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Thoracolumbar Spine & Deformity MCQs

Practice Set 49 of 49

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

Question 961

Topic: Thoracolumbar Spine & Deformity

A patient with symptomatic cerebral palsy exhibits a 'crouch gait'. Surgical correction often targets hamstring tightness. If isolated hamstring lengthening is performed without addressing other concurrent deformities, which of the following is a common postoperative complication?

. Anterior pelvic tilt and worsening of lumbar lordosis
. Severe equinus gait with secondary toe-walking
. Recurvatum of the knee during the stance phase
. Inability to flex the hip during the swing phase
. Worsening of hip internal rotation and in-toeing

Correct Answer & Explanation

. Anterior pelvic tilt and worsening of lumbar lordosis

Explanation

The hamstrings extend the hip and flex the knee, maintaining a posterior pull on the pelvis. Over-lengthening the hamstrings without addressing concurrent psoas/rectus tightness can lead to an unchecked anterior pelvic tilt and an exaggerated hyperlordosis of the lumbar spine.

Question 962

Topic: Thoracolumbar Spine & Deformity

A 3-year-old child presents with coarse facial features, severe corneal clouding, hepatosplenomegaly, and a prominent thoracolumbar kyphosis (gibbus deformity). Which accumulated glycosaminoglycans are most likely to be found in the urine?

. Keratan sulfate only
. Dermatan sulfate and heparan sulfate
. Heparan sulfate only
. Chondroitin-6-sulfate only
. Hyaluronic acid

Correct Answer & Explanation

. Dermatan sulfate and heparan sulfate

Explanation

The presentation is classic for Hurler syndrome (MPS I), caused by alpha-L-iduronidase deficiency. This leads to the accumulation and urinary excretion of both dermatan sulfate and heparan sulfate.

Question 963

Topic: Thoracolumbar Spine & Deformity

What is the characteristic spinal deformity finding associated with Hurler syndrome (MPS I)?

. Thoracolumbar kyphosis with anteroinferior beaking of the vertebral body
. Thoracolumbar kyphosis with central anterior beaking of the vertebral body
. Congenital scoliosis due to unsegmented bars
. High-grade isthmic spondylolisthesis
. Cervical kyphosis with block vertebrae

Correct Answer & Explanation

. Thoracolumbar kyphosis with anteroinferior beaking of the vertebral body

Explanation

Hurler syndrome typically presents with anteroinferior beaking of the vertebral bodies, leading to thoracolumbar kyphosis. In contrast, Morquio syndrome classically presents with central anterior beaking.

Question 964

Topic: Thoracolumbar Spine & Deformity

A 2-year-old boy presents with corneal clouding, coarse facial features, severe kyphosis, and progressive intellectual disability. Urinary tests reveal high levels of dermatan sulfate and heparan sulfate. What is the inheritance pattern and deficient enzyme for this condition?

. Autosomal recessive; Alpha-L-iduronidase
. X-linked recessive; Iduronate-2-sulfatase
. Autosomal recessive; Galactose-6-sulfatase
. X-linked recessive; Heparan N-sulfatase
. Autosomal dominant; Arylsulfatase B

Correct Answer & Explanation

. Autosomal recessive; Alpha-L-iduronidase

Explanation

The patient has Hurler syndrome (MPS I), which is inherited in an autosomal recessive manner and caused by a deficiency in alpha-L-iduronidase. It presents with severe systemic manifestations, including corneal clouding and cognitive decline.

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