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 3321
Topic: Lower Extremity Trauma
A 45-year-old female presents with a distal femoral valgus deformity. A standing full-length radiograph shows a lateral Mechanical Axis Deviation (MAD). Her Medial Proximal Tibial Angle (MPTA) is 87 degrees, and her mechanical Lateral Distal Femoral Angle (mLDFA) is 81 degrees. Based on Paley's principles, where is the primary source of the deformity?
Correct Answer & Explanation
. Distal femur
Explanation
The normal mLDFA is 87 degrees (range 85-90). An mLDFA of 81 degrees indicates a valgus deformity of the distal femur. The MPTA is normal (87 degrees), ruling out a tibial origin.
Question 3322
Topic: 2. Trauma
A 35-year-old male sustained a midshaft tibial fracture treated non-operatively, resulting in a pure translation deformity with no angular component. According to Paley's principles, where is the CORA located in a pure translation deformity?
Correct Answer & Explanation
. At infinity.
Explanation
In a pure translation deformity, the proximal and distal axes are parallel and never intersect. Therefore, mathematically, the CORA is located at infinity.
Question 3323
Topic: Lower Extremity Trauma
You are analyzing the sagittal profile of the femur. What is the normal anatomic Posterior Distal Femoral Angle (aPDFA), which dictates the normal sagittal orientation of the distal femur?
Correct Answer & Explanation
. 83 degrees
Explanation
The normal anatomic Posterior Distal Femoral Angle (aPDFA) is 83 degrees (range 79-87 degrees). This reflects the normal anterior bow and distal articular orientation of the femur in the sagittal plane.
Question 3324
Topic: Lower Extremity Trauma
A patient presents with a severe procurvatum deformity of the distal femur. To accurately define the Center of Rotation of Angulation (CORA) in the sagittal plane, the surgeon measures the Posterior Distal Femoral Angle (PDFA). What is the normal anatomical value for the PDFA?
Correct Answer & Explanation
. 83 degrees
Explanation
The normal Posterior Distal Femoral Angle (PDFA) in the sagittal plane is 83°. Deviations from this value indicate procurvatum or recurvatum deformities of the distal femur.
Question 3325
Topic: Lower Extremity Trauma
A 28-year-old patient is undergoing femur lengthening over an intramedullary nail (LON). What is the primary advantage of this technique compared to classic Ilizarov lengthening with a circular frame alone?
Correct Answer & Explanation
. Decreased total time the patient must wear the external fixator.
Explanation
Lengthening Over a Nail (LON) allows the external fixator to be removed immediately after the distraction phase. The internal nail supports the bone during the consolidation phase, significantly reducing frame time.
Question 3326
Topic: Lower Extremity Trauma
In evaluating a patient with a valgus knee, the Mechanical Axis Deviation (MAD) is lateral to the center of the knee. The mLDFA is 81° and the MPTA is 87°. Where is the primary deformity located?
Correct Answer & Explanation
. Distal femur.
Explanation
The MAD is lateral, indicating valgus. A decreased mLDFA (<85°) points to distal femoral valgus, while the normal MPTA confirms the proximal tibia is uninvolved.
Question 3327
Topic: 2. Trauma
During correction of a tibial shaft malunion, the surgeon places both the osteotomy cut and the hinge axis of the external fixator proximal to the Center of Rotation of Angulation (CORA). Which of the following complications is most likely to occur?
Correct Answer & Explanation
. Iatrogenic translation resulting in a secondary deformity
Explanation
Paley's Rule 3 states that if both the hinge and the osteotomy are placed outside the CORA, the correction will result in iatrogenic translation. This creates a secondary translation deformity and misalignment of the mechanical axis.
Question 3328
Topic: 2. Trauma
A patient has a multi-apical deformity of the femur following multiple trauma. How are the multiple Centers of Rotation of Angulation (CORAs) determined according to Paley's principles?
Correct Answer & Explanation
. By drawing the mid-diaphyseal lines of each deformed segment and finding their intersections
Explanation
For multi-apical deformities, CORAs are located by identifying the independent mid-diaphyseal lines of each discrete bone segment. The intersections of these adjacent mid-diaphyseal lines define the respective CORAs.
Question 3329
Topic: Lower Extremity Trauma
A 19-year-old female presents with a cosmetic "knock-knee" deformity. Radiographs reveal a Mechanical Axis Deviation (MAD) of 25 mm lateral to the knee center. Her mLDFA is 81 degrees and her MPTA is 88 degrees. Based on Paley's principles, what is the primary source of her deformity?
Correct Answer & Explanation
. Distal femoral valgus
Explanation
The normal mLDFA is 87 degrees. An mLDFA of 81 degrees indicates an abnormal distal femur with a valgus deformity (angle < 87 degrees). The MPTA of 88 degrees is within normal limits.
Question 3330
Topic: Lower Extremity Trauma
A 40-year-old patient presents with a valgus knee deformity. Radiographic analysis, similar to the principles shown in the diagram below, reveals a mechanical lateral distal femoral angle (mLDFA) of 95 degrees and a medial proximal tibial angle (MPTA) of 88 degrees. Based on these measurements, where is the primary apex of the deformity located?
Correct Answer & Explanation
. Distal femur.
Explanation
Correct Answer: BThe normal range for the mechanical lateral distal femoral angle (mLDFA) is typically 85-90 degrees. A value of 95 degrees indicates that the distal femur is in valgus relative to the femoral mechanical axis (i.e., the distal femur is angled more laterally than normal). The normal range for the medial proximal tibial angle (MPTA) is also typically 85-90 degrees. An MPTA of 88 degrees is within the normal range, indicating no significant deformity originating from the proximal tibia. Therefore, the primary apex of the valgus deformity is located in the distal femur.Option A is incorrect because the MPTA is normal. Options C and D are incorrect because the mLDFA and MPTA specifically assess the angles at the knee joint, indicating deformities in the metaphyseal regions of the femur and tibia, respectively, not typically the mid-diaphysis unless there's a specific diaphyseal bend. Option E is incorrect as the ankle joint angles are not assessed by mLDFA or MPTA.
Question 3331
Topic: Lower Extremity Trauma
A 35-year-old female presents with chronic lateral compartment knee pain and a valgus deformity. Radiographs show a mechanical axis passing 15 mm lateral to the center of the knee. Her mLDFA is 94 degrees, and her MPTA is 87 degrees. She is active and wishes to avoid arthroplasty. Based on the principles of frontal plane realignment, which osteotomy is most appropriate for this patient?
Correct Answer & Explanation
. Medial closing wedge distal femoral osteotomy.
Explanation
Correct Answer: CThe patient has a valgus knee deformity (mechanical axis 15 mm lateral) and lateral compartment pain. The mLDFA is 94 degrees, which is greater than the normal range (85-90 degrees), indicating a valgus deformity originating from the distal femur. The MPTA is 87 degrees, which is within the normal range, ruling out a significant tibial deformity. Therefore, a distal femoral osteotomy (DFO) is indicated to correct the valgus deformity. To correct valgus, a closing wedge osteotomy on the medial side of the distal femur (or an opening wedge on the lateral side) is performed to decrease the mLDFA and shift the mechanical axis medially, offloading the lateral compartment.Option A, medial opening wedge high tibial osteotomy, is used for varus correction originating from the tibia. Option B, lateral closing wedge high tibial osteotomy, is also used for varus correction originating from the tibia. Option D, lateral opening wedge distal femoral osteotomy, would worsen a valgus deformity by increasing the mLDFA further. Option E, proximal fibular osteotomy, is a newer technique primarily for medial compartment osteoarthritis and varus knee, not for valgus deformity.
Question 3332
Topic: 2. Trauma
A 45-year-old construction worker undergoes a high tibial osteotomy for symptomatic medial compartment osteoarthritis and varus deformity. Six months postoperatively, he presents with persistent pain, and radiographs show delayed union at the osteotomy site. Which of the following factors is most commonly associated with delayed union or nonunion following a high tibial osteotomy?
Correct Answer & Explanation
. Smoking history.
Explanation
Correct Answer: CSmoking is a well-established risk factor for delayed union and nonunion in various orthopedic procedures, including osteotomies. Nicotine and other toxins in tobacco smoke impair blood flow, reduce osteoblast activity, and interfere with the inflammatory and reparative phases of bone healing, significantly increasing the risk of complications.Option A, aggressive early weight-bearing, can contribute to fixation failure or loss of correction, but delayed union is more directly related to biological healing factors. Controlled, protected weight-bearing is typically part of the rehabilitation protocol. Option B, use of a locking plate, generally provides stable fixation, which is beneficial for healing, making it less likely to cause delayed union compared to less stable fixation methods. Option D, while opening wedge osteotomies require bone graft and have a larger gap to heal, both opening and closing wedge osteotomies have good union rates with proper technique and patient selection. The choice between them is often based on limb length and specific deformity characteristics, not a significantly higher nonunion rate for one over the other in general. Option E, correction of less than 5 degrees of deformity, is unlikely to cause delayed union; in fact, larger corrections might theoretically pose more healing challenges due to larger gaps or more stress on fixation, though this is not a primary cause of nonunion.
Question 3333
Topic: Lower Extremity Trauma
A 55-year-old female presents with a symptomatic varus knee deformity. Preoperative full-length weight-bearing radiographs are obtained. Measurements reveal a Mechanical Lateral Distal Femoral Angle (mLDFA) of 95° (normal 88°) and a Medial Proximal Tibial Angle (MPTA) of 87° (normal 87°). The Joint Line Convergence Angle (JLCA) is 1°. Based on these findings, what is the primary anatomical location of the deformity requiring surgical correction?
Correct Answer & Explanation
. B. Distal femur, requiring a Distal Femoral Osteotomy (DFO).
Explanation
Correct Answer: BThe teaching case states that the mLDFA defines the orientation of the knee joint relative to the femur, and an abnormal mLDFA indicates a femoral deformity, requiring a Distal Femoral Osteotomy (DFO). The patient's mLDFA is 95°, which is significantly higher than the normal average of 88°. This indicates a valgus deformity originating from the distal femur, which can contribute to a varus knee if the femur is in relative valgus. Conversely, the MPTA is 87°, which is within the normal range (87°), indicating no significant deformity originating from the proximal tibia. The JLCA of 1° is also within the normal range (0-2°), suggesting no significant ligamentous laxity or asymmetric cartilage loss.Therefore, the primary anatomical location of the deformity is the distal femur, necessitating a Distal Femoral Osteotomy (DFO) to correct the abnormal mLDFA. Options A, C, D, and E are incorrect as they misidentify the primary location of the deformity based on the given angle measurements.
Question 3334
Topic: 2. Trauma
A 30-year-old male sustained a malunited mid-shaft tibial fracture, resulting in a significant varus angulation. Preoperative planning involves identifying the Center of Rotation of Angulation (CORA). Which of the following steps correctly identifies the CORA for this uniapical deformity?
Correct Answer & Explanation
. C. Draw the proximal and distal axis lines of the deformed bone and identify their intersection point.
Explanation
Correct Answer: CThe teaching case explicitly defines how to locate the CORA: 'Draw the proximal axis line (either the anatomic mid-diaphyseal line or the mechanical axis line) of the deformed bone and extend it distally past the deformity. Draw the distal axis line of the deformed bone and extend it proximally past the deformity. The exact point where these two lines intersect is the CORA.' This geometric construction identifies the apex of the deformity.Option A describes drawing the mechanical axis, which is used to determine MAD, not CORA. Option B describes measuring the MAD. Option D describes measuring the Joint Line Convergence Angle (JLCA). Option E describes the placement of the osteotomy and Angulation Correction Axis (ACA), which is related to surgical execution, not the initial identification of the CORA.
Question 3335
Topic: 2. Trauma
A 35-year-old male with a significant varus deformity of the proximal tibia and a 1.5 cm limb length discrepancy (LLD) with the affected limb being shorter, is scheduled for a high tibial osteotomy. The surgeon opts for an opening wedge technique. Which of the following is a key advantage of the opening wedge osteotomy in this specific patient, and what is a critical intraoperative consideration?
Correct Answer & Explanation
. C. Advantage: Limb lengthening; Consideration: Meticulous protection of the cortical hinge.
Explanation
Correct Answer: CThe teaching case highlights that a crucial biomechanical consequence of an opening wedge osteotomy is that it inherently lengthens the bone. This is a 'massive advantage if the patient has a pre-existing limb length discrepancy (LLD) and the operative leg is shorter,' which is precisely the scenario described for this patient (1.5 cm LLD with the affected limb being shorter). Regarding surgical pearls, the case emphasizes 'Hinge Protection': 'The cortical hinge is the lifeline of the procedure. Meticulously protect it. Use fluoroscopy to ensure the saw blade stops 1cm short of the far cortex. A broken hinge ("hinge fracture") leads to multi-planar instability and potential loss of correction.'Option A is incorrect; opening wedge lengthens, not shortens, and it involves adding graft, not removing bone. Option B is incorrect; opening wedge is not inherently more stable than closing wedge, and neurovascular structures (common peroneal nerve, popliteal artery) are at risk, especially on the lateral side (peroneal nerve) and posterior (popliteal artery) with opening on the medial side. Option D is incorrect; larger gaps often require structural graft, and compartment syndrome risk is higher with larger corrections, not smaller ones. Option E is incorrect; opening wedge does not inherently reduce infection risk, and the superficial MCL is typically released, not the LCL, to facilitate opening and reduce tension on neurovascular structures.
Question 3336
Topic: Lower Extremity Trauma
A 48-year-old male presents with a complex varus deformity of the right lower extremity. Full-length weight-bearing radiographs reveal the following measurements: mLDFA = 92° (normal 88°), MPTA = 80° (normal 87°), and MAD = +20mm. The JLCA is 3°. Based on these findings and Paley's principles, what is the most appropriate initial surgical strategy?
Correct Answer & Explanation
. C. Bi-level osteotomy (distal femur and proximal tibia) to address both deformities.
Explanation
Correct Answer: CThe teaching case emphasizes that 'while the MAD tells usifthere is a problem and how severe it is, the joint orientation angles tell us exactlywherethe problem is located.' In this patient, both the mLDFA and MPTA are abnormal. The mLDFA of 92° (normal 88°) indicates a femoral deformity (valgus angulation of the distal femur contributing to overall varus). The MPTA of 80° (normal 87°) indicates a tibial deformity (varus angulation of the proximal tibia). The MAD of +20mm confirms a significant varus malalignment. The JLCA of 3° (normal 0-2°) suggests some joint line convergence, possibly due to cartilage loss or ligamentous laxity, which needs to be considered but is not the primary bone deformity.Since both the femur and tibia contribute to the overall varus malalignment, an isolated osteotomy at either level would not fully correct the deformity and normalize the MAD. Therefore, a bi-level osteotomy addressing both the distal femur (DFO) and proximal tibia (HTO) is the most appropriate initial surgical strategy to restore physiological alignment. Options A and B are insufficient. Option D is incorrect as supramalleolar osteotomy addresses distal tibial deformities, and JLCA is not the primary target for osteotomy. Option E is inappropriate given the significant and symptomatic deformity.
Question 3337
Topic: 2. Trauma
During distraction osteogenesis using the Ilizarov method, the standard rate of distraction is typically 1 mm per day in a healthy adult. Which of the following complications is most likely to occur if the distraction rate is excessively increased to 2 mm per day?
Correct Answer & Explanation
. Atrophic regenerate with poor bone formation
Explanation
Distracting at a rate faster than 1 mm per day outpaces the body's ability to form osteoid, resulting in an atrophic regenerate and potential nonunion. Distracting too slowly (e.g., 0.25 mm/day) risks premature consolidation.
Question 3338
Topic: 2. Trauma
After performing a metaphyseal corticotomy for limb lengthening, a latency period of 5 to 7 days is typically observed prior to initiating distraction. What is the primary biological purpose of this latency period?
Correct Answer & Explanation
. To permit the formation of an initial fracture hematoma and early vascularized granulation tissue
Explanation
The latency period allows for the initial inflammatory phase of fracture healing to subside and for a highly vascularized granulation tissue network to form. Premature distraction risks pulling apart this essential cellular matrix, leading to poor regenerate.
Question 3339
Topic: 2. Trauma
During a medial opening-wedge high tibial osteotomy (HTO), preserving an intact lateral cortical hinge is crucial for multi-planar stability. To prevent fracture of this hinge, the osteotomy cut should ideally be directed towards which of the following anatomical landmarks?
Correct Answer & Explanation
. The superior aspect of the proximal tibiofibular joint
Explanation
To maintain a robust lateral hinge, the osteotomy should aim approximately 10-15 mm below the lateral joint line, typically directed toward the tip of the fibular head or the superior proximal tibiofibular joint.
Question 3340
Topic: Lower Extremity Trauma
When analyzing a full-length standing lower extremity radiograph for deformity planning, an abnormally increased Joint Line Convergence Angle (JLCA) is calculated. This finding most strongly suggests the presence of which of the following?
Correct Answer & Explanation
. Ligamentous laxity or significant intra-articular cartilage loss
Explanation
The JLCA measures the angle between the articular surface of the distal femur and the proximal tibia. An increased JLCA (typically >2 degrees) indicates either asymmetric joint space narrowing (cartilage loss) or ligamentous laxity opening the joint space.
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