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7. Hand and Wrist MCQs

Practice Set 265 of 266

This practice set contains high-yield board review questions covering key concepts in 7. Hand and Wrist. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 5281

Topic: 7. Hand and Wrist

A newborn exhibits a significantly shortened left lower leg. Clinical examination shows a rigid varus foot deformity and duplication of the great toe. Radiographs demonstrate a completely absent tibia but an intact, relatively normally developed fibula. What is the most common genetic inheritance pattern for the familial form of this deficiency?

. X-linked recessive
. Autosomal dominant
. Autosomal recessive
. Mitochondrial
. Sporadic somatic mutation

Correct Answer & Explanation

. Autosomal dominant

Explanation

Congenital tibial hemimelia often presents with a varus foot and preaxial polydactyly (duplication of the great toe). While many cases are sporadic, familial forms are typically inherited in an autosomal dominant pattern, frequently linked to the GLI3 gene or the ZRS enhancer of SHH.

Question 5282

Topic: 7. Hand and Wrist
A 4-year-old boy is brought in for a unilateral chest wall asymmetry and a right hand deformity. Examination reveals absence of the sternocostal head of the right pectoralis major muscle and ipsilateral short, webbed fingers (symbrachydactyly). What is the most likely diagnosis?
. Apert syndrome
. Poland syndrome
. Holt-Oram syndrome
. VACTERL association
. Treacher Collins syndrome

Correct Answer & Explanation

. Poland syndrome

Explanation

Poland syndrome is classically characterized by the unilateral absence of the sternocostal head of the pectoralis major muscle and ipsilateral hand anomalies, most commonly symbrachydactyly. It is thought to result from a transient interruption of the embryonic subclavian artery.

Question 5283

Topic: 7. Hand and Wrist

A newborn presents with a severe upper extremity anomaly featuring no thumb, seven triphalangeal digits, two ulnas, and an absent radius. This mirror-hand deformity (ulnar dimelia) is primarily caused by abnormal embryological signaling from which of the following?

. Apical Ectodermal Ridge (AER)
. Zone of Polarizing Activity (ZPA)
. Dorsal Ectoderm
. Somitic Mesoderm
. Neural Crest Cells

Correct Answer & Explanation

. Zone of Polarizing Activity (ZPA)

Explanation

Ulnar dimelia (mirror hand) results from a duplication of the Zone of Polarizing Activity (ZPA). The ZPA expresses Sonic Hedgehog (SHH) protein, which is responsible for the radioulnar (anterior-posterior) patterning of the developing limb.

Question 5284

Topic: 7. Hand and Wrist

A 13-year-old girl is evaluated for mesomelic short stature and a bilateral wrist deformity characterized by dorsal bowing of the distal radius and limited forearm rotation. Which gene mutation is responsible for this condition?

. SHOX
. RUNX2
. COMP
. FGFR3
. COL1A1

Correct Answer & Explanation

. SHOX

Explanation

Leri-Weill dyschondrosteosis is caused by a pseudoautosomal SHOX gene mutation. It classically presents with mesomelic dwarfism and Madelung deformity of the wrists.

Question 5285

Topic: Wrist & Carpus

In idiopathic Madelung deformity, premature fusion of the volar-ulnar aspect of the distal radial physis occurs due to mechanical tethering. Which anomalous structure is responsible for this tether?

. Triangular fibrocartilage complex
. Brachioradialis tendon
. Short radiolunate ligament
. Pronator quadratus
. Extensor carpi ulnaris sheath

Correct Answer & Explanation

. Short radiolunate ligament

Explanation

Madelung deformity is characterized by an abnormal volar tether known as Vickers ligament. This structure is a thickened, dysplastic short radiolunate ligament that bridges the radius and lunate, restricting the growth of the volar-ulnar distal radius.

Question 5286

Topic: Nerve & Tendon

A 3-year-old child presents with disproportionate enlargement of the right index and middle fingers. The overgrowth involves both soft tissue and bone, and the fingers exhibit palmar deviation. The overgrowth in this condition is most classically distributed along the territory of which of the following structures?

. Lymphatic vessels
. Median nerve
. Ulnar artery
. Radial nerve
. Dorsal venous arch

Correct Answer & Explanation

. Median nerve

Explanation

Macrodystrophia lipomatosa is a rare, localized form of congenital gigantism characterized by fibrofatty overgrowth that follows the distribution of a specific nerve. In the upper extremity, it most commonly follows the territory of the median nerve.

Question 5287

Topic: Nerve & Tendon

A 4-year-old child presents with disproportionate overgrowth of the index and middle fingers. Imaging shows massive enlargement of the fibrofatty tissue and phalanges strictly localized within the distribution of the median nerve. What is the primary underlying genetic etiology?

. Germline PTEN mutation
. Post-zygotic somatic PIK3CA mutation
. Somatic AKT1 mutation
. NF1 gene microdeletion
. GLI3 gene mutation

Correct Answer & Explanation

. Post-zygotic somatic PIK3CA mutation

Explanation

Macrodystrophia lipomatosa is a localized form of congenital gigantism associated with somatic mosaic mutations in the PIK3CA gene. It typically causes fibrofatty overgrowth along a specific nerve territory, most often the median nerve.

Question 5288

Topic: 7. Hand and Wrist

A newborn presents with a shortened right lower extremity, an adducted and supinated foot, and preaxial polydactyly. Radiographs demonstrate complete absence of the tibia with a normal fibula and intact distal femoral epiphysis. According to the Jones classification, which type of tibial hemimelia is this, and what is its most common inheritance pattern if familial?

. Type 1a; Autosomal dominant
. Type 1a; Autosomal recessive
. Type 2; X-linked recessive
. Type 3; Autosomal dominant
. Type 4; Sporadic

Correct Answer & Explanation

. Type 1a; Autosomal dominant

Explanation

Complete absence of the tibia with a present distal femoral epiphysis represents a Type 1a tibial hemimelia. When familial, such as in tibial hemimelia-polydactyly syndrome, it is classically inherited in an autosomal dominant pattern.

Question 5289

Topic: 7. Hand and Wrist
A 13-year-old girl presents with wrist pain and limited range of motion. Examination reveals a prominent distal ulna and volar subluxation of the hand. Radiographs show increased volar and ulnar tilt of the distal radius. Which gene mutation is responsible for her primary skeletal manifestation?
. SHOX
. COMP
. COL1A1
. RUNX2
. LEMD3

Correct Answer & Explanation

. SHOX

Explanation

Lรฉri-Weill dyschondrosteosis is characterized by disproportionate short stature and Madelung deformity. It is an autosomal dominant condition caused by mutations or deletions of the SHOX gene located on the pseudoautosomal region of the sex chromosomes.

Question 5290

Topic: 7. Hand and Wrist

A patient with right hip osteoarthritis is advised to use a cane. Holding the cane in the contralateral (left) hand reduces the right hip joint reaction force primarily by:

. Decreasing the lever arm of the abductor mechanism
. Increasing the lever arm of the abductor mechanism
. Providing an upward moment that counteracts the body weight moment
. Shifting the body's center of mass further away from the right hip joint
. Activating the contralateral hip abductors to share the load

Correct Answer & Explanation

. Providing an upward moment that counteracts the body weight moment

Explanation

Using a cane in the contralateral hand provides a long lever arm that generates an upward moment. This counteracts the moment of body weight, drastically reducing the force required by the ipsilateral hip abductors and lowering the total joint reaction force.

Question 5291

Topic: 7. Hand and Wrist

A patient with severe right hip osteoarthritis is advised to use a cane. To maximally decrease the joint reactive forces across the affected hip, how should the cane be used, and what is the primary biomechanical mechanism?

. Used in the right hand; it shifts the center of gravity towards the affected side.
. Used in the right hand; it increases the abductor moment arm.
. Used in the left hand; it decreases the body weight vector force directly.
. Used in the left hand; it provides a counter-moment that reduces the required hip abductor muscle force.
. Used in the left hand; it directly increases the tension in the right iliotibial band.

Correct Answer & Explanation

. Used in the left hand; it provides a counter-moment that reduces the required hip abductor muscle force.

Explanation

Using a cane in the contralateral hand provides an upward force at a long distance from the affected hip. This generates a counter-moment that significantly reduces the force required by the hip abductors to maintain pelvic level, substantially lowering the total joint reactive force.

Question 5292

Topic: 7. Hand and Wrist

A patient with severe right hip osteoarthritis uses a cane in the left hand during ambulation. Which of the following best describes the biomechanical rationale for the pain relief provided by this intervention?

. Decreases the moment arm of the body weight relative to the knee
. Increases the moment arm of the right hip abductors
. Decreases joint reaction force by reducing the requisite right hip abductor force
. Shifts the center of gravity laterally away from the unaffected hip
. Increases the required left hip abductor force

Correct Answer & Explanation

. Decreases joint reaction force by reducing the requisite right hip abductor force

Explanation

Using a cane in the contralateral hand creates a long moment arm to help counteract the torque produced by body weight. This significantly reduces the compensatory force required by the ipsilateral hip abductors. Consequently, the overall hip joint reaction force is substantially decreased.

Question 5293

Topic: 7. Hand and Wrist

A patient with severe right hip osteoarthritis uses a cane in the left hand during ambulation. What is the primary biomechanical mechanism by which this intervention relieves right hip pain?

. Decreases the body weight moment arm
. Increases the hip abductor moment arm
. Decreases the required hip abductor muscle force
. Shifts the center of gravity laterally to the right
. Increases the joint reaction force to stabilize the joint

Correct Answer & Explanation

. Decreases the required hip abductor muscle force

Explanation

Using a cane in the contralateral hand provides an upward ground reaction force that assists the hip abductors. This significantly decreases the required abductor muscle force, thereby reducing the overall hip joint reaction force.

Question 5294

Topic: 7. Hand and Wrist

A 65-year-old man with right hip osteoarthritis uses a cane to improve his gait and decrease pain. To optimally reduce the joint reaction force across his right hip, how should he hold the cane and what is the primary biomechanical mechanism?

. In the right hand; it shifts the center of gravity laterally.
. In the right hand; it increases the moment arm of the abductor muscles.
. In the left hand; it creates a counter-moment that decreases the required abductor muscle force.
. In the left hand; it increases the moment arm of the right hip abductor muscles.
. In either hand; it relies entirely on weight offloading through the upper extremity.

Correct Answer & Explanation

. In the left hand; it creates a counter-moment that decreases the required abductor muscle force.

Explanation

Using a cane in the contralateral hand provides a long lever arm to assist in supporting body weight. This significantly reduces the necessary force generated by the ipsilateral hip abductors to maintain pelvic level, thereby decreasing the overall hip joint reaction force.

Question 5295

Topic: 7. Hand and Wrist

A patient with severe left-sided hip osteoarthritis is instructed to carry a heavy 15 kg suitcase. To minimize the joint reaction force on the arthritic hip, how should the patient carry the load?

. In the left hand, because it shifts the center of gravity towards the affected hip, reducing the abductor moment required.
. In the right hand, because it acts as a counterbalance, reducing the abductor moment required.
. In the left hand, because it decreases the effective lever arm of the body weight.
. In the right hand, because it effectively offloads the left leg during the stance phase.
. Carrying a load in either hand equally increases the joint reaction force on the left hip.

Correct Answer & Explanation

. In the left hand, because it shifts the center of gravity towards the affected hip, reducing the abductor moment required.

Explanation

Carrying a load in the ipsilateral hand shifts the total body center of mass closer to the affected hip joint. This decreases the gravitational moment arm, which reduces the force required by the abductors, ultimately decreasing the hip joint reaction force.

Question 5296

Topic: 7. Hand and Wrist

A patient with unilateral right hip osteoarthritis is advised to use a cane to reduce pain. To optimally decrease the joint reaction force on the right hip, in which hand should the cane be held and what is the primary biomechanical reason?

. Right hand; it directly unloads the body weight vector on the ipsilateral side.
. Right hand; it decreases the abductor moment arm required by the left hip.
. Left hand; it generates a counter-moment that decreases the required force from the right hip abductors.
. Left hand; it increases the lever arm of the body weight acting on the right hip.
. Either hand; the force reduction is independent of the side the cane is held.

Correct Answer & Explanation

. Left hand; it generates a counter-moment that decreases the required force from the right hip abductors.

Explanation

Using a cane in the contralateral (left) hand provides a long lever arm to assist the right hip abductors in balancing body weight. This significantly reduces the force the right abductors must generate, profoundly decreasing the joint reaction force on the right hip.

Question 5297

Topic: 7. Hand and Wrist

To minimize the joint reaction force on the left hip while carrying a heavy 20-lb suitcase, how should the patient carry the load?

. In the right hand, with the arm abducted
. In the right hand, held close to the body
. In the left hand, held close to the body
. Equally distributed between both hands, but slightly biased to the right
. In a backpack worn firmly over both shoulders

Correct Answer & Explanation

. In the right hand, held close to the body

Explanation

Carrying a load in the ipsilateral hand shifts the body's superincumbent weight vector closer to the affected hip joint, which decreases the abductor force needed to maintain a level pelvis. Carrying it in the contralateral hand significantly increases the hip joint reaction force.

Question 5298

Topic: 7. Hand and Wrist

A 65-year-old patient with severe right hip osteoarthritis uses a cane to reduce hip pain during ambulation. To optimally decrease the joint reaction force across the right hip, the patient should be instructed to hold the cane in which hand, and by what biomechanical mechanism does this work?

. Right hand; decreases the body weight moment arm.
. Left hand; creates a counter-moment that decreases the required abductor muscle force.
. Right hand; increases the abductor moment arm.
. Left hand; shifts the center of gravity laterally towards the stance leg.

Correct Answer & Explanation

. Left hand; creates a counter-moment that decreases the required abductor muscle force.

Explanation

Holding a cane in the contralateral (left) hand provides a supportive upward force at a long distance from the hip, creating a moment that assists the hip abductors. This significantly decreases the force required by the abductors, thereby reducing the total hip joint reaction force.

Question 5299

Topic: 7. Hand and Wrist

A patient with osteoarthritis of the left hip is tasked with carrying a 20-pound suitcase. To minimize the joint reaction force across the painful left hip during ambulation, the patient should be instructed to carry the suitcase in which manner?

. In the right hand
. In the left hand
. In a backpack
. Carrying weight does not affect the joint reaction force of the stance leg

Correct Answer & Explanation

. In the left hand

Explanation

Carrying a load in the ipsilateral (left) hand shifts the body's center of gravity closer to the stance hip, reducing the body weight moment arm. This decreases the abductor muscle force required, thereby reducing the joint reaction force.

Question 5300

Topic: 7. Hand and Wrist

A patient with severe right hip osteoarthritis is advised to use a cane for offloading. In which hand should the cane be held, and what is the primary biomechanical mechanism of action?

. Contralateral hand; it increases the body weight moment arm.
. Contralateral hand; it reduces the required abductor force.
. Ipsilateral hand; it reduces the abductor moment arm.
. Ipsilateral hand; it shifts the center of gravity laterally.
. Contralateral hand; it increases the required abductor force.

Correct Answer & Explanation

. Contralateral hand; it reduces the required abductor force.

Explanation

Using a cane in the contralateral hand reduces the body weight moment. This significantly decreases the force required by the hip abductors, which in turn drastically reduces the overall joint reaction force.

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