Menu

Lower Extremity Trauma MCQs

Practice Set 33 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 641

Topic: Lower Extremity Trauma
A 3-year-old girl is diagnosed with infantile Blount disease (Langenskiöld stage III). Conservative management with knee-ankle-foot orthoses (KAFOs) has failed, and the deformity is progressive. What is the most appropriate surgical intervention?
. Proximal tibial valgus-derotation osteotomy
. Lateral hemiepiphysiodesis of the proximal tibia
. Medial tibial plateau elevation
. Taylor Spatial Frame gradual lengthening
. Observation until skeletal maturity

Correct Answer & Explanation

. Proximal tibial valgus-derotation osteotomy

Explanation

For infantile Blount disease failing bracing by age 3 or presenting at stage III or higher, a proximal tibial valgus-derotation osteotomy is indicated to correct both the varus and the internal tibial torsion before irreversible physeal damage occurs.

Question 642

Topic: Lower Extremity Trauma

A 9-year-old boy presents with idiopathic bilateral genu valgum. Standing radiographs show the mechanical axis falls in the lateral zone 3 of the knee. Tension-band plating (guided growth) is planned. Where should the plates be placed to correct the deformity?

. Medial distal femur and medial proximal tibia
. Lateral distal femur and lateral proximal tibia
. Medial distal femur only
. Anterior distal femur and anterior proximal tibia
. Posterior distal femur

Correct Answer & Explanation

. Medial distal femur and medial proximal tibia

Explanation

Genu valgum is corrected by tethering the medial physis of the distal femur and/or proximal tibia. This restricts medial growth while allowing the lateral side to continue growing, effectively correcting the valgus alignment.

Question 643

Topic: Lower Extremity Trauma



A patient presents with severe genu varum. Standing long-leg radiographs show a mechanical axis deviation (MAD) falling completely medial to the medial tibial plateau (Zone 3). During an acute correction using a high tibial opening wedge osteotomy, what is the primary soft tissue structure at risk?

. Common peroneal nerve
. Saphenous nerve
. Popliteal artery
. Tibial nerve
. Deep peroneal nerve

Correct Answer & Explanation

. Common peroneal nerve

Explanation

Acute correction of severe varus deformities places significant stretch on the lateral structures, particularly the common peroneal nerve. Prophylactic peroneal nerve decompression is frequently indicated in substantial corrections.

Question 644

Topic: Lower Extremity Trauma

A 10-year-old boy of Ashkenazi Jewish descent presents with severe acute right hip pain. Radiographs demonstrate avascular necrosis of the right femoral head and a classic "Erlenmeyer flask" deformity of the distal femurs bilaterally. He also has significant splenomegaly. A defect in which of the following enzymes is the primary etiology?

. Beta-glucocerebrosidase
. Arylsulfatase A
. Hexosaminidase A
. Acid maltase
. Alpha-galactosidase A

Correct Answer & Explanation

. Beta-glucocerebrosidase

Explanation

The patient has Gaucher disease, an autosomal recessive lysosomal storage disorder caused by a deficiency in beta-glucocerebrosidase. The accumulation of glucocerebroside in macrophages expands the marrow cavity, causing bone pain crises, osteonecrosis, and Erlenmeyer flask deformities.

Question 645

Topic: Lower Extremity Trauma

A radiograph of a 20-year-old female taken for a minor knee sprain incidentally reveals dense, longitudinal striations in the metaphyses of the distal femur and proximal tibia. The patient is otherwise healthy and asymptomatic. This radiographic finding is characteristic of which of the following skeletal dysplasias?

. Osteopathia striata
. Melorheostosis
. Osteopoikilosis
. Pycnodysostosis

Correct Answer & Explanation

. Osteopathia striata

Explanation

Correct Answer: Osteopathia striataOsteopathia striata (Voorhoeve disease) is a benign, usually asymptomatic skeletal dysplasia characterized radiographically by dense, longitudinal linear striations in the metaphyses and diaphyses of long bones, and sometimes a fan-like appearance in the ilium. It is caused by mutations in the WTX (AMER1) gene and is inherited in an X-linked dominant pattern. It is often an incidental finding and requires no treatment.

Question 646

Topic: Lower Extremity Trauma

A 28-year-old female with disproportionate short stature reports progressive, bilateral knee pain. She has a history of mild short-limbed dwarfism but normal spine radiographs. Lateral knee radiographs reveal a distinctive bony anomaly. Which of the following is the pathognomonic finding for her likely condition?

. Erlenmeyer flask deformity of the distal femur
. Bipartite patella at the superolateral pole
. Double-layer patella
. Popliteal exostosis
. Dysplastic medial femoral condyle

Correct Answer & Explanation

. Double-layer patella

Explanation

Multiple Epiphyseal Dysplasia (MED) can be caused by mutations in COMP, MATN3, or type IX collagen genes. A double-layer patella visualized on the lateral radiograph is a highly characteristic and pathognomonic finding for MED.

Question 647

Topic: Lower Extremity Trauma

A 12-year-old male presents with a palpable mass behind his knee and restricted knee flexion. Imaging is shown below. The mass is seen protruding from the distal femoral epiphysis. Which of the following best describes the characteristic growth pattern of this pathology?




. Symmetrical involvement of the entire epiphysis
. Hemimelic involvement of either the medial or lateral epiphyseal side
. Diaphyseal expansion with cortical thinning
. Metaphyseal origin with extension into the joint space
. Intramedullary lytic lesion with a sclerotic rim

Correct Answer & Explanation

. Hemimelic involvement of either the medial or lateral epiphyseal side

Explanation

Correct Answer: BThe images demonstrate DEH of the distal femur. Characteristically, the involvement in DEH is 'hemimelic', meaning it affects only one half (either the medial or the lateral side) of the epiphysis. It does not typically involve the entire epiphysis symmetrically, nor does it originate in the metaphysis or diaphysis.

Question 648

Topic: Lower Extremity Trauma

A 7-year-old girl is diagnosed with Trevor's disease affecting her distal femur. Which of the following statements regarding the genetic profile of her condition is most accurate?

. It is inherited in an autosomal dominant pattern.
. It is strongly associated with EXT1 and EXT2 gene mutations.
. It is a sporadic developmental anomaly.
. It is caused by a mutation in the GNAS gene.
. It is an X-linked recessive disorder.

Correct Answer & Explanation

. It is a sporadic developmental anomaly.

Explanation

Unlike Multiple Hereditary Exostoses (MHE), which is linked to EXT1 and EXT2 mutations, DEH is a sporadic developmental anomaly with no established genetic inheritance pattern or specific gene mutation.

Question 649

Topic: Lower Extremity Trauma

A 42-year-old woman undergoes radiographs for a knee sprain, revealing an incidental finding in the distal femur:

She denies thigh pain. MRI confirms a well-circumscribed, lobulated cartilaginous lesion without endosteal scalloping or cortical breakthrough. What is the next best step in management?

. CT-guided core needle biopsy
. Intralesional curettage and bone grafting
. Wide en bloc resection
. Clinical observation and serial radiographs
. Prophylactic intramedullary nailing

Correct Answer & Explanation

. Clinical observation and serial radiographs

Explanation

The image demonstrates a classic asymptomatic enchondroma with typical 'popcorn' calcifications. Lesions without aggressive features (like deep endosteal scalloping or pain) are benign and should be managed with clinical observation.

Question 650

Topic: Lower Extremity Trauma

A full-length standing AP radiograph of the lower extremities is obtained to evaluate a patient's deformity. The mechanical lateral distal femoral angle (mLDFA) is measured at 99 degrees, and the medial proximal tibial angle (MPTA) is measured at 87 degrees. What is the correct interpretation of these radiographic findings?

. Normal alignment of both the femur and the tibia.
. Varus deformity of the distal femur with a normal proximal tibia.
. Valgus deformity of the distal femur with a normal proximal tibia.
. Normal distal femur with a varus deformity of the proximal tibia.
. Valgus deformity of both the distal femur and proximal tibia.

Correct Answer & Explanation

. Varus deformity of the distal femur with a normal proximal tibia.

Explanation

The normal mLDFA is approximately 87-88 degrees (range 85-90). An mLDFA of 99 degrees indicates an abnormally large lateral angle, meaning the distal femur is in varus. The normal MPTA is also approximately 87 degrees, so the tibia is normal.

Question 651

Topic: Lower Extremity Trauma

A 16-year-old male with a 6-cm post-traumatic femoral length discrepancy is undergoing lengthening over a nail (LON). Compared to classic Ilizarov lengthening using only an external fixator, what is the primary advantage of the LON technique?

. Decreased risk of deep intramedullary infection.
. Elimination of the need for an osteotomy.
. Significantly reduced time required in the external fixator.
. Ability to correct larger rotational deformities simultaneously.
. Prevention of pin-track infections during the distraction phase.

Correct Answer & Explanation

. Significantly reduced time required in the external fixator.

Explanation

Lengthening over a nail (LON) allows the external fixator to be removed immediately after the distraction phase is completed, with the intramedullary nail locked to support the bone during the prolonged consolidation phase. This dramatically reduces the time the patient must wear the external frame.

Question 652

Topic: Lower Extremity Trauma

A 28-year-old male is undergoing assessment for varus malalignment of the lower extremity. A full-length standing AP radiograph reveals the Mechanical Axis Deviation (MAD) is significantly medial to the knee joint center. The mechanical Lateral Distal Femoral Angle (mLDFA) is 88 degrees (normal 87-89 deg), and the Medial Proximal Tibial Angle (MPTA) is 79 degrees (normal 85-90 deg). What is the primary source of the varus deformity?

. Distal femur
. Knee joint line convergence (ligamentous laxity)
. Proximal tibia
. Femoral neck-shaft angle
. Ankle mortise

Correct Answer & Explanation

. Proximal tibia

Explanation

The malalignment test identifies the source of deviation. Here, the mLDFA is normal, indicating the femur is not the primary source. The MPTA is abnormally low (<85 degrees), confirming the varus deformity originates in the proximal tibia.

Question 653

Topic: Lower Extremity Trauma

A 10-year-old boy is undergoing femoral lengthening with an external fixator. Radiographs at 4 weeks demonstrate rigid bridging bone across the distraction gap, preventing further mechanical lengthening despite turning the struts. What is the most appropriate management for this premature consolidation?

. Dramatically increase the distraction rate to 3.0 mm per day
. Administer high-dose non-steroidal anti-inflammatory drugs (NSAIDs)
. Remove the external fixator and switch to a locked intramedullary nail
. Perform extracorporeal shockwave therapy (ESWT) over the regenerate
. Take the patient back to the operating room to repeat the corticotomy

Correct Answer & Explanation

. Take the patient back to the operating room to repeat the corticotomy

Explanation

Premature consolidation occurs when the bone heals faster than the distraction rate. If mechanical manipulation (osteoclasis) fails or bridging is advanced, a repeat surgical corticotomy is required to resume lengthening.

Question 654

Topic: Lower Extremity Trauma

Trichorhinophalangeal syndrome type 1 (TRPS1) is characterized by a specific triad of clinical findings. Which of the following radiographic features is the hallmark of this condition?

. Cone-shaped epiphyses of the phalanges
. Erlenmeyer flask deformity of the distal femur
. Rugger jersey spine
. Bone within a bone appearance
. Cotton wool appearance of the skull

Correct Answer & Explanation

. Cone-shaped epiphyses of the phalanges

Explanation

TRPS1 is classically associated with cone-shaped epiphyses of the phalanges, sparse hair, and a pear-shaped nose. The cone-shaped epiphyses often lead to premature fusion and brachydactyly.

Question 655

Topic: Lower Extremity Trauma



During treatment of a complex tibial deformity with a hexapod circular external fixator, the surgeon notes a residual varus and procurvatum deformity after completing the initial correction schedule. What is the most appropriate next step to correct the residual deformity?

. Perform an acute adjustment in the clinic under sedation.
. Generate a new 'total residual' program using updated orthogonal radiographs.
. Remove the frame and convert to an intramedullary nail.
. Adjust only the anterior and medial struts empirically.
. Perform a closing wedge osteotomy.

Correct Answer & Explanation

. Generate a new 'total residual' program using updated orthogonal radiographs.

Explanation

The primary advantage of a hexapod circular frame is the ability to easily correct residual multiplanar deformities. The surgeon should obtain new orthogonal radiographs, re-measure the parameters, and enter them into the software to generate a precise residual correction schedule.

Question 656

Topic: Lower Extremity Trauma

During a femoral lengthening procedure utilizing the Lengthening Over a Nail (LON) technique, what is the primary advantage compared to lengthening with an external fixator alone?

. Reduced risk of deep intramedullary infection
. Decreased duration of external fixator wear
. Complete elimination of pin-tract infections
. Ability to use standard reamed nails in skeletally immature patients
. Better preservation of the endosteal blood supply

Correct Answer & Explanation

. Decreased duration of external fixator wear

Explanation

Lengthening over a nail (LON) allows the external fixator to be removed immediately once the desired length is achieved, with the intramedullary nail locked to maintain length during the consolidation phase. This drastically reduces the time the patient is burdened by the external frame.

Question 657

Topic: Lower Extremity Trauma

A 7-year-old boy with Dysplasia epiphysealis hemimelica (Trevor disease) of the distal femur presents with a worsening mechanical block to knee flexion and increasing pain. What is the most appropriate management?

. Observation and physical therapy
. Intra-articular corticosteroid injection
. Radiofrequency ablation of the lesion
. Surgical excision of the lesion with preservation of the underlying articular surface
. Distal femoral epiphysiodesis

Correct Answer & Explanation

. Surgical excision of the lesion with preservation of the underlying articular surface

Explanation

Symptomatic Trevor disease causing a mechanical block or deformity is managed with surgical excision. It is critical to meticulously remove the epiphyseal mass while preserving the normal underlying chondral surface and joint congruity.

Question 658

Topic: Lower Extremity Trauma

At skeletal maturity, a healthy, asymptomatic patient is diagnosed with a projected leg length discrepancy of 1.5 cm. What is the most appropriate initial management?

. Observation and reassurance.
. Prescription of a 1.5 cm shoe lift.
. Contralateral distal femoral epiphysiodesis.
. Femoral shortening osteotomy.
. Tibial lengthening over an intramedullary nail.

Correct Answer & Explanation

. Observation and reassurance.

Explanation

Limb length discrepancies less than 2.0 cm at skeletal maturity are typically asymptomatic and well-tolerated. Observation without any active intervention or shoe lift is the most appropriate management.

Question 659

Topic: Lower Extremity Trauma

In evaluating sagittal plane deformities of the proximal tibia, what is the normal posterior proximal tibial angle (PPTA)?

. 70 degrees
. 81 degrees
. 90 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 81 degrees

Explanation

The normal posterior proximal tibial angle (PPTA) is 81 degrees (range 77-84 degrees). This parameter describes the normal posterior slope of the tibial plateau in the sagittal plane.

Question 660

Topic: Lower Extremity Trauma

During deformity planning for a varus knee, the Joint Line Convergence Angle (JLCA) is measured at 7 degrees medially convergent. The normal JLCA is 0 to 2 degrees. What does this abnormal JLCA strongly imply?

. An extra-articular bony deformity of the distal femur.
. An extra-articular bony deformity of the proximal tibia.
. A primary valgus alignment of the mechanical axis.
. Fixed medial compartment cartilage loss or lateral collateral ligament laxity.
. Normal physiologic bowing in a skeletal mature patient.

Correct Answer & Explanation

. Fixed medial compartment cartilage loss or lateral collateral ligament laxity.

Explanation

An abnormal JLCA indicates an intra-articular source of deformity. In a varus knee with a medially convergent JLCA, this is typically due to asymmetric medial joint space narrowing (cartilage loss) or lateral ligamentous laxity.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page