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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 207 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 4121

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male with a history of a bimalleolar ankle fracture 20 years ago presents with severe ankle pain. Radiographs reveal end-stage ankle osteoarthritis with 5 degrees of valgus deformity. He has no significant medical comorbidities. Which of the following is an absolute or strong relative contraindication to total ankle arthroplasty (TAA) in this patient?

. Age greater than 65 years
. Previous open reduction and internal fixation of the ankle
. Post-traumatic etiology of osteoarthritis
. History of a deep infection in the ipsilateral ankle joint 15 years ago
. Valgus deformity of 5 degrees

Correct Answer & Explanation

. History of a deep infection in the ipsilateral ankle joint 15 years ago

Explanation

A history of deep intra-articular infection is a strict relative (and in most cases absolute) contraindication for total ankle arthroplasty due to the unacceptable risk of catastrophic periprosthetic joint infection. Post-traumatic etiology and mild coronal deformity (<10 degrees) are acceptable indications for TAA.

Question 4122

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male with end-stage post-traumatic ankle arthritis has severe pain. He is an avid golfer and walker. Examination reveals a well-aligned hindfoot and functional adjacent joints. He has no history of infection or severe neuropathy. Which of the following is an absolute contraindication to total ankle arthroplasty (TAA)?

. Advanced patient age
. Avascular necrosis of >50% of the talar body
. Previous hardware in the distal tibia
. End-stage subtalar arthritis
. Obesity (BMI > 30)

Correct Answer & Explanation

. Avascular necrosis of >50% of the talar body

Explanation

Significant avascular necrosis (typically >50%) of the talar body compromises the bony support required for the talar component. This makes it an absolute contraindication to total ankle arthroplasty due to high risk of implant subsidence.

Question 4123

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male with primary glenohumeral osteoarthritis undergoes surgical planning for a total shoulder arthroplasty. A preoperative CT scan demonstrates a Walch B2 glenoid with 20 degrees of retroversion and biconcave posterior wear. If a standard anatomic polyethylene glenoid component is implanted without correcting the version, what is the most likely mechanism of early component failure?

. Polyethylene melting from increased friction
. Anterior instability due to overtightening of the subscapularis
. Early loosening secondary to eccentric posterior loading and the 'rocking horse' phenomenon
. Superior migration of the humeral head
. Iatrogenic fracture of the coracoid process

Correct Answer & Explanation

. Early loosening secondary to eccentric posterior loading and the 'rocking horse' phenomenon

Explanation

A Walch B2 glenoid is characterized by posterior subluxation of the humeral head and biconcave wear. Failing to correct the severe retroversion leads to eccentric posterior loading on the new glenoid component, causing a 'rocking horse' effect and subsequent early aseptic loosening.

Question 4124

Topic: 3. Adult Reconstruction (Hip & Knee)

According to Hertel's criteria, which of the following is the strongest predictor of ischemia and subsequent avascular necrosis following a proximal humerus fracture?

. Metaphyseal head extension less than 8 mm
. Greater tuberosity displacement greater than 5 mm
. Lesser tuberosity displacement
. Varus angulation greater than 20 degrees
. Shortening of the surgical neck

Correct Answer & Explanation

. Metaphyseal head extension less than 8 mm

Explanation

Hertel identified a short calcar length (metaphyseal extension < 8 mm) and disruption of the medial hinge as the strongest predictors of ischemia and avascular necrosis of the humeral head.

Question 4125

Topic: 3. Adult Reconstruction (Hip & Knee)

A 25-year-old male weightlifter complains of superior shoulder pain exacerbated by the bench press and push-ups. He has localized tenderness over the AC joint. Radiographs show subchondral cystic changes and widening of the AC joint. What is the most appropriate initial management?

. Arthroscopic distal clavicle excision
. Open distal clavicle excision
. Activity modification, NSAIDs, and a corticosteroid injection
. Coracoclavicular ligament reconstruction
. Acromioplasty

Correct Answer & Explanation

. Activity modification, NSAIDs, and a corticosteroid injection

Explanation

The clinical presentation is consistent with distal clavicle osteolysis, a common finding in weightlifters. Initial treatment is nonoperative with activity modification and injections. Distal clavicle excision is reserved for refractory cases.

Question 4126

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following organisms is a gram-positive, anaerobic rod that is a frequent cause of delayed periprosthetic joint infection in shoulder arthroplasty?

. Staphylococcus epidermidis
. Cutibacterium (Propionibacterium) acnes
. Streptococcus pyogenes
. Pseudomonas aeruginosa
. Enterococcus faecalis

Correct Answer & Explanation

. Cutibacterium (Propionibacterium) acnes

Explanation

Cutibacterium acnes is a gram-positive, slow-growing anaerobic rod naturally found in the sebaceous glands of the shoulder and chest. It is a leading cause of indolent periprosthetic joint infections in shoulder arthroplasty.

Question 4127

Topic: Total Hip Arthroplasty (THA)

A 45-year-old highly active patient requires a total hip arthroplasty. A ceramic-on-ceramic bearing couple is selected. Compared to a traditional metal-on-polyethylene bearing, what is the primary tribological advantage of the ceramic-on-ceramic articulation?

. Elimination of the risk of catastrophic component fracture
. Lower resistance to third-body wear
. Lowest volumetric wear rate among bearing couples
. Increased tolerance to edge-loading and component malposition
. Generation of osteoinductive wear debris

Correct Answer & Explanation

. Lowest volumetric wear rate among bearing couples

Explanation

Ceramic-on-ceramic bearings exhibit the lowest volumetric wear rate due to their extreme hardness, high scratch resistance, and excellent fluid film lubrication. However, they are sensitive to malposition (edge-loading), squeaking, and have a risk of brittle fracture.

Question 4128

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient develops a chronic periprosthetic joint infection (PJI) three years after total knee arthroplasty. Cultures yield a coagulase-negative organism. Which of the following bacteria is most notorious for evading host defenses by producing a robust polysaccharide glycocalyx biofilm on the implant?

. Streptococcus pyogenes
. Staphylococcus epidermidis
. Escherichia coli
. Pseudomonas aeruginosa
. Cutibacterium acnes

Correct Answer & Explanation

. Staphylococcus epidermidis

Explanation

Staphylococcus epidermidis is a ubiquitous skin commensal that is highly adept at colonizing foreign bodies. Its primary virulence factor in orthopedic infections is the production of a thick exopolysaccharide biofilm that severely limits antibiotic penetration.

Question 4129

Topic: 3. Adult Reconstruction (Hip & Knee)

Aseptic loosening is the most common cause of long-term total hip arthroplasty failure. The classic osteolysis seen in this condition is predominantly initiated by the activation of which of the following cell types in response to wear debris?

. Osteoblasts
. Fibroblasts
. Macrophages
. T-lymphocytes
. Neutrophils

Correct Answer & Explanation

. Macrophages

Explanation

Particulate wear debris (commonly polyethylene) is phagocytosed by macrophages. This activates the macrophages to release pro-inflammatory cytokines, driving RANKL-mediated osteoclastogenesis and periprosthetic osteolysis.

Question 4130

Topic: 3. Adult Reconstruction (Hip & Knee)
A researcher is evaluating the mechanical properties of different materials used in total hip arthroplasty. Increasing the radiation dose during the cross-linking process of ultra-high-molecular-weight polyethylene (UHMWPE) has which of the following effects?
. Increases wear resistance and decreases fatigue strength
. Increases both wear resistance and fatigue strength
. Decreases wear resistance and increases fatigue strength
. Decreases both wear resistance and fatigue strength
. Has no effect on wear resistance but increases fatigue strength

Correct Answer & Explanation

. Increases wear resistance and decreases fatigue strength

Explanation

Highly cross-linking UHMWPE significantly improves its wear resistance, reducing the risk of osteolysis. However, the cross-linking process reduces the material's fatigue strength and toughness.

Question 4131

Topic: 3. Adult Reconstruction (Hip & Knee)
Adverse local tissue reaction (ALTR) or aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) following metal-on-metal hip arthroplasty is primarily mediated by which type of hypersensitivity reaction?
. Type I (IgE-mediated)
. Type II (Cytotoxic)
. Type III (Immune complex)
. Type IV (Delayed cell-mediated)
. Type V (Stimulatory)

Correct Answer & Explanation

. Type IV (Delayed cell-mediated)

Explanation

ALVAL is an adverse host immune response to metal wear debris that behaves as a Type IV delayed, cell-mediated hypersensitivity reaction. Histologically, it is characterized by a dense perivascular infiltration of T-lymphocytes and macrophages.

Question 4132

Topic: 3. Adult Reconstruction (Hip & Knee)
Aseptic loosening is a major cause of failure in total hip arthroplasty. This process is most commonly driven by macrophage phagocytosis of which specific type of wear debris?
. Cobalt-chromium particles
. Titanium alloy particles
. Polymethylmethacrylate (PMMA) cement
. Ultra-high-molecular-weight polyethylene (UHMWPE) particles
. Ceramic debris

Correct Answer & Explanation

. Ultra-high-molecular-weight polyethylene (UHMWPE) particles

Explanation

UHMWPE wear debris generated at the articulating bearing surface is phagocytosed by macrophages. This triggers an inflammatory cascade releasing TNF-alpha and IL-6, which activates osteoclasts via RANKL to cause periprosthetic osteolysis.

Question 4133

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old man undergoes a total hip arthroplasty utilizing a highly cross-linked polyethylene liner.

Which of the following manufacturing steps is most responsible for enhancing the wear resistance of this bearing surface?

. Gamma or electron beam irradiation followed by thermal treatment
. Ethylene oxide gas sterilization
. Incorporation of unreacted free radicals
. Decreasing the femoral head size to increase liner thickness
. Eliminating vitamin E from the polymer matrix

Correct Answer & Explanation

. Gamma or electron beam irradiation followed by thermal treatment

Explanation

Highly cross-linked polyethylene is manufactured by exposing the material to gamma or electron beam irradiation, which creates cross-links that drastically reduce adhesive and abrasive wear. Subsequent thermal treatment (melting or annealing) eliminates residual free radicals to prevent oxidation.

Question 4134

Topic: Total Hip Arthroplasty (THA)

During a posterior approach to the hip, preserving the insertion of which of the following muscles protects the deep branch of the medial femoral circumflex artery (MFCA)?

. Piriformis
. Superior gemellus
. Obturator internus
. Obturator externus
. Quadratus femoris

Correct Answer & Explanation

. Obturator externus

Explanation

The deep branch of the MFCA courses posteriorly between the quadratus femoris and obturator externus. Maintaining the obturator externus tendon intact protects the artery from iatrogenic injury during a posterior approach.

Question 4135

Topic: 3. Adult Reconstruction (Hip & Knee)

The proximal pole of the scaphoid is highly susceptible to avascular necrosis following a fracture due to its retrograde blood supply. The primary vascular contribution enters the scaphoid at which of the following locations?

. Volar distal pole
. Volar proximal pole
. Dorsal ridge of the scaphoid waist
. Scaphotrapezial joint capsule
. Scapholunate interosseous ligament

Correct Answer & Explanation

. Dorsal ridge of the scaphoid waist

Explanation

The primary blood supply to the scaphoid is derived from the dorsal carpal branch of the radial artery, which enters the bone at the dorsal ridge of the scaphoid waist. The blood flows in a retrograde fashion to supply the proximal pole.

Question 4136

Topic: Total Hip Arthroplasty (THA)

A surgeon is performing a posterior approach to the popliteal fossa. Which of the following structures is located most deeply (closest to the joint capsule)?

. Tibial nerve
. Common peroneal nerve
. Popliteal vein
. Popliteal artery
. Small saphenous vein

Correct Answer & Explanation

. Popliteal artery

Explanation

From superficial to deep, the structures in the popliteal fossa are the tibial nerve, popliteal vein, and popliteal artery. The popliteal artery lies deepest, resting directly against the posterior aspect of the femur and knee joint capsule.

Question 4137

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following accurately describes the primary blood supply to the scaphoid, predisposing its proximal pole to avascular necrosis following a fracture?

. Branches of the ulnar artery entering volar-distal
. Branches of the radial artery entering volar-proximal
. Branches of the radial artery entering dorsal-distal
. Branches of the anterior interosseous artery entering dorsal-proximal
. Branches of the deep palmar arch entering volar-distal

Correct Answer & Explanation

. Branches of the radial artery entering dorsal-distal

Explanation

The primary blood supply to the scaphoid is retrograde, originating from the radial artery and entering the dorsal ridge distally. This retrograde vascular flow puts the proximal pole at high risk for avascular necrosis following a fracture.

Question 4138

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient presents with groin pain exacerbated by resisted hip flexion following a total hip arthroplasty. If an oversized acetabular component is impinging on a soft tissue structure anteriorly, which structure is most likely involved?

. Obturator externus
. Iliopsoas tendon
. Rectus femoris
. Sartorius
. Pectineus

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

Anterior overhang of an acetabular cup can cause direct impingement and secondary tendinitis of the iliopsoas tendon. This typically presents as groin pain that is reproducibly exacerbated by active, resisted hip flexion.

Question 4139

Topic: Total Hip Arthroplasty (THA)

To avoid injury to the medial femoral circumflex artery (MFCA) during a posterior approach to the hip, an essential anatomical landmark is the superior border of which muscle?

. Piriformis
. Obturator internus
. Quadratus femoris
. Gluteus medius
. Superior gemellus

Correct Answer & Explanation

. Quadratus femoris

Explanation

The ascending branch of the MFCA courses posteriorly between the superior border of the quadratus femoris and the inferior gemellus. Preserving the superior portion of the quadratus femoris tendon during a posterior approach helps protect this critical blood supply to the femoral head.

Question 4140

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient undergoes total hip arthroplasty via a posterior approach. To preserve the primary blood supply to the femoral head in joint-preserving surgery, the surgeon must protect the deep branch of the medial femoral circumflex artery (MFCA). Where does this vessel anatomically course?

. Between the pectineus and iliopsoas muscles
. Superficial to the quadratus femoris and deep to the inferior gemellus
. Deep to the quadratus femoris and posterior to the obturator externus
. Anterior to the hip capsule and deep to the rectus femoris
. Through the ligamentum teres directly from the obturator artery

Correct Answer & Explanation

. Deep to the quadratus femoris and posterior to the obturator externus

Explanation

The deep branch of the MFCA runs deep to the quadratus femoris and posterior to the obturator externus. Protecting the obturator externus tendon during posterior hip approaches helps protect this critical vessel.

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