This practice set contains high-yield board review questions covering key concepts in 2. Trauma. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 2961
Topic: 2. Trauma
A patient undergoes correction of a severe multi-planar tibial deformity using a Taylor Spatial Frame (TSF). The software program requires the input of specific variables. Which of the following sets of parameters must be defined to utilize the TSF software correctly?
Correct Answer & Explanation
. Deformity parameters, frame parameters, and mounting parameters.
Explanation
The Taylor Spatial Frame relies on a computerized algorithm that computes strut adjustments based on three crucial sets of data: deformity parameters, frame parameters (ring sizes/strut types), and mounting parameters (how the reference ring is mounted relative to the bone).
Question 2962
Topic: 2. Trauma
A surgeon is evaluating a 55-year-old patient with severe genu valgum and lateral compartment knee arthrosis.
Radiographs demonstrate an mLDFA of 78 degrees. A varus-producing distal femoral osteotomy is planned. Which of the following surgical options is most frequently preferred to address this specific deformity while minimizing the risk of peroneal nerve injury and nonunion?
Correct Answer & Explanation
. Medial closing wedge osteotomy
Explanation
A distal femoral valgus deformity (low mLDFA) is typically corrected with a medial closing wedge distal femoral osteotomy. Lateral opening wedges are less favored due to higher nonunion rates and the need for structural bone graft, though they are an option.
Question 2963
Topic: 2. Trauma
When applying the 'tension band principle' for the internal fixation of a long bone deformity using a plate and screws, where must the plate ideally be positioned to provide maximal mechanical advantage and stability?
Correct Answer & Explanation
. On the convex side of the deformity.
Explanation
The tension band principle requires the plate to be placed on the tension (convex) side of the bone. This allows eccentric loading forces to be converted into compressive forces at the fracture or osteotomy site.
Question 2964
Topic: 2. Trauma
A surgeon is treating a distal third tibial shaft nonunion complicated by deep infection with an Ilizarov external fixator. During the 6-month treatment course, what is statistically the most common complication the patient is likely to experience?
Correct Answer & Explanation
. Pin tract infection
Explanation
Superficial pin tract infection is the single most common complication associated with circular external fixation (Ilizarov). Most cases are managed successfully with oral antibiotics and local pin care without needing pin removal.
Question 2965
Topic: Lower Extremity Trauma
During preoperative planning for a femoral diaphyseal deformity, the surgeon notes two distinct Centers of Rotation of Angulation (CORAs). The surgeon opts to perform a single osteotomy at the level of the normal diaphyseal bone between the two deformities. Which of the following corrections is strictly required at the osteotomy site to perfectly realign the mechanical axis?
Correct Answer & Explanation
. Angular correction with simultaneous translation.
Explanation
When a multi-apical deformity is corrected with a single osteotomy that does not pass through either CORA (or their intersection), a combination of angular correction and translation is required to perfectly restore the mechanical axis.
Question 2966
Topic: 2. Trauma
A 30-year-old patient is treated with a circular external fixator for a complex tibial nonunion. To maximize the axial stiffness of the construct and minimize shear micromotion, what is the optimal angle for crossing the tensioned fine wires in the axial plane?
Correct Answer & Explanation
. 90 degrees
Explanation
Axial stiffness in a circular frame is maximized when the tensioned fine wires intersect at an angle of 90 degrees. Decreasing the crossing angle significantly reduces the construct's stability against orthogonal bending and translational forces.
Question 2967
Topic: Lower Extremity Trauma
A 55-year-old man presents with a severe varus knee deformity. Full-length standing radiographs show a mechanical axis passing medial to the knee. The mLDFA is 88 degrees, and the medial proximal tibial angle (MPTA) is 87 degrees. The joint line convergence angle (JLCA) is measured at 8 degrees (apex lateral). What is the primary source of the varus deformity?
Correct Answer & Explanation
. Intra-articular space loss or ligamentous laxity
Explanation
Normal mLDFA and MPTA values indicate there is no significant bony deformity in the distal femur or proximal tibia. A high JLCA (normal 0-2 degrees) indicates that the varus malalignment is driven by intra-articular factors, such as medial cartilage loss or lateral ligamentous laxity.
Question 2968
Topic: Lower Extremity Trauma
A 55-year-old male presents with chronic knee pain and difficulty ambulating due to a 'bent knee' that he cannot straighten. Clinical examination reveals a fixed flexion deformity (FFD) of 25 degrees. Radiographic analysis confirms a significant sagittal plane deformity. According to the provided case, which of the following statements BEST describes the primary biomechanical consequence of a procurvatum deformity leading to this patient's symptoms?
Correct Answer & Explanation
. It forces the knee into a functional fixed flexion deformity, requiring increased quadriceps effort and leading to early joint degeneration.
Explanation
Correct Answer: CThe case explicitly states that 'A procurvatum deformity forces the knee into a functional fixed flexion deformity (FFD), triggering a massive cascade of compensatory mechanisms that increase energy expenditure, fatigue the quadriceps, and eventually lead to early-onset joint degeneration.' This directly aligns with the patient's symptoms of a 'bent knee' and difficulty ambulating. The increased quadriceps effort is required to maintain an upright posture against the constant flexion moment.Option A is incorrectbecause varus/valgus stress relates to coronal plane deformities, not primarily sagittal plane procurvatum.Option B is incorrectbecause a normal sagittal mechanical axis passesanteriorto the knee, creating a passive extension moment. A procurvatum deformity shifts the mechanical axisposteriorto the knee, creating aflexionmoment, not an extension moment, thusincreasingquadriceps effort, not overloading it due to a passive extension moment.Option D is incorrectbecause a procurvatum deformity is characterized by adecreasedPDFA, not an increased one, indicating anterior bowing of the distal femur. Patellofemoral tracking issues are secondary and not the primary biomechanical consequence described.Option E is incorrectbecause while a decreased PPTA can contribute to a flexion deformity (tibial procurvatum), the statement describes it as 'mechanically blocking full knee extension,' which is a consequence, but the primary biomechanical disruption is the creation of a functional FFD and the resulting compensatory cascade, which is a more comprehensive answer.
Question 2969
Topic: Lower Extremity Trauma
A 60-year-old patient presents with a long-standing history of a 'bent knee' deformity. Clinical examination reveals a fixed flexion deformity (FFD) of 15 degrees. Full-length weight-bearing lateral radiographs show a true osseous femoral procurvatum deformity of 25 degrees. Based on Paley's principles, what does this discrepancy between the osseous deformity and the clinical FFD signify?
Correct Answer & Explanation
. The patient has 10 degrees of compensatory joint hyperextension due to stretching of the posterior capsule.
Explanation
Correct Answer: BThe case explicitly addresses this critical concept: 'When the true osseous deformity (e.g., 30° of structural femoral procurvatum) isgreaterthan the clinically measured fixed flexion deformity (e.g., 20° FFD), it signifies that the posterior capsule has stretched. It has allowed the joint to pathologically hyperextend by 10° simply to minimize the severe flexion crouch.' In this patient's scenario, 25° (osseous deformity) - 15° (clinical FFD) = 10° of compensatory joint hyperextension.Option A is incorrectbecause a soft tissue contracture wouldaddto the FFD, making itgreaterthan the osseous deformity, not less.Option C is incorrectbecause while quadriceps weakness can affect active extension, the discrepancy described here specifically points to passive soft tissue stretching to compensate for the bone deformity, allowing the knee to extendmorethan the bone deformity would otherwise dictate.Option D is incorrectas the scenario provides specific measurements and asks for their interpretation, assuming the measurements are correct for the purpose of the question.Option E is incorrectbecause the question specifies a 'true osseous femoral procurvatum deformity,' indicating the location is already identified.
Question 2970
Topic: Lower Extremity Trauma
A 35-year-old patient presents with a 'bent knee' deformity. Radiographic analysis is performed using Paley's method. The surgeon measures the angle between the anatomical axis of the femur and the distal femoral joint line (tangent to the most posterior aspects of the femoral condyles) and finds it to be 68 degrees. What is this angle, and what does this measurement indicate?
Correct Answer & Explanation
. Posterior Distal Femoral Angle (PDFA); indicates anterior bowing of the distal femur (procurvatum).
Explanation
Correct Answer: BThe case defines the Posterior Distal Femoral Angle (PDFA) as 'the angle between the anatomical axis of the femur and the distal femoral joint line (drawn as a tangent to the most posterior aspects of the femoral condyles).' The normal value for PDFA is 83° (± 4°). A measured value of 68° is significantly decreased (< 79°), which 'definitively indicates anterior bowing of the distal femur, which mechanically forces the knee into a flexed posture,' i.e., procurvatum.Option A is incorrectbecause the description is for the femur, not the tibia, and the PPTA relates to the tibia.Option C is incorrectbecause adecreasedPDFA indicates procurvatum (anterior bowing), while anincreasedPDFA (> 87°) would indicate recurvatum (posterior bowing).Option D is incorrectbecause the Mechanical Lateral Distal Femoral Angle (mLDFA) is a coronal plane measurement, not sagittal, and indicates varus/valgus deformity.Option E is incorrectbecause 'Anterior Distal Femoral Angle' is not one of the key sagittal angles described, and 68° is highly abnormal, not normal.
Question 2971
Topic: Lower Extremity Trauma
A 50-year-old patient presents with a functional knee flexion deformity. Radiographic analysis using Paley's method reveals a normal Posterior Distal Femoral Angle (PDFA) of 82 degrees. However, the angle between the anatomical axis of the tibia and the proximal tibial joint line (representing the posterior slope of the tibial plateau) is measured at 75 degrees. What is this measured angle, and what is its significance in this patient?
Correct Answer & Explanation
. Posterior Proximal Tibial Angle (PPTA); indicates an excessive posterior slope of the tibial plateau (tibial procurvatum).
Explanation
Correct Answer: BThe case defines the Posterior Proximal Tibial Angle (PPTA) as 'the angle between the anatomical axis of the tibia and the proximal tibial joint line (representing the posterior slope of the tibial plateau).' The normal value for PPTA is 81° (± 4°). A measured value of 75° is decreased (< 77°), which 'indicates an excessive posterior slope of the tibial plateau. This causes the femur to slide posteriorly, functionally contributing to a knee flexion deformity,' i.e., tibial procurvatum.Option A is incorrectbecause the description is for the tibia, not the femur, and the PDFA relates to the femur. Also, 82 degrees PDFA is normal, and 75 degrees PPTA indicates procurvatum, not femoral recurvatum.Option C is incorrectbecause adecreasedPPTA indicates anexcessiveposterior slope (procurvatum), while anincreasedPPTA (> 85°) would indicate insufficient posterior slope (recurvatum).Option D is incorrectbecause the Mechanical Medial Proximal Tibial Angle (mMPTA) is a coronal plane measurement, not sagittal, and indicates varus/valgus deformity.Option E is incorrectbecause 'Anterior Proximal Tibial Angle' is not one of the key sagittal angles described, and 75° is highly abnormal, not normal.
Question 2972
Topic: Lower Extremity Trauma
A 65-year-old patient with a history of severe osteomyelitis in childhood presents with a significant tibial procurvatum deformity. Clinical examination reveals a marked knee flexion deformity and a gait pattern characterized by a 'crouch.' Based on the case's description of tibial procurvatum, which of the following best explains the biomechanical consequence of this deformity?
Correct Answer & Explanation
. The anterior bow of the proximal tibia increases the posterior slope of the tibial plateau, causing posterior subluxation of the femur.
Explanation
Correct Answer: BThe case states: 'Tibial procurvatum creates a remarkably similar clinical picture to femoral deformity, but the mechanical culprit lies distal to the joint line. The anterior bow of the proximal tibia drastically increases the posterior slope of the tibial plateau. This steep slope causes the rounded femoral condyles to slide and subluxate posteriorly during weight-bearing, creating a severe functional flexion deformity.'Option A is incorrectbecause tibial procurvatumincreasesthe posterior slope, and this causesposteriorsubluxation of the femur, not anterior.Option C is incorrectbecause a varus thrust is characteristic of coronal plane deformities, not primarily sagittal plane tibial procurvatum.Option D is incorrectbecause tibial procurvatum is characterized by adecreasedPPTA (indicating an excessive posterior slope), not an increased one.Option E is incorrectbecause tibial procurvatum leads to aflexiondeformity (crouch gait), not a fixed extension deformity.
Question 2973
Topic: 2. Trauma
A 35-year-old active duty military personnel presents with persistent anterior knee pain and difficulty with deep knee bends following a previous tibial fracture. Clinical examination reveals a 5° fixed flexion deformity. A lateral radiograph of the knee is obtained in maximum passive extension, as shown below. Based on the image and the case's principles, if the measured Posterior Proximal Tibial Angle (PPTA) is 88°, what is the most likely osseous deformity contributing to the patient's symptoms?
Correct Answer & Explanation
. Tibial recurvatum (increased posterior slope)
Explanation
Correct Answer: DThe normal Posterior Proximal Tibial Angle (PPTA) is 81° (clinical range 77° to 84°). An increased PPTA signifies tibial recurvatum or an increased posterior slope. A measured PPTA of 88° is significantly increased from the normal 81°, indicating a tibial recurvatum. This deformity can lead to knee hyperextension, increased anterior knee pain, and ligamentous strain, which aligns with the patient's symptoms and the clinical presentation of a fixed flexion deformity (FFD) often being a composite pathology.Option A (Femoral procurvatum) is incorrectbecause this would be indicated by a decreased Posterior Distal Femoral Angle (PDFA), not an increased PPTA.Option B (Tibial procurvatum) is incorrectbecause this would be indicated by a decreased PPTA, not an increased PPTA.Option C (Femoral recurvatum) is incorrectbecause this would be indicated by an increased PDFA, not an increased PPTA.Option E (Normal tibial alignment with isolated soft tissue contracture) is incorrectbecause an 88° PPTA is abnormal, indicating an osseous deformity is present and contributing to the FFD, even if soft tissue contracture is also present.
Question 2974
Topic: Lower Extremity Trauma
A 58-year-old male presents with chronic left knee pain, worse with activity, and a noticeable deformity. Clinical examination reveals the appearance shown in the image. Radiographs confirm lateral compartment osteoarthritis (LCOA) and a valgus mechanical axis deviation. According to Paley's principles for valgus knee realignment, what is the primary biomechanical goal of surgical correction in this patient?
Correct Answer & Explanation
. To shift the mechanical axis medially, typically aiming for 2-4 degrees of mechanical varus.
Explanation
Correct Answer: CThe primary biomechanical goal of valgus knee realignment for lateral compartment osteoarthritis (LCOA) is to shift the mechanical axis medially. This offloads the diseased lateral compartment and transfers weight-bearing forces to the healthier medial compartment. While a truly 'neutral' mechanical axis (0 degrees) might seem ideal, studies and clinical experience, particularly following principles like those advocated by Paley, suggest that a slight overcorrection into 2-4 degrees of mechanical varus is often beneficial for long-term pain relief and delaying progression of OA in the affected compartment. This slight varus ensures consistent offloading of the lateral compartment.Option A is incorrectbecause passing the mechanical axis through the center of the lateral compartment would maintain or exacerbate the existing LCOA, as it would continue to bear the primary load. The goal is to offload it.Option B is incorrectbecause restoring the anatomical axis to 0 degrees is not the primary goal; the mechanical axis is the critical determinant of load distribution across the knee joint. Furthermore, the anatomical axis is inherently in slight valgus (typically 5-7 degrees) in a normal knee.Option D is incorrectbecause while patellofemoral tracking can be affected by severe valgus, it is not the primary biomechanical goal of a valgus realignment osteotomy for LCOA. The main focus is on tibiofemoral load distribution.Option E is incorrectbecause increasing the MPTA to 90 degrees would correct a varus deformity at the tibia, not a valgus deformity. In a valgus knee, the MPTA is often normal or slightly decreased, and the primary deformity is usually in the distal femur (decreased mLDFA).
Question 2975
Topic: Lower Extremity Trauma
A 42-year-old active patient presents with LCOA and a valgus deformity. A long leg standing radiograph is obtained, as shown. The mechanical lateral distal femoral angle (mLDFA) is measured at 82 degrees, and the medial proximal tibial angle (MPTA) is 87 degrees. Based on these measurements and Paley's principles, what is the primary anatomical location of the deformity requiring correction?
Correct Answer & Explanation
. Distal femur
Explanation
Correct Answer: BAccording to Paley's principles, the anatomical location of a deformity is determined by comparing measured angles to normal reference values. The normal mLDFA is 87 ± 3 degrees (range 84-90 degrees), and the normal MPTA is 87 ± 3 degrees (range 84-90 degrees). In this patient, the mLDFA is 82 degrees, which is significantly less than the normal range, indicating a valgus deformity originating from the distal femur. The MPTA of 87 degrees is within the normal range, indicating no significant deformity at the proximal tibia. Therefore, the primary anatomical location of the deformity is the distal femur.Option A is incorrectbecause the MPTA of 87 degrees is normal, indicating no significant deformity in the proximal tibia.Option C is incorrectbecause the deformity is primarily femoral, with a normal MPTA.Option D is incorrectbecause while patellofemoral issues can coexist, the primary angular deformity affecting the mechanical axis is at the tibiofemoral level, specifically the distal femur in this case.Option E is incorrectbecause a deformity in the mid-diaphysis of the femur would typically manifest as a bowing deformity, which is less common for primary valgus knee OA and would be reflected in different angular measurements or a more diffuse curvature.
Question 2976
Topic: Lower Extremity Trauma
A 60-year-old patient with LCOA and a valgus knee deformity is undergoing preoperative planning for a distal femoral osteotomy (DFO). The image shows a close-up of the knee joint. The surgeon aims to correct the mechanical axis while preserving the joint line obliquity. Which of the following angular measurements is most critical for determining the *amount* of correction needed at the distal femur to achieve a neutral mechanical axis?
Correct Answer & Explanation
. Mechanical Lateral Distal Femoral Angle (mLDFA)
Explanation
Correct Answer: CThe Mechanical Lateral Distal Femoral Angle (mLDFA) is the angle between the mechanical axis of the femur and the distal femoral joint line. It directly quantifies the angular deformity of the distal femur relative to the mechanical axis. A normal mLDFA is 87 ± 3 degrees. In a valgus knee with a distal femoral deformity, the mLDFA will be less than 84 degrees. The amount of correction needed for a DFO is calculated to bring the mLDFA back to the desired range (e.g., 87 degrees) to realign the mechanical axis. This is a cornerstone of Paley's principles for deformity correction, focusing on correcting the deformity at its anatomical location (CORA).Option A is incorrectbecause the MPTA measures the deformity at the proximal tibia. While important for overall assessment, it does not directly determine the amount of correction for adistal femoralosteotomy if the deformity is primarily femoral.Option B is incorrectbecause the anatomical LDFA (aLDFA) is measured relative to the anatomical axis, which is less relevant for mechanical axis correction than the mLDFA.Option D is incorrectbecause the Posterior Tibial Slope (PTS) measures the sagittal plane alignment of the tibia and is not directly used for coronal plane valgus correction.Option E is incorrectbecause the Joint Line Convergence Angle (JLCA) indicates the amount of joint space opening or closing due to cartilage loss or ligamentous laxity, but it does not directly quantify the bony angular deformity requiring osteotomy correction.
Question 2977
Topic: Lower Extremity Trauma
A 50-year-old patient with symptomatic LCOA and a valgus deformity is being planned for a distal femoral osteotomy. The image illustrates a common method for planning osteotomies. If the surgeon chooses an opening wedge distal femoral osteotomy, which of the following is a potential advantage compared to a closing wedge osteotomy in this specific scenario?
Correct Answer & Explanation
. Ability to simultaneously lengthen the limb, which can be beneficial in cases of limb length discrepancy.
Explanation
Correct Answer: CAn opening wedge distal femoral osteotomy (OWDFO) involves creating a wedge-shaped gap on the medial side of the distal femur. This technique effectively lengthens the limb on the medial side. If the patient has a pre-existing limb length discrepancy (LLD) with the affected limb being shorter, an OWDFO can be advantageous as it can simultaneously correct the valgus deformity and address the LLD by lengthening the limb. This is a key consideration in surgical planning.Option A is incorrectbecause opening wedge osteotomies typically heal by secondary intention (gap healing) and may require bone grafting, which can sometimes lead to slower healing compared to closing wedge osteotomies where bone-to-bone contact and compression are achieved.Option B is incorrectbecause an OWDFO typically involves a medial approach, which places the femoral artery and vein at risk, particularly if the osteotomy is performed too proximally or if the medial periosteum is not carefully protected. A closing wedge osteotomy is usually performed laterally.Option D is incorrectbecause opening wedge osteotomies, especially larger corrections, can be less stable initially due to the gap and may require more robust fixation and/or delayed weight-bearing compared to closing wedge osteotomies which benefit from inherent bony stability and compression.Option E is incorrectbecause an opening wedge DFO does not typically cause patella baja. Patella baja is more commonly associated with proximal tibial osteotomies, particularly closing wedge techniques, due to shortening of the patellar tendon relative to the tibial tubercle.
Question 2978
Topic: Lower Extremity Trauma
A 35-year-old patient presents with symptomatic LCOA and a valgus deformity. Preoperative planning, as depicted in the image, reveals a mechanical axis deviation of 15 degrees valgus, mLDFA of 80 degrees, and MPTA of 88 degrees. The surgeon plans a distal femoral osteotomy. Which of the following statements best describes the appropriate correction strategy based on Paley's principles?
Correct Answer & Explanation
. Perform an opening wedge distal femoral osteotomy to increase the mLDFA to 87 degrees.
Explanation
Correct Answer: BThe normal mLDFA is 87 ± 3 degrees, and the normal MPTA is 87 ± 3 degrees. In this patient, the mLDFA is 80 degrees, which is significantly decreased (valgus deformity at the femur). The MPTA of 88 degrees is within the normal range. Therefore, the deformity is primarily located at the distal femur. To correct a valgus deformity at the distal femur, an opening wedge osteotomy on the medial side (or a closing wedge on the lateral side) is performed to increase the mLDFA towards the normal range, typically aiming for 87 degrees to achieve a neutral mechanical axis, or slightly more (e.g., 89-90 degrees) for slight varus overcorrection to offload the lateral compartment.Option A is incorrectbecause the MPTA is normal (88 degrees), so a proximal tibial osteotomy is not indicated. Correcting it to 90 degrees would create a varus deformity at the tibia.Option C is incorrectbecause the deformity is isolated to the distal femur (normal MPTA), so a combined osteotomy is not necessary and would violate the principle of correcting the deformity at its CORA.Option D is incorrectbecause a closing wedge distal femoral osteotomy on the lateral side wouldincreasethe mLDFA, not decrease it. Decreasing the mLDFA would worsen the valgus deformity. The goal is to increase the mLDFA from 80 degrees to 87 degrees.Option E is incorrectbecause while a medial opening wedge osteotomy is the correct approach, aiming for a final mLDFA of 90 degrees would result in a significant varus overcorrection at the femur, potentially leading to excessive medial compartment loading and an overly steep joint line. A target of 87-89 degrees is generally preferred.
Question 2979
Topic: 2. Trauma
A 28-year-old male heals with a 20-degree distal femoral procurvatum deformity following intramedullary nailing of a femur fracture. Which of the following clinical conditions is most likely to develop as a direct biomechanical consequence of this specific sagittal malalignment?
Correct Answer & Explanation
. Anterior knee pain due to increased patellofemoral contact pressures
Explanation
A distal femoral procurvatum deformity essentially acts as a 'flexed' distal femur, leading to significantly increased tension in the extensor mechanism. This reliably produces elevated patellofemoral contact pressures and anterior knee pain.
Question 2980
Topic: 2. Trauma
A 35-year-old male presents with a healed distal femoral recurvatum malunion following a high-energy trauma. Assuming his intra-articular joint mechanics and capsular structures are completely normal, how will this osseous deformity predictably alter his clinical arc of knee motion?
Correct Answer & Explanation
. Apparent hyperextension and a relative loss of terminal flexion
Explanation
A recurvatum extra-articular deformity angles the joint posteriorly. Clinically, this results in apparent hyperextension of the knee when standing, and an equivalent degree of terminal flexion loss due to geometric impingement.
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