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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 35 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 681

Topic: 3. Adult Reconstruction (Hip & Knee)

The patient has extensive bone loss, concerns about collateral ligament integrity, and calcified soft tissues. The surgeon is planning a single-stage revision.

. Exclusive use of a standard primary total knee arthroplasty system.
. Prioritizing a minimally invasive approach to reduce soft tissue dissection.
. Meticulous soft tissue management and careful consideration of wound closure due to calcification.
. Avoiding the use of stemmed components to preserve future revision options.
. Relying solely on cement fixation for all components to ensure immediate stability.

Correct Answer & Explanation

. Meticulous soft tissue management and careful consideration of wound closure due to calcification.

Explanation

Correct Answer: CThe candidate in the case explicitly states, "The soft tissues appear contracted and calcified which may lead to wound complications." This highlights a critical concern for revision surgery, where soft tissue quality is often compromised. Meticulous soft tissue management, including careful dissection, debridement, and thoughtful wound closure techniques, is essential to minimize the risk of wound complications, infection, and skin necrosis. A standard primary TKA system would be inadequate for extensive bone loss and ligamentous instability. A minimally invasive approach is generally not suitable for complex revisions with significant bone loss and soft tissue issues. Avoiding stemmed components would compromise stability and fixation in the presence of extensive bone loss. Relying solely on cement fixation might not be sufficient for severe bone defects, especially in a young patient where bone ingrowth is desired for long-term stability.

Question 682

Topic: Total Knee Arthroplasty (TKA)

The patient is described as "reasonably young" with extensive bone loss, and the examiner emphasizes the importance of long-term planning.

. Achieving the highest possible range of motion regardless of bone stock.
. Minimizing the cost of the implants used in the revision.
. Preserving and restoring bone stock to facilitate potential future revisions.
. Ensuring the shortest possible hospital stay.
. Utilizing a rotating hinge knee (RHK) prosthesis in all cases of extensive bone loss.

Correct Answer & Explanation

. Preserving and restoring bone stock to facilitate potential future revisions.

Explanation

Correct Answer: CThe case explicitly states, "In this patient who is reasonably young restoration of bone stock is preferable, because of likelihood of further revision surgery." For younger patients, the expectation of a longer lifespan means a higher probability of requiring additional revision surgeries in the future. Therefore, the primary long-term goal in the current revision is to preserve and, if possible, restore the existing bone stock. This approach ensures that there is adequate bone available for subsequent procedures, making future revisions technically feasible and potentially more successful. While range of motion, cost, and hospital stay are important, they are secondary to the fundamental goal of bone stock management in a young patient with extensive defects. An RHK is not indicated in all cases of extensive bone loss; the choice depends on the specific type of instability and bone defect.

Question 683

Topic: 3. Adult Reconstruction (Hip & Knee)

In revision total knee arthroplasty, restoring the joint line is critical for proper kinematics. Which of the following landmarks is most accurate for estimating the anatomic joint line?

. 10 mm distal to the medial epicondyle
. 15 mm distal to the lateral epicondyle
. 15 mm proximal to the tip of the fibular head
. 30 mm distal to the adductor tubercle
. 10 mm proximal to the tibial tubercle

Correct Answer & Explanation

. 15 mm proximal to the tip of the fibular head

Explanation

The anatomic joint line is typically located approximately 15 mm proximal to the tip of the fibular head. It is also roughly 25-30 mm distal to the medial epicondyle and 10 mm proximal to the inferior pole of the patella.

Question 684

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female undergoes revision TKA for aseptic loosening. Intraoperatively, the surgeon notes complete incompetence of the medial collateral ligament (MCL). Which of the following constraint levels is definitively indicated?

. Posterior stabilized (PS)
. Cruciate retaining (CR)
. Constrained condylar knee (CCK)
. Rotating hinge
. Unicompartmental knee

Correct Answer & Explanation

. Rotating hinge

Explanation

A rotating hinge implant is indicated when there is global instability or complete deficiency of the medial collateral ligament. CCK implants, while providing varus/valgus stability, require an intact and functional MCL to prevent premature failure.

Question 685

Topic: Total Knee Arthroplasty (TKA)
According to the Anderson Orthopaedic Research Institute (AORI) classification, what characterizes a Type III bone defect in revision TKA?
. Intact metaphyseal bone with minor articular defects
. Cancellous bone loss with intact cortices
. Deficient metaphyseal segment requiring structural graft or custom implants
. Extensive diaphyseal cortical bone loss without metaphyseal involvement
. Asymmetric condylar loss manageable with cement alone

Correct Answer & Explanation

. Deficient metaphyseal segment requiring structural graft or custom implants

Explanation

AORI Type III defects involve severe bone loss comprising a major portion of the condyles or plateau, compromising the entire metaphyseal segment. They typically require structural allograft, metaphyseal cones/sleeves, or a hinge prosthesis for stable fixation.

Question 686

Topic: Total Knee Arthroplasty (TKA)

During a revision TKA, the surgeon notes that the flexion gap is extremely tight, but the extension gap is perfectly balanced. Which of the following is the most appropriate corrective step?

. Downsize the femoral component
. Increase the femoral component size
. Resect more proximal tibia
. Downsize the polyethylene insert
. Use a thicker polyethylene insert

Correct Answer & Explanation

. Downsize the femoral component

Explanation

A tight flexion gap with a balanced extension gap is managed by reducing the anteroposterior (AP) dimension of the femur. Downsizing the femoral component achieves this without altering the distal cut or the extension gap.

Question 687

Topic: Total Knee Arthroplasty (TKA)

In revision TKA, long diaphyseal engaging stems are frequently used to achieve stable implant fixation. According to the zonal fixation concept, in which zone do these stems primarily function?

. Zone 1
. Zone 2
. Zone 3
. Zone 4
. Zone 5

Correct Answer & Explanation

. Zone 4

Explanation

The zonal fixation classification for revision TKA divides the bone into the joint surface/epiphysis (Zone 1), the metaphysis (Zone 2), and the diaphysis (Zone 3). Engaging stems primarily achieve robust fixation in Zone 3.

Question 688

Topic: Total Knee Arthroplasty (TKA)

A patient presents with a chronic patellar tendon rupture 3 years after a primary TKA, demonstrating an active extension lag of 40 degrees. What is currently considered the most reliable surgical reconstruction method?

. Primary end-to-end repair
. Hamstring autograft reconstruction
. Synthetic mesh (Marlex) reconstruction
. Achilles tendon allograft without bone block
. Patellar component excision

Correct Answer & Explanation

. Synthetic mesh (Marlex) reconstruction

Explanation

Synthetic mesh (e.g., Marlex) reconstruction has become the preferred and most reliable method for treating chronic extensor mechanism disruption post-TKA. It demonstrates superior early tensioning and lower failure rates compared to traditional whole extensor mechanism allografts.

Question 689

Topic: 3. Adult Reconstruction (Hip & Knee)

When extracting a well-fixed cementless porous-coated femoral component during a revision TKA, which technique is most highly recommended to minimize catastrophic femoral bone loss?

. Aggressive levering with broad osteotomes
. Immediate splitting of the femoral condyles
. Use of a Gigli saw or flexible osteotomes along the bone-implant interface
. Sectioning the component with a high-speed burr in all cases
. Application of extreme rotational torque using a wrench

Correct Answer & Explanation

. Use of a Gigli saw or flexible osteotomes along the bone-implant interface

Explanation

Flexible osteotomes, oscillating saws, and Gigli saws must be used to carefully disrupt the biologic bone-implant interface. This minimizes host bone loss and avoids iatrogenic condylar fractures that easily occur with forceful levering or torqueing.

Question 690

Topic: Total Knee Arthroplasty (TKA)

A patient requires a revision TKA with significant uncontained metaphyseal bone defects but an intact diaphysis. The surgeon opts for highly porous tantalum cones. What is the primary biomechanical and biologic advantage of these cones in this setting?

. They provide immediate load-bearing support and potential for long-term biologic fixation
. They completely eliminate the need for diaphyseal engaging stems
. They restore the articular joint line directly without augments
. They act as a primary antibiotic delivery system
. They completely bypass Zone 2 fixation to rely on Zone 3

Correct Answer & Explanation

. They provide immediate load-bearing support and potential for long-term biologic fixation

Explanation

Porous tantalum cones fill large, uncontained metaphyseal defects (Zone 2) and provide immediate structural support. Their highly porous, trabecular metal surface allows for robust biologic osseointegration, ensuring long-term stable fixation.

Question 691

Topic: 3. Adult Reconstruction (Hip & Knee)

During a revision total knee arthroplasty, the surgeon inadvertently elevates the joint line by 12 mm while attempting to balance the flexion and extension gaps. Which of the following is the most likely clinical consequence of this technical error?

. Patella alta and extension instability
. Pseudo-patella baja and mid-flexion instability
. True patella baja and recurvatum
. Decreased patellofemoral contact forces
. Improved maximal knee flexion

Correct Answer & Explanation

. Pseudo-patella baja and mid-flexion instability

Explanation

Elevating the joint line in TKA leads to pseudo-patella baja (the patella is lower relative to the joint line) and often results in mid-flexion instability. Restoration of the native joint line is critical for proper extensor mechanism function and ligamentous tension throughout the arc of motion.

Question 692

Topic: Total Knee Arthroplasty (TKA)
A 71-year-old patient presents with a painful, loose primary total knee arthroplasty. Intraoperatively, the surgeon notes AORI Type III bone loss on both the femur and tibia, with complete incompetence of the medial collateral ligament. Which of the following implant constraints is most appropriate?
. Posterior stabilized (PS)
. Cruciate retaining (CR)
. Constrained condylar knee (CCK)
. Rotating hinge
. Unicompartmental knee

Correct Answer & Explanation

. Rotating hinge

Explanation

A rotating hinge prosthesis is indicated for profound collateral ligament incompetence (especially the MCL) combined with severe bone loss. A CCK device relies on an intact, though potentially attenuated, MCL to prevent post fracture and dislocation.

Question 693

Topic: 3. Adult Reconstruction (Hip & Knee)

In two-stage revision total knee arthroplasty for periprosthetic joint infection, an articulating spacer is generally preferred over a static spacer. However, which of the following is an absolute indication for using a static spacer instead?

. AORI Type I bone loss
. Intact extensor mechanism
. Severe extensor mechanism deficiency with massive bone loss
. Patient age greater than 70 years
. Infection with Staphylococcus epidermidis

Correct Answer & Explanation

. Severe extensor mechanism deficiency with massive bone loss

Explanation

Static spacers are indicated when there is severe soft tissue compromise, such as an incompetent extensor mechanism, massive uncontained bone loss, or inadequate skin coverage. Articulating spacers in these scenarios have a high risk of dislocation and soft tissue failure.

Question 694

Topic: Total Knee Arthroplasty (TKA)

A surgeon is balancing the gaps during a revision TKA. With trial components in place, the extension gap is perfectly balanced, but the flexion gap is unacceptably loose. Which of the following is the most appropriate step to achieve a balanced knee?

. Increase the thickness of the polyethylene insert
. Use a thicker distal femoral augment
. Upsize the femoral component in the anteroposterior (AP) dimension
. Release the posterior cruciate ligament
. Downsize the femoral component

Correct Answer & Explanation

. Upsize the femoral component in the anteroposterior (AP) dimension

Explanation

A loose flexion gap with a balanced extension gap requires isolated tightening of the flexion space. Upsizing the AP dimension of the femoral component or using posterior femoral augments achieves this without altering the extension gap.

Question 695

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old male sustains a traumatic avulsion of the patellar tendon from the tibial tubercle 3 years after a primary TKA. Primary repair is attempted but fails. For definitive reconstruction using an allograft extensor mechanism, what postoperative protocol is mandatory for success?

. Immediate continuous passive motion (CPM) to 90 degrees
. Immobilization in full extension for a minimum of 6 to 8 weeks
. Early active unassisted straight leg raises at 1 week
. Weight-bearing as tolerated with the knee locked in 30 degrees of flexion
. Immediate manipulation under anesthesia to prevent stiffness

Correct Answer & Explanation

. Immobilization in full extension for a minimum of 6 to 8 weeks

Explanation

Allograft extensor mechanism reconstruction for chronic TKA disruption requires strict immobilization in full extension for 6 to 8 weeks to allow for allograft-host tissue healing. Early motion invariably leads to stretching and failure of the graft.

Question 696

Topic: 3. Adult Reconstruction (Hip & Knee)

When utilizing diaphyseal engaging cementless stems in revision total knee arthroplasty, what is the minimum required distance of "scratch fit" (cortical engagement) in the diaphysis to achieve adequate initial stability?

. 10 to 15 mm
. 20 to 30 mm
. 40 to 50 mm
. 70 to 80 mm
. Diaphyseal engagement is strictly contraindicated; metaphyseal fixation is solely required

Correct Answer & Explanation

. 40 to 50 mm

Explanation

Cementless revision TKA stems rely on diaphyseal engagement for immediate stability. A minimum of 4 to 5 cm (40-50 mm) of tight "scratch fit" within the isthmus is biomechanically required to prevent toggle and subsidence.

Question 697

Topic: Total Knee Arthroplasty (TKA)

In the setting of revision TKA for highly porous metal cones versus metaphyseal sleeves, which of the following best describes a biomechanical characteristic of metaphyseal sleeves?

. They are typically primarily bonded or mechanically coupled directly to the revision stem
. They require an intact diaphyseal isthmus for independent fixation
. They are exclusively cemented to the host bone
. They are fundamentally unable to correct rotational alignment
. They eliminate the need for any stem augmentation

Correct Answer & Explanation

. They are typically primarily bonded or mechanically coupled directly to the revision stem

Explanation

Metaphyseal sleeves are distinct from cones in that they typically taper-lock directly onto the revision stem, functioning as a single unit to share loads between the metaphysis and diaphysis. Cones are generally implanted independently and cemented to the implant.

Question 698

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient with a well-fixed, painful TKA is suspected of having a metal hypersensitivity. Patch testing shows a mild reaction to nickel. What is the consensus regarding patch testing prior to revision TKA for suspected metal allergy?

. Patch testing has a 100% positive predictive value for periprosthetic hypersensitivity
. It is the sole indication required for prescribing oxidized zirconium components
. Patch testing correlates poorly with deep intra-articular metal hypersensitivity and should be interpreted with caution
. A negative patch test definitively rules out aseptic loosening
. Patch testing is superior to Lymphocyte Transformation Testing (LTT) in all cases

Correct Answer & Explanation

. Patch testing correlates poorly with deep intra-articular metal hypersensitivity and should be interpreted with caution

Explanation

Cutaneous patch testing correlates poorly with actual deep joint hypersensitivity. Many patients with positive dermal patch tests for nickel have successful, asymptomatic standard TKA implants. Diagnosis remains primarily a diagnosis of exclusion.

Question 699

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old male is undergoing a single-stage revision TKA for aseptic loosening. Intraoperatively, there is a massive uncontained medial tibial plateau defect (AORI Type IIb) extending 35 mm distal to the joint line. What is the most appropriate reconstruction method?

. Cement fill without structural augmentation
. Standard primary tibial baseplate with an extended keel
. Porous tantalum cone or structural allograft with a stemmed tibial component
. Excision of the proximal tibia and massive endoprosthesis
. Impaction bone grafting with a short primary stem

Correct Answer & Explanation

. Porous tantalum cone or structural allograft with a stemmed tibial component

Explanation

A massive uncontained defect (AORI IIb) > 15-20 mm cannot be managed with cement or standard metal augments alone. It requires biologic fixation with highly porous metal cones, metaphyseal sleeves, or structural allografts combined with a diaphyseal engaging stem.

Question 700

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon performs a modified McBride bunionectomy. During the procedure, the fibular sesamoid is completely excised. What is the most significant biomechanical risk associated with this specific step?

. Loss of intrinsic plantar flexion of the great toe
. Hallux varus deformity
. Avascular necrosis of the first metatarsal head
. Rupture of the extensor hallucis longus
. Dorsal subluxation of the first TMT joint

Correct Answer & Explanation

. Hallux varus deformity

Explanation

Excision of the fibular sesamoid removes the lateral stabilizing forces of the adductor hallucis and lateral head of the flexor hallucis brevis. This severely imbalances the joint, resulting in a high incidence of iatrogenic hallux varus.

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