinuity (medial migration past Kohler's, >3cm superior migration, >50% rim absent, and independent movement of the hemipelvis). Such massive defects with pelvic discontinuity cannot be reliably treated with jumbo cups or isolated structural grafts due to lack of stable host bone contact. A custom triflange acetabular component, a cup-cage construct, or a pelvic distraction technique with a trabecular metal cup are the preferred options to achieve rigid fixation across the discontinuity.

Question 5075

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient presents with persistent anterior knee pain and a 'clunking' sensation 1 year following a primary total knee arthroplasty. On physical exam, the patella tracks laterally and there is tenderness over the lateral retinaculum. Radiographs and CT scan are obtained. Which of the following component malpositions is most likely responsible for lateral patellar maltracking?

. External rotation of the femoral component
. Internal rotation of the femoral component
. Lateral translation of the tibial tray
. External rotation of the tibial tray
. Excessive valgus alignment of the tibial resection

Correct Answer & Explanation

. External rotation of the femoral component

Explanation

Internal rotation of the femoral component medializes the trochlear groove, effectively increasing the Q-angle and causing the patella to track laterally. Other factors causing lateral maltracking include internal rotation of the tibial component (medializes the tibial tubercle), medial translation of the femoral component, and medial translation of the tibial component.

Question 5076

Topic: Total Knee Arthroplasty (TKA)

A surgeon is performing a primary TKA and decides to use the surgical epicondylar axis (SEA) to set the rotation of the femoral component. Which of the following best defines the SEA?

. A line connecting the most prominent point of the medial epicondyle to the most prominent point of the lateral epicondyle
. A line connecting the medial sulcus (sulcus of the medial epicondyle) to the lateral epicondylar prominence
. A line perpendicular to Whiteside's line
. A line parallel to the posterior condylar axis
. A line connecting the adductor tubercle to the lateral epicondyle

Correct Answer & Explanation

. A line connecting the most prominent point of the medial epicondyle to the most prominent point of the lateral epicondyle

Explanation

The Surgical Epicondylar Axis (SEA) is defined as the line connecting the sulcus of the medial epicondyle to the most prominent point of the lateral epicondyle. This axis more closely approximates the flexion-extension axis of the knee. The Clinical Epicondylar Axis (CEA) connects the most prominent points of both epicondyles and is typically internally rotated about 3 degrees relative to the SEA. Whiteside's line (the anteroposterior axis) is typically perpendicular to the SEA.

Question 5077

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old male presents with groin pain and a palpable mass 5 years after receiving a metal-on-polyethylene total hip arthroplasty with a large diameter modular cobalt-chromium head on a titanium stem. Serum cobalt levels are significantly elevated while chromium levels are mildly elevated. A metal artifact reduction sequence (MARS) MRI shows a cystic pseudotumor. What is the most likely diagnosis?

. Bearing surface wear
. Periprosthetic joint infection
. Trunnionosis (mechanically assisted crevice corrosion)
. Polyethylene hypersensitivity
. Acetabular loosening

Correct Answer & Explanation

. Bearing surface wear

Explanation

The patient is presenting with adverse local tissue reaction (ALTR) or ALVAL secondary to trunnionosis. Trunnionosis is mechanically assisted crevice corrosion that occurs at the modular head-neck junction. It is particularly associated with large-diameter metal heads (which increase torque at the trunnion) on titanium stems (mixed-alloy coupling). Serum metal ions typically show a higher cobalt-to-chromium ratio (often >2:1) compared to metal-on-metal bearing wear, which usually has roughly equal elevation of both ions.

Question 5078

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the classification of cementless femoral stems, a fully porous-coated cylindrical stem relies on which area for its primary mechanical fixation?

. Metaphyseal fit and fill
. Diaphyseal engagement (scratch fit)
. Proximomedial calcar loading
. Lateral flare loading
. Collar-calcar contact

Correct Answer & Explanation

. Metaphyseal fit and fill

Explanation

Fully porous-coated cylindrical stems (often considered Type 4 in some classifications) bypass the metaphysis and rely on diaphyseal engagement for their primary stability and long-term biologic fixation (osteointegration). The isthmus provides a 'scratch fit' which confers immediate mechanical stability, while the extensive porous coating allows for bone ingrowth. Proximally coated stems (wedge-shaped, Type 1 or 2) rely on metaphyseal fit and fill.

Question 5079

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old female presents 6 months post-total knee arthroplasty with an inability to actively extend her knee. Examination reveals a palpable defect at the superior pole of the patella. What is the most appropriate surgical reconstruction option for a chronic quadriceps tendon rupture following TKA with inadequate remaining tissue?

. Direct end-to-end repair using non-absorbable sutures
. V-Y quadricepsplasty
. Reconstruction with synthetic mesh (e.g., Marlex) or extensor mechanism allograft
. Patellectomy and advancement of the rectus femoris
. Hamstring autograft augmentation

Correct Answer & Explanation

. Direct end-to-end repair using non-absorbable sutures

Explanation

Chronic extensor mechanism disruption post-TKA is a devastating complication. Direct repair usually fails due to poor tissue quality and the mechanics of the joint. When tissue is inadequate, the current gold standard treatments involve either reconstruction using a synthetic mesh (like Marlex mesh, which allows for robust fibrous tissue ingrowth) or a full extensor mechanism allograft (tibial tubercle, patellar tendon, patella, and quad tendon). The mesh technique has shown increasingly favorable long-term results and avoids the disease transmission/resorption risks of allograft.

Question 5080

Topic: 3. Adult Reconstruction (Hip & Knee)
The wear rate of ultra-high molecular weight polyethylene (UHMWPE) in total hip arthroplasty has been significantly reduced by cross-linking. Which of the following manufacturing steps is required after gamma irradiation to prevent long-term oxidative degradation of the polyethylene?
. Sterilization in ethylene oxide
. Machining the bearing surface
. Remelting or annealing (thermal treatment)
. Adding vitamin C to the resin
. Irradiation in the presence of oxygen

Correct Answer & Explanation

. Remelting or annealing (thermal treatment)

Explanation

Gamma irradiation is used to cross-link UHMWPE, which improves wear resistance. However, irradiation creates free radicals within the polyethylene chains. If these free radicals are exposed to oxygen in vivo, they lead to oxidative degradation, embrittlement, and catastrophic failure of the plastic. To eliminate these free radicals, the polyethylene must undergo thermal treatment (either remelting or annealing) after irradiation, or an antioxidant (like Vitamin E) must be infused into the material.

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