Orthopedic MCQs: Dysplasia Epiphysealis Hemimelica (Trevor's)

Question 1

A 6-year-old boy presents with a painless, hard swelling on the lateral aspect of his left ankle, as shown in the clinical photograph below. He has a limited range of motion in the affected joint. Given the most likely diagnosis, which of the following is true regarding the typical epidemiological profile of this condition?

Explanation

Correct Answer: C

The clinical image demonstrates a bone-hard swelling typical of Dysplasia Epiphysealis Hemimelica (DEH), also known as Trevor's disease. DEH is a rare skeletal developmental disorder that typically presents in young children between the ages of 2 and 14 years. It has an incidence of 1 in 1,000,000, affects males twice as frequently as females, and predominantly involves the lower limbs (distal femur, distal tibia, and talus).

Question 2

A 9-year-old boy presents with chronic ankle pain and stiffness. The MRI and CT scans of his hindfoot are provided below. Based on the imaging findings demonstrating a lesion arising from the epiphysis, what is the most likely histological diagnosis of this mass?

Explanation

Correct Answer: C

The imaging shows Dysplasia Epiphysealis Hemimelica (DEH) localized on the lateral side of the talus. Histologically, DEH is identical to an osteochondroma. The key distinguishing feature is its location: DEH arises from the epiphysis, whereas a classic osteochondroma arises from the metaphysis or diaphysis.

Question 3

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?

Explanation

Correct Answer: B

The 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 4

Dysplasia epiphysealis hemimelica (DEH) shares identical histological features with which of the following benign bone tumors, and how is it primarily distinguished from it clinically and radiographically?

Explanation

Correct Answer: B

Histologically, the lesion in Dysplasia Epiphysealis Hemimelica (DEH) is similar to an osteochondroma (composed of bone covered by a cartilage cap). However, they are distinguished by their site of origin: osteochondromas arise from the metaphysis or diaphysis, whereas DEH uniquely arises from the epiphysis.

Question 5

Which of the following statements accurately reflects the epidemiology and etiology of Dysplasia Epiphysealis Hemimelica (DEH)?

Explanation

Correct Answer: C

DEH is a very rare disorder with an incidence of 1 in 1,000,000. It affects males twice as frequently as females. The etiology remains unknown (unlike multiple hereditary exostoses which are linked to EXT genes). The age of onset is usually between 2 and 14 years, and it predominantly affects the lower extremities.

Question 6

A 5-year-old boy is being evaluated for a hard, asymmetrical mass around his knee. Radiographs are obtained. Which of the following radiographic findings is most characteristic of Dysplasia Epiphysealis Hemimelica?

Explanation

Correct Answer: B

On radiographs, DEH characteristically shows asymmetric epiphyseal enlargement with multiple ossification centers. This reflects the abnormal, hemimelic overgrowth of the epiphyseal cartilage and its subsequent irregular ossification.

Question 7

Dysplasia epiphysealis hemimelica (DEH) most frequently affects the lower extremities. Which of the following groups of bones represents the most common sites of involvement?

Explanation

Correct Answer: B

DEH usually occurs in the lower limb. The most commonly affected sites are the distal femur, distal tibia, and the talus. Upper limb involvement is extremely rare.

Question 8

A 7-year-old male is brought to the orthopedic clinic by his parents. Which of the following constellations of symptoms is most consistent with a presentation of Dysplasia Epiphysealis Hemimelica (DEH)?

Explanation

Correct Answer: C

The most common presenting symptoms of DEH include the presence of a mass with the consistency of bone, joint deformity, aching pains, and a limited range of motion due to the mechanical block caused by the epiphyseal overgrowth.

Question 9

Review the provided MRI and CT images of a pediatric patient presenting with hindfoot pain and restricted motion. The pathology is localized to the lateral side of the affected bone. Based on the typical distribution of this disease, which bone is primarily affected in this image?

Explanation

Correct Answer: C

The images (MRI frontal plane and CT slides) demonstrate DEH localized on the lateral side of the talus. The talus is one of the three most common locations for DEH, alongside the distal femur and distal tibia.

Question 10

The images below show a lateral radiograph and a sagittal MRI of a knee in a young patient with aching pain and limited range of motion. The mass originates from the distal femoral epiphysis. Into which anatomical space is the bone mass predominantly protruding?

Explanation

Correct Answer: B

The sagittal MRI slide clearly shows a protruding bone mass extending posteriorly from the distal femoral epiphysis directly into the popliteal fossa. This posterior extension can cause significant mechanical block to knee flexion and aching pain.

Question 11

A 7-year-old boy presents with the clinical finding shown below. Radiographs reveal an underlying epiphyseal lesion. Histological examination of this mass would most likely reveal features identical to which of the following conditions?

Explanation

Correct Answer: Osteochondroma

The image shows a moderate, bone-hard swelling typical of Dysplasia Epiphysealis Hemimelica (DEH). Histologically, DEH is indistinguishable from an osteochondroma, featuring a cartilage cap with underlying trabecular bone. The key difference is anatomical location: DEH arises from the epiphysis, whereas osteochondromas arise from the metaphysis or diaphysis.

Question 12

Review the provided MRI and CT images of a pediatric patient's ankle. What is the primary anatomical feature that distinguishes this specific pathology from a solitary osteochondroma?

Explanation

Correct Answer: It arises from the epiphysis rather than the metaphysis

The imaging demonstrates Dysplasia Epiphysealis Hemimelica (DEH) localized to the lateral side of the talus. While histologically similar to an osteochondroma, DEH is uniquely characterized by its origin from the epiphysis. It is typically unilateral, asymmetric (hemimelic), and more common in males.

Question 13

The imaging below demonstrates a protruding bone mass in the posterior aspect of the knee in a 10-year-old child. Based on the typical behavior of this disease, which of the following statements regarding its anatomical distribution is most accurate?

Explanation

Correct Answer: It characteristically involves either the medial or lateral half of the epiphysis

The images show DEH of the distal femur. The term 'hemimelica' refers to the characteristic involvement of only one half (either medial or lateral) of the affected epiphysis. It rarely affects the upper extremities and does not typically involve the entire epiphysis symmetrically.

Question 14

Dysplasia epiphysealis hemimelica (DEH) is a rare developmental disorder. Which of the following best describes the epidemiological profile of this condition?

Explanation

Correct Answer: Incidence of 1 in 1,000,000 with male predominance

DEH is an extremely rare skeletal developmental disorder with an estimated incidence of 1 in 1,000,000. Males are affected twice as frequently as females.

Question 15

A 9-year-old male presents with aching pain, deformity, and limited range of motion in his right knee. Radiographs show asymmetric epiphyseal enlargement of the distal femur with multiple ossification centers. What is the most likely diagnosis?

Explanation

Correct Answer: Dysplasia Epiphysealis Hemimelica

The clinical presentation of aching pain, deformity, and limited range of motion combined with the hallmark radiographic finding of asymmetric epiphyseal enlargement with multiple ossification centers is classic for Dysplasia Epiphysealis Hemimelica (DEH).

Question 16

Regarding the age of onset for Dysplasia Epiphysealis Hemimelica (DEH), during which of the following age ranges do patients most commonly present with initial symptoms?

Explanation

Correct Answer: 2 to 14 years

DEH is a developmental disorder affecting the epiphyses in young children. The age of onset is usually between 2 and 14 years, corresponding to the period of active epiphyseal growth and ossification.

Question 17

A pediatric orthopedic surgeon is evaluating a child with suspected Dysplasia Epiphysealis Hemimelica (DEH). Which of the following anatomical locations is the LEAST likely to be the primary site of involvement?

Explanation

Correct Answer: Proximal humerus

DEH usually occurs in the lower limb, with the distal femur, distal tibia, and talus being the most commonly affected sites. Upper limb involvement, such as the proximal humerus, is extremely rare.

Question 18

Which of the following radiographic findings is considered the hallmark of Dysplasia Epiphysealis Hemimelica in a growing child?

Explanation

Correct Answer: Asymmetric epiphyseal enlargement with multiple ossification centers

The characteristic radiographic appearance of DEH is asymmetric epiphyseal enlargement (hemimelic involvement) accompanied by multiple ossification centers within the affected area.

Question 19

The advanced imaging provided shows a lesion characteristic of Dysplasia Epiphysealis Hemimelica (DEH). Given the intra-articular nature of this pathology, what is the most common clinical presentation associated with this specific location?

Explanation

Correct Answer: Presence of a bone-hard mass with aching pains and limited range of motion

The most common presenting symptoms of DEH include the presence of a mass with the consistency of bone, deformity, aching pains, and limited range of motion due to the intra-articular and epiphyseal nature of the overgrowth.

Question 20

The sagittal MRI provided demonstrates a mass protruding from the distal femoral epiphysis into the popliteal fossa. In the context of Dysplasia Epiphysealis Hemimelica, what is the fundamental etiology of this condition?

Explanation

Correct Answer: Unknown etiology

Despite its histological similarity to osteochondromas (which can be linked to EXT1/EXT2 mutations in multiple hereditary exostoses), the etiology of Dysplasia Epiphysealis Hemimelica (DEH) remains unknown.

Question 21

A 7-year-old boy presents with the clinical finding shown below. Palpation reveals a painless, bone-hard swelling. Based on the most likely diagnosis, what is the histological appearance of this lesion most similar to?

Explanation

Correct Answer: Osteochondroma

The clinical image demonstrates a bone-hard swelling on the lateral side of the ankle, characteristic of Dysplasia Epiphysealis Hemimelica (DEH). Histologically, DEH is identical to an osteochondroma. The key differentiating factor is its anatomical origin: DEH arises from the epiphysis, whereas a classic osteochondroma arises from the metaphysis or diaphysis.

Question 22

Review the coronal MRI and CT images of a pediatric patient's ankle below. The lesion is localized to the lateral aspect of the talus. Which of the following terms best describes this characteristic pattern of involvement?

Explanation

Correct Answer: Hemimelic

The images show Dysplasia Epiphysealis Hemimelica (DEH) localized to the lateral side of the talus. Characteristically, the involvement in this condition is 'hemimelic', meaning it affects only one half (either the medial or lateral side) of the epiphysis.

Question 23

A 10-year-old male presents with aching pain and limited knee range of motion. The lateral radiograph and sagittal MRI are shown below. The mass protrudes into the popliteal fossa. From which specific anatomical region does this pathology primarily arise?

Explanation

Correct Answer: Epiphysis

The images demonstrate Dysplasia Epiphysealis Hemimelica (DEH) of the knee. Unlike osteochondromas which arise from the metaphysis, DEH is a developmental disorder that specifically arises from the epiphysis, leading to asymmetric epiphyseal overgrowth and joint deformity.

Question 24

Dysplasia epiphysealis hemimelica (DEH) is a rare skeletal developmental disorder. Which of the following demographic profiles is most consistent with the typical presentation of DEH?

Explanation

Correct Answer: A 4-year-old male

The age of onset for DEH is usually between 2 and 14 years. Furthermore, males are affected twice as frequently as females, making a young male child the most typical demographic presentation.

Question 25

When evaluating a child with suspected Dysplasia Epiphysealis Hemimelica (DEH), what is the classic radiographic hallmark observed in the affected joint?

Explanation

Correct Answer: Asymmetric epiphyseal enlargement with multiple ossification centers

On radiographs, DEH characteristically presents as asymmetric epiphyseal enlargement (due to its hemimelic nature) accompanied by multiple ossification centers within the affected epiphyseal region.

Question 26

A biopsy is obtained from a bony mass in the distal tibia of an 8-year-old boy. The pathologist reports that the histology is identical to an osteochondroma. Which of the following clinical or radiographic findings would definitively point to a diagnosis of Dysplasia Epiphysealis Hemimelica (DEH) rather than a standard osteochondroma?

Explanation

Correct Answer: The lesion arises from the epiphysis

While DEH and osteochondroma share identical histological features (including a cartilage cap), their anatomical origins differ. Osteochondromas arise from the metaphysis or diaphysis, whereas DEH arises exclusively from the epiphysis.

Question 27

Dysplasia epiphysealis hemimelica (DEH) predominantly affects the lower extremities. Which of the following groups of bones represents the most common sites of involvement?

Explanation

Correct Answer: Distal femur, distal tibia, and talus

DEH usually occurs in the lower limb. The most commonly affected anatomical sites are the distal femur, distal tibia, and the talus. Upper limb involvement is considered extremely rare.

Question 28

Dysplasia epiphysealis hemimelica (DEH) is an extremely rare condition. According to epidemiological data, what is the estimated incidence of this disorder?

Explanation

Correct Answer: 1 in 1,000,000

DEH is a very rare skeletal developmental disorder with an estimated incidence of 1 in 1,000,000 in the general population.

Question 29

A 9-year-old boy is evaluated for a mass around his ankle. Which of the following is NOT a typical presenting symptom or sign of Dysplasia Epiphysealis Hemimelica (DEH)?

Explanation

Correct Answer: Rapidly progressive overlying skin erythema and warmth

DEH typically presents with a bone-hard mass, deformity, aching pains, and limited range of motion. Rapidly progressive erythema and warmth are signs of acute inflammation or infection (e.g., osteomyelitis or septic arthritis) and are not characteristic of DEH.

Question 30

A resident is reviewing cases of Dysplasia Epiphysealis Hemimelica (DEH) for a departmental presentation. They note a specific pattern regarding the anatomical distribution of the lesions. Which of the following statements is true regarding the anatomical distribution of DEH?

Explanation

Correct Answer: Upper limb involvement is extremely rare.

DEH is predominantly a condition of the lower extremities (distal femur, distal tibia, talus). Upper limb involvement is documented in the literature but is considered extremely rare.

Question 31

A 6-year-old boy presents with the clinical finding shown below. Based on the most likely diagnosis, what is the typical age of onset for this condition?

Explanation

Correct Answer: 2 to 14 years

The image demonstrates a moderate, painless, bone-hard swelling at the lateral side of the ankle, characteristic of Dysplasia Epiphysealis Hemimelica (DEH). According to the text, the age of onset for DEH is usually between 2 and 14 years.

Question 32

The imaging below shows a lesion localized on the lateral side of the talus. Histologically, this lesion is identical to an osteochondroma. What is the primary anatomical difference between this condition and a classic osteochondroma?

Explanation

Correct Answer: This lesion arises from the epiphysis

The imaging shows Dysplasia Epiphysealis Hemimelica (DEH) of the talus. Histologically, DEH is similar to an osteochondroma. However, the key distinguishing feature is that an osteochondroma arises from the metaphysis or diaphysis, whereas DEH arises directly from the epiphysis.

Question 33

A 9-year-old male presents with limited range of motion in the knee. Imaging is shown below. Which of the following statements is true regarding the epidemiology of this condition?

Explanation

Correct Answer: Males are affected twice as frequently as females

The images display DEH of the distal femoral epiphysis protruding into the popliteal fossa. DEH is a rare skeletal developmental disorder with an incidence of 1 in 1,000,000. Epidemiologically, males are affected twice as frequently as females.

Question 34

Dysplasia epiphysealis hemimelica (DEH) is characterized by asymmetric overgrowth. Which of the following best describes the typical radiographic appearance of DEH?

Explanation

Correct Answer: Asymmetric epiphyseal enlargement with multiple ossification centers

Characteristically, DEH lesions show on radiographs as asymmetric epiphyseal enlargement with multiple ossification centers. This reflects the irregular, hemimelic overgrowth of the affected epiphysis.

Question 35

A 10-year-old boy is diagnosed with Dysplasia Epiphysealis Hemimelica (DEH). Which of the following anatomical locations is MOST commonly affected by this disorder?

Explanation

Correct Answer: Distal femur

DEH usually occurs in the lower limb. The distal femur, distal tibia, and talus are the most commonly affected sites. Upper limb involvement is considered extremely rare.

Question 36

The term 'hemimelica' in Dysplasia Epiphysealis Hemimelica refers to which of the following characteristic patterns of involvement?

Explanation

Correct Answer: Involvement of either the medial or lateral side of the epiphysis

The text explicitly states that characteristically the involvement is hemimelic, meaning that either the medial or the lateral epiphyseal side is involved, rather than the entire epiphysis symmetrically.

Question 37

A 7-year-old child presents with a painless, bone-hard swelling at the lateral side of the left ankle, as shown below. What is the estimated incidence of the suspected condition?

Explanation

Correct Answer: 1 in 1,000,000

The clinical image shows a typical presentation of Dysplasia Epiphysealis Hemimelica (DEH). DEH is a very rare skeletal developmental disorder with an estimated incidence of 1 in 1,000,000.

Question 38

Regarding the clinical presentation of Dysplasia Epiphysealis Hemimelica (DEH), which of the following is considered extremely rare?

Explanation

Correct Answer: Involvement of the upper limb

DEH predominantly affects the lower extremities (distal femur, distal tibia, and talus). The text notes that upper limb involvement is extremely rare. Presentation with a bone-hard mass and aching pains are common symptoms.

Question 39

A patient presents with a protruding bone mass from the distal femoral epiphysis to the popliteal fossa, as seen in the sagittal MRI below. If a biopsy were performed on this mass, the histological findings would most closely resemble which of the following?

Explanation

Correct Answer: Osteochondroma

The MRI shows DEH of the distal femur. Histologically, DEH is similar to an osteochondroma (featuring a cartilage cap over bony trabeculae). The main difference is anatomical origin: DEH arises from the epiphysis, whereas osteochondromas arise from the metaphysis or diaphysis.

Question 40

A 12-year-old boy presents with a deformity and limited range of motion in his right ankle. Imaging reveals an asymmetric epiphyseal enlargement with multiple ossification centers on the medial side of the distal tibia. Which of the following is the most likely diagnosis?

Explanation

Correct Answer: Dysplasia Epiphysealis Hemimelica

The clinical presentation of a young male with limited ROM, deformity, and radiographic findings of asymmetric epiphyseal enlargement with multiple ossification centers on one side (hemimelic) of the distal tibia is the classic description of Dysplasia Epiphysealis Hemimelica (DEH).

Question 41

A 6-year-old boy presents with the clinical finding shown below. Palpation reveals a bone-hard, painless mass. Given the most likely diagnosis of Dysplasia Epiphysealis Hemimelica (DEH), which of the following statements regarding the epidemiology of this condition is most accurate?

Explanation

Correct Answer: C

Dysplasia Epiphysealis Hemimelica (DEH), also known as Trevor's disease, typically presents in young children with an age of onset usually between 2 and 14 years. It is extremely rare (incidence of 1 in 1,000,000), affects males twice as frequently as females, and predominantly involves the lower limbs (distal femur, distal tibia, and talus). It presents as a mass with the consistency of bone, not a soft fluctuant mass.

Question 42

A 9-year-old male presents with restricted ankle motion and a palpable hard mass. The imaging studies below are obtained. Based on the typical characteristics of the demonstrated pathology, which of the following best describes the expected histological findings?

Explanation

Correct Answer: B

The imaging shows Dysplasia Epiphysealis Hemimelica (DEH) localized on the lateral side of the talus. Histologically, DEH is indistinguishable from an osteochondroma. The critical differentiating factor is anatomical location: osteochondromas arise from the metaphysis or diaphysis, whereas DEH arises from the epiphysis.

Question 43

A 12-year-old boy presents with aching pain and limited range of motion in his knee. The imaging below reveals a protruding bone mass extending into the popliteal fossa. Which of the following is the most likely origin of this lesion?

Explanation

Correct Answer: C

The images demonstrate Dysplasia Epiphysealis Hemimelica (DEH) of the knee. By definition, DEH is a developmental disorder affecting the epiphyses. In this specific case, the protruding bone mass originates from the distal femoral epiphysis and extends into the popliteal fossa.

Question 44

When evaluating a pediatric patient suspected of having Dysplasia Epiphysealis Hemimelica (DEH), what is the hallmark radiographic feature typically observed?

Explanation

Correct Answer: B

Characteristically, DEH lesions show on radiographs as asymmetric epiphyseal enlargement with multiple ossification centers. The involvement is typically hemimelic, meaning it affects either the medial or lateral side of the epiphysis, leading to this asymmetric appearance.

Question 45

Which of the following anatomical locations is considered extremely rare for the development of Dysplasia Epiphysealis Hemimelica (DEH)?

Explanation

Correct Answer: D

DEH usually occurs in the lower limb, with the distal femur, distal tibia, and talus being the most commonly affected sites. Upper limb involvement (such as the distal radius) is considered extremely rare.

Question 46

The term 'hemimelica' in Dysplasia Epiphysealis Hemimelica refers to which of the following characteristic patterns of involvement?

Explanation

Correct Answer: C

The term 'hemimelica' denotes that the involvement is characteristically limited to one half of the epiphysis—either the medial or the lateral epiphyseal side is involved, leading to asymmetric growth and deformity.

Question 47

A pediatric orthopedic surgeon is counseling the parents of a child recently diagnosed with Dysplasia Epiphysealis Hemimelica (DEH). When discussing the rarity of the condition, what is the accepted estimated incidence?

Explanation

Correct Answer: E

Dysplasia Epiphysealis Hemimelica (DEH) is an exceptionally rare skeletal developmental disorder. The reported incidence in the literature is approximately 1 in 1,000,000.

Question 48

A 7-year-old boy presents with a bony mass around the knee. Radiographs show an exostosis. The surgeon is differentiating between an osteochondroma and Dysplasia Epiphysealis Hemimelica (DEH). Which of the following features definitively distinguishes DEH from a classic osteochondroma?

Explanation

Correct Answer: C

Histologically, DEH is similar or identical to an osteochondroma. The definitive distinguishing feature is the anatomical origin: an osteochondroma arises from the metaphysis or diaphysis, whereas DEH arises specifically from the epiphysis.

Question 49

Review the advanced imaging of the ankle provided below. The pathology is localized to the lateral side of the talus. In a patient with this specific presentation of Dysplasia Epiphysealis Hemimelica (DEH), which of the following clinical symptoms is most likely to be the primary complaint alongside the palpable mass?

Explanation

Correct Answer: B

The most common presenting symptoms of DEH include the presence of a mass with the consistency of bone, deformity, aching pains, and limited range of motion. Neurological deficits, nocturnal pain relieved by NSAIDs (typical of osteoid osteoma), and pathological fractures are not classic primary presentations of DEH.

Question 50

A resident is reviewing a case series of patients with Dysplasia Epiphysealis Hemimelica (DEH). Based on the established epidemiological profile of this disorder, which of the following demographic presentations is most typical?

Explanation

Correct Answer: B

DEH typically affects young children, with the age of onset usually between 2 and 14 years. Furthermore, males are affected twice as frequently as females. Therefore, an 8-year-old male fits the classic demographic profile perfectly.

Question 51

A 4-year-old boy is brought to the orthopedic clinic with a painless, bony prominence on the medial aspect of his right knee. Radiographs reveal an irregular, multi-centric ossification center arising from the medial distal femoral epiphysis. Which of the following is true regarding the genetic etiology of this condition?

Explanation

Dysplasia Epiphysealis Hemimelica (DEH), or Trevor's disease, is a sporadic, non-hereditary developmental disorder. Unlike multiple hereditary exostoses, DEH is not associated with EXT1 or EXT2 gene mutations.

Question 52

A 6-year-old child is diagnosed with Dysplasia Epiphysealis Hemimelica of the ankle.

The parents inquire about the potential for malignant transformation of this lesion over the child's lifetime. What is the most accurate information to provide?

Explanation

Malignant transformation of DEH has almost never been reported in the literature. It is considered a benign developmental anomaly of epiphyseal cartilage overgrowth.

Question 53

A 7-year-old boy presents with an enlarging mass on the medial aspect of his right foot and ankle.

He complains of a mechanical block to ankle dorsiflexion. Based on the pathogenesis of Dysplasia Epiphysealis Hemimelica, this lesion is histologically indistinguishable from which of the following bone tumors?

Explanation

Histologically, DEH is identical to an osteochondroma, consisting of a hyaline cartilage cap overlying trabecular bone. The defining difference is its origin from the epiphysis or carpal/tarsal equivalents, rather than the metaphysis.

Question 54

Which of the following bones is statistically the most frequently affected site in Dysplasia Epiphysealis Hemimelica?

Explanation

The talus is the most commonly affected bone in DEH, followed by the distal femur and proximal tibia. The lower extremities are overwhelmingly more involved than the upper extremities.

Question 55

A 5-year-old boy is incidentally found to have an irregular calcified mass arising from the lateral aspect of the proximal tibial epiphysis. He has full range of motion, no pain, and no angular deformity. What is the most appropriate initial management?

Explanation

In asymptomatic cases of DEH without joint impingement or deformity, the standard of care is clinical and radiographic observation. Surgical intervention is reserved for symptomatic patients or those with progressive mechanical block.

Question 56

In patients diagnosed with Dysplasia Epiphysealis Hemimelica, the term 'hemimelica' specifically refers to which characteristic clinical feature?

Explanation

The term 'hemimelica' describes the classic distribution of the disease, which typically affects either the medial (more common) or lateral half of a single limb. It rarely crosses the midline of the affected joint.

Question 57

A 10-year-old male with a known diagnosis of Trevor's disease presents with increasing varus deformity of the knee. The lesion originates from the medial femoral epiphysis. When does this mass typically cease its active growth?

Explanation

The growth of a DEH lesion is commensurate with the physiological growth of the child. It typically ceases to enlarge once the physes close and skeletal maturity is reached.

Question 58

Which of the following epidemiological profiles best fits the typical presentation of Dysplasia Epiphysealis Hemimelica?

Explanation

DEH predominantly affects young males (male-to-female ratio of 3:1) and usually presents in early childhood. It classically involves a single lower extremity.

Question 59

According to the Azouz classification for Dysplasia Epiphysealis Hemimelica, a patient presenting with involvement of the distal femur, proximal tibia, and talus in the same lower extremity is classified as which of the following?

Explanation

In the Azouz classification, Type I is localized (one bone), Type II is classic (more than one bone in a single limb), and Type III is generalized (involving the entire limb or multiple limbs). Multiple bones in a single limb fits Type II.

Question 60

A 4-year-old boy is scheduled for excision of a symptomatic epiphyseal lesion of the ankle.

The surgeon carefully plans to resect the overgrowth while protecting the normal epiphysis. What is the most common reason for recurrence following surgical excision of DEH?

Explanation

Similar to standard osteochondromas, recurrence of DEH after surgical excision is primarily due to incomplete removal of the cartilaginous cap. The active growing cells are located within this cap.

Question 61

A 3-year-old is being evaluated for a hard, asymmetrical swelling of the ankle. Magnetic Resonance Imaging (MRI) is ordered. What is the primary advantage of MRI over plain radiography in early stages of Dysplasia Epiphysealis Hemimelica?

Explanation

In young children, much of the epiphysis and the DEH lesion itself may be unossified cartilage. MRI is superior for delineating the extent of the unossified cartilage cap and evaluating joint congruity.

Question 62

Which of the following clinical findings best distinguishes Dysplasia Epiphysealis Multiplex (Multiple Epiphyseal Dysplasia) from Dysplasia Epiphysealis Hemimelica?

Explanation

Multiple Epiphyseal Dysplasia (MED) is a genetic disorder causing bilateral, symmetrical epiphyseal irregularities and short stature. In contrast, DEH is unilateral, localized to half a joint, and characterized by an exophytic osteocartilaginous mass.

Question 63

A 9-year-old male with untreated DEH of the medial talus presents with worsening pain during ambulation. What is the most likely long-term sequela if the mechanical incongruity of the joint is left unaddressed?

Explanation

If left untreated, the mechanical block and joint incongruity caused by an enlarging epiphyseal mass in DEH predictably lead to premature secondary osteoarthritis of the affected joint.

Question 64

Trevor's disease was originally described in 1950 under a different nomenclature. What historical term did Trevor use to describe this pathology?

Explanation

Trevor originally named the condition 'tarso-epiphyseal aclasis' in 1950 because he observed it predominantly affecting the tarsal bones and epiphyses. It was later renamed Dysplasia Epiphysealis Hemimelica by Fairbank.

Question 65

When planning an excision for a symptomatic DEH lesion of the distal femur, which of the following describes the most significant challenge specific to this condition compared to a traditional metaphyseal osteochondroma?

Explanation

Because DEH arises directly from the epiphysis, the mass often blends indistinguishably with the normal articular cartilage. Preserving the normal articular congruity while resecting the lesion is the primary surgical challenge.

Question 66

A 5-year-old boy presents with a hard mass on the lateral aspect of his ankle. Plain radiographs demonstrate an eccentric ossific mass adjacent to the lateral talar body. Which of the following conditions presents as an intra-epiphyseal lytic lesion rather than an exostotic mass, distinguishing it from DEH?

Explanation

Chondroblastoma is an intra-epiphyseal benign tumor that presents as a lytic lesion on radiographs. DEH, conversely, presents as an exophytic osteocartilaginous overgrowth (exostosis) arising from the epiphysis.

Question 67

Which zone of the epiphyseal cartilage is theorized to be the origin of the abnormal proliferation in Dysplasia Epiphysealis Hemimelica?

Explanation

DEH is believed to result from an abnormal proliferation of the epiphyseal cartilage cells, functioning similarly to an ectopic germinal/resting zone that produces enchondral ossification outward.

Question 68

A 12-year-old boy undergoes surgical excision of a DEH mass from his medial proximal tibia. Postoperatively, what secondary deformity must the surgeon closely monitor for during his remaining growing years?

Explanation

Surgical excision of a medial epiphyseal lesion can inadvertently damage the medial physis or articular cartilage, leading to growth arrest on the medial side and a subsequent progressive varus deformity.

Question 69

In evaluating a new patient with suspected DEH, which of the following systemic syndromic associations should the clinician screen for?

Explanation

DEH (Trevor's disease) is typically an isolated developmental anomaly. It is not characteristically associated with any underlying systemic syndromes or known genetic cascades.

Question 70

A pediatric orthopedic surgeon reviews a plain radiograph of a 6-year-old ankle showing a multi-lobulated, stippled ossification center distinct from, but adjacent to, the main talar ossification center. Over time, what is the expected natural radiographic progression of this lesion?

Explanation

In early stages, DEH appears as separate, irregular ossification centers adjacent to the epiphysis. As the child grows, these secondary centers typically enlarge and merge with the main epiphyseal ossification center.

Question 71

A 4-year-old boy presents with a painless, hard swelling on the medial aspect of his ankle. Radiographs reveal irregular, multicentric opacities adjacent to the medial aspect of the talar epiphysis. Histological examination of a biopsy from the lesion would most likely reveal which of the following?

Explanation

Dysplasia Epiphysealis Hemimelica (DEH), or Trevor's disease, is essentially an osteochondroma arising from the epiphysis. Its histology is identical to a classic metaphyseal osteochondroma, demonstrating a cartilage cap overlying normal trabecular bone.

Question 72

Dysplasia Epiphysealis Hemimelica (DEH) is characterized by asymmetric cartilaginous overgrowth. Which of the following best describes the most common anatomical distribution of this disease?

Explanation

DEH almost exclusively affects the lower extremities in an asymmetrical, unilateral fashion. The lesions most frequently arise from the medial half of the epiphysis (hemimelic).

Question 73

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?

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 74

What is the fundamental pathophysiological mechanism underlying the development of Dysplasia Epiphysealis Hemimelica?

Explanation

DEH is caused by a localized, abnormal proliferation of epiphyseal osteochondromatous tissue. It represents a benign overgrowth of cartilage at the epiphysis that subsequently ossifies.

Question 75

Which of the following classification systems is utilized to describe the anatomical extent and multiplicity of lesions in Dysplasia Epiphysealis Hemimelica?

Explanation

The Azouz classification is used for DEH, dividing it into localized (single epiphysis), classic/regional (>1 epiphysis in one limb), and generalized (involvement of the entire lower limb).

Question 76

A 5-year-old child presents with a mass around the knee. Imaging reveals an epiphyseal bony outgrowth consistent with DEH. Which of the following is the most appropriate primary indication for surgical excision?

Explanation

Asymptomatic DEH lesions are observed. Surgical excision is indicated primarily when the mass causes a mechanical block to joint motion, pain, or a progressive angular deformity.

Question 77

When surgical intervention is performed for a symptomatic DEH lesion of the distal femur, what is the most significant potential iatrogenic complication?

Explanation

Surgical excision of DEH risks iatrogenic damage to the normal parent articular cartilage and the adjacent growth plate, potentially leading to premature physeal closure and early-onset osteoarthritis.

Question 78

Which of the following imaging modalities is considered the most accurate for delineating the unossified cartilage cap and determining the extent of articular surface involvement in DEH?

Explanation

MRI is the gold standard for evaluating DEH as it precisely delineates the unossified cartilage cap, evaluates its continuity with the parent epiphysis, and maps out articular surface involvement.

Question 79

A 6-year-old boy has an irregular, multi-centric ossification mass adjacent to the medial talar epiphysis.

According to the natural history of this condition, when is the progressive growth of the lesion expected to cease?

Explanation

Similar to typical osteochondromas, the growth of a DEH lesion is tied to skeletal growth. The lesion will naturally stop enlarging once skeletal maturity is reached and the physes close.

Question 80

In differentiating Dysplasia Epiphysealis Hemimelica (DEH) from Multiple Hereditary Exostoses (MHE), which of the following is a key distinguishing feature of DEH?

Explanation

MHE is characterized by multiple osteochondromas arising from the metaphysis, whereas DEH uniquely describes osteochondromas arising from the epiphysis or apophysis.

Question 81

A 4-year-old boy presents with painless swelling of the medial ankle. Imaging shows irregular ossification centers adjacent to the medial malleolus. What is the classic eponymous name for this exact condition?

Explanation

Dysplasia Epiphysealis Hemimelica is classically referred to as Trevor disease, named after David Trevor who described the condition as 'tarso-epiphyseal aclasis'.

Question 82

Dysplasia Epiphysealis Hemimelica (DEH) typically presents in a specific epidemiological group. Which demographic is overwhelmingly most commonly affected?

Explanation

DEH primarily affects young children, typically presenting between the ages of 2 and 8 years. It has a strong male predilection, occurring in males three times more frequently than in females.

Question 83

An 8-year-old male child has established Trevor disease involving the medial aspect of the distal femur. If left untreated, what resulting limb deformity is most likely to develop as the child grows?

Explanation

Overgrowth of the medial epiphysis of the distal femur or proximal tibia typically results in an asymmetric increase in medial joint height, subsequently pushing the knee into a varus deformity (genu varum).

Question 84

A 10-year-old boy with a history of DEH of the ankle develops worsening pain. Serial radiographs are obtained. Which of the following is true regarding the risk of malignant transformation in DEH?

Explanation

Unlike Multiple Hereditary Exostoses, which carries a known risk of malignant transformation to chondrosarcoma, malignant transformation in DEH is virtually non-existent.

Question 85

An MRI of a knee in a 5-year-old with suspected DEH is evaluated.

Which of the following findings on MRI definitively confirms DEH and differentiates it from synovial chondromatosis?

Explanation

On MRI, DEH demonstrates an osteochondromatous mass where both the marrow space and the cartilage cap are in direct continuity with the parent epiphysis, unlike the multiple separate loose bodies seen in synovial chondromatosis.

Question 86

The Azouz classification system for DEH describes three distinct anatomical forms. A patient presenting with involvement of both the talus and the distal tibia on the ipsilateral side would be classified as which of the following?

Explanation

In the Azouz classification, 'Localized' involves a single epiphysis. 'Classic' or 'regional' involves more than one epiphysis within a single lower limb (e.g., distal tibia and talus). 'Generalized' involves the entire lower limb.

Question 87

During the surgical excision of a DEH lesion causing a mechanical block in the knee, the surgeon must exercise extreme caution.

What specific anatomical structure is at the highest risk of iatrogenic damage that could lead to severe long-term joint dysfunction?

Explanation

The primary challenge in excising a DEH lesion is completely removing the pathological exostosis while preserving the normal articular cartilage and underlying normal epiphyseal bone to prevent secondary osteoarthritis.

Question 88

While Dysplasia Epiphysealis Hemimelica is most commonly found in the lower extremities, it can rarely involve the upper limb. When the upper limb is involved, which of the following areas is most frequently affected?

Explanation

Although upper extremity involvement in DEH is rare, when it does occur, the most common sites are the carpal bones (such as the scaphoid) and the distal radius.

Question 89

A 5-year-old boy presents with progressive right knee and ankle asymmetry. Radiographs reveal cartilaginous overgrowth involving the medial distal femoral epiphysis, the proximal tibial epiphysis, and the medial aspect of the talus, all confined to the right lower extremity. According to the Azouz classification for Dysplasia Epiphysealis Hemimelica (DEH), which category best describes this patient's presentation?

Explanation

The Azouz classification divides DEH into three types: Localized (one epiphysis), Classic (more than one epiphysis in a single limb), and Generalized (involvement of the entire lower limb from pelvis to foot). This patient has multiple involved epiphyses in a single limb, fitting the Classic form.

Question 90

The parents of a 4-year-old boy recently diagnosed with Dysplasia Epiphysealis Hemimelica (Trevor's disease) of the left ankle ask about the risk of their future children inheriting the condition. Which of the following is the most accurate genetic counseling information to provide?

Explanation

Unlike Multiple Hereditary Exostoses (which involves EXT1/EXT2 gene mutations and is autosomal dominant), DEH (Trevor's disease) is a sporadic, non-hereditary developmental disorder. The recurrence risk for future siblings is virtually zero.

Question 91

A 6-year-old child presents with a painless, restricted range of motion in the right ankle. An MRI is ordered to evaluate a suspected Dysplasia Epiphysealis Hemimelica (DEH) lesion of the talus. Which of the following MRI findings is most characteristic of this pathology?

Explanation

On MRI, a DEH lesion demonstrates continuity of its cartilaginous cap with the native articular epiphyseal cartilage. This contrasts with an osteochondroma, which arises from the metaphysis and shows continuity with the metaphyseal medullary cavity.

Question 92

A 7-year-old boy presents with an enlarging mass on the medial side of his knee and a progressive varus deformity. You suspect Dysplasia Epiphysealis Hemimelica (DEH). Epidemiologically and anatomically, which of the following best describes the most common presentation of this condition?

Explanation

DEH predominantly affects males (approximately 3:1 ratio compared to females). It most commonly involves the lower extremity (especially the ankle/talus and knee) and favors the medial side of the epiphysis over the lateral side (2:1 ratio).

Question 93

A 9-year-old male with known Dysplasia Epiphysealis Hemimelica (DEH) of the distal femur presents for a routine follow-up. The parents inquire about the long-term growth behavior of the lesion. Which of the following best describes the natural history of the mass in DEH?

Explanation

DEH lesions grow proportionally with the child's skeletal growth and typically cease enlarging once skeletal maturity (physis closure) is reached. Malignant transformation is exceedingly rare.

Question 94

A 10-year-old child with an untreated, large Dysplasia Epiphysealis Hemimelica (DEH) lesion of the talus presents with worsening foot pain. Radiographs demonstrate significant joint space narrowing and subchondral sclerosis in the tibiotalar joint. What is the most common long-term complication of unmanaged symptomatic DEH?

Explanation

The most common significant long-term complication of DEH is secondary osteoarthritis. This occurs due to the progressive articular incongruity, mechanical block, and altered joint biomechanics caused by the epiphyseal overgrowth.

Question 95

A 5-year-old boy undergoes an excisional biopsy of an irregular, hard mass protruding from the medial distal tibial epiphysis. The histopathology report indicates mature trabecular bone covered by a hyaline cartilage cap undergoing endochondral ossification. Based on these findings, how does the histology of Dysplasia Epiphysealis Hemimelica (DEH) compare to an osteochondroma?

Explanation

Histologically, DEH is identical to an osteochondroma, demonstrating mature bone covered by a hyaline cartilage cap undergoing endochondral ossification. The primary difference is anatomical location (epiphyseal in DEH vs. metaphyseal in osteochondroma).

Question 96

A 6-year-old male child presents with a progressive valgus deformity of his right knee and a palpable mass. Reviewing the classic imaging of Dysplasia Epiphysealis Hemimelica

, what is the most appropriate primary surgical principle if a mechanical block and significant deformity are present?

Explanation

Surgical management of symptomatic DEH involves careful excision of the bony overgrowth to relieve mechanical blocks and correct deformity. It is critical to meticulously preserve the normal native epiphyseal cartilage to prevent early secondary osteoarthritis.

Question 97

During a resident teaching round, the attending asks for the defining anatomical distinction between Multiple Hereditary Exostoses (MHE) and Dysplasia Epiphysealis Hemimelica (DEH). While both present with osteochondroma-like lesions, DEH is uniquely characterized by its origin from which specific region of the developing bone?

Explanation

The hallmark of DEH (Trevor's disease) is the asymmetric overgrowth of cartilage arising directly from the epiphysis. In contrast, the lesions in MHE (osteochondromas) arise from the metaphysis.

Question 98

An 8-year-old boy presents with progressive restricted subtalar motion and a firm medial hindfoot mass. Radiographs show irregular, multicentric ossification centers adjacent to the talar body that appear to be coalescing. In planning surgical excision for this suspected Dysplasia Epiphysealis Hemimelica, the surgeon must be aware that the mass often blends indistinguishably with which structure?

Explanation

In DEH, the abnormal cartilaginous overgrowth typically blends seamlessly with the adjacent normal native articular cartilage of the epiphysis. This makes determining the exact resection margins challenging and requires meticulous technique to avoid damaging the true joint surface.

Arab Board Orthopedic B Review | Dr Hutaif General Orth -...

Dysplasia Epiphysealis Hemimelica (DEH) MCQs - Arab Board

Dysplasia Epiphysealis Hemimelica (DEH) MCQs - Arab Board

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