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Lower Extremity Trauma MCQs

Practice Set 13 of 34

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

Question 241

Topic: Lower Extremity Trauma

A 68-year-old patient with a long-standing genu varum deformity is scheduled for a high tibial osteotomy. Preoperative radiographs confirm a significant varus deformity with a Mechanical Lateral Distal Femoral Angle (mLDFA) of 87°, a Medial Proximal Tibial Angle (MPTA) of 75°, and a Joint Line Convergence Angle (JLCA) of 4°. The surgeon plans to correct the deformity to restore neutral alignment. Based on these findings, what is the most appropriate interpretation of the patient's deformity?

. The primary deformity is in the distal femur, requiring a femoral osteotomy.
. The MPTA indicates a valgus deformity of the proximal tibia.
. The JLCA suggests significant intra-articular deformity or ligamentous laxity contributing to the malalignment.
. The mLDFA indicates a significant varus deformity of the distal femur.
. The patient's mechanical axis is likely passing lateral to the knee joint.

Correct Answer & Explanation

. The JLCA suggests significant intra-articular deformity or ligamentous laxity contributing to the malalignment.

Explanation

Correct Answer: CThe Joint Line Convergence Angle (JLCA) is measured at 4°. The normal range for JLCA is 0-2°. The case states: '>2° strongly suggests joint space narrowing or ligamentous instability.' A JLCA of 4° is significantly elevated, indicating a substantial intra-articular component to the deformity, likely due to medial compartment cartilage loss or medial collateral ligament laxity, which contributes to the overall varus alignment.Option A is incorrect:The mLDFA is 87°, which is within the normal range of 85-90°. This indicates no significant deformity in the distal femur. The MPTA of 75° (normal 85-90°) indicates a significant proximal tibial varus deformity, making the tibia the primary site of extra-articular deformity.Option B is incorrect:The MPTA is 75°. An MPTA <85° indicates varus, while >90° indicates valgus. Therefore, 75° indicates a varus deformity of the proximal tibia, not valgus.Option D is incorrect:The mLDFA of 87° is within the normal range (85-90°), indicating no significant varus deformity of the distal femur.Option E is incorrect:Genu varum (bow-legged) means the mechanical axis passes medial to the knee joint, overloading the medial compartment. If it passed lateral, it would indicate genu valgum.

Question 242

Topic: Lower Extremity Trauma

A 35-year-old male presents with a long-standing varus knee deformity and a 2 cm limb length discrepancy in the affected limb. Preoperative planning reveals a CORA located in the distal femoral metaphysis. The surgeon plans an acute correction using internal fixation. Based on Paley's principles and the patient's specific presentation, which osteotomy technique would be most appropriate?

. Closing wedge osteotomy with bone graft
. Neutral wedge osteotomy
. Closing wedge osteotomy without bone graft
. Opening wedge osteotomy with structural allograft
. Acute correction with intramedullary nailing and blocking screws

Correct Answer & Explanation

. Opening wedge osteotomy with structural allograft

Explanation

Correct Answer: DThe patient presents with a varus knee deformity and a concomitant 2 cm limb length discrepancy. The case content explicitly states that a primary advantage of anopening wedge osteotomyis that itincreases overall limb length, which is highly beneficial for patients presenting with a concomitant limb length discrepancy alongside their angular deformity. Since the CORA is in the distal femoral metaphysis, an opening wedge osteotomy at this site would allow for both angular correction and limb lengthening. The use of structural allograft is often necessary with internal fixation to bridge the created gap and provide initial stability, as mentioned in the disadvantages of opening wedge osteotomies with internal fixation.Option A (Closing wedge osteotomy with bone graft)is incorrect because closing wedge osteotomies inherently shorten the limb, which would exacerbate the existing limb length discrepancy. While bone graft can be used, it doesn't address the shortening.Option B (Neutral wedge osteotomy)is incorrect because it results in no net change in overall limb length, which would not address the 2 cm limb length discrepancy.Option C (Closing wedge osteotomy without bone graft)is incorrect for the same reason as option A; it shortens the limb, which is contraindicated in this patient.Option E (Acute correction with intramedullary nailing and blocking screws)is less appropriate for a metaphyseal deformity around the knee. While IM nailing can correct diaphyseal deformities, acute metaphyseal corrections with IM nails are challenging and often require specialized jigs or temporary external fixators (FAN). More importantly, IM nailing itself does not inherently lengthen the limb in the same controlled manner as an opening wedge osteotomy, and the primary issue here is addressing the limb length discrepancy.

Question 243

Topic: Lower Extremity Trauma

A 30-year-old patient with a congenital femoral bowing deformity is undergoing correction using an intramedullary nail. The preoperative radiographs show a significant diaphyseal curve. To ensure the straight IM nail corrects the deformity and does not follow the original curved canal, which technique, as described in the case, would be most appropriate?

. Performing a fixator-assisted nailing (FAN) procedure.
. Using a longer, larger diameter intramedullary nail.
. Placing blocking (Poller) screws strategically on the concave side of the deformity.
. Performing a closing wedge osteotomy prior to nail insertion.
. Utilizing a custom-bent intramedullary nail.

Correct Answer & Explanation

. Placing blocking (Poller) screws strategically on the concave side of the deformity.

Explanation

Correct Answer: CThe case content specifically addresses this scenario under "Intramedullary Nailing Techniques":"Because the IM canal in a deformed bone is much wider than the nail, a straight nail will often follow the path of least resistance, recreating the deformity. To guide a straight nail through a deformed bone segment and force it into the center of the canal,blocking screws are placed strategically into the cancellous bone on the concave side of the deformity. These screws physically block the nail from translating, ensuring the mechanical axis is maintained."This technique is precisely designed to prevent the recreation of the deformity when using a straight IM nail in a curved canal.Option A (Performing a fixator-assisted nailing (FAN) procedure)is incorrect. While FAN is a valid technique for acute correction with IM nailing, its primary purpose is to acutely obtain and rigidly hold the correctionbeforenail insertion, not specifically to guide a straight nail through a curved canal once the nail is being inserted. Blocking screws are usedduringnail insertion to guide it.Option B (Using a longer, larger diameter intramedullary nail)is incorrect. A larger diameter nail might fill the canal more, but it doesn't guarantee correction of the deformity if the canal is curved. A longer nail doesn't inherently guide it into a corrected path.Option D (Performing a closing wedge osteotomy prior to nail insertion)is incorrect. While an osteotomy is necessary for correction, performing a closing wedgepriorto nail insertion doesn't, by itself, ensure the nail will maintain the correction or prevent it from following the remaining curve. Blocking screws are still needed to guide the nail through the corrected segment.Option E (Utilizing a custom-bent intramedullary nail)is incorrect. The case content focuses on usingstraightIM nails and techniques to guide them. Custom-bent nails are not discussed as a primary strategy for deformity correction in this context.

Question 244

Topic: Lower Extremity Trauma

A 24-year-old male requires correction of a distal femur deformity. The CORA is located 1 cm from the articular surface. The surgeon places the hinge at the CORA to avoid joint penetration but performs the osteotomy 4 cm proximally. Based on Paley's rules, what is the expected mechanical outcome?

. A new translation deformity will be created, misaligning the mechanical axis.
. The mechanical axis will realign, but the osteotomy site will translate.
. The osteotomy site will close cleanly without any translation.
. Pure translation will occur without any angular correction.
. The joint line convergence angle will increase significantly.

Correct Answer & Explanation

. The mechanical axis will realign, but the osteotomy site will translate.

Explanation

Paley's Rule 2 states that if the hinge is placed at the CORA but the osteotomy is at a different level, the mechanical and anatomic axes will fully realign. However, translation will inherently occur at the osteotomy site to achieve this collinearity.

Question 245

Topic: Lower Extremity Trauma

A 50-year-old female presents with bilateral knee pain and clinical genu varum. Standing full-length radiographs show a mechanical axis deviation (MAD) of 40 mm medially on the right leg. The right mechanical lateral distal femoral angle (mLDFA) is 87 degrees (normal 85-90 degrees) and the medial proximal tibial angle (MPTA) is 76 degrees (normal 85-90 degrees). The joint line convergence angle (JLCA) is 1 degree. Where is the primary source of the varus deformity?

. The distal femur
. The knee joint due to lateral collateral ligament laxity
. The proximal tibia
. Combined femoral and tibial shaft deformities
. The femoral neck

Correct Answer & Explanation

. The proximal tibia

Explanation

The source of the mechanical axis deviation must be analyzed using joint orientation angles. An mLDFA of 87 degrees is normal, while an MPTA of 76 degrees is abnormally decreased, indicating that the varus deformity is isolated to the proximal tibia. The normal JLCA rules out intra-articular laxity.

Question 246

Topic: Lower Extremity Trauma

A 30-year-old patient is undergoing femoral lengthening with an external fixator. Radiographs at 5 weeks show an hourglass-shaped regenerate bone with widening of the radiolucent distraction gap. What is the most appropriate next step in management?

. Increase the daily rate of distraction.
. Perform immediate autologous bone grafting of the gap.
. Decrease the rate of distraction or perform temporary compression.
. Remove the external fixator and place a static intramedullary nail.
. Maintain the current protocol and re-evaluate in 4 weeks.

Correct Answer & Explanation

. Decrease the rate of distraction or perform temporary compression.

Explanation

An hourglass-shaped regenerate with a widening radiolucent gap indicates a hypotrophic regenerate, typically resulting from a distraction rate that is too fast for the bone biology. Management involves decreasing the distraction rate or applying temporary compression (accordion maneuver) to stimulate osteogenesis.

Question 247

Topic: Lower Extremity Trauma

A 45-year-old male presents with medial knee pain. Weight-bearing radiographs show a varus mechanical axis deviation (MAD) 30 mm medial to the knee center. Measurements reveal a Mechanical Lateral Distal Femoral Angle (mLDFA) of 88 degrees and a Medial Proximal Tibial Angle (MPTA) of 75 degrees. Where is the primary source of the structural deformity?

. Distal femur
. Proximal tibia
. Knee joint due to ligamentous laxity
. Both femur and tibia equally
. Proximal femur

Correct Answer & Explanation

. Proximal tibia

Explanation

The mLDFA is within normal limits (normal is roughly 87-88 degrees), indicating the distal femur is structurally normal. The MPTA is significantly decreased (normal is 87 degrees), correctly identifying the proximal tibia as the source of the varus deformity.

Question 248

Topic: Lower Extremity Trauma

During preoperative deformity planning for a patient with severe osteoarthritis and varus malalignment, the joint line convergence angle (JLCA) is measured at 6 degrees (normal is 0-2 degrees). What does an increased JLCA most likely indicate in this setting?

. A diaphyseal tibial angular deformity.
. A diaphyseal femoral angular deformity.
. An intra-articular deformity due to cartilage loss or ligamentous laxity.
. A fixed rotational malalignment of the tibia.
. Normal anatomic variation seen in aging adults.

Correct Answer & Explanation

. An intra-articular deformity due to cartilage loss or ligamentous laxity.

Explanation

The JLCA measures the angle between the articular surface of the distal femur and the articular surface of the proximal tibia. An increased JLCA typically reflects intra-articular pathology, such as asymmetric cartilage loss (osteoarthritis) or collateral ligament laxity.

Question 249

Topic: Lower Extremity Trauma

A 45-year-old male presents with symptomatic varus malalignment of the lower extremity. Full-length radiographs show a mechanical axis deviation (MAD) of 35 mm medial to the knee center. The mechanical lateral distal femoral angle (mLDFA) is 96 degrees, and the medial proximal tibial angle (MPTA) is 88 degrees. Where is the primary source of the deformity?

. Proximal tibia
. Distal femur
. Knee joint line (ligamentous laxity)
. Proximal femur
. Both distal femur and proximal tibia

Correct Answer & Explanation

. Distal femur

Explanation

The normal mLDFA is 88 degrees (range 85-90 degrees). An mLDFA of 96 degrees indicates a significant varus deformity originating in the distal femur. The MPTA of 88 degrees is within normal limits.

Question 250

Topic: Lower Extremity Trauma

A surgeon is planning a complex lower extremity osteotomy for a patient with significant combined angulation and rotational deformity. While clinical examination provides initial insights into the torsional profile, what is considered the 'gold standard' imaging modality for the most precise, objective quantification of rotation, and what specific landmarks are typically used?

. Full-length standing radiographs, measuring the angle between the mechanical axis and the joint line.
. MRI of the knee, assessing the orientation of the menisci relative to the femoral condyles.
. CT version study, measuring angles between the femoral neck, distal femoral condyles, proximal tibial plateau, and distal tibial plafond.
. Standard AP and lateral radiographs of the tibia, using the fibular head and malleoli as landmarks.
. Ultrasound of the lower extremity, evaluating muscle and tendon orientation.

Correct Answer & Explanation

. CT version study, measuring angles between the femoral neck, distal femoral condyles, proximal tibial plateau, and distal tibial plafond.

Explanation

Correct Answer: CThe case explicitly states, 'For the most precise, objective quantification of rotation, a CT version study is the gold standard. Specific axial slices are obtained through the femoral neck, the distal femoral condyles, the proximal tibial plateau, and the distal tibial plafond (ankle). By measuring the angles between these established bony landmarks, the surgeon can determine the exact degrees of femoral version and tibial torsion, removing all clinical guesswork.'Option A is incorrectbecause full-length standing radiographs are essential for assessing mechanical axis deviation and angular deformities, but they are not the gold standard for precise rotational quantification.Option B is incorrectbecause while MRI can show soft tissue and bony anatomy, it is not the gold standard for quantifying bone torsion in the way a CT version study is, nor are meniscal orientations the primary landmarks for this purpose.Option D is incorrectbecause standard 2D radiographs are prone to projection errors and cannot accurately quantify 3D rotational deformities.Option E is incorrectbecause ultrasound is not used for precise quantification of bone torsion.

Question 251

Topic: Lower Extremity Trauma

A 60-year-old patient presents with a distal femoral deformity. During preoperative planning, the surgeon measures the Mechanical Lateral Distal Femoral Angle (mLDFA) on a true AP view of the knee with the patella pointing forward. What is the normal range for the mLDFA, and what does it primarily define?

. 77-84 degrees; defines proximal tibia posterior slope.
. 85-90 degrees; defines distal femur valgus alignment.
. 0-2 degrees; assesses intra-articular deformity.
. 86-92 degrees; defines ankle alignment.
. 85-90 degrees; defines proximal tibia varus.

Correct Answer & Explanation

. 85-90 degrees; defines distal femur valgus alignment.

Explanation

Correct Answer: BThe table 'Joint Orientation Angles' in the case lists the Mechanical Lateral Distal Femoral Angle (mLDFA) with a normal value range of 85-90° (Avg 87°) and states its clinical significance as 'Defines distal femur valgus alignment. Crucial for knee joint congruency.'Option A is incorrectbecause 77-84 degrees is the normal range for the Posterior Proximal Tibial Angle (PPTA), which defines proximal tibia posterior slope.Option C is incorrectbecause 0-2 degrees is the normal range for the Joint Line Congruency Angle (JLCA), which assesses intra-articular deformity.Option D is incorrectbecause 86-92 degrees is the normal range for the Mechanical Lateral Distal Tibial Angle (mLDTA), which defines ankle alignment.Option E is incorrectbecause 85-90 degrees defines proximal tibia varus for the MPTA, not the mLDFA.

Question 252

Topic: Lower Extremity Trauma

A 55-year-old patient presents with knee pain and a varus deformity. Full-length standing radiographs reveal a Mechanical Lateral Distal Femoral Angle (mLDFA) of 92° and a Medial Proximal Tibial Angle (MPTA) of 80°. The Joint Line Convergence Angle (JLCA) is 1°. Based on these measurements and Dr. Paley's principles, where is the primary source of the angular deformity located?

. Primarily in the distal femur.
. Primarily in the proximal tibia.
. Equally distributed between the distal femur and proximal tibia.
. Primarily due to intra-articular cartilage loss.
. The deformity is likely in the proximal femur, not reflected by these angles.

Correct Answer & Explanation

. Primarily in the proximal tibia.

Explanation

Correct Answer: BThe case provides the normal values for joint orientation angles: mLDFA is 85° to 90° (Avg 88°), and MPTA is 85° to 90° (Avg 87°). The patient's mLDFA of 92° is within or very close to the normal range, indicating that the distal femur is not significantly in varus or valgus. However, the MPTA of 80° is significantly less than the normal range (85-90°). A decreased MPTA indicates a varus deformity of the proximal tibia. The JLCA of 1° is within the normal range (0-2°), suggesting no significant intra-articular deformity or cartilage loss contributing to the angular malalignment.Option A is incorrectbecause the mLDFA of 92° is within the normal range (85-90°), indicating no significant distal femoral deformity.Option C is incorrectbecause the MPTA is clearly abnormal while the mLDFA is normal, indicating the deformity is not equally distributed.Option D is incorrectbecause the JLCA of 1° is normal, ruling out significant intra-articular cartilage loss as the primary cause of the angular deformity.Option E is incorrectbecause mLDFA and MPTA specifically assess distal femoral and proximal tibial alignment. While proximal femoral deformities exist, these angles directly point to the knee region. The given values clearly indicate a proximal tibial issue.

Question 253

Topic: Lower Extremity Trauma

A 60-year-old patient undergoes a derotational osteotomy for a proximal femoral internal rotation deformity. The surgeon chooses to rotate the femur around its anatomic axis, as is often done with intramedullary nailing. Based on the unique biomechanics of femoral deformities and the provided diagram, what is the most likely immediate consequence of this surgical choice if no compensatory planning is performed?

. Perfect preservation of the limb's overall mechanical axis alignment.
. An iatrogenic valgus deformity of the entire limb.
. An iatrogenic varus deformity of the entire limb.
. Significant shortening of the femoral segment.
. Increased femoral neck anteversion.

Correct Answer & Explanation

. An iatrogenic valgus deformity of the entire limb.

Explanation

Correct Answer: BThe case explains: 'Because the anatomic axis is angled 5-7° relative to the mechanical axis, rotating the bone around its own medullary canal causes the offset femoral head to sweep through a large arc. This sweeping movement physically displaces the starting point of the mechanical axis medially or laterally, inducing a new, iatrogenic varus or valgus deformity.' The diagram (left side shows mechanical axis rotation, right side shows anatomic axis rotation) visually confirms this. Specifically, internal rotation (correcting retroversion) causes an 'apparent lengthening' of the femoral neck on AP radiograph, shifting the center of the femoral head medially. This medial shift of the femoral head's starting point for the mechanical axis will induce an iatrogenic valgus deformity of the entire limb.Option A is incorrectbecause perfect preservation of alignment only occurs when rotation is performed around the mechanical axis, not the anatomic axis, due to the divergence of these axes in the femur.Option C is incorrectbecause an iatrogenic varus deformity would result from external rotation (correcting anteversion), which causes an apparent shortening of the femoral neck and a lateral shift of the femoral head. The question specifies internal rotation deformity correction.Option D is incorrectbecause rotation primarily affects angular alignment and projectional length, not actual bone shortening, unless there's a specific osteotomy design for lengthening/shortening.Option E is incorrectbecause the surgery iscorrectingan internal rotation deformity, which implies reducing retroversion or excessive internal rotation. The goal is to normalize anteversion, not increase it.

Question 254

Topic: Lower Extremity Trauma

A 48-year-old patient presents with a combined femoral deformity requiring both angular and rotational correction. As part of the 'Definitive Preoperative Planning Protocol,' the surgeon obtains a 'Patella Forward Radiograph' (Knee Forward View). What is the primary and most accurate information derived from this specific radiographic view?

. The true, post-correction projection of the femoral neck and the accurate, final location of the femoral head center.
. The precise three-dimensional location of the Center of Rotation of Angulation (CORA) without rotational distortion.
. The most accurate depiction of the distal femur's joint orientation (mLDFA) and the true angular deformity at the knee joint.
. The exact amount of femoral anteversion or retroversion.
. The true mechanical axis deviation (MAD) of the entire limb, unaffected by rotation.

Correct Answer & Explanation

. The most accurate depiction of the distal femur's joint orientation (mLDFA) and the true angular deformity at the knee joint.

Explanation

Correct Answer: CThe case describes the 'Patella Forward Radiograph (Knee Forward View)' as: 'This is the standard AP view, taken with the patient's patella facing directly forward, regardless of where the foot is pointing. This view provides the most accurate depiction of the distal femur's joint orientation (mLDFA) and the true angular deformity at the knee joint. However, because of the torsion, it shows the proximal femur in its rotationally deformed, projected state.'Option A is incorrectbecause this information is derived from the 'Hip Forward Radiograph,' not the Patella Forward view.Option B is incorrectbecause the Patella Forward view shows the proximal femur in its rotationally deformed state, which distorts the apparent CORA. The true CORA requires factoring in rotational correction.Option D is incorrectbecause a single 2D AP radiograph (Patella Forward or otherwise) cannot accurately measure femoral anteversion/retroversion; specialized CT scans or dedicated rotational views are needed for that.Option E is incorrectbecause the Patella Forward view shows the proximal femur in its rotationally deformed state, which means the starting point of the mechanical axis (femoral head center) is projectionally shifted, rendering the MAD calculation from this view alone inaccurate for combined deformities.

Question 255

Topic: Lower Extremity Trauma

In assessing a patient's sagittal plane deformity, the posterior distal femoral angle (PDFA) is measured on a lateral radiograph. What is the normal average value of the anatomic PDFA?

. 75 degrees
. 83 degrees
. 90 degrees
. 97 degrees
. 105 degrees

Correct Answer & Explanation

. 83 degrees

Explanation

The normal anatomic posterior distal femoral angle (aPDFA) is approximately 83 degrees. An angle significantly greater or lesser than this indicates a flexion or extension deformity of the distal femur.

Question 256

Topic: Lower Extremity Trauma

A 45-year-old female presents with knee pain and a valgus deformity. During preoperative planning on a long-leg alignment film, the mechanical lateral distal femoral angle (mLDFA) is measured. What is the generally accepted normal value for the mLDFA?

. 81 degrees
. 84 degrees
. 88 degrees
. 93 degrees
. 97 degrees

Correct Answer & Explanation

. 88 degrees

Explanation

The normal mechanical lateral distal femoral angle (mLDFA) is approximately 88 degrees (range 85-90 degrees). Values lower than 85 degrees typically indicate a valgus deformity of the distal femur.

Question 257

Topic: Lower Extremity Trauma

A patient with advanced medial compartment knee osteoarthritis and a varus thrust has a long-leg radiograph showing significant mechanical axis deviation. The Joint Line Convergence Angle (JLCA) is measured at 6 degrees. What does this specific finding indicate?

. A purely diaphyseal tibial deformity
. Intra-articular deformity due to cartilage loss or ligamentous laxity
. A normal physiologic variant
. A compensatory valgus deformity of the distal femur
. A rotational malalignment of the lower extremity

Correct Answer & Explanation

. Intra-articular deformity due to cartilage loss or ligamentous laxity

Explanation

The JLCA measures the angle between the distal femoral and proximal tibial articular surfaces. A normal JLCA is 0-2 degrees; an increased angle like 6 degrees indicates an intra-articular source of deformity, such as asymmetric cartilage wear or collateral ligament laxity.

Question 258

Topic: Lower Extremity Trauma

During preoperative standing long-leg radiograph evaluation for a varus knee, the Joint Line Convergence Angle (JLCA) is measured. The normal JLCA is typically 0 to 2 degrees. A patient with a severe varus deformity has a JLCA measuring 7 degrees, diverging laterally. What does this abnormal JLCA primarily indicate?

. Isolated extra-articular diaphyseal tibial bowing
. Compensatory valgus deformity of the distal femur
. Intra-articular deformity, cartilage loss, or collateral ligament laxity
. A failed prior high tibial osteotomy
. An excessively anterior CORA

Correct Answer & Explanation

. Intra-articular deformity, cartilage loss, or collateral ligament laxity

Explanation

The JLCA measures the convergence of the distal femoral and proximal tibial articular surfaces. An increased JLCA indicates intra-articular pathology such as asymmetric cartilage loss (osteoarthritis) or lateral collateral ligament laxity in a varus knee.

Question 259

Topic: Lower Extremity Trauma

A 30-year-old patient has a prominent lateral thrust during gait. Radiographic analysis reveals a mechanical axis deviation (MAD) significantly medial to the knee center. The mechanical lateral distal femoral angle (mLDFA) is calculated. What is the generally accepted normal population average for the mLDFA?

. 75 degrees
. 80 degrees
. 88 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 88 degrees

Explanation

The normal mechanical lateral distal femoral angle (mLDFA) is consistently reported as 88 degrees (range 85-90 degrees). Values significantly higher than this indicate a valgus deformity of the distal femur, while lower values indicate varus.

Question 260

Topic: Lower Extremity Trauma

When evaluating a patient for sagittal plane tibial deformity, the proximal posterior tibial angle (PPTA) is assessed on the lateral radiograph. Which of the following represents the normal average value for the PPTA?

. 71 degrees
. 81 degrees
. 91 degrees
. 101 degrees
. 111 degrees

Correct Answer & Explanation

. 81 degrees

Explanation

The normal average proximal posterior tibial angle (PPTA) is 81 degrees, which corresponds to the normal posterior slope of the tibial plateau of approximately 9 degrees relative to the tibial anatomic axis.

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