Menu

3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 277 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 5521

Topic: Total Hip Arthroplasty (THA)

A 68-year-old patient undergoes a primary total hip arthroplasty (THA). Over the next 6 months, the patient experiences recurrent anterior hip dislocations. Which of the following combinations of component positioning is the most likely biomechanical cause of these recurrent anterior dislocations?

. Excessive acetabular anteversion and excessive femoral anteversion
. Excessive acetabular retroversion and excessive femoral retroversion
. Inadequate acetabular abduction and excessive femoral anteversion
. Excessive acetabular anteversion and inadequate femoral offset
. Inadequate acetabular anteversion and inadequate femoral retroversion

Correct Answer & Explanation

. Excessive acetabular anteversion and excessive femoral anteversion

Explanation

Anterior dislocation in THA is typically the result of excessive combined anteversion (i.e., excessive acetabular anteversion coupled with excessive femoral anteversion). This position causes the femoral head to lever out of the front of the socket during hip extension and external rotation.

Question 5522

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female returns to the clinic 8 months after a posterior-stabilized (PS) total knee arthroplasty. She reports a painful catching and popping sensation in her anterior knee when extending the leg from a flexed position. What is the most likely etiology of her symptoms?

. Asymmetric polyethylene wear
. Fibrous nodule at the superior pole of the patella engaging the intercondylar box
. Aseptic loosening of the tibial baseplate
. Patellar maltracking secondary to an internally rotated femoral component
. Late avulsion of the patellar tendon

Correct Answer & Explanation

. Asymmetric polyethylene wear

Explanation

The patient is describing 'patellar clunk syndrome,' which classically occurs in posterior-stabilized (PS) total knee replacements. It is caused by the formation of a fibrosynovial nodule on the undersurface of the quadriceps tendon/superior pole of the patella. During knee extension from a flexed position, this nodule catches in the intercondylar box of the femoral component, producing a painful 'clunk'.

Question 5523

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old active male presents with an audible 'squeaking' sound originating from his total hip arthroplasty (THA), performed 3 years ago. He is asymptomatic and denies pain. Radiographs show a ceramic-on-ceramic bearing surface. What surgical factor is most consistently associated with the generation of this noise?

. Use of a highly cross-linked polyethylene liner
. Acetabular component placed in excessive anteversion
. Acetabular component placed in excessive abduction (steep cup)
. Use of a short-stem femoral component
. Mismatch of femoral head and stem trunnion tapers

Correct Answer & Explanation

. Use of a highly cross-linked polyethylene liner

Explanation

Squeaking is a specific, known complication of ceramic-on-ceramic THA bearings. The strongest biomechanical predictor for squeaking is component malposition, specifically high acetabular inclination (a 'steep cup' usually >45-50 degrees) or abnormal version. This geometry leads to edge loading, a loss of the fluid film lubrication, micro-separation, and subsequent stripe wear that generates the acoustic phenomenon.

Question 5524

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient who underwent a primary posterior stabilized (PS) total knee arthroplasty 18 months ago presents with anterior knee pain and a painful 'catching' or 'popping' sensation when extending the knee from a flexed position. What is the most likely pathophysiologic mechanism for this specific complication?

. Avascular necrosis of the unresurfaced patella
. Overstuffing of the anterior compartment by a thick patellar component
. Formation of a fibrous nodule at the superior pole of the patella that catches in the intercondylar box
. Loosening of the tibial baseplate with subsequent anterior translation during extension
. Impingement of the popliteus tendon on the posterolateral aspect of the femoral condyle

Correct Answer & Explanation

. Avascular necrosis of the unresurfaced patella

Explanation

This is the classic presentation of 'patellar clunk syndrome,' a complication seen almost exclusively in posterior stabilized (PS) TKA designs. It is caused by the formation of a proliferative fibrous nodule at the superior pole of the patella or distal quadriceps tendon. As the knee extends from flexion, this nodule catches in the intercondylar box (cam mechanism) of the femoral component, popping out with an audible or palpable clunk.

Question 5525

Topic: 3. Adult Reconstruction (Hip & Knee)

The primary cell responsible for particle-induced osteolysis in total hip arthroplasty responds most vigorously to polyethylene wear particles of what size?

. < 0.1 µm
. 0.1 - 1.0 µm
. 1.0 - 5.0 µm
. 5.0 - 10.0 µm
. > 10.0 µm

Correct Answer & Explanation

. < 0.1 µm

Explanation

Macrophages are the primary cells responsible for the biological response to polyethylene wear debris, leading to osteolysis. The most biologically active particles are submicron in size, specifically in the 0.1 to 1.0 µm range. Particles of this size are readily phagocytosed, triggering the release of pro-inflammatory cytokines (like TNF-alpha, IL-1, IL-6) that stimulate osteoclastogenesis.

Question 5526

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following femoral stem designs in total hip arthroplasty is most closely associated with extensive proximal stress shielding of the femur?

. Single-wedge tapered stem
. Double-wedge tapered stem
. Fully porous-coated cylindrical stem
. Proximally coated hydroxyapatite stem
. Cemented polished taper stem

Correct Answer & Explanation

. Single-wedge tapered stem

Explanation

Stress shielding occurs according to Wolff's law when the mechanical load is bypassed away from the bone and absorbed by the implant. Fully porous-coated cylindrical stems achieve extensive diaphyseal (distal) fixation. Because the stem rigidly loads the bone distally, the proximal femur is 'shielded' from stress, leading to proximal bone resorption (stress shielding). Proximally coated or tapered wedges rely on proximal loading, thereby minimizing this effect.

Question 5527

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty, the surgeon utilizes gap balancing. Evaluation reveals that the extension gap is symmetric and rectangular. However, the flexion gap is asymmetric: tight medially and loose laterally. What is the most appropriate surgical maneuver to balance the knee?

. Release the medial collateral ligament
. Externally rotate the femoral component
. Upsize the femoral component
. Increase the posterior slope of the tibial cut
. Recut the distal femur in more valgus

Correct Answer & Explanation

. Release the medial collateral ligament

Explanation

A tight medial/loose lateral flexion gap with a balanced extension gap implies an isolated asymmetry in flexion. Externally rotating the femoral component moves the medial posterior femoral condyle anteriorly (decreasing its thickness) and the lateral posterior condyle posteriorly (increasing its thickness). This effectively loosens the tight medial side and tightens the loose lateral side in flexion, without altering the symmetric extension gap. Releasing the MCL would inappropriately open the medial side in extension as well.

Question 5528

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old female with rheumatoid arthritis undergoes a total elbow arthroplasty (TEA) for a comminuted distal humerus fracture. Postoperatively, she is counseled on permanent activity restrictions. What is the recommended lifelong weight-lifting restriction for this patient?

. No restriction
. 5 lbs repetitive, 10-15 lbs single event
. 1 lb repetitive, 5 lbs single event
. 20 lbs repetitive, 40 lbs single event
. 15 lbs repetitive, 25 lbs single event

Correct Answer & Explanation

. No restriction

Explanation

Patients with total elbow arthroplasty are generally restricted to lifting no more than 5 pounds repetitively, and 10 to 15 pounds for a single event. This restriction is critical to prevent aseptic loosening and bushing wear, which are common failure modes in TEA.

Question 5529

Topic: 3. Adult Reconstruction (Hip & Knee)

In a 4-part proximal humerus fracture, which single radiographic factor is most strongly associated with subsequent avascular necrosis of the humeral head according to Hertel's criteria?

. Metaphyseal calcar segment length <8 mm attached to the articular surface
. Greater tuberosity displacement >1 cm
. Lesser tuberosity comminution
. Humeral head varus angulation >20 degrees
. Valgus impaction of the humeral head

Correct Answer & Explanation

. Metaphyseal calcar segment length <8 mm attached to the articular surface

Explanation

According to Hertel et al., a metaphyseal calcar segment of less than 8 mm attached to the articular fragment is a highly reliable predictor of humeral head ischemia. A disrupted medial hinge (>2 mm) is another independent and strong predictor of avascular necrosis.

Question 5530

Topic: 3. Adult Reconstruction (Hip & Knee)

A 19-year-old male sustains a posterior sternoclavicular joint dislocation during a rugby match. He complains of mild dysphagia and shortness of breath. After confirming the diagnosis with a CT scan, what is the most appropriate next step in management?

. Immediate closed reduction in the emergency department
. Open reduction and internal fixation with K-wires
. Closed reduction in the OR with cardiothoracic surgery on standby
. Sling immobilization and observation
. Resection arthroplasty of the medial clavicle

Correct Answer & Explanation

. Immediate closed reduction in the emergency department

Explanation

Posterior sternoclavicular dislocations can compress critical mediastinal structures, presenting a life-threatening emergency. Closed reduction should be performed in the operating room under general anesthesia with a cardiothoracic surgeon available due to the high risk of catastrophic vascular injury.

Question 5531

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old rheumatoid arthritis patient undergoes a semiconstrained linked total elbow arthroplasty. Postoperatively, what is the most common long-term complication leading to revision surgery in this patient population?

. Ulnar neuropathy
. Deep infection
. Triceps avulsion
. Aseptic loosening
. Periprosthetic fracture

Correct Answer & Explanation

. Ulnar neuropathy

Explanation

Aseptic loosening is the most common long-term complication and the leading cause of revision in linked total elbow arthroplasty. Polyethylene bushing wear and subsequent osteolysis contribute significantly to this failure mode.

Question 5532

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old male presents with right groin pain 6 years after a primary total hip arthroplasty utilizing a titanium stem, a 36-mm modular cobalt-chromium head, and a highly cross-linked polyethylene liner. Serum cobalt levels are markedly elevated, while serum chromium levels are only slightly above normal. MRI with Metal Artifact Reduction Sequence (MARS) reveals a solid and cystic mass communicating with the joint. What is the most likely etiology of this pathology?

. Adverse reaction to metal debris originating from the bearing surface
. Mechanically assisted crevice corrosion at the head-neck trunnion
. Galvanic corrosion between the titanium stem and acetabular shell
. Polyethylene wear-induced osteolysis
. Subacute periprosthetic joint infection with gas-forming organisms

Correct Answer & Explanation

. Adverse reaction to metal debris originating from the bearing surface

Explanation

This clinical scenario describes trunnionosis, which is mechanically assisted crevice corrosion at the modular head-neck junction. It commonly presents with an ALVAL (aseptic lymphocyte-dominated vasculitis-associated lesion) or pseudotumor. A key diagnostic marker is a disproportionately elevated serum cobalt relative to chromium, which points to the cobalt-chromium modular head degrading at the titanium trunnion, unlike metal-on-metal bearing wear where cobalt and chromium are typically elevated equally.

Question 5533

Topic: Total Hip Arthroplasty (THA)

During a primary total hip arthroplasty through a posterior approach, the surgeon successfully increases the femoral offset by 8 mm using an extended offset stem without altering the vertical limb length. Which of the following is the most direct biomechanical consequence of this geometric change?

. Increased joint reaction force at the hip
. Increased abductor muscle force requirement to maintain a level pelvis
. Increased risk of sciatic nerve traction palsy
. Decreased risk of bony impingement at extremes of motion
. Decreased resting tension on the iliofemoral ligament

Correct Answer & Explanation

. Increased joint reaction force at the hip

Explanation

Increasing the femoral offset moves the femur laterally away from the pelvis. This has two primary benefits: 1) it increases the moment arm of the abductor musculature, thereby decreasing the required abductor force and consequently decreasing the overall joint reaction force; and 2) it increases the clearance between the greater trochanter and the pelvis, which decreases the risk of bony impingement at extremes of motion, improving stability.

Question 5534

Topic: 3. Adult Reconstruction (Hip & Knee)
A 38-year-old female with systemic lupus erythematosus on chronic corticosteroids presents with insidious onset left hip pain. An AP radiograph shows a subchondral radiolucent line (crescent sign) in the anterosuperior femoral head, with early flattening of the articular surface but preservation of the joint space. What is the most appropriate surgical management for this patient?
. Core decompression with bone marrow aspirate concentrate
. Total hip arthroplasty
. Non-vascularized fibular strut grafting
. Vascularized free fibular grafting
. Arthroscopic labral debridement and microfracture

Correct Answer & Explanation

. Total hip arthroplasty

Explanation

The presence of a subchondral radiolucency (crescent sign) and early flattening indicates Ficat Stage III (post-collapse) avascular necrosis of the femoral head. Once subchondral collapse has occurred, joint-preserving procedures such as core decompression or bone grafting have unacceptably high failure rates. Total hip arthroplasty provides the most reliable pain relief and functional improvement for post-collapse AVN.

Question 5535

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary posterior-stabilized total knee arthroplasty, the surgeon assesses the flexion and extension gaps. The extension gap is symmetric and perfectly balanced, but the flexion gap is symmetrically tight. Which of the following surgical modifications is the most appropriate step to balance the knee?

. Recut the distal femur, taking an additional 2 mm of bone
. Release the posterior cruciate ligament from its femoral origin
. Downsize the femoral component and use thicker posterior augments
. Downsize the femoral component using an anterior referencing system
. Resect an additional 2 mm of the proximal tibia

Correct Answer & Explanation

. Recut the distal femur, taking an additional 2 mm of bone

Explanation

A symmetrically tight flexion gap with a balanced extension gap means the anteroposterior (AP) dimension of the femoral component is too large, keeping the posterior condyles too tight against the tibia in flexion. Downsizing the femoral component using an anterior referencing system will decrease the posterior condylar offset, loosening the flexion gap without altering the distal cut (which dictates the extension gap). Releasing the PCL is already done in a PS knee. Resecting more tibia would loosen both flexion and extension gaps.

Question 5536

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male returns to the clinic 1 year following a posterior-stabilized total knee arthroplasty. He complains of a painful 'pop' and catching sensation in his knee as he actively extends it from a deeply flexed position, typically occurring at around 30 to 40 degrees of flexion. Radiographs show well-fixed components. What is the most likely diagnosis?

. Patellar maltracking due to internal rotation of the femoral component
. Aseptic loosening of the tibial baseplate
. Patellar clunk syndrome
. Polyethylene liner wear
. Pes anserine bursitis

Correct Answer & Explanation

. Patellar maltracking due to internal rotation of the femoral component

Explanation

Patellar clunk syndrome is a known complication of posterior-stabilized (PS) TKAs. It is caused by the formation of a fibrous nodule at the superior pole of the patella. As the knee flexes, the nodule drops into the intercondylar box of the PS femoral component. As the knee actively extends (usually around 30-45 degrees), the nodule gets caught on the superior margin of the box and suddenly pops out, creating a painful clunk.

Question 5537

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty for a severe varus knee deformity, you find that the medial gap is persistently tight in both flexion and extension after standard exposure, removal of all medial osteophytes, and initial deep medial collateral ligament release. What is the most appropriate next step in the soft tissue balancing sequence to address this symmetric tightness?

. Release the posterior cruciate ligament (PCL)
. Release the posteromedial capsule and semimembranosus
. Subperiosteal release of the superficial medial collateral ligament (sMCL) from the proximal tibia
. Release the medial head of the gastrocnemius
. Downsize the tibial tray to lateralize the polyethylene

Correct Answer & Explanation

. Release the posterior cruciate ligament (PCL)

Explanation

In a varus knee, symmetric medial tightness in both flexion and extension indicates contracture of structures that cross the joint and affect both positions. After osteophyte removal and deep MCL release, the primary structure tethering the medial side in both flexion and extension is the superficial medial collateral ligament (sMCL). Subperiosteal release of the sMCL off the proximal tibia is the standard next step. Releasing the posteromedial corner and semimembranosus predominantly affects the extension gap.

Question 5538

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female presents with a painful total hip arthroplasty 4 years postoperatively. Her serum CRP is 25 mg/L and ESR is 45 mm/hr. A joint aspiration is performed. According to the 2018 International Consensus Meeting (ICM) criteria for Periprosthetic Joint Infection (PJI), which of the following findings represents a 'Major Criterion' that definitively establishes the diagnosis of PJI?

. A synovial fluid WBC count of 4,500 cells/µL
. A synovial fluid polymorphonuclear percentage (PMN%) of 85%
. A positive alpha-defensin test
. Two positive periprosthetic tissue cultures growing identical organisms
. An elevated synovial fluid C-reactive protein level

Correct Answer & Explanation

. A synovial fluid WBC count of 4,500 cells/µL

Explanation

According to the 2018 ICM criteria, the diagnosis of PJI is definitive if at least one Major Criterion is met. The two Major Criteria are: 1) A sinus tract communicating with the prosthesis, and 2) Two positive periprosthetic cultures with phenotypically identical organisms. Elevated synovial WBC, PMN%, alpha-defensin, and synovial CRP are all Minor Criteria, which contribute points to a diagnostic scoring system but do not singularly confirm infection.

Question 5539

Topic: Total Hip Arthroplasty (THA)

You are planning a primary total hip arthroplasty on a 45-year-old female with bilateral Crowe IV developmental dysplasia of the hip (DDH). To bring the femoral component down to the true acetabulum without causing severe sciatic nerve traction, you perform a transverse subtrochanteric shortening osteotomy. Which of the following femoral stem choices is absolutely critical to maximize the union rate of this osteotomy?

. A fully porous-coated cylindrical diaphyseal-engaging stem
. A highly polished, tapered, cemented stem
. An extensively hydroxylapatite-coated metaphyseal fitting short stem
. A standard length, proximally porous-coated tapered wedge stem
. A dual-mobility monoblock stem

Correct Answer & Explanation

. A fully porous-coated cylindrical diaphyseal-engaging stem

Explanation

When performing a subtrochanteric shortening osteotomy during THA for Crowe IV DDH, the femoral stem acts as an intramedullary splint for the osteotomy. To achieve union, the construct must have absolute rotational stability. A fully porous-coated or fluted, cylindrical diaphyseal-engaging stem that intimately fits the diaphysis below the osteotomy provides the necessary rigid fixation and rotational control. Short or metaphyseal fitting stems will not bridge the osteotomy adequately and result in nonunion.

Question 5540

Topic: 3. Adult Reconstruction (Hip & Knee)
A 75-year-old female presents with severe pain above her left knee after a fall. She has a history of a posterior-stabilized total knee arthroplasty (TKA) performed 8 years ago, which was functioning perfectly. Radiographs demonstrate a displaced distal femur fracture 3 cm superior to the femoral flange. The femoral component shows no radiolucent lines and appears well-fixed. This is classified as a Rorabeck Type II fracture. What is the standard of care for this injury?
. Non-operative management with a hinged knee brace locked in extension
. Open reduction and internal fixation utilizing a lateral locking plate
. Radical resection and distal femoral replacement (tumor prosthesis)
. Revision total knee arthroplasty with a long-stemmed constrained femoral component
. Application of a bridging circular external fixator

Correct Answer & Explanation

. Open reduction and internal fixation utilizing a lateral locking plate

Explanation

The Rorabeck classification guides treatment for periprosthetic distal femur fractures above a TKA. Type I is non-displaced with a well-fixed component (treated non-operatively). Type II is displaced with a well-fixed component. The standard of care for Rorabeck Type II fractures is open reduction and internal fixation (ORIF), most commonly utilizing a laterally based locked plating system or a retrograde intramedullary nail (if the femoral component design allows). Type III involves a loose component, which requires revision arthroplasty or distal femoral replacement.

Test Yourself

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

On this Page