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8. Foot and Ankle MCQs

Practice Set 73 of 353

This practice set contains high-yield board review questions covering key concepts in 8. Foot and Ankle. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1441

Topic: 8. Foot and Ankle

According to Paley's principles for lower limb deformity analysis, which of the following best defines the overall limb mechanical axis?

. A line connecting the center of the femoral head to the center of the knee joint.
. A line connecting the center of the knee joint to the center of the ankle joint.
. A continuous straight line running from the center of the femoral head directly to the center of the ankle.
. The mid-diaphyseal line of the femur and tibia.
. A line drawn parallel to the ground, passing through the knee joint.

Correct Answer & Explanation

. A continuous straight line running from the center of the femoral head directly to the center of the ankle.

Explanation

Correct Answer: CThe text clearly defines the overall limb mechanical axis: 'Overall Limb Mechanical Axis: The single most important reference line in deformity correction, running continuously from the center of the femoral head directly to the center of the ankle.'Option A (Femoral mechanical axis):This defines thefemoralmechanical axis, not theoverall limbmechanical axis.Option B (Tibial mechanical axis):This defines thetibialmechanical axis, not theoverall limbmechanical axis.Option C (Continuous line from femoral head to ankle):Correct. This is the precise definition of the overall limb mechanical axis.Option D (Mid-diaphyseal line):This describes theanatomic axisof the bones, not the mechanical axis.Option E (Parallel to the ground):Incorrect. The mechanical axis is a vertical line of force, not necessarily parallel to the ground, and its position relative to the knee is key.

Question 1442

Topic: 8. Foot and Ankle

A 35-year-old patient undergoes an Ilizarov tibial lengthening procedure. During the distraction phase, the patient develops a progressive equinus contracture of the ankle despite aggressive physical therapy. Which anatomical structure's relative shortening is the primary cause of this complication?

. Tibialis anterior
. Soleus
. Gastrocnemius
. Flexor hallucis longus
. Extensor digitorum longus

Correct Answer & Explanation

. Gastrocnemius

Explanation

The gastrocnemius crosses both the knee and the ankle joints, making it highly susceptible to contracture during tibial lengthening. As the tibia is lengthened, the gastrocnemius becomes relatively tight, pulling the ankle into equinus and the knee into flexion.

Question 1443

Topic: 8. Foot and Ankle

You are planning a proximal tibial osteotomy for a severe valgus deformity (20 degrees) in a 24-year-old female. Which concomitant prophylactic procedure is strongly recommended during the surgical correction to prevent a major postoperative complication?

. Tarsal tunnel release
. Prophylactic anterior compartment fasciotomy
. Common peroneal nerve decompression
. Achilles tendon lengthening
. Prophylactic posterior tibial artery bypass

Correct Answer & Explanation

. Common peroneal nerve decompression

Explanation

Significant valgus corrections of the proximal tibia (typically >15 degrees) place the common peroneal nerve at high risk for traction injury. Prophylactic decompression of the common peroneal nerve at the fibular neck is strongly recommended in these scenarios.

Question 1444

Topic: 8. Foot and Ankle

On a full-length, weight-bearing AP radiograph of the lower extremities, the mechanical axis line is drawn from the center of the femoral head to the center of the ankle plafond. The surgeon notes this line passes 20 mm medial to the center of the knee joint. What does this measurement objectively represent?

. Normal physiological alignment
. Varus mechanical axis deviation (MAD)
. Valgus mechanical axis deviation (MAD)
. Pathologic procurvatum deformity
. Pathologic recurvatum deformity

Correct Answer & Explanation

. Varus mechanical axis deviation (MAD)

Explanation

Mechanical axis deviation (MAD) is determined by the position of the mechanical axis line relative to the center of the knee. When the line passes medial to the knee center, it indicates a varus MAD.

Question 1445

Topic: 8. Foot and Ankle

A 45-year-old patient presents with an untreated diaphyseal varus deformity of the femur from a childhood injury. Over several decades, which compensatory coronal plane deformity is most likely to develop in the tibia to maintain a horizontal ankle joint line?

. Distal femoral valgus
. Proximal tibial varus
. Proximal tibial valgus
. Distal tibial varus
. Proximal femoral varus

Correct Answer & Explanation

. Proximal tibial valgus

Explanation

To compensate for a varus femoral deformity and keep the ground-foot relationship horizontal, the body naturally develops a compensatory valgus deformity in the proximal tibia. This maintains the overall mechanical axis orientation, albeit with a non-horizontal knee joint line.

Question 1446

Topic: 8. Foot and Ankle

A patient is undergoing an 8 cm lengthening of the tibia using an external fixator. To prevent the most common soft-tissue complication associated with this specific procedure, which prophylactic measure is most often required?

. Prophylactic complete fasciotomy
. Prophylactic peroneal nerve decompression
. Gastrocnemius-soleus lengthening or rigid splinting of the foot in neutral
. Hamstring lengthening
. Anterior tibial artery bypass

Correct Answer & Explanation

. Gastrocnemius-soleus lengthening or rigid splinting of the foot in neutral

Explanation

Equinus contracture is the most common soft-tissue complication during tibial lengthening due to the resistance of the Achilles tendon. Prophylactic splinting or percutaneous tendo-Achilles lengthening is often necessary.

Question 1447

Topic: 8. Foot and Ankle

A 28-year-old male with an uncorrected malunion of a midshaft tibial fracture exhibits a 20-degree procurvatum deformity (apex anterior). Based on Paley's principles of sagittal plane alignment, what long-term compensatory mechanism is most likely to develop to maintain a plantigrade foot during the stance phase of gait?

. Compensatory genu recurvatum
. Fixed ankle dorsiflexion contracture
. Compensatory ankle equinus (plantarflexion)
. Genu varum thrust
. Fixed hip extension contracture

Correct Answer & Explanation

. Compensatory ankle equinus (plantarflexion)

Explanation

In a tibial procurvatum deformity, the distal tibial articular surface is tilted posteriorly. To achieve a plantigrade foot, the patient must plantarflex the ankle, which frequently leads to an adaptive equinus contracture over time.

Question 1448

Topic: 8. Foot and Ankle

A surgeon is planning a proximal tibial osteotomy and application of a circular external fixator for a complex multiplanar tibial deformity. A concurrent fibular osteotomy is required. To minimize the risk of common peroneal nerve injury while preserving the integrity of the distal tibiofibular syndesmosis, at which anatomic level should the fibular osteotomy optimally be performed?

. Fibular neck
. Proximal metaphyseal-diaphyseal junction
. Junction of the middle and distal thirds of the fibular diaphysis
. Within 2 cm of the ankle joint line
. Trans-syndesmotic level

Correct Answer & Explanation

. Junction of the middle and distal thirds of the fibular diaphysis

Explanation

Performing the fibular osteotomy at the junction of the middle and distal thirds minimizes the risk of injuring the common peroneal nerve proximally. It also safely avoids disrupting the distal tibiofibular syndesmosis.

Question 1449

Topic: 8. Foot and Ankle

A radiology technician, unaware of Paley's principles, positions a patient with known internal tibial torsion for a full-length standing AP radiograph by ensuring the patient's feet point straight ahead. Based on the provided case and the diagram below, what is the most likely consequence of this positioning error?

. A. The patella will appear perfectly centered, providing an accurate AP view of the knee.
. B. The radiograph will accurately reflect the patient's true coronal plane alignment.
. C. The knee will be forced into internal rotation, resulting in a 'squinting patella' and a false radiographic image.
. D. The mechanical axis deviation (MAD) will be underestimated, leading to an undercorrection.
. E. The joint orientation angles will be overestimated, leading to an overcorrection.

Correct Answer & Explanation

. C. The knee will be forced into internal rotation, resulting in a 'squinting patella' and a false radiographic image.

Explanation

Correct Answer: CThe text explicitly states: "The most common error in radiography suites is positioning the patient with their feet pointing straight ahead... this technique completely ignores underlying tibial or femoral torsion, projecting a distorted 2D image of a 3D problem." It further elaborates, "consider the classic presentation of a patient with internal tibial torsion. When such a patient's foot is forced forward, the patella inevitably faces outward." The diagram (a) clearly shows a patient with internal tibial torsion positioned with feet forward, resulting in the knee being internally rotated and the patella 'squinting' (facing outward/inward depending on perspective, but not centered). This creates a false radiographic image.Incorrect Options:A. The patella will appear perfectly centered, providing an accurate AP view of the knee:This is incorrect. As described, the patella will appear 'squinting' or facing outward due to the forced internal rotation of the knee.B. The radiograph will accurately reflect the patient's true coronal plane alignment:This is the opposite of what the text states. The image will be distorted, leading to inaccurate measurements.D. The mechanical axis deviation (MAD) will be underestimated, leading to an undercorrection:While incorrect positioning will lead to inaccurate MAD measurements, the specific direction of error (underestimation or overestimation) is complex and depends on the exact nature and degree of torsion and how it projects. The primary and most direct consequence described is the distorted image and 'squinting patella'.E. The joint orientation angles will be overestimated, leading to an overcorrection:Similar to option D, while joint orientation angles will be inaccurate, the specific direction of error is not directly stated as a primary consequence in the text, which focuses on the 'false radiographic image' and 'squinting patella'.

Question 1450

Topic: 8. Foot and Ankle

A 55-year-old female with a history of childhood rickets presents for evaluation of severe genu varum. Her physical exam reveals significant internal tibial torsion. To obtain a true AP standing radiograph of her knee, which method, as depicted in the diagram below, is most reliable?

. A. Instructing the patient to stand with her feet pointing straight ahead, parallel to the cassette, as shown in figure (a).
. B. Visually aligning the patient's feet to ensure they are externally rotated to compensate for the internal tibial torsion.
. C. Using tactile feedback to palpate the patella and rotating the limb until the patella is centered and pointing forward, as shown in figure (b).
. D. Positioning the patient in a supine position to eliminate gravitational effects on alignment.
. E. Obtaining a computed tomography (CT) scan instead of a radiograph to bypass positioning errors.

Correct Answer & Explanation

. C. Using tactile feedback to palpate the patella and rotating the limb until the patella is centered and pointing forward, as shown in figure (b).

Explanation

Correct Answer: CThe text explicitly states: "The only reliable method to achieve the knee forward position, especially in the presence of torsion, is through tactile feedback. Visual alignment of the foot is misleading and must be completely abandoned." Figure (b) in the diagram illustrates this by showing the clinician using tactile feedback to palpate the patella and rotating the limb until the patella is centered and pointing forward, achieving a true AP view irrespective of the foot's final position.Incorrect Options:A. Instructing the patient to stand with her feet pointing straight ahead, parallel to the cassette, as shown in figure (a):Figure (a) demonstrates theincorrectmethod, which leads to a 'squinting patella' and a false radiographic image, especially with internal tibial torsion.B. Visually aligning the patient's feet to ensure they are externally rotated to compensate for the internal tibial torsion:The text warns that "Visual alignment of the foot is misleading and must be completely abandoned." Relying on visual foot alignment, even with an attempt to compensate, is unreliable.D. Positioning the patient in a supine position to eliminate gravitational effects on alignment:While supine radiographs can be useful for other purposes, the text emphasizes the need for astandingradiograph to assess weight-bearing alignment, which is crucial for deformity correction.E. Obtaining a computed tomography (CT) scan instead of a radiograph to bypass positioning errors:While CT can provide 3D information, the case specifically focuses on theradiographicanalysis for coronal plane deformity correction and the critical importance of a true AP standing radiograph. CT is not presented as a replacement for this specific initial step in the context of Paley's principles for coronal plane analysis.

Question 1451

Topic: 8. Foot and Ankle

A 42-year-old patient with significant internal tibial torsion is correctly positioned for a true AP knee radiograph using tactile feedback to ensure the patella is centered and pointing forward. Based on the case description, what would be the expected appearance of the patient's foot position in this scenario?

. A. The foot will point straight ahead, parallel to the imaging cassette.
. B. The foot will point outward (externally rotated).
. C. The foot will point inward (internally rotated).
. D. The foot position is irrelevant and cannot be predicted.
. E. The foot will be dorsiflexed to a neutral position.

Correct Answer & Explanation

. C. The foot will point inward (internally rotated).

Explanation

Correct Answer: CThe text directly addresses this scenario: "To truly understand this, consider the classic presentation of a patient with internal tibial torsion. When such a patient's foot is forced forward, the patella inevitably faces outward. Conversely, if the patella is correctly oriented facing forward, the foot will point inward." Therefore, with internal tibial torsion, if the patella is correctly oriented forward, the foot will point inward (internally rotated).Incorrect Options:A. The foot will point straight ahead, parallel to the imaging cassette:This would be the case if there were no torsion, or if the foot was forced into this position, which would then cause the patella to face outward (squinting).B. The foot will point outward (externally rotated):This would be expected in a patient with external tibial torsion if the patella is correctly oriented forward.D. The foot position is irrelevant and cannot be predicted:The text explicitly states the predictable relationship between patella orientation and foot position in the presence of torsion.E. The foot will be dorsiflexed to a neutral position:Foot dorsiflexion/plantarflexion is a different plane of motion and not directly related to the rotational alignment discussed for the true AP view.

Question 1452

Topic: 8. Foot and Ankle

A 60-year-old patient with a complex rotational deformity of the femur undergoes a full-length standing AP radiograph where the technician inadvertently positions the patient with their feet pointing straight ahead. Which of the following measurements, crucial for deformity correction, would be most directly and significantly compromised by this positioning error?

. A. Ankle-foot angle (AFA)
. B. Tibial torsion angle
. C. Mechanical Axis Deviation (MAD)
. D. Patellar height (Insall-Salvati ratio)
. E. Sagittal plane alignment (e.g., posterior tibial slope)

Correct Answer & Explanation

. C. Mechanical Axis Deviation (MAD)

Explanation

Correct Answer: CThe text emphasizes that incorrect positioning (feet pointing straight ahead, ignoring torsion) projects a "distorted 2D image of a 3D problem." This distortion directly impacts the perceived coronal plane alignment. The Mechanical Axis Deviation (MAD) is a primary measurement of coronal plane alignment, representing the deviation of the mechanical axis from the center of the knee. If the knee is rotated (e.g., internally rotated due to torsion when feet are forced forward), the projected image of the femur and tibia will be altered, leading to an inaccurate MAD measurement. The text specifically mentions MAD as one of the core concepts requiring accurate imaging.Incorrect Options:A. Ankle-foot angle (AFA):While foot position is involved, the AFA is a measure of foot rotation relative to the ankle, and while it might be influenced, the primary impact of knee rotation on a full-length AP film is on the overall limb alignment, particularly MAD.B. Tibial torsion angle:Tibial torsion is a rotational deformity measured in the axial plane, typically using CT or clinical examination. A standard AP radiograph, even a true one, is not the primary tool for directly measuring tibial torsion angle. The positioning errorresults fromunaddressed torsion but doesn't directly compromise the measurement of the torsion angle itself on an AP film.D. Patellar height (Insall-Salvati ratio):Patellar height is measured on a lateral radiograph of the knee, not a standing AP view.E. Sagittal plane alignment (e.g., posterior tibial slope):Sagittal plane measurements are primarily assessed on lateral radiographs. The positioning error discussed pertains to the coronal (AP) plane.

Question 1453

Topic: 8. Foot and Ankle

The case highlights that the entire framework of coronal plane deformity analysis rests on a single, non-negotiable image. What specific type of radiograph is this, and what is its primary purpose in the context of Paley's principles?

. A. A lateral standing radiograph of the knee, primarily for assessing patellar height and sagittal alignment.
. B. A full-length standing anteroposterior (AP) radiograph, essential for accurate measurement of alignment and joint orientation.
. C. A stress radiograph of the ankle, used to evaluate ligamentous stability.
. D. A skyline view of the patella, for assessing patellofemoral tracking.
. E. A computed tomography (CT) scanogram, for precise limb length discrepancy measurement.

Correct Answer & Explanation

. B. A full-length standing anteroposterior (AP) radiograph, essential for accurate measurement of alignment and joint orientation.

Explanation

Correct Answer: BThe text explicitly states: "The entire framework of coronal plane deformity analysis rests on a single, non-negotiable image: the true anteroposterior (AP) standing radiograph." It further clarifies that this allows for "accurate measurement of alignment and joint orientation."Incorrect Options:A. A lateral standing radiograph of the knee, primarily for assessing patellar height and sagittal alignment:While important, the text specifies theAPview as the foundation forcoronal planeanalysis.C. A stress radiograph of the ankle, used to evaluate ligamentous stability:This is a specialized view for ankle stability, not the foundational image for overall lower limb coronal deformity analysis.D. A skyline view of the patella, for assessing patellofemoral tracking:This view is specific to patellofemoral pathology and not the primary image for global limb alignment.E. A computed tomography (CT) scanogram, for precise limb length discrepancy measurement:While CT scanograms are excellent for limb length, the text emphasizes theradiographfor coronal plane deformity analysis and the importance of correct positioning for accurate alignment and joint orientation measurements, which are distinct from just length.

Question 1454

Topic: 8. Foot and Ankle

The case emphasizes that "Visual alignment of the foot is misleading and must be completely abandoned" when attempting to achieve the knee forward position. What is the primary reason for this directive?

. A. Patients often have varying shoe sizes, which can distort visual cues.
. B. Underlying tibial or femoral torsion can cause the foot to point in a direction that does not reflect the true frontal plane of the knee.
. C. The imaging cassette may not be perfectly parallel to the floor, leading to parallax errors.
. D. Radiologists prefer tactile feedback for consistency across different technicians.
. E. Visual alignment is too time-consuming in a busy radiology suite.

Correct Answer & Explanation

. B. Underlying tibial or femoral torsion can cause the foot to point in a direction that does not reflect the true frontal plane of the knee.

Explanation

Correct Answer: BThe text explicitly states: "The most common error in radiography suites is positioning the patient with their feet pointing straight ahead. While seemingly logical to a technician, this technique completely ignores underlying tibial or femoral torsion, projecting a distorted 2D image of a 3D problem." It then follows with "Visual alignment of the foot is misleading and must be completely abandoned." The reason is that the foot's orientation does not reliably indicate the knee's true frontal plane in the presence of torsion.Incorrect Options:A. Patients often have varying shoe sizes, which can distort visual cues:While shoe size might be a minor factor, it's not the primary anatomical reason cited for abandoning visual foot alignment.C. The imaging cassette may not be perfectly parallel to the floor, leading to parallax errors:Cassette alignment is important, but it's a separate issue from the patient's rotational positioning relative to their own anatomy.D. Radiologists prefer tactile feedback for consistency across different technicians:While consistency is a benefit, the primary reason given is the anatomical inaccuracy of visual foot alignment in the presence of torsion, not just preference.E. Visual alignment is too time-consuming in a busy radiology suite:The text implies that visual alignment iseasierbutincorrect, not necessarily more time-consuming than tactile feedback. The emphasis is on accuracy, not speed.

Question 1455

Topic: 8. Foot and Ankle

A surgeon is planning a corrective osteotomy for a patient with a significant lower extremity deformity. The resident presents a standard AP radiograph of the knee and a separate AP radiograph of the hip, taken individually.

According to the case, what is the gold standard radiographic study required for accurate deformity analysis and planning using Paley's principles?

. A standard AP and lateral radiograph of the affected joint.
. A CT scan with 3D reconstruction of the entire limb.
. A 51-inch standing anteroposterior (AP) radiograph of the lower extremities, capturing the entire limb from iliac crests to ankle plafond.
. A bilateral weight-bearing MRI of the knees.
. A non-weight-bearing full-length radiograph to avoid joint compression artifacts.

Correct Answer & Explanation

. A 51-inch standing anteroposterior (AP) radiograph of the lower extremities, capturing the entire limb from iliac crests to ankle plafond.

Explanation

Correct Answer: CThe case explicitly states: 'The gold standard in deformity analysis is the 51-inch standing anteroposterior (AP) radiograph of the lower extremities. This "long-leg" film must capture the entire limb—from the top of the iliac crests and femoral heads down to the ankle plafond—in a single, weight-bearing view.' This comprehensive view is essential for accurately assessing the overall mechanical axis and joint orientation angles across the entire limb, which cannot be achieved with isolated joint films or non-weight-bearing studies.

Question 1456

Topic: 8. Foot and Ankle

A 55-year-old male presents with genu varum. The radiology technician obtains a full-length radiograph, but the patient's patella is internally rotated, and the film cuts off the distal tibia and ankle joint. The resident attempts to measure angles from this image.

Based on Paley's principles, what is the most likely consequence of planning an osteotomy using this improperly positioned and incomplete radiograph?

. The mechanical axis deviation will be underestimated, leading to undercorrection.
. The joint orientation angles will be accurately measured despite the rotation.
. The surgical calculations will be entirely invalid, potentially leading to unpredictable outcomes and iatrogenic deformities.
. Only the sagittal plane deformity will be affected, while frontal plane measurements remain reliable.
. The osteotomy can still be accurately planned by estimating the missing segments.

Correct Answer & Explanation

. The surgical calculations will be entirely invalid, potentially leading to unpredictable outcomes and iatrogenic deformities.

Explanation

Correct Answer: CThe case emphasizes the 'Radiographic Imperative: Garbage In, Garbage Out,' stating, 'Without a high-quality, properly positioned image, any subsequent measurements, angles, or surgical calculations are entirely invalid.' Improper positioning (patellar rotation) distorts joint orientation and axis measurements, and an incomplete film (missing ankle) prevents accurate assessment of the overall mechanical axis. Using such a flawed image for planning will inevitably lead to errors, unpredictable surgical outcomes, and potentially new, iatrogenic deformities, as was common in the pre-Paley era of subjective assessment.

Question 1457

Topic: 8. Foot and Ankle

A resident is reviewing a series of radiographs for a patient with a lower extremity deformity. They need to select the appropriate image for comprehensive Paley-style analysis.

Which of the following images best represents the "gold standard" radiograph for comprehensive lower extremity deformity analysis as described in the case?

. The image provided above.
. A standard AP view of the knee only.
. A lateral view of the entire femur.
. A non-weight-bearing AP view of the hip and knee.
. A standard AP view of the hip only.

Correct Answer & Explanation

. The image provided above.

Explanation

Correct Answer: AThe case defines the gold standard as a '51-inch standing anteroposterior (AP) radiograph of the lower extremities' that 'must capture the entire limb—from the top of the iliac crests and femoral heads down to the ankle plafond—in a single, weight-bearing view.' The image provided (Option A) clearly depicts a full-length standing AP radiograph of the entire lower extremity, from the pelvis to the ankles, which is precisely what is required for comprehensive deformity analysis. Options B, C, D, and E describe incomplete or improperly positioned radiographs that would not allow for accurate assessment of the overall mechanical axis and joint orientation angles across the entire limb.

Question 1458

Topic: 8. Foot and Ankle

A patient with a suspected lower extremity malalignment has a full-length radiograph taken while lying supine. The surgeon reviews the image and notes that the mechanical axis appears to pass through the center of the knee.

Why is a standing, weight-bearing radiograph crucial for accurate deformity analysis, even if a supine full-length film is obtained?

. Weight-bearing views are primarily used for sagittal plane analysis, not frontal.
. Supine films provide a more accurate representation of true bone length.
. Weight-bearing reveals the true load-bearing axis and any dynamic joint line changes or ligamentous laxity that contribute to malalignment under physiological stress.
. Non-weight-bearing films are preferred for assessing joint orientation angles.
. Standing films are only necessary for assessing foot and ankle deformities.

Correct Answer & Explanation

. Weight-bearing reveals the true load-bearing axis and any dynamic joint line changes or ligamentous laxity that contribute to malalignment under physiological stress.

Explanation

Correct Answer: CThe case emphasizes that the '51-inch standing anteroposterior (AP) radiograph of the lower extremities' must be a 'weight-bearing view.' It also defines malalignment as a deviation of the limb's overall mechanical axis where 'The load-bearing line of the leg does not pass through the center of the knee.' A supine film does not replicate the physiological loading conditions. Weight-bearing allows for the assessment of the true mechanical axis under load, revealing any dynamic changes in joint alignment, joint space narrowing due to cartilage loss, or ligamentous laxity that might not be apparent in a non-weight-bearing state. These factors are crucial for understanding the true extent and nature of the malalignment and planning an effective correction.

Question 1459

Topic: 8. Foot and Ankle

When obtaining standard long-leg radiographs to assess an oblique plane deformity for software-based correction, what is the most critical radiographic positioning parameter?

. Patella-forward positioning regardless of foot position
. Foot-forward positioning regardless of patella position
. 10 degrees of internal rotation of the beam
. Beam centered exactly on the mid-diaphysis
. Weight-bearing without a magnification marker

Correct Answer & Explanation

. Patella-forward positioning regardless of foot position

Explanation

A true AP radiograph of the lower extremity requires the patella to be pointing straight forward. Foot positioning will reflect any torsional deformity, but patella-forward guarantees standard assessment of the knee.

Question 1460

Topic: 8. Foot and Ankle

A 45-year-old female presents with knee pain and a suspected frontal plane deformity. You perform a Malalignment Test on a full-length standing AP radiograph. What is the normal location of the mechanical axis line (center of femoral head to center of ankle) relative to the knee joint center?

. Exactly through the center of the knee joint
. 8 mm medial to the center of the knee joint
. 15 mm medial to the center of the knee joint
. 8 mm lateral to the center of the knee joint
. 15 mm lateral to the center of the knee joint

Correct Answer & Explanation

. 8 mm medial to the center of the knee joint

Explanation

In a normal lower limb, the mechanical axis line passes approximately 8 mm medial to the center of the knee joint. This places slightly more physiologic weight-bearing stress on the medial compartment compared to the lateral.

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