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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 42 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 821

Topic: 3. Adult Reconstruction (Hip & Knee)

A 50-year-old male presents with symptomatic medial compartment osteoarthritis and a varus knee deformity, as illustrated in the initial state of the image below. His mechanical axis passes 20 mm medial to the center of the knee. He has a normal mLDFA of 88 degrees and an MPTA of 80 degrees. He desires to remain active and is not yet a candidate for total knee arthroplasty. Which of the following surgical interventions is most appropriate for correcting his deformity and offloading the medial compartment?

. Distal femoral opening wedge osteotomy.
. Proximal tibial closing wedge osteotomy.
. Proximal tibial opening wedge osteotomy.
. Total knee arthroplasty.
. Ankle fusion.

Correct Answer & Explanation

. Proximal tibial opening wedge osteotomy.

Explanation

Correct Answer: CThe patient presents with a varus knee deformity (mechanical axis 20 mm medial) and medial compartment osteoarthritis. The mLDFA is normal (88 degrees), indicating no significant femoral deformity. The MPTA is 80 degrees, which is less than the normal range (85-90 degrees), indicating a varus deformity originating from the proximal tibia. Therefore, a proximal tibial osteotomy is indicated to correct the deformity. To correct a varus deformity, an opening wedge osteotomy on the medial side of the tibia (or a closing wedge on the lateral side) is performed to increase the MPTA and shift the mechanical axis laterally. An opening wedge osteotomy is often preferred as it allows for precise correction and can also address mild limb length discrepancy if present.Option A, a distal femoral opening wedge osteotomy, would be used to correct a valgus deformity originating from the femur, which is not the case here. Option B, a proximal tibial closing wedge osteotomy, if performed on the lateral side, would correct varus, but if performed on the medial side, it would worsen varus. Typically, a closing wedge for varus is done laterally. An opening wedge medially is more common for HTO. Option D, total knee arthroplasty, is generally reserved for older patients with more advanced osteoarthritis or those who have failed osteotomy, and the patient is described as not yet a candidate. Option E, ankle fusion, is unrelated to knee deformity correction.

Question 822

Topic: Total Knee Arthroplasty (TKA)

A 62-year-old patient with unicompartmental knee osteoarthritis and a significant angular deformity is being considered for either a realignment osteotomy or total knee arthroplasty (TKA). Which of the following patient characteristics would most strongly favor an osteotomy over a TKA?

. Sedentary lifestyle with multiple comorbidities.
. Advanced tricompartmental osteoarthritis.
. Age greater than 70 years.
. High activity level with good bone stock and no inflammatory arthritis.
. Significant knee instability and ligamentous laxity.

Correct Answer & Explanation

. High activity level with good bone stock and no inflammatory arthritis.

Explanation

Correct Answer: DRealignment osteotomy is generally preferred for younger, active patients with unicompartmental osteoarthritis, good bone stock, and no inflammatory arthritis. These patients often desire to maintain a high activity level, including sports, which may be limited or contraindicated after TKA. Osteotomy preserves the native joint and allows for future TKA if needed. The image illustrates the concept of correcting deformity to restore alignment, which is the goal of osteotomy in such patients.Option A, a sedentary lifestyle with multiple comorbidities, would typically favor TKA, especially if the patient's activity demands are low and the risks of osteotomy (longer recovery, potential for nonunion) outweigh the benefits. Option B, advanced tricompartmental osteoarthritis, is a strong contraindication for osteotomy, as osteotomy is designed for unicompartmental disease. TKA would be the treatment of choice. Option C, age greater than 70 years, generally favors TKA due to the higher likelihood of advanced osteoarthritis, lower activity demands, and faster recovery compared to osteotomy. Option E, significant knee instability and ligamentous laxity, is often a contraindication for osteotomy, as osteotomy primarily corrects angular deformity and does not address ligamentous instability. TKA, especially with constrained components, might be more appropriate in such cases.

Question 823

Topic: Total Hip Arthroplasty (THA)

A surgeon evaluating a varus knee notes an elevated Joint Line Convergence Angle (JLCA) of 6 degrees on standing AP radiographs. What does this finding primarily suggest?

. Bony diaphyseal deformity of the femur
. Ligamentous laxity or intra-articular cartilage loss
. Torsional malalignment of the tibia
. Normal anatomic variation
. Leg length discrepancy

Correct Answer & Explanation

. Ligamentous laxity or intra-articular cartilage loss

Explanation

The JLCA measures the convergence of the distal femoral and proximal tibial articular surfaces, which is normally 0-2 degrees. An increased JLCA indicates intra-articular deformity, asymmetrical cartilage loss, or collateral ligament laxity.

Question 824

Topic: Total Hip Arthroplasty (THA)

A 32-year-old male presents for evaluation of progressive genu varum. Preoperative planning requires a full-length standing anteroposterior (AP) radiograph of the lower limbs. The radiologic technologist positions the patient with their feet pointing straight forward, ensuring the X-ray beam is centered appropriately. However, the surgeon notes that the patellae appear internally rotated on the initial film. According to Paley's principles, what is the most likely consequence of this rotational error?

. The Mechanical Axis Deviation (MAD) will be underestimated, leading to undercorrection.
. The Joint Orientation Angles (e.g., mLDFA, MPTA) will be accurately measured, but the CORA will be misplaced.
. The frontal plane projection of the knee joint will be distorted, rendering joint orientation angle measurements inaccurate.
. The leg length discrepancy will be exaggerated, requiring additional compensatory blocks.
. The sagittal plane deformity will be masked, leading to an incorrect assessment of procurvatum or recurvatum.

Correct Answer & Explanation

. The frontal plane projection of the knee joint will be distorted, rendering joint orientation angle measurements inaccurate.

Explanation

Correct Answer: CThe case explicitly states that the 'Patella-Forward Rule' is the single most critical parameter in radiographic acquisition. Aligning the feet forward when there is inherent femoral anteversion or tibial torsion can induce significant rotation at the knee. This rotation distorts the frontal plane projection, making all subsequent joint orientation angle measurements (like the mLDFA and MPTA) completely inaccurate. The patella-forward position ensures a true AP view of the knee joint, which is essential for accurate frontal plane analysis.Option A is incorrectbecause while an inaccurate frontal plane projection can lead to errors in MAD calculation and subsequent under/overcorrection, the primary and direct consequence of rotational error at the knee is the distortion of joint orientation angles, which then cascades to MAD errors. The statement focuses on the direct impact.Option B is incorrectbecause the text clearly states that rotation 'distorts the frontal plane projection, rendering all subsequent joint orientation angle measurements completely inaccurate.' Therefore, the mLDFA and MPTA would not be accurately measured.Option D is incorrectbecause rotational alignment primarily affects frontal plane angular measurements, not leg length discrepancy. LLD is assessed by the overall length and is compensated by blocks to level the pelvis, independent of knee rotation.Option E is incorrectbecause rotational errors primarily affect frontal plane assessment. Sagittal plane deformities (procurvatum/recurvatum) are assessed on lateral views or by specific techniques to overcome their distortion on AP views, but they are not directly masked by a rotational error in the AP view itself in the manner described.

Question 825

Topic: Total Knee Arthroplasty (TKA)

A 60-year-old female presents with severe knee osteoarthritis and a suspected varus deformity. The orthopedic surgeon emphasizes the need for a full-length standing anteroposterior (AP) radiograph of the lower limbs for preoperative planning. Why is this specific type of radiograph considered the 'only acceptable starting point' for deformity analysis, according to Paley's principles?

. It provides superior detail of intra-articular pathology compared to short-cassette films.
. It allows for accurate assessment of the global mechanical relationship between all joints of the lower extremity under weight-bearing conditions.
. It is the only view that can accurately measure femoral anteversion and tibial torsion.
. It minimizes radiation exposure compared to multiple short-cassette views.
. It is primarily used to identify soft tissue contractures around the knee joint.

Correct Answer & Explanation

. It allows for accurate assessment of the global mechanical relationship between all joints of the lower extremity under weight-bearing conditions.

Explanation

Correct Answer: BThe text explicitly states: 'The full-length film is essential to visualize the continuous line of weight-bearing force from the center of the femoral head down to the ankle joint.' It further clarifies that standard, short-cassette radiographs 'provide a myopic, localized view that completely obscures the global mechanical relationship between the joints of the lower extremity.' Therefore, the full-length standing AP radiograph is crucial for assessing the global mechanical alignment under functional weight-bearing conditions.Option A is incorrectbecause the text states that standard, short-cassette radiographs 'are useful for diagnosing intra-articular pathology (like joint space narrowing or osteophytes),' implying that full-length films are not primarily superior for this specific purpose, but rather for global alignment.Option C is incorrectbecause femoral anteversion and tibial torsion are rotational deformities best assessed by specialized CT scans or clinical examination, not primarily by a frontal plane AP radiograph.Option D is incorrectbecause a full-length radiograph typically involves a larger field of view and potentially more radiation than a single short-cassette view, though it avoids multiple exposures if several short views were needed to cover the entire limb. The primary reason for its use is diagnostic accuracy, not radiation minimization.Option E is incorrectbecause while severe soft tissue contractures might be inferred, the primary purpose of the full-length AP radiograph is bony alignment and mechanical axis assessment, not direct soft tissue evaluation.

Question 826

Topic: Total Hip Arthroplasty (THA)

A 50-year-old patient with a complex multiplanar deformity of the distal femur is undergoing preoperative planning. The surgeon obtains a standard full-length standing AP radiograph. However, the patient has a significant sagittal plane deformity (procurvatum) at the knee. According to Paley's principles, what is the primary concern regarding the interpretation of this AP radiograph?

. The Mechanical Axis Deviation (MAD) will be accurately represented, but joint line obliquity will be exaggerated.
. The radiograph will appear highly distorted, making accurate assessment of frontal plane angles unreliable.
. The patella-forward rule cannot be applied, leading to inevitable rotational errors.
. The leg length discrepancy will be underestimated due to the sagittal plane component.
. The Sugioka view will be required to correct for the sagittal plane distortion.

Correct Answer & Explanation

. The radiograph will appear highly distorted, making accurate assessment of frontal plane angles unreliable.

Explanation

Correct Answer: BThe text specifically addresses this scenario under 'Overcoming Distortion in Sagittal and Frontal Plane Deformities': 'When there is a significant sagittal plane component of deformity (such as severe procurvatum or recurvatum), an AP view radiograph obtained in the usual fashion will appear highly distorted.' This distortion makes accurate assessment of frontal plane angles and overall alignment unreliable.Option A is incorrectbecause the text states the AP view will be 'highly distorted,' implying that the MAD and other frontal plane measurements will be unreliable, not accurately represented.Option C is incorrectbecause while a severe sagittal deformity can make positioning difficult, the patella-forward rule is about rotational alignment in the transverse plane, not directly about sagittal plane distortion on an AP view. The issue here is the projection of a sagittal deformity onto the frontal plane.Option D is incorrectbecause sagittal plane deformity primarily affects the projection of angular alignment in the frontal plane, not directly the measurement of leg length discrepancy.Option E is incorrectbecause the Sugioka view is for assessing proximal femoral deformities in the sagittal plane (true lateral of the femoral neck), not for correcting distortion caused by knee procurvatum/recurvatum on a full-length AP view. Specialized techniques for sagittal plane deformities would involve true lateral films or specific beam angulation, not the Sugioka view.

Question 827

Topic: 3. Adult Reconstruction (Hip & Knee)

A 16-year-old athlete presents with chronic hip pain and a suspected diagnosis of avascular necrosis (AVN) of the femoral head. The orthopedic surgeon requires a precise radiographic view to assess the relationship of the femoral neck to the head with maximum accuracy. Which of the following describes the biomechanical rationale behind the specific positioning for the Sugioka view to achieve this goal?

. Flexing the hip to 90 degrees externally rotates the femoral neck, making it parallel to the X-ray beam.
. Abducting the thigh moves the femoral neck's orientation into the sagittal plane, perpendicular to the film.
. Flexing the hip to 90 degrees moves the femoral neck's orientation into the transverse plane, and abducting the thigh then rotates this plane until the neck is perfectly horizontal and parallel to the radiographic film.
. The Sugioka view primarily aims to eliminate femoral anteversion, allowing for a true AP projection of the femoral head.
. The specific positioning minimizes radiation exposure to the gonads by shielding the pelvis.

Correct Answer & Explanation

. Flexing the hip to 90 degrees moves the femoral neck's orientation into the transverse plane, and abducting the thigh then rotates this plane until the neck is perfectly horizontal and parallel to the radiographic film.

Explanation

Correct Answer: CThe text provides a detailed biomechanical rationale: 'The biomechanical rationale behind this positioning is brilliant: flexing the hip 90 degrees moves the femoral neck's orientation completely into the transverse plane. Abducting the thigh then rotates this plane until the neck is perfectly horizontal and parallel to the radiographic film.'Option A is incorrectbecause flexing the hip to 90 degrees moves the neck into the transverse plane, and abduction then makes it parallel to the film, not external rotation making it parallel to the beam.Option B is incorrectbecause flexing the hip moves the neck into the transverse plane, and abduction makes it parallel to the film, not into the sagittal plane perpendicular to the film.Option D is incorrectbecause the Sugioka view aims for a true lateral of the femoral neck, not to eliminate femoral anteversion or provide a true AP projection of the femoral head. Femoral anteversion is a rotational deformity assessed differently.Option E is incorrectbecause while radiation safety is always a concern, the primary purpose and biomechanical rationale of the Sugioka view are for precise anatomical visualization, not radiation minimization.

Question 828

Topic: Total Knee Arthroplasty (TKA)

A 55-year-old male presents with chronic medial knee pain. A full-length standing radiograph reveals that the mechanical axis of the lower limb passes 18 mm medial to the center of the knee joint. Based on Paley's principles, what is the most accurate interpretation of this finding and its biomechanical implication?

. The patient has a valgus deformity, leading to increased stress on the lateral compartment of the knee.
. The patient has a procurvatum deformity, indicating an anterior bow of the limb in the sagittal plane.
. The patient has a varus deformity, resulting in increased loading of the medial compartment of the knee.
. The patient has a recurvatum deformity, indicating a posterior bow of the limb in the sagittal plane.
. The mechanical axis deviation is within normal limits, and the knee pain is likely unrelated to alignment.

Correct Answer & Explanation

. The patient has a varus deformity, resulting in increased loading of the medial compartment of the knee.

Explanation

Correct Answer: CThe text defines the mechanical axis of the lower limb as a line from the center of the femoral head to the center of the ankle mortise. It states, 'In a perfectly aligned limb, this line passes directly through the center of the knee joint (or slightly medial, typically 8ยฑ7 mm medial to the center).' It further clarifies, 'When the mechanical axis falls medial to the knee center, the patient has a varus deformity (bow-legged).' The biomechanical implication is that 'A medial MAD overloads the medial compartment of the knee, leading to medial unicompartmental osteoarthritis.' An 18 mm medial deviation is significantly outside the normal range (8ยฑ7 mm medial) and indicates a varus deformity with medial compartment overload.Option A is incorrectbecause a valgus deformity occurs when the mechanical axis falls lateral to the knee center, not medial.Option B is incorrectbecause procurvatum is a sagittal plane deformity (anterior bow), whereas MAD in the coronal plane assesses varus/valgus.Option D is incorrectbecause recurvatum is a sagittal plane deformity (posterior bow), not a coronal plane deviation.Option E is incorrectbecause an 18 mm medial deviation is outside the normal range of 8ยฑ7 mm medial, indicating a significant varus malalignment that is highly likely related to the knee pain.

Question 829

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old patient with severe medial compartment osteoarthritis and a varus deformity is being planned for a high tibial osteotomy. The preoperative 51-inch standing radiograph shows a Mechanical Axis Deviation (MAD) of 30 mm medial and a Joint Line Congruency Angle (JLCA) of 6 degrees, with lateral gapping. What is the most critical implication of this abnormal JLCA finding for surgical planning, according to Paley's principles?

. The JLCA indicates a primary distal femoral deformity, requiring a distal femoral osteotomy instead.
. The abnormal JLCA suggests the deformity is purely intra-articular and cannot be corrected by osteotomy.
. The bony osteotomy correction should aim for slight overcorrection into valgus, anticipating joint closure under load.
. The JLCA is irrelevant for bony osteotomy planning and can be ignored.
. The patient requires a total knee arthroplasty due to the severity of the intra-articular pathology.

Correct Answer & Explanation

. The bony osteotomy correction should aim for slight overcorrection into valgus, anticipating joint closure under load.

Explanation

Correct Answer: CThe text highlights the critical importance of the JLCA: 'Ignoring an abnormal JLCA is a critical surgical error. If a surgeon corrects a varus bony deformity to neutral based purely on bone angles, but there is significant lateral joint line opening (high JLCA), the patient will be thrust into functional valgus when weight-bearing post-operatively. The JLCA must be mathematically factored into the overall correction plan.' It further states: 'In a varus knee with lateral gapping (abnormal JLCA), the bony osteotomy correction should aim for slight overcorrection into valgus, anticipating that the joint will 'close down' and parallelize under dynamic load post-operatively.'Option A (Primary distal femoral deformity):Incorrect. JLCA assesses intra-articular alignment, not the primary bone deformity location.Option B (Purely intra-articular, no osteotomy):Incorrect. While intra-articular, it must be factored into osteotomy planning.Option C (Aim for slight overcorrection into valgus):Correct. This directly reflects the surgical pearl provided in the text for managing an abnormal JLCA in a varus knee with lateral gapping.Option D (Irrelevant):Incorrect. The text explicitly warns against ignoring an abnormal JLCA.Option E (Requires TKA):While severe OA might eventually lead to TKA, the question is about the implication for osteotomy planning, and the JLCA itself doesn't automatically preclude osteotomy if other criteria are met.

Question 830

Topic: Total Knee Arthroplasty (TKA)

According to the principles outlined, a 25-year-old patient with a complex lower limb deformity requires a true anteroposterior (AP) standing radiograph. Which of the following accurately defines the 'knee forward position' essential for obtaining this view?

. A. The patient's feet are positioned with the toes pointing straight ahead, parallel to the imaging cassette.
. B. The patient's hips are externally rotated until the femoral condyles appear symmetrical on the radiograph.
. C. The patella is perfectly centered between the medial and lateral femoral condyles, irrespective of foot position.
. D. The patient's knees are flexed to 30 degrees to ensure optimal joint space visualization.
. E. The fibular head is superimposed over the lateral aspect of the tibia.

Correct Answer & Explanation

. C. The patella is perfectly centered between the medial and lateral femoral condyles, irrespective of foot position.

Explanation

Correct Answer: CThe text explicitly states: "The gold standard for a true AP view is theknee forward position. This position is defined by one simple, critical anatomical landmark: the patella must be perfectly centered between the medial and lateral femoral condyles." It further clarifies that this is achieved "irrespective of the foot's final position."Incorrect Options:A. The patient's feet are positioned with the toes pointing straight ahead, parallel to the imaging cassette:The text identifies this as "the most common error in radiography suites" and a technique that "completely ignores underlying tibial or femoral torsion, projecting a distorted 2D image."B. The patient's hips are externally rotated until the femoral condyles appear symmetrical on the radiograph:While aiming for symmetry is part of good imaging, the specific definition of the knee forward position focuses on the patella's relationship to the femoral condyles, not hip rotation as the primary determinant.D. The patient's knees are flexed to 30 degrees to ensure optimal joint space visualization:A true AP standing radiograph for deformity analysis is typically performed with the knee in full extension, not flexed, to assess mechanical alignment accurately.E. The fibular head is superimposed over the lateral aspect of the tibia:This describes a radiographic sign of rotation, but it is not the definition of the knee forward position itself. The goal is to avoid such superimposition by achieving the knee forward position.

Question 831

Topic: 3. Adult Reconstruction (Hip & Knee)

A young orthopedic resident is struggling with a complex multi-planar lower extremity deformity. Their attending surgeon emphasizes the importance of a systematic approach to avoid unpredictable outcomes.

Which of the following best encapsulates Dr. Dror Paley's most significant contribution to the field of orthopedic deformity correction, as described in the case?

. Popularizing the use of external fixators for limb lengthening.
. Developing novel surgical techniques for joint replacement in deformed limbs.
. Establishing a standardized, geometric methodology for analyzing and correcting deformities.
. Introducing the concept of biological bone transport for large bone defects.
. Advocating for non-operative management of most lower extremity malalignments.

Correct Answer & Explanation

. Establishing a standardized, geometric methodology for analyzing and correcting deformities.

Explanation

Correct Answer: CThe case explicitly states that Dr. Dror Paley 'revolutionized the field of orthopedics by establishing a systematic methodology grounded in mechanical axes, joint orientation angles, and precise osteotomy rules.' This standardized, geometric approach transformed deformity correction from an intuitive art into a precise science, leading to more predictable outcomes. Options A, B, D, and E represent other important advancements or concepts in orthopedics but are not highlighted as Paley's primary, foundational contribution to the systematic analysis and correction of deformities in the provided text.

Question 832

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old patient presents with progressive knee pain and a visible varus deformity. Radiographs show significant medial compartment osteoarthritis. The surgeon is trying to differentiate the primary cause of the deformity to plan the most appropriate intervention.

According to Paley's principles, which statement accurately distinguishes between malalignment and malorientation?

. Malalignment refers to abnormal angulation of a joint surface, while malorientation refers to a deviation of the overall mechanical axis.
. Malalignment is always caused by a diaphyseal deformity, whereas malorientation is always epiphyseal.
. Malalignment describes a deviation of the limb's overall mechanical axis, while malorientation describes abnormal angulation of a joint surface relative to its own bone's axis.
. Malorientation is correctable with an osteotomy, while malalignment requires joint replacement.
. Malalignment is a sagittal plane issue, and malorientation is a frontal plane issue.

Correct Answer & Explanation

. Malalignment describes a deviation of the limb's overall mechanical axis, while malorientation describes abnormal angulation of a joint surface relative to its own bone's axis.

Explanation

Correct Answer: CThe case clearly defines these two critical concepts: 'Malalignment: This refers to a deviation of the limb's overall mechanical axis. The load-bearing line of the leg does not pass through the center of the knee...' and 'Malorientation: This refers to the abnormal angulation of a joint surface relative to the anatomic or mechanical axis of its own bone.' Understanding this distinction is fundamental to accurate deformity analysis and surgical planning. Option A reverses the definitions. Option B is incorrect as malalignment can be caused by joint line issues (malorientation) and malorientation can be metaphyseal/epiphyseal. Option D is an oversimplification and often incorrect, as both can be addressed with osteotomies. Option E is incorrect as both are primarily frontal plane considerations in the context of this discussion.

Question 833

Topic: Total Hip Arthroplasty (THA)

In pre-operative planning for deformity correction, the Joint Line Convergence Angle (JLCA) is measured. What is its normal value, and what does an abnormally increased JLCA typically indicate?

. Normal is 0-2 degrees; increased indicates ligamentous laxity or cartilage loss
. Normal is 5-7 degrees; increased indicates bony deformity
. Normal is 0-2 degrees; increased indicates femoral shaft bowing
. Normal is 3-5 degrees; increased indicates rotational malalignment
. Normal is 8-10 degrees; increased indicates leg length discrepancy

Correct Answer & Explanation

. Normal is 0-2 degrees; increased indicates ligamentous laxity or cartilage loss

Explanation

The normal JLCA is 0 to 2 degrees. An increased JLCA suggests intra-articular pathology, such as asymmetric cartilage loss or collateral ligament laxity.

Question 834

Topic: 3. Adult Reconstruction (Hip & Knee)
Figures below show the radiographs obtained from an 86-year-old woman who has had chronic left hip pain for several years. She now uses a walker and a wheelchair for ambulation. She is medically healthy. What is the most appropriate surgical intervention?
. Cemented left total hip arthroplasty (THA)
. Cementless left THA with a proximally porous coated femoral stem
. Hybrid left THA
. Cementless left THA with a diaphyseal engaging conical femoral stem

Correct Answer & Explanation

. Hybrid left THA

Explanation

This 86-year-old woman has poor bone quality and osteoarthritis of the left hip. Her lateral radiograph confirms Dorr type C bone quality. A hybrid left THA with a cemented femoral stem would be the treatment of choice.

Question 835

Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old patient fell 3 weeks after undergoing a total hip arthroplasty using cementless fixation of the femoral component. She sustained a comminuted Vancouver type B-2 fracture with displacement of the calcar fragment. What is the best treatment option?
. Revision using a proximal femoral replacement prosthesis
. Revision using a diaphyseal engaging femoral prosthesis along with cerclage fixation
. Open reduction internal fixation using a locking plate with strut graft
. Protected weight bearing with abduction bracing

Correct Answer & Explanation

. Revision using a diaphyseal engaging femoral prosthesis along with cerclage fixation

Explanation

The patient has an acute postoperative fracture of the proximal femur with subsidence. It is also common that the stem retroverts relative to the femur. It is most often seen in proximally porous coated stems within 90 days of surgery. There is always a debate whether this is a missed intraoperative fracture, or a new fracture that has resulted from an event of increased hoop stresses. Removal of the primary stem, placement of a diaphyseal engaging stem (most frequently a tapered-fluted stem), and cabling of the fracture is the most successful treatment.

Question 836

Topic: Total Knee Arthroplasty (TKA)
A 47-year-old obese man with a body mass index of 42 comes into the office with left knee pain 1 year after undergoing an uncomplicated left medial unicompartmental knee arthroplasty (UKA). Radiographs show a loose tibial component in varus. What is the most appropriate next step to treat this failed construct?
. Aspiration of joint fluid to obtain a cell count
. Revision of the UKA using primary total knee arthroplasty (TKA) components
. Revision of the UKA using a revision TKA with augments
. Procurement of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level

Correct Answer & Explanation

. Procurement of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level

Explanation

DISCUSSION: This patient likely is experiencing failure of the UKA secondary to poor patient selection. In this young, heavy man, the component likely loosened due to the ongoing varus alignment of the knee and his elevated weight. Despite this likely scenario, the next step is determining whether an infection is the cause of his pain. Prior to obtaining an aspiration, the surgeon can order ESR and CRP studies to determine whether aspiration is warranted. If the laboratory studies are unremarkable, the surgeon likely can forgo the aspiration and proceed to a revision TKA with possible augments on standby.

Question 837

Topic: 3. Adult Reconstruction (Hip & Knee)

The best definitive treatment for this patientโ€™s left knee is

. total knee replacement.
. knee arthrodesis using an anterior plate and screws.
. knee arthrodesis using an external fixator.
. observation.

Correct Answer & Explanation

. observation.

Explanation

DISCUSSIONThis patient now has a major fixed flexion contracture and severe varus alignment and instability. Infection of the knee joint has to be ruled out. The radiograph shows all the hallmarks of Charcot arthropathy, including disintegration and fragmentation of the joint with major deformity. Infection of the knee joint and contiguous osteomyelitis still have to be ruled out. The clinical and radiographic findings are highly suggestive of a Charcot neurogenic arthropathy associated with uncontrolled diabetes. This patient is an unsuitable candidate for total knee arthroplasty (TKA) because he is noncompliant regarding his diabetes and has had a previously infected native joint that now is associated with Charcot arthropathy. He is nonambulatory. The failure rate of TKA or knee arthrodesis is extremely high in this setting. He will best be served with observation or amputation depending upon his symptom severity.

Question 838

Topic: 3. Adult Reconstruction (Hip & Knee)
A 52-year-old man has had groin and deep buttock pain for the past 2 months. Examination reveals that hip range of motion is mildly restricted, and he has pain with both weight bearing and at rest. An MRI scan is shown in Figure 28. Management should consist of
. protected weight bearing and anti-inflammatory drugs.
. core decompression of the femoral head.
. vascularized free fibular grafting to the femoral head.
. bipolar hemiarthroplasty of the hip.
. total hip arthroplasty.

Correct Answer & Explanation

. protected weight bearing and anti-inflammatory drugs.

Explanation

DISCUSSION: The MRI findings show highly increased signal through the entire femoral head and neck that is diagnostic of transient osteoporosis of the femoral head. This recently described entity is often seen in middle-aged men and should be treated nonsurgically with protected weight bearing and anti-inflammatory drugs. The natural history is that of self-resolution. REFERENCES: Guerra JJ, Steinberg ME: Distinguishing transient osteoporosis from avascular necrosis of the hip. J Bone Joint Surg Am 1995;77:616-624. Urbanski SR, de Lange EE, Eschenroeder HC Jr: Magnetic resonance imaging of transient osteoporosis of the hip: A case report. J Bone Joint Surg Am 1991;73:451-455.

Question 839

Topic: 3. Adult Reconstruction (Hip & Knee)

Figure 62 shows the radiograph of a 46-year-old man who has had increasing shoulder pain and diminishing motion over the last 10 years. Because his difficulties are severely impacting his quality of life, he is seeking advice and treatment options. Twenty five years ago, he underwent a shoulder stabilization procedure for recurrent shoulder dislocations. Examination reveals he can only elevate his arm to less than shoulder level and his external rotation is no more than 10 degrees. Management consisting of nonsteroidal anti-inflammatory drugs and intra-articular steroid injections has failed to provide relief. What is the most appropriate treatment recommendation? Review Topic

. Humeral head arthroplasty
. Total shoulder arthroplasty
. Reverse shoulder arthroplasty
. Arthroscopic debridement/capsular release
. Corticosteroid injection and physical therapy

Correct Answer & Explanation

. Total shoulder arthroplasty

Explanation

The patient has classic "arthritis of dislocation." Procedures done years ago were designed to enhance shoulder stability by limiting external rotation. However, it is now understood that limiting external rotation results in significant alteration of joint mechanics and kinematics, thus leading to the development of osteoarthritis. The average age of patients who developarthritis of dislocationis 45 years old. Despite the young age of these patients, total shoulder arthroplasty offers the most predictable improvement in pain and function. However, the patient must be made aware of the need to protect the arm from excessive loads to protect the glenoid implant. Because there is complete loss of articular cartilage and incongruent joint surfaces, there is no role for arthroscopic debridement and capsular release. Injections offer little, if any, chance of improvement with the prior history of nonresponse. Physical therapy predictably makes patients worse because loading the arthritic joint generates more pain. Reverse shoulder arthroplasty is reserved for elderly patients with severe rotator cuff deficiency. A humeral head arthroplasty, while potentially more ideal than a total shoulder arthroplasty because of glenoid concerns, would likely not offer pain relief in the face of the significant glenoid involvement and incongruity.

Question 840

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old woman had advanced right knee arthritis and total knee replacement was planned. She learned she had primary biliary cirrhosis at age 41 and now has advancing liver failure. Preoperative coagulation tests show a baseline International Normalized Ratio (INR) of 1.36. Appropriate methods to prevent thromboembolic disease as recommended by the 2011 AAOS Clinical Practice Guideline, Preventing Venous Thromboembolic Disease in Patients Undergoing Elective Hip and Knee Arthroplasty , include

. use of mechanical prophylaxis (eg, pneumatic calf compressors) while in the hospital.
. oral warfarin with a goal INR between 2.0 and 3.0.
. low-dose warfarin for 3 weeks postsurgically beginning 48 hours after surgery.
. no prophylaxis because this patient already is partially anticoagulated secondary to her liver disease.

Correct Answer & Explanation

. use of mechanical prophylaxis (eg, pneumatic calf compressors) while in the hospital.

Explanation

The 2011 AAOS Clinical Practice Guideline,Preventing Venous Thromboembolic Disease in Patients Undergoing Elective Hip and Knee Arthroplasty, recommends the use of mechanical prophylaxis for patients at increased risk for bleeding (including those with liver disease or hemophilia). This recommendation is the consensus of the workgroup that established these guidelines because there was insufficient evidence to justify a stronger recommendation in this clinical scenario. The other responses use no prophylaxis or pharmacological prophylaxis. Pharmacological prophylaxis is not recommended in patients who are at increased risk for bleeding.

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