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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 36 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 701

Topic: 3. Adult Reconstruction (Hip & Knee)

During a revision total knee arthroplasty, the surgeon notes massive distal femoral bone loss. Elevating the joint line 10 mm proximally will most likely result in which of the following kinematic changes?

. Mid-flexion instability
. Extension gap tightness
. Patella baja
. Decreased patellofemoral contact forces
. Improved deep flexion

Correct Answer & Explanation

. Mid-flexion instability

Explanation

Elevating the joint line in revision TKA changes the relationship between the collateral ligaments and the articulation, predominantly leading to mid-flexion instability. It also results in relative patella baja and increased patellofemoral contact forces.

Question 702

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old male requires a revision TKA for aseptic loosening. Preoperative imaging reveals massive osteolysis with deficient metaphyseal bone compromising the collateral ligament attachments on the femur and tibia. Which of the following constraint levels is most appropriate?

. Posterior stabilized (PS)
. Cruciate retaining (CR)
. Condylar constrained knee (CCK)
. Rotating hinge
. Unicompartmental

Correct Answer & Explanation

. Rotating hinge

Explanation

A rotating hinge implant is indicated for massive bone loss compromising the collateral ligaments (e.g., epicondylar absence) or for severe flexion gap instability. CCK implants require an intact and functional medial collateral ligament.

Question 703

Topic: 3. Adult Reconstruction (Hip & Knee)

In revision total knee arthroplasty, the use of highly porous tantalum metaphyseal cones is best indicated for which AORI (Anderson Orthopaedic Research Institute) bone loss classification?

. Type 1
. Type F2A
. Type T2A
. Type 2B and Type 3
. Type 4

Correct Answer & Explanation

. Type 2B and Type 3

Explanation

Tantalum metaphyseal cones are primarily indicated for AORI Type 2B (asymmetric, requiring large augments or cones) and Type 3 (massive, involving a major portion of the condyle or plateau) defects. They provide structural support and a surface for biologic fixation.

Question 704

Topic: 3. Adult Reconstruction (Hip & Knee)

When placing diaphyseal engaging stems during a revision total knee arthroplasty, which of the following is an advantage of cemented stems over cementless stems?

. Better stress shielding profile
. Easier future revision if necessary
. Immediate rigid fixation in the presence of wide diaphyseal canals
. Ability to control alignment independent of the diaphyseal bow
. Enhanced biologic ingrowth

Correct Answer & Explanation

. Ability to control alignment independent of the diaphyseal bow

Explanation

Cemented stems allow the surgeon to alter the alignment of the components independent of the diaphyseal bow. Cementless, diaphyseal-engaging stems obligate the component to the anatomical axis of the canal, which can result in component malposition if the canal is significantly bowed.

Question 705

Topic: Total Knee Arthroplasty (TKA)

A patient undergoes a revision TKA complicated by a complete, intraoperative disruption of the patellar tendon from the tibial tubercle. Primary repair is tenuous. Which of the following reconstruction options provides the best long-term outcome?

. Primary repair with cerclage wire augmentation
. Achilles tendon allograft with calcaneal bone block
. Semitendinosus autograft weave
. Gastrocnemius rotational flap
. Synthetic mesh reconstruction

Correct Answer & Explanation

. Achilles tendon allograft with calcaneal bone block

Explanation

Extensor mechanism disruption in TKA is a catastrophic complication. Extensor mechanism allograft (often an Achilles tendon with calcaneal bone block) is the gold standard for reconstruction when primary repair is impossible or tenuous in the revision setting.

Question 706

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female is evaluated for a painful TKA placed 4 years ago. ESR is 45 mm/hr and CRP is 18 mg/L. Aspiration yields a synovial fluid WBC of 3,500 cells/uL with 75% PMNs. Based on the 2018 MSIS criteria, what is the most appropriate next step?

. Schedule single-stage revision TKA
. Perform a 2-stage exchange arthroplasty
. Obtain synovial fluid alpha-defensin or leukocyte esterase
. Prescribe 6 weeks of IV antibiotics
. Perform a diagnostic arthroscopy

Correct Answer & Explanation

. Obtain synovial fluid alpha-defensin or leukocyte esterase

Explanation

The patient's lab values fall into an indeterminate range for PJI (WBC 3,000-10,000 cells/uL). According to the updated MSIS criteria, additional biomarkers such as alpha-defensin, leukocyte esterase, or synovial CRP should be obtained to confirm or rule out infection before proceeding.

Question 707

Topic: Total Knee Arthroplasty (TKA)

During a difficult revision TKA, the surgeon cannot evert the patella or gain adequate flexion without risking patellar tendon avulsion. Which of the following extensile exposures provides the most direct lateral translation of the extensor mechanism while maintaining blood supply?

. Rectus snip
. V-Y quadricepsplasty
. Tibial tubercle osteotomy
. Lateral parapatellar arthrotomy
. Femoral epicondylar osteotomy

Correct Answer & Explanation

. Tibial tubercle osteotomy

Explanation

A tibial tubercle osteotomy allows for excellent exposure and lateral translation of the extensor mechanism, especially when stem removal is anticipated. It provides reliable bone-to-bone healing, unlike V-Y quadricepsplasty which often results in an extensor lag.

Question 708

Topic: Total Knee Arthroplasty (TKA)

A patient complains of the knee 'giving way' when rising from a chair and descending stairs 2 years after a primary TKA. Examination shows laxity to varus and valgus stress at 90 degrees of flexion, but stability in full extension. Which complication has occurred?

. Global instability
. Extension gap instability
. Flexion gap instability
. Genu recurvatum
. Patellofemoral maltracking

Correct Answer & Explanation

. Flexion gap instability

Explanation

Flexion gap instability presents with a knee that is stable in extension but unstable in flexion. It is often caused by undersizing the femoral component in the A-P plane, excessive posterior slope of the tibial cut, or late PCL failure in a cruciate-retaining knee.

Question 709

Topic: Total Knee Arthroplasty (TKA)

During a revision TKA, the original epicondylar axis is obscured by massive bone loss. Which of the following secondary landmarks is most reliable for establishing proper femoral component rotation?

. Whiteside's line (anteroposterior axis)
. Posterior condylar axis
. Tibial tubercle
. Linea aspera (posterior femoral shaft)
. Medial collateral ligament origin

Correct Answer & Explanation

. Linea aspera (posterior femoral shaft)

Explanation

In revision TKA where the epicondyles and trochlear groove are absent, the linea aspera of the femur is a reliable landmark. It can be used to set stem version, which consequently guides the rotational alignment of the femoral component.

Question 710

Topic: 3. Adult Reconstruction (Hip & Knee)

A 71-year-old female undergoes revision total knee arthroplasty (TKA) for aseptic loosening. Intraoperatively, the medial collateral ligament (MCL) is found to be completely attenuated and incompetent. The knee is globally unstable in both flexion and extension despite the use of a condylar constrained knee (CCK) insert. Which of the following constraint options is the most appropriate next step?

. Cruciate-retaining (CR) prosthesis
. Posterior-stabilized (PS) prosthesis
. Unicompartmental knee arthroplasty
. Rotating hinge prosthesis
. Custom triflange acetabular component

Correct Answer & Explanation

. Rotating hinge prosthesis

Explanation

A rotating hinge prosthesis is indicated in revision TKA when there is global instability, particularly with an incompetent or absent medial collateral ligament (MCL). A CCK component relies on functional collateral ligaments to prevent excessive varus/valgus stress.

Question 711

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female presents with a loose TKA. Preoperative planning indicates severe cavitary and segmental bone loss of the proximal tibia with compromised metaphyseal cancellous bone, but an intact diaphyseal isthmus (AORI Type 2B/3).

Which of the following is the most biomechanically sound fixation method for the tibial component?

. Standard primary baseplate with a thick cement mantle
. Tantalum metaphyseal cone with a diaphyseal engaging stem
. Impaction bone grafting with a short unstemmed baseplate
. Allograft-prosthetic composite without diaphyseal fixation
. Fully cemented short stem component

Correct Answer & Explanation

. Tantalum metaphyseal cone with a diaphyseal engaging stem

Explanation

For severe metaphyseal bone loss (AORI Type 2B or 3), highly porous tantalum cones or titanium sleeves combined with diaphyseal engaging stems provide excellent initial mechanical stability and allow for biologic ingrowth. Cement alone or short stems are insufficient for massive defects.

Question 712

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient develops iatrogenic hallux varus 6 months after a modified McBride bunionectomy. The deformity is symptomatic, but the first metatarsophalangeal (MTP) joint remains fully flexible without arthritic changes. Which of the following is the most appropriate surgical management?

. First MTP arthrodesis
. Keller resection arthroplasty
. Medial capsular release, lateral capsular plication, and EHL transfer
. Closing wedge osteotomy of the medial cuneiform
. Scarf osteotomy with medial translation

Correct Answer & Explanation

. Medial capsular release, lateral capsular plication, and EHL transfer

Explanation

In a flexible, non-arthritic iatrogenic hallux varus, joint-preserving soft tissue reconstruction is preferred. This typically involves medial capsular release, lateral capsular plication, and transferring the extensor hallucis longus (EHL) or split extensor hallucis brevis (EHB) to correct the dynamic imbalance.

Question 713

Topic: Total Knee Arthroplasty (TKA)

During a complex revision TKA, the surgeon encounters severe extensor mechanism tightness preventing adequate exposure and eversion of the patella. A tibial tubercle osteotomy (TTO) is chosen. Which of the following is a critical technical aspect of performing this TTO?

. Creating a distal bevel to prevent stress risers
. Leaving a medial soft tissue hinge to protect the anterior tibial artery
. Limiting the length of the osteotomy to 2-3 cm
. Placing the osteotomy strictly lateral to the tibial crest
. Reattaching the fragment with non-absorbable sutures only

Correct Answer & Explanation

. Creating a distal bevel to prevent stress risers

Explanation

A TTO for TKA exposure should be approximately 6-8 cm long, maintain a lateral soft-tissue hinge, and crucially include a distal bevel. The distal bevel prevents the creation of a sharp cortical stress riser, reducing the risk of postoperative tibial shaft fractures.

Question 714

Topic: Total Knee Arthroplasty (TKA)

During intraoperative gap balancing in a revision TKA, the surgeon notes that the joint is stable in extension but exhibits symmetric, excessive laxity in flexion.

Which of the following is the most appropriate corrective action?

. Downsize the femoral component
. Increase the size of the femoral component and use posterior augments
. Use a thicker tibial polyethylene insert
. Apply distal femoral augments
. Release the posterior cruciate ligament

Correct Answer & Explanation

. Increase the size of the femoral component and use posterior augments

Explanation

Symmetric flexion instability with a stable extension gap is corrected by increasing the anteroposterior (AP) dimension of the femur. This is achieved by upsizing the femoral component and utilizing posterior augments to tighten the flexion gap without affecting the extension gap.

Question 715

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon is performing a two-stage exchange arthroplasty for a periprosthetic joint infection. During reimplantation, accurate restoration of the joint line is critical for optimal kinematics. The joint line in a standard TKA is typically referenced to be approximately 2.5 to 3.0 cm distal to which reliable anatomic landmark?

. Inferior pole of the patella
. Tibial tubercle
. Fibular head
. Medial epicondyle
. Adductor tubercle

Correct Answer & Explanation

. Medial epicondyle

Explanation

The medial epicondyle is a highly reliable landmark for joint line restoration in revision TKA, as it is relatively unaffected by bone loss. The normal joint line is located approximately 25-30 mm distal to the medial epicondyle.

Question 716

Topic: Total Knee Arthroplasty (TKA)

Intraoperative assessment during a revision TKA demonstrates symmetrical tightness in both the flexion and extension gaps. The current polyethylene insert is a standard 10 mm thickness. What is the most appropriate next step to balance the knee?

. Upsize the femoral component
. Apply posterior femoral augments
. Resect additional posterior femoral condyle
. Resect additional proximal tibia or use a thinner polyethylene insert
. Perform a fractional lengthening of the medial collateral ligament

Correct Answer & Explanation

. Resect additional proximal tibia or use a thinner polyethylene insert

Explanation

Symmetrical tightness in both flexion and extension gaps indicates that the overall joint space is too small. The correct management is to increase both gaps equally by either using a thinner polyethylene insert (if available) or resecting additional proximal tibia.

Question 717

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old male is evaluated for a painful TKA 4 years postoperatively. Synovial fluid aspiration yields a WBC count of 4,500 cells/uL with 85% neutrophils. Fungal and routine cultures are pending. According to the 2018 MSIS/ICM criteria, what additional test would provide the highest specificity for confirming a chronic periprosthetic joint infection (PJI)?

. Serum erythrocyte sedimentation rate (ESR)
. Serum C-reactive protein (CRP)
. Synovial fluid alpha-defensin level
. Bone scintigraphy (Bone scan)
. Plain radiographs of the knee

Correct Answer & Explanation

. Synovial fluid alpha-defensin level

Explanation

Synovial fluid alpha-defensin is an antimicrobial peptide with extremely high sensitivity and specificity for PJI. It is incorporated into the modern MSIS/ICM scoring systems as a major laboratory biomarker to confirm infection when cell counts are equivocal or elevated.

Question 718

Topic: Total Knee Arthroplasty (TKA)

Which of the following statements best encapsulates the ultimate goal of Paley's geometric principles in lower extremity deformity correction?

. To achieve maximal limb lengthening, regardless of angular correction.
. To simplify surgical techniques by avoiding complex geometric calculations.
. To restore normal mechanical alignment and joint orientation through meticulous, mathematically sound preoperative planning.
. To primarily address intra-articular deformities, leaving extra-articular issues for secondary procedures.
. To ensure that all osteotomies are performed acutely to minimize patient discomfort.

Correct Answer & Explanation

. To restore normal mechanical alignment and joint orientation through meticulous, mathematically sound preoperative planning.

Explanation

Correct Answer: CThe introductory and foundational geometry sections of the text repeatedly emphasize this core objective. The text states: 'The ultimate goal of any deformity correction is the restoration of normal mechanical alignment and joint orientation through meticulous, mathematically sound preoperative planning.' It also highlights that 'a deep, intuitive understanding of these principles is not just beneficial—it is an absolute clinical mandate.'Option A is incorrect as lengthening is one aspect, but not the sole or ultimate goal, and it must be coupled with angular correction. Option B is incorrect; Paley's principles are highly geometric and require complex calculations, though they simplify theoutcomeby making it predictable. Option D is incorrect as the principles address both intra- and extra-articular deformities (e.g., Rule Two for intra-articular CORAs). Option E is incorrect as both acute and gradual corrections are discussed, and the timing of correction is not the ultimate goal of the geometric principles themselves.

Question 719

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old patient presents with a severe varus knee deformity. Preoperative planning reveals a Mechanical Axis Deviation (MAD) of 20mm medial to the center of the knee. What is the clinical significance of this finding, and what is the ultimate goal for this measurement after correction?

. It indicates a valgus deformity, overloading the lateral compartment; the goal is a MAD of 20mm lateral.
. It indicates a varus deformity, overloading the medial compartment; the goal is a MAD of exactly zero millimeters.
. It indicates a rotational deformity, requiring derotation osteotomy; the goal is to align the patella centrally.
. It indicates a leg length discrepancy, requiring lengthening; the goal is to equalize limb lengths.
. It indicates an intra-articular deformity, requiring arthroplasty; the goal is to achieve a JLCA of 0°.

Correct Answer & Explanation

. It indicates a varus deformity, overloading the medial compartment; the goal is a MAD of exactly zero millimeters.

Explanation

Correct Answer: BThe case defines MAD: 'Medial MAD: Indicates a varus (bowleg) deformity. The mechanical axis passes medial to the center of the knee, overloading the medial compartment.' It further states: 'The Ultimate Goal: A MAD of exactly zero millimeters. At this neutral point, the mechanical axis passes directly through the center of the knee joint, ensuring optimal, symmetric load distribution across the articular cartilage and preventing the rapid progression of unilateral compartment osteoarthritis.'Therefore, a MAD of 20mm medial indicates a varus deformity overloading the medial compartment, and the ultimate goal is a MAD of exactly zero millimeters.Option A is incorrectbecause medial MAD indicates varus, not valgus, and the goal is zero, not 20mm lateral.Option C is incorrectbecause MAD primarily measures angular alignment in the coronal plane, not rotational deformity directly.Option D is incorrectbecause MAD measures alignment, not leg length discrepancy, although severe deformities can be associated with length issues.Option E is incorrectbecause MAD is an extra-articular measurement of overall limb alignment, not an indicator for intra-articular deformity or arthroplasty, although it can contribute to joint degeneration.

Question 720

Topic: Total Hip Arthroplasty (THA)

A surgeon is performing a complex femoral deformity correction. Due to an error in preoperative planning and intraoperative execution, both the osteotomy and the corrective hinge of the external fixator are inadvertently placed away from the identified CORA. According to Paley's Osteotomy Rules, what is the most likely geometric outcome of this surgical error?

. Pure angulation will occur without any translation, resulting in a perfectly straight bone.
. The mechanical axes will become collinear, but significant translation will occur at the osteotomy site.
. A secondary iatrogenic deformity will be created, where the mechanical axes are parallel but not collinear, resulting in persistent translational deformity.
. The bone will be over-lengthened, leading to a significant leg length discrepancy.
. The osteotomy will fail to unite due to biomechanical instability.

Correct Answer & Explanation

. A secondary iatrogenic deformity will be created, where the mechanical axes are parallel but not collinear, resulting in persistent translational deformity.

Explanation

Correct Answer: CThis scenario directly describes Paley's Osteotomy Rule Three: 'When both the osteotomy and the corrective hinge are located away from the CORA, a secondary iatrogenic deformity is created. The mechanical axes will become parallel but willnotbe collinear. This results in a persistent, unsightly translational deformity.'Option A is incorrectbecause pure angulation without translation occurs only when both osteotomy and hinge are at the CORA (Rule One).Option B is incorrectbecause collinear axes with translation occur when the hinge is at the CORA but the osteotomy is away (Rule Two).Option D is incorrectbecause Rule Three describes an angular and translational deformity, not primarily a lengthening error, although length can be affected.Option E is incorrectbecause Rule Three describes the geometric outcome of the correction, not necessarily a failure of union, although malalignment can contribute to nonunion.

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