Menu

3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 274 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 5461

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient with a metal-on-metal total hip arthroplasty presents with groin pain and a palpable mass. MRI reveals a large solid/cystic pseudotumor. Histological analysis of the periprosthetic tissue reveals a heavy perivascular lymphocytic infiltrate characterized predominantly by T-cells and macrophages. This adverse local tissue reaction (ALVAL) is an example of which type of immune response?
. Type I Hypersensitivity
. Type II Hypersensitivity
. Type III Hypersensitivity
. Type IV Hypersensitivity
. Innate immune hyperactivation

Correct Answer & Explanation

. Type IV Hypersensitivity

Explanation

Adverse local tissue reactions (ALTR) or Aseptic Lymphocytic Vasculitis-Associated Lesions (ALVAL) in metal-on-metal implants represent a Type IV (delayed-type, cell-mediated) hypersensitivity reaction. Metal ions act as haptens, activating T-lymphocytes which recruit macrophages and cause extensive tissue necrosis.

Question 5462

Topic: 3. Adult Reconstruction (Hip & Knee)
In total hip arthroplasty, aseptic loosening due to osteolysis is most commonly driven by a macrophage-mediated inflammatory response to which type of wear debris?
. Cobalt-chromium ions
. Titanium particles
. Polymethylmethacrylate particles
. Ultra-high-molecular-weight polyethylene particles
. Ceramic particles

Correct Answer & Explanation

. Ultra-high-molecular-weight polyethylene particles

Explanation

In total hip arthroplasty, the most common cause of aseptic loosening is particle disease (osteolysis). Ultra-high-molecular-weight polyethylene (UHMWPE) wear particles are phagocytosed by macrophages, initiating an inflammatory cascade. The macrophages release pro-inflammatory cytokines (such as TNF-alpha, IL-1, and IL-6), which stimulate osteoclast differentiation and activation via the RANKL pathway, leading to localized bone resorption.

Question 5463

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient presents with persistent groin pain, a large cystic mass, and local tissue necrosis 5 years after receiving a metal-on-metal total hip arthroplasty. Histopathology of the periprosthetic tissue reveals a perivascular lymphocytic infiltrate. This adverse local tissue reaction is best characterized as:
. Type I hypersensitivity
. Type II hypersensitivity
. Type III hypersensitivity
. Type IV hypersensitivity
. Foreign body granulomatous reaction

Correct Answer & Explanation

. Type IV hypersensitivity

Explanation

Adverse local tissue reaction (ALTR) or aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) is a complication of metal-on-metal total hip arthroplasties. It is driven by an immune reaction to cobalt and chromium wear debris. Histologically characterized by a perivascular lymphocytic infiltrate, this represents a delayed cell-mediated immune response, corresponding to a Type IV hypersensitivity reaction.

Question 5464

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient presents with an unexplained, painful skin rash and aseptic loosening of a total knee arthroplasty. Patch testing reveals a severe metal allergy. Which element in standard cobalt-chromium-molybdenum alloys is the most common cause of hypersensitivity reactions in joint arthroplasty?

. Cobalt
. Chromium
. Molybdenum
. Nickel
. Titanium

Correct Answer & Explanation

. Cobalt

Explanation

Nickel is the most common sensitizing metal in the general population. It is present as a trace element in cobalt-chromium and stainless steel orthopedic implants and can cause Type IV delayed hypersensitivity reactions.

Question 5465

Topic: 3. Adult Reconstruction (Hip & Knee)
What is the primary biologic cascade leading to aseptic loosening (osteolysis) in a metal-on-polyethylene total hip arthroplasty?
. Neutrophil-mediated acute inflammatory response
. Lymphocyte-mediated delayed hypersensitivity (Type IV) reaction
. Macrophage phagocytosis of particulate debris leading to cytokine release
. Direct toxic effect of cobalt and chromium ions on osteoblasts
. Complement activation via the alternative pathway

Correct Answer & Explanation

. Macrophage phagocytosis of particulate debris leading to cytokine release

Explanation

Aseptic loosening is primarily driven by ultra-high-molecular-weight polyethylene (UHMWPE) wear particles. Macrophages phagocytose these submicron particles and release pro-inflammatory cytokines (TNF-alpha, IL-1, IL-6), which stimulate osteoclastic bone resorption.

Question 5466

Topic: 3. Adult Reconstruction (Hip & Knee)

In total joint arthroplasty, the release of polyethylene debris due to microscopic irregularities on the metal articular surface scratching the polymer is an example of which type of wear?

. Adhesive wear
. Abrasive wear
. Third-body wear
. Fatigue wear
. Corrosive wear

Correct Answer & Explanation

. Adhesive wear

Explanation

Abrasive wear occurs when a harder surface (metal) plows into or scratches a softer surface (polyethylene) due to surface asperities. Adhesive wear involves the transfer of material from the softer to the harder surface.

Question 5467

Topic: 3. Adult Reconstruction (Hip & Knee)
In the mechanism of aseptic loosening following total joint arthroplasty, particulate polyethylene wear debris primarily stimulates which cell type to release osteolytic cytokines?
. Osteoblasts
. T-lymphocytes
. Macrophages
. Chondrocytes
. Polymorphonuclear leukocytes

Correct Answer & Explanation

. Macrophages

Explanation

Macrophages phagocytose ultra-high-molecular-weight polyethylene (UHMWPE) wear particles and subsequently release pro-inflammatory and osteolytic cytokines like TNF-alpha, IL-1, and IL-6. This cascade leads to osteoclast activation and periprosthetic osteolysis.

Question 5468

Topic: 3. Adult Reconstruction (Hip & Knee)

In a randomized controlled trial comparing two total knee arthroplasty designs, the investigators find no statistically significant difference in patient-reported outcome scores. However, a true difference exists in the general population. Which of the following defines this study outcome?

. Type I error
. Type II error
. Selection bias
. Observer bias
. Confounding variable error

Correct Answer & Explanation

. Type I error

Explanation

A Type II (beta) error occurs when a study fails to reject the null hypothesis when it is actually false (i.e., failing to detect a true difference, a 'false negative'). This often happens when a study is underpowered. A Type I (alpha) error is a 'false positive'—concluding there is a difference when one does not truly exist.

Question 5469

Topic: 3. Adult Reconstruction (Hip & Knee)

Alumina and zirconia are ceramic bearing surfaces utilized in total hip arthroplasty due to their excellent wear properties. Zirconia demonstrates higher fracture toughness than pure alumina through a mechanism known as 'transformation toughening'. This process involves a stress-induced phase transition from:

. Monoclinic to tetragonal phase
. Tetragonal to monoclinic phase
. Cubic to tetragonal phase
. Orthorhombic to monoclinic phase
. Tetragonal to cubic phase

Correct Answer & Explanation

. Monoclinic to tetragonal phase

Explanation

Transformation toughening in zirconia ceramics occurs when the stress field at the tip of an advancing microscopic crack triggers a phase transformation from the metastable tetragonal crystalline phase to the stable monoclinic phase. This transformation is accompanied by a 3-5% volume expansion, which creates compressive stresses that pinch the crack shut and halt its propagation.

Question 5470

Topic: 3. Adult Reconstruction (Hip & Knee)

In a well-functioning metal-on-polyethylene total hip arthroplasty, what is the primary mode of wear responsible for generating the submicron polyethylene debris that leads to macrophage-mediated osteolysis?

. Abrasive wear
. Adhesive wear
. Third-body wear
. Corrosive wear
. Fretting wear

Correct Answer & Explanation

. Abrasive wear

Explanation

Adhesive wear occurs as the asperities of the metal head temporarily bond to the polyethylene surface, tearing off submicron particles. It is the primary baseline wear mechanism in well-functioning metal-on-polyethylene bearings and is the main source of the critical submicron osteolytic particles.

Question 5471

Topic: 3. Adult Reconstruction (Hip & Knee)

Elastohydrodynamic lubrication is a primary mechanism in normal human articular joints. This type of lubrication relies on which of the following physical principles?

. Direct physical contact of opposing asperities
. Glycoprotein binding to the articular surface
. Deformation of the bearing surfaces under load
. Chemical bonds forming between synovial fluid and collagen
. A rigid gap maintained by a pressurized fluid alone

Correct Answer & Explanation

. Direct physical contact of opposing asperities

Explanation

Elastohydrodynamic lubrication occurs when the pressure of the fluid film separating the joint surfaces causes elastic deformation of the articular cartilage. This deformation increases the surface area, decreasing local stress and helping maintain the fluid film.

Question 5472

Topic: 3. Adult Reconstruction (Hip & Knee)

In total hip arthroplasty, ceramic-on-ceramic bearings offer the lowest wear rates. However, they carry a specific risk associated with their physical properties. Which characteristic best describes alumina ceramics?

. High ductility and high fracture toughness
. Low scratch resistance and high elasticity
. High compressive strength and low fracture toughness
. High tensile strength and high plastic deformation
. Low wettability and high yield strength

Correct Answer & Explanation

. High ductility and high fracture toughness

Explanation

Ceramics like alumina have excellent compressive strength and scratch resistance, leading to very low wear rates. However, they are extremely brittle, possessing low fracture toughness and tensile strength, predisposing them to catastrophic fracture.

Question 5473

Topic: 3. Adult Reconstruction (Hip & Knee)

In an obese patient undergoing unicondylar knee arthroplasty (UKA):

. The results are worse than in a normal weight patient.
. The results are better than in a normal weight patient.
. The results are not predictably better or worse.
. The results depend on the design of the prosthesis.
. Results are gender dependent.

Correct Answer & Explanation

. The results are worse than in a normal weight patient.

Explanation

The knee should have less than 15° of deformity in varus or valgus and less than 10° flexion contracture. Inflammatory or crystalline-induced arthritis, knee subluxation, gross ligamentous laxity, and obesity are relative contraindications to the procedure. Scott and colleagues found that increased body weight contributed to failure in UKA and suggested that the best candidates are less than 180 lb

Question 5474

Topic: 3. Adult Reconstruction (Hip & Knee)

A 40-year-old man who is a manual laborer has had 3 years of worsening medial-sided left knee pain that

has inhibited his ability to work. He reports undergoing a left subtotal medial meniscectomy 10 years ago. He has been treated with nonsteroidal anti-inflammatory drugs and two different corticosteroids, with the most recent injection given 1 month ago. Each injection provided him with a few weeks of pain control. His medical history is unremarkable, and he has smoked 20 cigarettes per day for the last 15 years. His BMI is 22. On examination, he has varus alignment of the involved leg and medial joint line tenderness and no lateral or patellofemoral pain. His knee range of motion is 3° shy of full extension to 130° of flexion. He has negative Lachman and posterior drawer test results. He demonstrates no lateral thrust with ambulation. The patient is provided with a medial unloader brace that provides substantial pain relief, and he is able to work while wearing the brace. After 4 months, he returns to work and reports that while the brace enables him to work, it is uncomfortable. Consequently, his symptoms return when he is not wearing the brace, and he is requesting a surgical intervention for his problem. What is the most appropriate surgical treatment?

. Valgus-producing high tibial osteotomy (VPHTO)
. Repeat knee arthroscopy
. Total knee arthroplasty (TKA)
. Medial meniscus transplant

Correct Answer & Explanation

. Valgus-producing high tibial osteotomy (VPHTO)

Explanation

This patient has a classic presentation of postmeniscectomy medial compartment arthritis. The appropriate diagnostic study is weight-bearing radiographs to confirm the diagnosis. An MRI scan will reveal medial compartment arthritis but will not provide information about alignment. A CT scan would be appropriate to detect an occult fracture; however, this condition is not suspected in this clinical scenario. Ultrasonography can provide information about fluid collection around the knee or a deep vein thrombosis; however, these conditions also are not suspected in this clinical scenario. Because the patient has a correctable deformity (gaps 3 mm with valgus stress), and his symptoms are localized to the involved compartment, a trial of a medial unloader brace is appropriate both diagnostically and therapeutically. If unloading the medial compartment resolves the patient’s symptoms, he would be an excellent candidate for an osteotomy. An MRI scan may be obtained to evaluate ligamentous integrity or to evaluate degenerative involvement of the lateral and patellofemoral compartment for presurgical planning of an osteotomy; however, the integrity of the medial meniscus has no clinical importance in a patient with severe medial compartment arthritis. A repeat corticosteroid injection is not indicated within 1 month of his last injection, and referral to pain management is not appropriate with other options available to help this patient. A VPHTO is the appropriate intervention considering the patient’s young age, high-functional occupation, examination, radiographic findings, and response to medial unloader bracing. A revision knee arthroscopy would be appropriate for a recurrent medial meniscus tear, but not appropriate in a patient with severe medial compartment arthritis. The patient’s young age and high functional requirements are contraindications to TKA. The presence of severe arthritis is a contraindication to medial meniscus transplant. The patient is a candidate for a VPHTO. The technical options include a medial opening-wedge or a lateral closing-wedge osteotomy. Both techniques have advantages and disadvantages; however, a medial opening-wedge osteotomy is contraindicated in a smoker because of concern for nonunion. As a result, current smoking history is the only factor listed that would influence the technique used. The history of prior arthroscopy has no relevance in the decision about which type of osteotomy is appropriate. Normal BMI is between 18.5 and 24.9, so this patient’s BMI is considered normal and would not affect the surgical technique (if this patient were obese, a lateral closing-wedge osteotomy would be considered, but this is controversial). His age of 40 years is an indication for HTO but does not influence technique.

Question 5475

Topic: 3. Adult Reconstruction (Hip & Knee)

aOne year after undergoing a primary total knee arthroplasty, a 65-year-old man has a 1-week history of new onset anterior knee pain. He can perform a straight-leg raise with no extension lag. Radiographs reveal a transverse patella fracture with 8 mm of displacement and an intact patellar component. The best course of treatment is

. patellectomy with retinacular repair.
. immobilization in extension for 6 weeks.
. open reduction and cerclage wiring.
. internal fixation and patellar component revision.

Correct Answer & Explanation

. patellectomy with retinacular repair.

Explanation

This patient has a displaced periprosthetic patella fracture with an intact extensor mechanism. Surgical treatment for this condition has been associated with relatively poor clinical results because the fracture occurs late (attributable to patella osteonecrosis). The optimal initial treatment is to treat the fracture nonsurgically with immobilization of the knee in extension either with a long-leg cast or knee immobilizer.18

Question 5476

Topic: 3. Adult Reconstruction (Hip & Knee)
If the culture results are positive, which treatment will most likely resolve the infection?
. Arthroscopic debridement
. Intravenous antibiotics
. Single-stage revision
. Double-stage revision

Correct Answer & Explanation

. Double-stage revision

Explanation

Osteolysis of this magnitude is uncommon in the setting of an uncemented hemiarthroplasty. Further workup for infection is indicated. Intravenous antibiotics can be used for suppression, but the best results in terms of resolving the infection would be achieved with 2-stage revision.

Question 5477

Topic: 3. Adult Reconstruction (Hip & Knee)

The risk of nerve injury following revision total hip arthroplasty (THA) is approximately:

. 5%
. 1%
. 1% to 10%
. 10% to 20%
. More than 20%

Correct Answer & Explanation

. 5%

Explanation

Following primary THA, the incidence of nerve palsy is reported to be approximately 1.3%, but may be as high as 5.2% for primary THA performed for developmental dysplasia or dislocation. For revision surgery, the incidence may be as high as7.60%

Question 5478

Topic: 3. Adult Reconstruction (Hip & Knee)
What is the most common cause of reoperation following contemporary hip resurfacing for degenerative coxarthrosis?
. Limb-length discrepancy
. Altered femoral offset
. Snapping psoas tendon
. Limitation of hip movement
. Femoral neck fracture

Correct Answer & Explanation

. Femoral neck fracture

Explanation

Femoral neck fracture, necessitating revision surgery to a total hip arthroplasty, is the most likely common early complication after hip resurfacing. Cortical notching, varus positioning, and other technical variables appear to predispose to this complication.

Question 5479

Topic: 3. Adult Reconstruction (Hip & Knee)
When compared with a conventional ultra-high molecular weight polyethylene (UHMWPE) bearing surface in total hip arthroplasty, a highly cross-linked polyethylene (XLPE) bearing surface is associated with:
. significantly reduced wear and greater mid-term implant survival.
. increased wear and increased fracture rate of the liner.
. decreased mid-term implant survival when compared with UHMWPE.
. reduced wear, but increased osteolysis.

Correct Answer & Explanation

. significantly reduced wear and greater mid-term implant survival.

Explanation

XLPE was developed to address the problem of wear and osteolysis associated with conventional UHMWPE-bearing surfaces. Data have shown, with randomized controlled trials, that XLPE liners have significantly reduced wear and are associated with greater implant survival at 10 years compared with UHMWPE-bearing surfaces.

Question 5480

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the most well-documented advantage of computer-assisted navigation for total knee arthroplasty (TKA)?

. Lowers risk for symptomatic fat embolization
. Improves range of motion
. Decreases radiographic outliers
. Decreases blood loss

Correct Answer & Explanation

. Lowers risk for symptomatic fat embolization

Explanation

Studies of patients following TKA utilizing navigation have failed to show a significant difference in the degree of fat embolization or changes in cognition compared to standard instrumentation. Clinical results also have not changed following TKA with and without navigation in terms of range of motion or blood loss. Most studies do show a decreased incidence of radiographic outliers, however, at least in the coronal plane.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page