Proper cell functioning requires close regulation of plasma osmolality and intravascular volume. Which of the following statements is TRUE?
Rationale:
A: maintenance of a normal osmolality depends on regulation of sodium balance. While sodium balance plays a role in osmolality, the direct stimulus for thirst arises primarily from osmolality changes rather than sodium levels.
B: control of volume status depends on regulation of potassium balance. Potassium regulation affects cellular functions but does not significantly influence overall intravascular volume status compared to sodium and other factors.
C: the plasma osmolality is controlled between 295 and 305 mosm/kg. The normal plasma osmolality range is typically narrower, generally around 280 to 300 mosm/kg, making this statement misleading.
Differential diagnosis of Legg-Calvé-Perthes disease include all the following EXCEPT
Rationale:
C: Marfan syndrome. This condition primarily affects connective tissue and is characterized by features such as tall stature and cardiovascular issues, which do not align with the symptoms of Legg-Calvé-Perthes disease.
A: osteochondromatosis. This disorder involves multiple benign bone tumors and can mimic the hip symptoms seen in Legg-Calvé-Perthes, making it a relevant differential diagnosis.
B: Schwartz-Jampel syndrome. This rare genetic disorder features muscle stiffness and skeletal abnormalities, which can overlap with the presentation of Legg-Calvé-Perthes disease, warranting its consideration in differential diagnoses.
D: Maroteaux-Lamy syndrome. This lysosomal storage disorder leads to skeletal dysplasia and joint issues, similar to what is observed in Legg-Calvé-Perthes disease, justifying its inclusion in differential considerations.
Legg-Calvé-Perthes disease is a hip disorder of unknown etiology that results from temporary interruption of the blood supply to the proximal femoral epiphysis, leading to osteonecrosis and femoral head deformity. Of the following, the MOST common presenting symptom is
Rationale:
Limp of varying duration. This symptom is most common in Legg-Calvé-Perthes disease as it directly results from the hip's compromised blood supply, causing pain and instability that typically manifests as a noticeable limp.
B: Pain. While pain is a significant symptom, it is often secondary to the limp and may not be the initial or most common presenting feature in this condition.
C: Failure to ambulate. This represents a severe progression of symptoms and is less frequently reported at the onset compared to the more subtle presentation of a limp.
D: Atrophy of the muscles of the thigh. Muscle atrophy usually occurs later in the disease process and is not a primary symptom experienced at the initial presentation of Legg-Calvé-Perthes disease.
Normal full-term newborns can have up to 20-30 degree hip and knee flexion contractures, these contractures tend to resolve by
Rationale:
Normal full-term newborns can have up to 20-30 degree hip and knee flexion contractures, these contractures tend to resolve by 4-6 months.
This timeframe aligns with typical developmental milestones, where infants gradually gain greater mobility and strength. As they grow, their muscles and joints adapt, leading to a natural reduction in these contractures, allowing for improved movement patterns.
A: 1-3 mo. This period is often too early for significant resolution of contractures as infants are still developing their range of motion and strength.
C: 7-9 mo. By this age, most contractures should have resolved; prolonged contractures can indicate underlying issues in muscle or joint development.
D: 10-12 mo. At this stage, infants should be actively moving and crawling, making it unlikely for contractures to persist without intervention or complicating factors.
The MOST common cause of out-toeing is
Rationale:
External femoral torsion is the most common cause of out-toeing. This condition occurs when the femur is rotated outward, leading to a visible alteration in leg alignment during ambulation, making it prevalent among various age groups.
B: external tibial torsion Involves the tibia's rotation but is less prevalent than femoral torsion in causing noticeable out-toeing in individuals, particularly in younger populations.
C: calcaneovalgus feet Primarily affects the positioning of the foot and heel, resulting in an abnormal alignment that does not typically manifest as out-toeing in the leg's overall structure.
D: hypermobile pes planus (flatfoot) Relates to the arch of the foot collapsing, which may cause gait alterations, but does not predominantly lead to the outward rotation seen in out-toeing.
Adverse effect of anabolic-androgenic steroids include all the following EXCEPT
Rationale:
D: Hypotension is not a known adverse effect of anabolic-androgenic steroids. Instead, these substances are typically associated with increased blood pressure, as they can lead to cardiovascular issues and other related health problems. The other options are recognized negative consequences of steroid use, impacting reproductive and physical characteristics in users.
A: Infertility results from hormonal imbalances caused by anabolic-androgenic steroids, which can disrupt the normal functioning of the reproductive system in both men and women.
B: Gynecomastia occurs due to an imbalance in estrogen and testosterone levels, often triggered by anabolic-androgenic steroid use, leading to the development of breast tissue in males.
C: Female virilization is a significant side effect of anabolic-androgenic steroids, as these substances can induce male physical characteristics such as increased body hair and deeper voice in women.
Leg-length discrepancy (LLD) is common and may be due to differences in the femur, tibia, or both bones. The MOST accurate method with reduced-radiation to measure (LLD) is
Rationale:
D: EOS/slot scanning is the most accurate method to measure leg-length discrepancy with reduced radiation exposure, offering precise imaging that minimizes the risks associated with traditional X-ray techniques while providing essential measurements of bone lengths.
A: clinical measurements using bony landmarks (anterior superior iliac spine to medial malleolus) rely on physical assessments, which may lack the precision needed for accurate LLD evaluation compared to advanced imaging methods.
B: teloradiograph utilizes conventional radiography, exposing patients to higher radiation levels, which diminishes its desirability for accurate LLD measurement when safer, more precise alternatives exist.
C: orthoradiograph, while useful for imaging, does not offer the same level of radiation reduction and accuracy as EOS/slot scanning, making it less optimal for evaluating leg-length discrepancies.
A 9-month-old infant presented with adducted forefoot, normal midfoot and hindfoot, and a convex lateral border of his foot, while his ankle dorsiflexion and plantar flexion are normal. Of the following, the BEST action at this time is
Rationale:
Reassurance provides the best action at this time, as the infant's presentation suggests a common and often self-resolving condition. Normal ankle dorsiflexion and plantar flexion indicate no immediate intervention is necessary, allowing for natural development.
A: evaluation by a pediatric orthopedist This option suggests an unnecessary specialist consultation, as the infant's condition appears non-severe and likely to improve without intervention.
B: serial casting This action implies a need for corrective treatment, which is unwarranted given the normal functional aspects of the infant’s foot and its potential for self-correction.
C: serial bracing Similar to casting, this implies intervention is required; however, the infant's normal range of motion and typical development indicate that bracing is not appropriate at this stage.
The best fluid bolus giving to a child with isolated vomiting and severe dehydration is
Rationale:
Normal saline is the best fluid bolus for a child with isolated vomiting and severe dehydration. It effectively restores intravascular volume and maintains electrolyte balance, essential for managing dehydration in pediatric patients.
B: Ringer lactate contains additional electrolytes that may not be necessary in isolated vomiting cases, potentially leading to an imbalance rather than straightforward volume resuscitation.
C: Half-normal saline provides a hypotonic solution that might exacerbate dehydration in children, failing to adequately replace lost fluids and electrolytes due to vomiting.
D: 5% dextrose + half-normal saline offers unnecessary sugar, which could complicate metabolic processes during acute dehydration and does not address immediate fluid volume deficits effectively.
Spurious hypokalemia occurs in patients with
Rationale:
Spurious hypokalemia occurs in patients with a high white blood cell count. This condition leads to false low potassium readings due to the intracellular shift of potassium during leukocytosis, particularly in severe infections or malignancies.
A: Laxative abuse results in true hypokalemia by increasing potassium excretion from the kidneys, rather than causing spurious readings related to blood cell counts.
C: Hypomagnesaemia typically causes true hypokalemia through renal potassium wasting, not spurious hypokalemia, which is linked to cellular shifts rather than magnesium levels.
D: Cushing syndrome causes true hypokalemia due to excess cortisol, which promotes potassium excretion and retains sodium, rather than inducing spurious low potassium readings.
Normal anion gap metabolic acidosis can occur in
Rationale:
Normal anion gap metabolic acidosis can occur in severe anemia.
Severe anemia leads to reduced oxygen delivery to tissues, resulting in increased lactic acid production. This condition often causes a normal anion gap metabolic acidosis due to the accumulation of metabolic acids without an increase in unmeasured anions, maintaining the anion gap within normal limits.
A: renal failure. Renal failure typically results in an elevated anion gap due to the accumulation of waste products and phosphate, which do not align with normal anion gap acidosis.
B: liver failure. Liver failure often leads to an accumulation of organic acids, causing an elevated anion gap metabolic acidosis rather than a normal one, as the liver cannot effectively metabolize these substances.
D: starvation ketoacidosis. Starvation ketoacidosis produces significant amounts of ketone bodies, which contribute to an increased anion gap, contradicting the criteria for normal anion gap metabolic acidosis.
Macrodactyly is seen in the following conditions EXCEPT
Rationale:
Macrodactyly is not seen in Alport syndrome. This condition primarily affects the kidneys and is characterized by progressive renal failure, hearing loss, and eye abnormalities, with no association with macrodactyly.
A: Proteus syndrome exhibits macrodactyly as a prominent feature, related to the overgrowth of tissues and various neoplasms, making it a key characteristic of this disorder.
B: Neurofibromatosis is associated with macrodactyly due to the presence of neurofibromas, which can cause significant growth abnormalities in the affected limbs, frequently leading to enlarged digits.
C: Tuberous sclerosis can lead to macrodactyly through hamartomas that cause abnormal growth in the tissues, impacting the bones and soft tissues of the fingers and toes.
The Barlow test is used to diagnose which condition?
Rationale:
The Barlow test is used to diagnose developmental dysplasia of the hip. This test focuses on identifying instability in the hip joint, which is a key indicator of developmental dysplasia, particularly in infants.
A: Patellar subluxation This condition pertains to the kneecap dislocating partially and is not assessed through the Barlow test, which specifically evaluates hip joint stability.
B: Legg-Calvé-Perthes disease This disorder involves blood supply issues to the femoral head, leading to bone degeneration, and does not relate to the hip instability assessed by the Barlow test.
D: Slipped capital femoral epiphysis This condition involves the displacement of the femoral head and requires different diagnostic approaches, making it unrelated to the Barlow test's focus on hip joint instability.
A young athlete develops heel pain with activity that decreases with rest; he is limping with no swelling. He has pain to palpation of the posterior calcaneus and tight heel cords. Infection and tumor were excluded by radiographs. Of the following, the MOST likely diagnosis is
Rationale:
Sever disease is the most likely diagnosis. This condition, common in young athletes, is characterized by heel pain, particularly at the growth plate of the calcaneus, often exacerbated by activity and relieved by rest.
A: Kohler disease affects the navicular bone, not the calcaneus, leading to pain in a different area of the foot. It typically presents with swelling and not heel pain from activity.
C: Freiberg disease primarily impacts the metatarsal bones, resulting in pain in the forefoot rather than the heel. This condition does not match the symptoms presented in this case.
D: Tarsal coalition involves abnormal connections between foot bones, often causing pain or stiffness. The symptoms here focus specifically on heel pain and do not suggest a coalition issue.
Which is the recommended management of a newborn with an unstable hip examination indicating developmental dysplasia of the hip?
Rationale:
B: Pavlik harness or use of double- or triple-diapering is the recommended management for a newborn with developmental dysplasia of the hip as it allows for proper positioning and stability. This approach facilitates hip joint development while minimizing complications associated with more invasive treatments. Early intervention is crucial for optimal outcomes in newborns with hip instability.
A: Observation alone fails to provide any intervention, risking further instability and potential long-term complications. Active management is essential to ensure proper hip development in affected infants.
C: Serial spica casts are typically reserved for older infants or those with failed conservative management. This option is more invasive and not suitable for initial treatment in newborns.
D: Open surgical reduction with pelvic or femoral osteotomy involves significant intervention and is inappropriate as a first-line approach for newborns with developmental dysplasia, who often respond well to less invasive methods.
An 8-year-old child with mild, intermittent right hip pain and a limp undergoes radiography of the hip (Fig. 31-2). What is the diagnosis?
Rationale:
Legg-Calvé-Perthes disease is the diagnosis indicated for the 8-year-old child with mild, intermittent right hip pain and a limp following hip radiography.
This condition typically presents in children aged 4 to 8, characterized by avascular necrosis of the femoral head, leading to hip pain and limping, aligning with the child's symptoms.
A: Slipped capital femoral epiphysis involves displacement of the femoral head, usually presenting with more significant pain and a different age demographic, typically between 10 and 16 years.
C: Osgood-Schlatter disease primarily affects the knee and is characterized by pain at the tibial tuberosity, making it an unlikely cause of hip pain in this case.
D: Salter-Harris type III fracture refers to a fracture through the growth plate, which would typically indicate acute trauma rather than the intermittent pain described in the child's symptoms.
A 16-year-old athlete male presented with burning pain, weakness, and numbness of right upper extremity after lateral flexion of the neck away from the involved upper extremity, the symptoms resolve after 10 minutes. Of the following, the MOST likely cause is
Rationale:
Burning pain, weakness, and numbness in the right upper extremity after neck flexion suggest brachial plexopathy, a condition often resulting from traction injuries. The temporary resolution of symptoms indicates a functional nerve issue rather than structural damage, aligning with the characteristics of brachial plexus involvement.
B: Proximal humeral epiphysiolysis typically presents with shoulder pain and functional impairment, not isolated upper extremity neurological symptoms following neck movements.
C: Overuse injury generally manifests as chronic pain and does not typically resolve within a short period like 10 minutes, indicating a different pathology.
D: Glenohumeral dislocation would present with severe pain and an inability to move the shoulder, contrasting with the temporary and specific symptoms described in this case.
Dolichocephalic head is a feature of
Rationale:
Dolichocephalic head is a feature of myotubular myopathy. This condition is characterized by a distinctive head shape, often associated with muscle weakness and developmental delays, which are hallmark signs of myotubular myopathy.
A: Central core myopathy This type of myopathy primarily affects the muscle fibers, leading to weakness, but does not specifically feature the dolichocephalic head shape.
C: Nemaline rod myopathy While this condition involves muscle weakness and the presence of nemaline rods, it does not typically present with the dolichocephalic head characteristic.
D: Becker muscular dystrophy This muscular dystrophy variant results in progressive muscle degeneration but is not linked to the distinct head shape seen in myotubular myopathy.
The earliest and MOST constant sign of myasthenia gravis is
Rationale:
Ptosis. This condition represents the most frequent and initial manifestation of myasthenia gravis, characterized by drooping of one or both eyelids due to muscle weakness, often occurring before other symptoms appear.
B: dysphagia Difficulty swallowing is a common symptom but not typically the first sign. It usually develops later as muscle weakness progresses in myasthenia gravis patients.
C: slurred speech Articulation issues may arise as muscle control diminishes; however, slurred speech is generally not the earliest indication of the disorder compared to more prevalent symptoms like ptosis.
D: difficult chewing Chewing difficulties can occur with myasthenia gravis but tend to manifest after more primary symptoms like ptosis, not as an initial sign of the condition.
All the following are preserved in Charcot-Marie-Tooth disease EXCEPT
Rationale:
All the following are preserved in Charcot-Marie-Tooth disease EXCEPT tibial nerves. The disease primarily affects the peripheral nerves, leading to muscle weakness and atrophy, particularly in the lower limbs, while intelligence and cranial nerves generally remain intact.
A: intelligence Cognitive functions are typically unaffected in Charcot-Marie-Tooth disease, maintaining normal intellectual capabilities despite the physical impairments associated with the condition.
C: axial muscles While axial muscles may experience some weakness, they are generally not as severely impacted as the distal limb muscles, preserving some function.
D: cranial nerves Cranial nerves typically remain unaffected in Charcot-Marie-Tooth disease, allowing for normal facial and sensory functions despite the peripheral nerve damage.
The best treatment for the patient described in Question 1 is
Rationale:
Decreased activity of the knee is the best treatment for the patient described. This approach allows for reduced stress on the joint, facilitating healing and minimizing pain while promoting recovery in cases of injury or inflammation.
B: Anti-inflammatory drugs might alleviate pain, but they do not address the underlying need for reduced joint activity, which is crucial for recovery in this scenario.
C: Antibiotics target infections and have no relevance to the treatment of non-infectious conditions or injuries affecting the knee, failing to provide the required therapeutic benefit.
D: Casting for 6-8 weeks immobilizes the knee, potentially leading to stiffness and delayed recovery, rather than promoting the necessary active healing through reduced movement.
Matching: Cavus feet
Rationale:
C: Peripheral neuropathy is associated with cavus feet. This condition often leads to altered sensations and muscle imbalances, contributing to the high arches characteristic of cavus feet, which can exacerbate foot deformities.
A: Soft tissue surgical release required does not apply as cavus feet can often be managed conservatively without surgery. Surgical intervention is typically considered only in more severe cases or complications.
B: Usually painless contradicts common experiences; many individuals with cavus feet report discomfort due to pressure points and imbalances. Pain is a significant aspect of managing this foot deformity.
D: Fusion or failure of segmentation describes a different set of foot deformities, such as congenital issues, rather than the structural characteristics and implications associated with cavus feet.
Muscle denervation is any loss of nerve supply regardless of the cause. Of the following, the MOST specific clinical sign of denervation is
Rationale:
Fasciculation is the most specific clinical sign of denervation. This involuntary muscle twitching indicates spontaneous motor unit activity and is directly associated with disrupted nerve supply, distinguishing it from other signs.
A: Myotonia refers to delayed muscle relaxation after contraction, not indicative of denervation. It originates from different neuromuscular conditions rather than a direct loss of nerve supply.
B: Weakness denotes a general reduction in muscle strength, which can stem from various sources, including fatigue, disuse, or systemic diseases, making it less specific than fasciculation.
C: Fatigability indicates a decrease in muscle strength with prolonged activity, often related to metabolic issues or muscle conditions, rather than specifically revealing denervation of nerve supply.
Most children exhibit an eczematous eruption composed of red, excoriated papules and nodules. The classic linear papule or burrow is often difficult to find. Distribution is the most diagnostic finding; the papules are found in the axillae, umbilicus, groin, penis, instep of the foot, and web spaces of the fingers and toes.
Rationale:
Most children exhibit an eczematous eruption composed of red, excoriated papules and nodules. This describes scabies.
The classic signs of scabies include intensely itchy papules located in specific areas, such as the axillae and groin. The mention of difficult-to-find burrows aligns with scabies, distinguishing it from other skin conditions that may present similarly but lack this specific distribution and symptomatology.
B: This describes eczema. Eczema typically presents with dry, inflamed skin, but its distribution and appearance differ from the distinctive papular lesions observed in scabies.
C: This describes psoriasis. Psoriasis is characterized by thick, silvery scales and generally presents on extensor surfaces, making its clinical picture and affected areas dissimilar to scabies.
D: This describes dermatitis. Dermatitis covers a range of inflammatory skin conditions but does not specifically exhibit the classic burrows and papule distribution indicative of scabies.
Matching: Bone and joint orthopedic terminology - High-arched foot
Rationale:
High-arched foot refers to a condition known as cavus.
Cavus describes a foot structure with an exaggerated arch, leading to an imbalance in weight distribution and increased pressure on the forefoot and heel, which aligns perfectly with the term "high-arched foot."
A: Varum This term signifies a bowing of the leg or foot, not specifically related to the arch height of the foot.
C: Valgum This refers to a knocking-knees condition, which involves the alignment of the legs rather than the arch structure of the foot.
D: Equinus This describes a lack of dorsiflexion in the foot, affecting mobility but not directly related to the high arch condition.
Emery-Dreifuss Muscular Dystrophy (scapuloperoneal or scapulohumeral muscular dystrophy) is a rare X-linked recessive dystrophy. Of the following, the MOST characteristic feature is
Rationale:
Dilated cardiomyopathy is the most characteristic feature of Emery-Dreifuss Muscular Dystrophy. This condition is known for its cardiac involvement, particularly the development of heart muscle weakening, which significantly impacts patient health.
A: Myotonia presents in other muscular dystrophies, but it is not a defining characteristic of Emery-Dreifuss Muscular Dystrophy, which focuses more on cardiac and skeletal muscle issues.
B: Facial weakness can occur in various muscular dystrophies but lacks the specificity associated with Emery-Dreifuss Muscular Dystrophy, where cardiac symptoms are more prominent and distinguishing.
C: Pseudohypertrophy typically relates to Duchenne Muscular Dystrophy, where muscle fibers are replaced by fat, making it a less relevant feature in Emery-Dreifuss Muscular Dystrophy's presentation.
Polydactyly (extra toes) is usually found on the initial newborn physical examination. It may be associated with the following malformation syndrome
Rationale:
Polydactyly (extra toes) is usually associated with Rubinstein-Taybi syndrome. This syndrome is characterized by distinctive physical features, including polydactyly, and is often identified during the initial examination of newborns.
A: Apert syndrome. This condition primarily involves craniosynostosis and syndactyly, lacking the specific association with polydactyly seen in Rubinstein-Taybi syndrome.
B: de Lange syndrome. While this syndrome has various physical abnormalities, polydactyly is not a characteristic feature linked to its diagnosis.
C: Holt-Oram syndrome. This syndrome affects heart and upper limb development, with polydactyly being less commonly observed than in Rubinstein-Taybi syndrome.
Maintenance fluids are composed of a solution of water, glucose, sodium, potassium, and chloride. How much of the normal caloric needs of the patient is provided by glucose in maintenance fluids?
Rationale:
Maintenance fluids provide 20% of the normal caloric needs of the patient through glucose. This proportion is crucial for ensuring adequate energy levels and maintaining metabolic processes during hydration therapy.
A: 5% This percentage is not sufficient to meet the caloric demands of patients, as it would provide inadequate energy to support basic physiological functions.
B: 10% While higher than 5%, this option still fails to deliver the necessary caloric intake required for optimal health and recovery during fluid maintenance.
C: 15% This amount falls short of the requisite calories for patients, potentially leading to energy deficits and impacting their overall recovery and well-being.
Hypervolemic hyponatremia is caused by
Rationale:
Hypervolemic hyponatremia is caused by cirrhosis. The presence of cirrhosis leads to fluid retention in the body, causing an imbalance in sodium levels and resulting in hypervolemic hyponatremia, as the liver's dysfunction disrupts normal fluid regulation.
B: cerebral salt wasting This condition typically results in hyponatremia due to excessive sodium loss, not fluid retention, contradicting the mechanism of hypervolemic hyponatremia.
C: pseudohypoaldosteronism type I This disorder involves resistance to aldosterone, leading to sodium loss and hypovolemia rather than the fluid overload characteristic of hypervolemic hyponatremia.
D: obstructive uropathy While this can cause kidney dysfunction, it primarily leads to fluid accumulation in the kidneys rather than hypervolemic hyponatremia, which is associated with systemic fluid overload.
Which of the following conditions should receive a careful examination of the hips to rule out developmental dysplasia of the hip (DDH)?
Rationale:
Congenital muscular torticollis should receive a careful examination of the hips to rule out developmental dysplasia of the hip (DDH). This condition is frequently associated with hip abnormalities, necessitating a thorough assessment to identify potential developmental issues early.
B: Klippel-Feil syndrome primarily involves cervical vertebral fusion and does not have a direct correlation with hip dysplasia, making hip examination less critical for diagnosis.
C: Scoliosis primarily affects spinal alignment and does not inherently suggest hip dysplasia, thus necessitating a hip examination is not typically prioritized in its assessment.
D: Spina bifida occulta focuses on spinal anomalies and does not directly impact hip joint development, leading to a lower concern regarding the examination of hip structures.
Proper cell functioning requires close regulation of plasma osmolality and intravascular volume. Which of the following statements is TRUE?
Rationale:
A: maintenance of a normal osmolality depends on regulation of sodium balance. While sodium balance is important for osmolality, the statement does not address the role of thirst, which directly influences hydration.
B: control of volume status depends on regulation of potassium balance. Potassium is essential for cellular functions, but it does not play a primary role in volume regulation compared to sodium and thirst mechanisms.
C: the plasma osmolality is controlled between 295 and 305 mosm/kg. This statement inaccurately describes the normal range; the physiological plasma osmolality typically ranges from 280 to 300 mosm/kg.
Differential diagnosis of Legg-Calvé-Perthes disease include all the following EXCEPT
Rationale:
Legg-Calvé-Perthes disease is differentiated from various conditions, but Marfan syndrome does not typically present with the hip joint involvement that characterizes this disease, making it the exception in the differential diagnosis.
A: osteochondromatosis This condition involves multiple benign bone tumors, which can affect the joints but does not exhibit the same specific features or presentation as Legg-Calvé-Perthes disease.
B: Schwartz-Jampel syndrome This disorder includes musculoskeletal manifestations, such as joint stiffness, but lacks the characteristic avascular necrosis seen in Legg-Calvé-Perthes disease, thus it is a reasonable differential.
D: Maroteaux-Lamy syndrome This condition is a mucopolysaccharidosis that leads to skeletal abnormalities, which can involve the hips. Its symptoms may overlap with those of Legg-Calvé-Perthes disease, warranting consideration in diagnosis.
Legg-Calvé-Perthes disease is a hip disorder of unknown etiology that results from temporary interruption of the blood supply to the proximal femoral epiphysis, leading to osteonecrosis and femoral head deformity. Of the following, the MOST common presenting symptom is
Rationale:
Limp of varying duration.
This symptom commonly manifests in patients with Legg-Calvé-Perthes disease due to the disruption of blood supply, impacting the femoral head and leading to altered gait patterns over time.
B: Pain. While discomfort is present, it often arises later, making limp a more prevalent initial symptom.
C: Failure to ambulate. This severe symptom occurs in advanced cases, rather than as a primary presenting issue.
D: Atrophy of the muscles of the thigh. Muscle atrophy develops over time due to disuse but is not a primary presenting symptom of this disorder.
Normal full-term newborns can have up to 20-30 degree hip and knee flexion contractures, these contractures tend to resolve by
Rationale:
Normal full-term newborns can have up to 20-30 degree hip and knee flexion contractures, these contractures tend to resolve by 4-6 months.
The resolution of hip and knee flexion contractures typically occurs within the 4-6 month timeframe due to the natural development of muscle tone and joint mobility in infants, facilitating their physical growth and functional abilities during this critical period.
A: 1-3 mo Early resolution is unlikely as infants are still developing muscle strength and coordination, and contractures usually require more time to naturally diminish as they grow.
C: 7-9 mo Waiting until this period is generally too late for resolution, as most infants would have already begun showing improvements in muscle tone and flexibility before this timeframe.
D: 10-12 mo By this age, significant developmental milestones should have been achieved, making it uncommon for contractures to persist if they have not resolved earlier.
The MOST common cause of out-toeing is
Rationale:
External femoral torsion is the most common cause of out-toeing. This condition arises when the femur is rotated outward, leading to the feet pointing away from the body's midline during walking or standing.
B: external tibial torsion This condition involves a twist in the tibia, typically resulting in varying foot positioning, but it is less prevalent than external femoral torsion regarding out-toeing prevalence.
C: calcaneovalgus feet This foot deformity is characterized by an exaggerated upward angle of the foot and is associated with in-toeing rather than out-toeing, making it an unlikely cause.
D: hypermobile pes planus (flatfoot) While flatfoot can affect foot positioning, it primarily results in a collapse of the arch rather than the outward rotation of the toes associated with out-toeing.
Adverse effect of anabolic-androgenic steroids include all the following EXCEPT
Rationale:
D: Hypotension is not a recognized adverse effect of anabolic-androgenic steroids. Instead, these substances are more commonly associated with increased blood pressure and cardiovascular issues, making hypotension an unlikely consequence of their use.
A: Infertility results from hormonal imbalances caused by anabolic steroids, leading to reduced sperm production and potential long-term reproductive issues in both men and women.
B: Gynecomastia occurs due to hormonal changes induced by anabolic steroids, which can result in the development of breast tissue in males, a common side effect of their use.
C: Female virilization is a notable effect of anabolic steroids, characterized by the development of male traits in women, such as increased body hair and voice deepening, due to altered hormone levels.
Leg-length discrepancy (LLD) is common and may be due to differences in the femur, tibia, or both bones. The MOST accurate method with reduced-radiation to measure (LLD) is
Rationale:
D: EOS/slot scanning offers the highest accuracy for measuring leg-length discrepancy (LLD) while minimizing radiation exposure. This advanced imaging technique allows for precise assessments of femur and tibia lengths using a slot-scanning method.
A: clinical measurements using bony landmarks (anterior superior iliac spine to medial malleolus) rely on physical examination and can introduce human error, making them less precise than advanced imaging methods.
B: teloradiograph involves a more conventional radiographic technique that does not provide the same level of precision in measurement and often exposes patients to higher radiation doses compared to EOS.
C: orthoradiograph, while useful, does not match the reduced radiation exposure and accuracy offered by EOS/slot scanning, limiting its effectiveness in precise LLD evaluations.
A 9-month-old infant presented with adducted forefoot, normal midfoot and hindfoot, and a convex lateral border of his foot, while his ankle dorsiflexion and plantar flexion are normal. Of the following, the BEST action at this time is
Rationale:
D: Reassurance is the best action at this time since the infant's foot alignment appears within normal limits for his age, suggesting that no immediate intervention is necessary for this condition.
A: Evaluation by a pediatric orthopedist is premature as the infant's symptoms indicate a typical developmental variation rather than a pathological condition requiring specialist intervention.
B: Serial casting is not warranted at this stage since the foot's current positioning is not severe enough to necessitate such treatment for correction.
C: Serial bracing is unnecessary because the infant demonstrates normal ankle function, indicating that the foot's alignment may resolve without the need for supportive devices.
The best fluid bolus giving to a child with isolated vomiting and severe dehydration is
Rationale:
Normal saline is the best fluid bolus for a child with isolated vomiting and severe dehydration. It efficiently replenishes extracellular fluid volume, effectively addressing the dehydration while maintaining electrolyte balance, crucial for recovery.
B: Ringer lactate contains electrolytes that may not be necessary for isolated vomiting and can complicate fluid management. Normal saline is more straightforward for rehydration in this scenario.
C: Half-normal saline offers a lower sodium concentration, which may not adequately address the needs of a dehydrated child. This could lead to further electrolyte imbalances during treatment.
D: 5% dextrose + half-normal saline introduces unnecessary sugars and alters osmolarity, which could exacerbate dehydration. Normal saline provides a more balanced and effective rehydration strategy in this case.
Spurious hypokalemia occurs in patients with
Rationale:
Spurious hypokalemia occurs in patients with a high white blood cell count. Elevated white blood cells can lead to potassium shifts in the body, resulting in falsely low serum potassium levels without true deficiency.
A: laxative abuse Excessive laxative use typically causes actual potassium depletion rather than spurious hypokalemia, as it leads to gastrointestinal losses of potassium from the body.
C: hypomagnesaemia Low magnesium levels often contribute to actual hypokalemia due to renal wasting of potassium, rather than causing misleading low serum potassium readings.
D: Cushing syndrome This condition typically results in true hypokalemia due to increased cortisol levels, leading to potassium loss instead of falsely low potassium measurements.
Normal anion gap metabolic acidosis can occur in
Rationale:
Normal anion gap metabolic acidosis can occur in severe anemia.
Severe anemia leads to reduced oxygen delivery, causing tissue hypoxia and increased lactic acid production. This process contributes to a normal anion gap metabolic acidosis, as bicarbonate levels decrease without significant accumulation of unmeasured anions.
A: renal failure Typically results in an elevated anion gap due to retained acids and reduced bicarbonate, not a normal anion gap.
B: liver failure Causes metabolic acidosis with an elevated anion gap due to impaired detoxification processes and accumulation of organic acids.
D: starvation ketoacidosis Characteristically causes an elevated anion gap due to increased ketone bodies, not a normal anion gap metabolic acidosis.
Macrodactyly is seen in the following conditions EXCEPT
Rationale:
Macrodactyly is seen in the following conditions EXCEPT Alport syndrome. This condition primarily affects the kidneys and is characterized by progressive renal disease, hearing loss, and eye abnormalities, without the limb deformities associated with macrodactyly.
A: Proteus syndrome features various overgrowths, including macrodactyly, due to abnormal tissue development, making it relevant to the question.
B: Neurofibromatosis can present with macrodactyly due to the proliferation of neural tissue affecting limb size and shape, linking it to the query.
C: Tuberous sclerosis can lead to macrodactyly through hamartomas affecting the limbs, thereby associating it with the occurrence of this condition in question.
The Barlow test is used to diagnose which condition?
Rationale:
The Barlow test is used to diagnose developmental dysplasia of the hip. This test specifically assesses hip stability in infants, identifying dislocation or subluxation, which is characteristic of developmental dysplasia, making it an essential diagnostic tool.
A: Patellar subluxation Involves knee instability rather than hip issues, hence the Barlow test does not apply to this condition.
B: Legg-Calvé-Perthes disease Primarily concerns femoral head avascular necrosis, unrelated to the hip's stability assessment performed by the Barlow test.
D: Slipped capital femoral epiphysis Focuses on femoral head displacement and does not involve the hip joint's stability testing that the Barlow evaluates.
A young athlete develops heel pain with activity that decreases with rest; he is limping with no swelling. He has pain to palpation of the posterior calcaneus and tight heel cords. Infection and tumor were excluded by radiographs. Of the following, the MOST likely diagnosis is
Rationale:
Sever disease is the most likely diagnosis. This condition commonly affects young athletes experiencing heel pain due to stress on the growth plate of the heel, exacerbated by activity and relieved by rest, alongside tight heel cords.
A: Kohler disease involves avascular necrosis of the navicular bone, presenting primarily in younger children, not typically leading to heel pain or tight heel cords as seen here.
C: Freiberg disease is related to avascular necrosis of the metatarsal heads, which causes pain in the forefoot, not heel pain, making it inconsistent with the symptoms described.
D: Tarsal coalition results in a bony or fibrous connection between tarsal bones, leading to foot stiffness and pain but does not specifically present with heel pain and limping in young athletes.
Which is the recommended management of a newborn with an unstable hip examination indicating developmental dysplasia of the hip?
Rationale:
B: Pavlik harness or use of double- or triple-diapering. This approach is recommended for managing developmental dysplasia of the hip in newborns as it helps maintain proper hip positioning and promotes joint stability during crucial early development stages.
A: Observation alone lacks proactive intervention, which is essential for addressing hip instability in newborns with developmental dysplasia, potentially leading to worsening conditions if left untreated.
C: Serial spica casts are typically reserved for more severe cases or those unresponsive to initial treatments, making them inappropriate as a first-line management option for newborns with unstable hip examinations.
D: Open surgical reduction with pelvic or femoral osteotomy is an invasive procedure suited for severe deformities and not indicated for initial management of developmental dysplasia of the hip in newborns.
An 8-year-old child with mild, intermittent right hip pain and a limp undergoes radiography of the hip (Fig. 31-2). What is the diagnosis?
Rationale:
Legg-Calvé-Perthes disease is the diagnosis. This condition typically presents in children aged 4 to 8, characterized by hip pain and limping due to avascular necrosis of the femoral head, aligning with the child’s symptoms.
A: Slipped capital femoral epiphysis presents with acute hip pain and limited internal rotation, often occurring in older children and adolescents, differing from the child’s age and symptom profile.
C: Osgood-Schlatter disease primarily affects the knee, resulting in localized pain and swelling below the knee joint, which does not correlate with the hip pain described in this case.
D: Salter-Harris type III fracture typically involves acute trauma and presents with specific joint pain and swelling, rather than the intermittent and mild symptoms observed in this child.
A 16-year-old athlete male presented with burning pain, weakness, and numbness of right upper extremity after lateral flexion of the neck away from the involved upper extremity, the symptoms resolve after 10 minutes. Of the following, the MOST likely cause is
Rationale:
Burning pain, weakness, and numbness in the upper extremity after neck lateral flexion suggest a brachial plexus injury. The transient nature of symptoms indicates a temporary disruption rather than a structural injury, aligning with brachial plexopathy diagnosis.
B: Proximal humeral epiphysiolysis typically involves shoulder pain and limited range of motion rather than acute neurological symptoms. The mechanism presented here does not support this diagnosis.
C: Overuse injury generally leads to chronic pain and weakness rather than acute, sudden-onset neurological symptoms following a specific movement. The acute nature of the symptoms suggests otherwise.
D: Glenohumeral dislocation would present with severe pain and instability, often accompanied by visible deformity. The described symptoms and their resolution do not match this condition's profile.
Dolichocephalic head is a feature of
Rationale:
Dolichocephalic head is a feature of myotubular myopathy. This condition is characterized by distinct craniofacial features, including a long head shape, which is a notable phenotypic trait of myotubular myopathy.
A: Central core myopathy features muscle weakness and hypotonia but does not specifically present with dolichocephalic head shape, focusing instead on muscle structure abnormalities without craniofacial implications.
C: Nemaline rod myopathy primarily manifests through muscle weakness and the presence of nemaline bodies in muscle fibers, lacking the craniofacial characteristics associated with dolichocephalic head morphology.
D: Becker muscular dystrophy is characterized by progressive muscle degeneration and does not exhibit the distinctive head shape associated with myotubular myopathy, focusing more on limb and muscle function.
The earliest and MOST constant sign of myasthenia gravis is
Rationale:
Ptosis. This symptom is often the first and most consistent manifestation of myasthenia gravis, characterized by weakness in the muscles that control eyelid elevation, leading to drooping eyelids.
B: dysphagia. While swallowing difficulties can occur in myasthenia gravis, they typically develop later as the disease progresses, making them less indicative of the condition's initial onset.
C: slurred speech. Speech abnormalities can result from muscle weakness in myasthenia gravis, but they are not the earliest nor most consistent symptom observed in affected patients.
D: difficult chewing. Chewing difficulties may arise as muscle weakness affects oral function, yet this symptom is generally not as prominent or early as the hallmark sign of ptosis.
All the following are preserved in Charcot-Marie-Tooth disease EXCEPT
Rationale:
Charcot-Marie-Tooth disease does not preserve tibial nerves. This condition primarily affects peripheral nerves, leading to muscle weakness and atrophy, particularly in the feet and lower legs, causing significant functional impairments.
A: intelligence Preserved cognitive functions remain intact, highlighting that the disease primarily impacts peripheral nerves rather than central neurological processing capabilities.
C: axial muscles While axial muscles may show some involvement, they generally retain more function compared to the distal extremities affected by the disease's progression.
D: cranial nerves Cranial nerves typically remain unaffected in Charcot-Marie-Tooth disease, maintaining normal function related to facial movement and sensation, unlike the peripheral nerves that are compromised.
The best treatment for the patient described in Question 1 is
Rationale:
Decreased activity of the knee is the best treatment for the patient described in Question 1. Reducing activity allows the knee to heal, minimizing strain and preventing further injury, which is essential for recovery in cases of inflammation or overuse. Resting the joint supports natural healing processes and alleviates pain associated with any underlying conditions.
B: Anti-inflammatory drugs This option does not address the root cause of the patient's issues, focusing instead on symptom relief without promoting the necessary healing through reduced activity.
C: Antibiotics This choice is irrelevant as antibiotics target bacterial infections, not conditions related to joint strain or inflammation, which the patient is experiencing.
D: Casting for 6-8 weeks While casting immobilizes the knee, it does not allow for gradual recovery or rehabilitation through controlled movement, which is crucial for restoring knee function.
Matching: Cavus feet
Rationale:
C: Peripheral neuropathy. Cavus feet are often associated with peripheral neuropathy, which affects the nerves and can lead to muscle imbalances, causing the foot's arch to become excessively high and rigid.
A: Soft tissue surgical release required. Soft tissue surgical release is typically not needed for cavus feet, as the condition usually arises from neurological issues rather than soft tissue tightness.
B: Usually painless. Cavus feet can often lead to discomfort and pain due to abnormal foot mechanics, contrary to the assumption that they are usually painless.
D: Fusion or failure of segmentation. While cavus feet may involve structural abnormalities, they do not primarily result from fusion or segmentation failure, which pertains to different congenital conditions.
Muscle denervation is any loss of nerve supply regardless of the cause. Of the following, the MOST specific clinical sign of denervation is
Rationale:
Fasciculation is the most specific clinical sign of denervation. This involuntary muscle twitching indicates direct damage to the motor neurons, highlighting a clear disruption in the nerve supply to the affected muscle fibers.
A: Myotonia involves delayed muscle relaxation, not directly indicative of nerve supply loss, and can occur in various muscle disorders unrelated to denervation.
B: Weakness denotes reduced muscle strength but can arise from numerous conditions, making it less specific for denervation compared to the distinctive involuntary contractions seen in fasciculation.
C: Fatigability refers to decreased muscle endurance during activity, which may result from various factors, including metabolic issues, rather than being a clear indicator of nerve supply loss.
Most children exhibit an eczematous eruption composed of red, excoriated papules and nodules. The classic linear papule or burrow is often difficult to find. Distribution is the most diagnostic finding; the papules are found in the axillae, umbilicus, groin, penis, instep of the foot, and web spaces of the fingers and toes.
Rationale:
Most children exhibit an eczematous eruption composed of red, excoriated papules and nodules. The classic linear papule or burrow is often difficult to find. Distribution is the most diagnostic finding; the papules are found in the axillae, umbilicus, groin, penis, instep of the foot, and web spaces of the fingers and toes.
A: This describes scabies. The context highlights the specific distribution of lesions in areas typical for scabies, such as web spaces and other hidden regions, supporting this diagnosis as the most accurate.
B: This describes eczema. While eczema involves red, itchy lesions, the specific distribution mentioned in the context does not align with the common areas affected by eczema, making this option less fitting.
C: This describes psoriasis. Psoriasis typically presents with silvery scales and specific locations like elbows and knees, differing significantly from the described papular eruption and its distinctive distribution pattern.
D: This describes dermatitis. Dermatitis encompasses various skin reactions, but the unique distribution of lesions in the context aligns more closely with scabies than with the broader, less specific categories of dermatitis.
Matching: Bone and joint orthopedic terminology - High-arched foot
Rationale:
High-arched foot is referred to as Cavus. This term describes a condition where the arch of the foot is higher than normal, leading to altered weight distribution and potential foot problems.
A: Varum A high-arched foot does not relate to varus, which indicates inward angulation of the lower limb, primarily affecting alignment rather than arch height.
C: Valgum Valgus refers to an outward angulation of the limbs, contrasting with the inward positioning associated with varus. It does not pertain to arch elevation.
D: Equinus Equinus describes a restricted ankle joint motion where the foot cannot assume a neutral position, unrelated to the structural characteristics of a high-arched foot.
Emery-Dreifuss Muscular Dystrophy (scapuloperoneal or scapulohumeral muscular dystrophy) is a rare X-linked recessive dystrophy. Of the following, the MOST characteristic feature is
Rationale:
Dilated cardiomyopathy is the most characteristic feature of Emery-Dreifuss Muscular Dystrophy. This condition significantly affects heart muscle function, leading to complications that are often associated with this specific dystrophy variant.
A: Myotonia does not characterize Emery-Dreifuss Muscular Dystrophy; it is more commonly linked to conditions like myotonic dystrophy, where muscle stiffness is a prominent symptom.
B: Facial weakness is not a defining characteristic of Emery-Dreifuss Muscular Dystrophy; while it may occur, the hallmark features are related more to shoulder and upper limb weakness.
C: Pseudohypertrophy is associated with other forms of muscular dystrophy, particularly Duchenne Muscular Dystrophy, where muscle tissue is replaced by fat, leading to an enlarged appearance.
Polydactyly (extra toes) is usually found on the initial newborn physical examination. It may be associated with the following malformation syndrome
Rationale:
Polydactyly (extra toes) is usually associated with Rubinstein-Taybi syndrome. This syndrome is characterized by broad thumbs, toes, and polydactyly, highlighting the significant link between the two conditions in newborns.
A: Apert syndrome features craniosynostosis and syndactyly but does not commonly present with polydactyly as a primary characteristic, making it less relevant to the question.
B: de Lange syndrome primarily involves growth delays and facial features but lacks a direct connection to polydactyly, which is not a typical manifestation of this syndrome.
C: Holt-Oram syndrome is associated with heart defects and upper limb malformations, rather than polydactyly, indicating that it does not pertain to the question's focus on extra toes.
Maintenance fluids are composed of a solution of water, glucose, sodium, potassium, and chloride. How much of the normal caloric needs of the patient is provided by glucose in maintenance fluids?
Rationale:
Maintenance fluids provide approximately 20% of the normal caloric needs of a patient through glucose. This percentage is crucial as it helps sustain energy levels during medical interventions without exceeding fluid requirements.
A: 5% This value is significantly lower than the actual contribution of glucose, failing to meet the energy demands of a patient receiving maintenance fluids.
B: 10% This option underestimates the glucose contribution, which is vital for maintaining adequate energy levels during patient care and does not align with standard practice.
C: 15% This choice also falls short of the correct caloric intake, as it does not fully account for the essential energy provided by glucose in maintenance fluids.
Hypervolemic hyponatremia is caused by
Rationale:
Hypervolemic hyponatremia is caused by cirrhosis. Cirrhosis leads to fluid overload and sodium dilution, resulting in decreased serum sodium levels. The condition is characterized by an excess of total body water relative to sodium, causing hyponatremia.
B: cerebral salt wasting Results from an inability to retain sodium, leading to hyponatremia without hypervolemia, differing fundamentally from the fluid overload seen in hypervolemic hyponatremia.
C: pseudohypoaldosteronism type I Causes sodium wasting and hyperkalemia, leading to hyponatremia but does not involve fluid retention, thus not fitting the hypervolemic context of this condition.
D: obstructive uropathy Primarily results in renal impairment and potential volume depletion. It does not typically cause the hypervolemic state associated with hyponatremia, making it unrelated to this condition.
Which of the following conditions should receive a careful examination of the hips to rule out developmental dysplasia of the hip (DDH)?
Rationale:
A: Congenital muscular torticollis often accompanies hip asymmetry and may indicate underlying developmental dysplasia of the hip (DDH). Careful hip examination is essential to identify any associated abnormalities early in affected infants.
B: Klippel-Feil syndrome involves cervical vertebral fusion and does not directly imply hip dysplasia, making hip assessment less relevant in this context.
C: Scoliosis primarily affects the spine's curvature and does not typically correlate with hip dysplasia, reducing the necessity for an extensive hip evaluation.
D: Spina bifida occulta is a spinal defect with minimal impact on hip development, thus requiring less focus on hip examination for potential dysplasia issues.