What percentage of the human genome represents the actual genes:
1) 80%
3) 50%
2) 66%
5) 5%
4) 20%
The percentage of the genome that represents the sequence of our genes is approximately 5%. The rest of the genome codes are for initiator and termination sequences, maintenance functions, and unknown functions.
■Correct Answer:5%
1852. (814) Q5-1075:
In studying a newly recognized disorder using a large population of affected individuals, geneticists discover that although the disorder often affects siblings, it is rarely found in any of their ancestors. This disorder most closely follows which pattern of inheritance:
1) Autosomal dominant
3) Sex-linked
2) Autosomal recessive
5) Anticipation
4) Multifactorial
Autosomal recessive conditions classically show âhorizontalâ inheritance. Ancestors do not display the gene because they would likely have only one copy of the mutant allele. Only when two carriers reproduce is the phenotype manifest in approximately one- fourth of their offspring.
Autosomal dominant inheritance is characterized by vertical transmission. Many generations manifest the trait because it takes only a single copy of a mutant allele to display the phenotype.
Sex-linked conditions are often traced back in a family. Normally the males are affected and the females are carriers. Multifactorial conditions are thought to result from the combination of different genes. Although the risk of recurrence in kindred is somewhat greater than the population as a whole, it is still quite low (only a few percent). It is rare for siblings to be affected.
Anticipation refers to the phenomenon in which successive generations are likely to display more severe forms of a given disorder. Myotonic dystrophy is a classic example of this phenomenon.
■Correct Answer:Autosomal recessive
1853. (815) Q5-1076:
Diseases caused by enzyme deficiency are commonly inherited by which of the following patterns:
1) Autosomal dominant
3) X-linked dominant
2) Autosomal recessive
5) Non-mendelian
4) Multifactorial
Two copies of a mutant allele are required to reduce enzyme function to levels that cause clinical impairment.
Enzyme defects are rarely inherited by an autosomal dominant pattern because even half of the normal activity of most enzymes is adequate to maintain normal function.
Enzyme defects are rarely inherited in an X-linked dominant pattern because one copy of a mutant allele is usually sufficient.
Multifactorial inheritance refers to the interaction of multiple, or different genes, to produce a disorder. Enzyme deficiencies are typically the result of a defect in a single gene.
Because enzymes are typically coded by a single gene, they follow mendelian patterns.
■Correct Answer:Autosomal recessive
1854. (816) Q5-1077:
Morquio syndrome is caused by a deficiency in:
1) Alpha-L-iduronidase
3) Beta-glucuronidase
2) Galactose-6-sulfatase
5) Sulfate transport protein
4) Fibroblast growth factor receptor protein
Morquio syndrome is a member of the family of mucopolysaccharidoses. Morquio syndrome is a deficiency in the enzyme galactose-6-sulfatase. A deficiency in galactose-6-sulfatase results in increased urinary excretion of keratosulfate.
Alpha-L-iduronidase is deficient in Hurler syndrome.
Beta-glucuronidase is deficient in some rare mucopolysaccharidoses. Fibroblast growth factor receptor protein is deficient in achondroplasia. Sulfate transport protein is deficient in diastrophic dysplasia.
■Correct Answer:Galactose-6-sulfatase
1855. (817) Q5-1078:
Polymerase chain reaction (PC R) is best characterized by which of the following descriptions:
1) Use of enzymes to link chains of deoxyribonucleic acid (DNA) together
3) Denaturing and reannealing DNA multiple times with known primers
2) Use of viral vectors to insert new DNA into a cell
5) The process by which a cell-surface receptor turns on the transcription process
4) Use of high temperatures to create ultra-high molecular weight polyethylene
Polymerase chain reaction refers to denaturing DNA, isolating a segment of interest with known primers, and reannealing the strands multiple times to produce exponential copies of a segment.
■Correct Answer:Denaturing and reannealing DNA multiple times with known primers
1856. (818) Q5-1079:
Pleiotropy is demonstrated by which of the following examples:
1) Patients with osteogenesis imperfecta differ in the number of fractures they have received.
3) Hurler syndrome is usually not present in prior generations of an affected patient.
2) Patients with hemophilia A have different target joints.
5) Patients with Ollier disease often have more involvement on one side of the body.
4) Some patients with Marfan syndrome have scoliosis or pectus carinatum, while other patients with Marfan syndrome do not.
The term pleiotropy refers to a disease taking different shapes in various patients.
Variation in the severity of a given problem is better termed "variable expressivity." Target joints are not genetically determined.
Hurler syndrome usually not being present in prior generations of an affected patient is an example of autosomal recessive inheritance.
The term pleiotropy refers to a disease taking different shapes in different subjects, whereas the cause of patients with
Ollier disease having more involvement on one side of the body is unknown.
■Correct Answer:Some patients with Marfan syndrome have scoliosis or pectus carinatum, while other patients with Marfan syndrome do not.
1857. (819) Q5-1080:
Which of the following is the most common concern regarding anesthesia for a patient with juvenile rheumatoid arthritis:
1) Basilar invagination
3) Subaxial subluxation
2) Rotatory subluxation of C 1-C 2
5) C ervical stenosis
4) Small, stiff jaw
Stiffness and mandibular hypoplasia are fairly common in juvenile rheumatoid arthritis (JRA) due to inflammation of the temporomandibular joint that affects the growth plates of the mandibles.
Basilar invagination is rare in JRA.
Rotatory subluxation of C 1-C 2 is rare in JRA. Subaxial subluxation is rare in JRA.
C ervical stenosis is not a clinical problem in JRA.
■Correct Answer:Small, stiff jaw
1858. (820) Q5-1081:
A 4-year-old boy is brought to a clinic because he has been fussy, febrile, and unable to bend over for the past 4 days. In the office, his temperature is 38.2° C and his neurologic examination is normal. His lumbar lordosis is flattened and he resists flexion or extension. He has normal range of hip motion. Plain films of the lumbar spine are normal. The next imaging study should be:
1) Magnetic resonance imaging of the spine
3) Spinal ultrasound
2) Hip arthrogram
5) Indium labeled white blood cell scan
4) C omputed tomograms of the lumbar spine
Magnetic resonance imaging should be the next step to rule out pyogenic spondylitis.
Ultrasound has not been proven effective in evaluation of anterior spinal pathology.
C omputed tomograms do not have a greater sensitivity than plain films in early diagnosis of infection.
An indium labeled scan may yield diagnostic information but would not be the preferred test because of the time needed and inability to provide other diagnostic information.
Hip arthrogram would not be the next step because the hip range of motion is normal. Even if hip pathology were suspected, the next step would be a plain film and an ultrasound.
■Correct Answer:Magnetic resonance imaging of the spine
1859. (821) Q5-1082:
A 6-year-old child suffers a displaced fracture of the distal humerus in the supracondylar region. The surgeon decides to reduce and pin the fracture. Which of the following risks increases if the procedure is delayed more than 8 hours?
1) Brachial artery damage
3) Radial nerve palsy
2) Median nerve palsy
5) No risks increase
4) Need for an open reduction
A retrospective comparison study has shown no increase of risks in delayed treatment of supracondylar fractures as long as the neurovascular examination is within normal limits.
■Correct Answer:No risks increase
1860. (822) Q5-1083:
Which of the following statements is true regarding the growth plates around the ankle:
1) The distal fibula grows more than the distal tibia.
3) The anterolateral portion of the tibial physis ceases growing first.
2) The distal tibia grows more than the distal fibula.
5) The two growth plates are part of a common physis.
4) The two physes should be at an even level.
The distal tibia grows more than the distal fibula.
The anterolateral portion of the tibial physis ceases growing last, thus explaining the phenomenon of the Tillaux fracture. The physis of the distal fibula is always located more distally than the distal tibia.
The two physes are not conjoined.
■Correct Answer:The distal tibia grows more than the distal fibula.
1861. (823) Q5-1084:
Which of the following is the most common final attribution of back pain in children and adolescents after all appropriate diagnostic studies are performed:
1) Spondylolysis
3) Infection
2) Osteoid osteoma
5) No identifiable cause
4) Herniated nucleus pulposus
The majority of children and adolescents do not have an identifiable cause of back pain after all appropriate tests are performed. Many times the diagnosis is "musculo-ligamentous strain." the most common identified cause is spondylolysis.
■Correct Answer:No identifiable cause
1862. (824) Q5-1085:
Which of the following is the most definitive means of making a diagnosis of active skeletal tuberculosis:
1) Positive tuberculin tine test
3) Positive culture and histological exam
2) Negative tuberculin tine test
5) Enzyme linked immunosorbent assay (ELISA) test
4) Magnetic resonance imaging
An early histology confirmed later by a culture is considered the definitive means of diagnosis for active skeletal tuberculsosis.
The tuberculin tine tests do not indicate active disease, only exposure.
Magnetic resonance imaging is not specific for a particular infectious organism.
The enzyme linked immunosorbent assay (ELISA) test is used to diagnose Lyme disease.
■Correct Answer:Positive culture and histological exam
1863. (825) Q5-1086:
The most common region of the spine affected by tuberculosis is:
1) C ervical
3) Lower thoracic-upper lumbar
2) Upper thoracic
5) C acral
4) Lower lumbar
The lower thoracic-upper lumbar spine is most commonly affected by tuberculosis. Multiple vertebrae are often involved in tuberculosis spondylitis.
■Correct Answer:Lower thoracic-upper lumbar
1864. (826) Q5-1087:
Which of the following descriptions is more characteristic of tuberculosis than pyogenic spondylitis:
1) Disc space is narrowed before significant bony changes occur.
3) Bony erosions seen on computerized tomography are usually small and focal.
2) Involvement of multiple contiguous levels is uncommon.
5) Magnetic resonance imaging rarely shows significant soft tissue swelling.
Vertebral destruction exceeds disc destruction in tuberculosis.
Bony changes occur earlier in tuberculosis than in pyogenic spondylitis.
Involvement of multiple contiguous levels is more common in tuberculosis than pyogenic spondylitis.
Bony erosions seen on computerized tomography are large in tuberclosis and small in pyogenic spondylitis. Magnetic resonance imaging often shows significant soft tissue involvement in both disorders.
A 5-year-old girl comes into the clinic with back pain. Her family has just moved to the United States from southeastern Asia. A lateral radiograph shows destruction of T11, T12, and L1. Magnetic resonance imaging shows a moderate posterior soft tissue mass. A neurological exam is normal. Biopsy confirms tuberculosis. For the girlâs spinal problem, recommended treatment includes:
1) A two-drug therapy for at least 6 months
3) A two-drug therapy and posterior spinal fusion to prevent deformity
2) A two-drug therapy for at least 6 months along with a body cast
5) Anterior debridement, strut graft, and posterior fusion with instrumentation
4) Anterior spinal debridement and a rib strut graft
Anterior debridement, strut graft, and posterior fusion with instrumentation provide the patient with the best chance of a positive result. This procedure minimizes graft dislodgement and posterior overgrowth.
A two-drug therapy alone for at least 6 months leaves the patient at a significant risk of progressive kyphosis and neurologic deficit.
A two-drug therapy for at least 6 months along with a body cast also leaves the patient with significant risk of progressive kyphosis and neurologic deficit.
The lack of anterior support from a two-drug therapy and posterior spinal fusion to prevent deformity leaves the patient with significant risk of kyphosis.
Even with an anterior spinal debridement and a rib strut graft, there is a risk of graft dislodgment over this large defect and of posterior growth into kyphosis.
■Correct Answer:Anterior debridement, strut graft, and posterior fusion with instrumentation
1866. (828) Q5-1089:
A dorsal approach has which of the following characteristics with regard to a posteromedial approach in the surgical treatment of congenital vertical talus:
1) The dorsal approach requires a more extensive dissection.
3) The dorsal approach requires plication of the talonavicular capsule.
2) The dorsal approach has a lower risk of avascular necrosis of the talus.
5) The dorsal approach requires a longer tourniquet time.
4) The dorsal approach has a higher risk of redislocation.
The dorsal approach has not shown evidence of avascular necrosis, whereas the posteromedial approach has shown such changes at follow-up in as many as 40% of cases.
The dorsal approach requires a less extensive dissection than the posteromedial approach.
The dorsal approach does not require or permit plication of the talonavicular capsule, whereas the posteromedial approach does.
The dorsal approach does not appear to have a higher rate of redislocation of the talonavicular joint than the posteromedial approach.
The dorsal approach requires a shorter tourniquet time than the posteromedial approach.
■Correct Answer:The dorsal approach has a lower risk of avascular necrosis of the talus.
1867. (829) Q5-1090:
Which of the following conditions is not associated with an increased incidence of congenital vertical talus:
1) C erebral palsy
3) Arthrogryposis
2) Myelomeningocele
5) Larsen syndrome
4) Nail patella syndrome
Patients with cerebral palsy do not have an increased risk of congenital vertical talus, but they may develop an acquired neuromuscular vertical talus.
Patients with myelomeningocele have approximately a 5% to 10% risk of vertical talus, far above that of the general population.
Arthrogryposis is associated with an increased risk of vertical talus.
Nail patella syndrome and Larsen syndrome are associated with an increased risk of vertical talus.
■Correct Answer:C erebral palsy
1868. (830) Q5-1092:
Scoliosis in Marfan syndrome is characterized by which of the following:
1) Scoliosis curves are more likely to begin in the juvenile period.
3) Brace treatment is more likely to be successful because of the flexibility.
2) There is an increased likelihood of left thoracic curves.
5) C urves are more likely to be stable in adulthood.
4) Patients are less likely to have back pain.
Scoliosis curves are much more likely to begin in the juvenile period than idiopathic scoliosis.
There is no significant difference in the likelihood of left thoracic curves in Marfan syndrome. Brace treatment is less likely to be successful in Marfan syndrome than in idiopathic scoliosis. Marfan patients with scoliosis are more likely to have back pain.
Marfan curves are more likely to progress in adulthood.
■Correct Answer:Scoliosis curves are more likely to begin in the juvenile period.
1869. (831) Q5-1093:
Which of the following statements is true of demineralized bone matrix:
1) Demineralized bone matrix is osteogenic.
3) Demineralized bone matrix is weakly osteoinductive.
2) Demineralized bone matrix is strongly osteoinductive.
5) Demineralized bone matrix is not osteoconductive.
4) Demineralized bone matrix is consistent between forms and different sterilization methods.
Demineralized bone matrix is weakly osteoinductive.
The term osteogenic refers to direct transmittal of cells capable of making bone. Demineralized bone matrix is not osteogenic.
Demineralized bone matrix varies in efficacy between different forms and different methods of sterilization. The term osteoconduction refers to provision of a favorable scaffold and environment for bone formation. Demineralized bone matrix is osteoconductive.
■Correct Answer:Demineralized bone matrix is weakly osteoinductive.
1870. (832) Q5-1094:
A 16-year-old boy with type I Ehlers-Danlos syndrome has a spinal curvature that has progressed 18° in the past year. The curve is a double major type with a C obb angle of 60° in each curve. There is no associated kyphosis. The following treatment is recommend:
1) Observation
3) Anterior fusion and instrumentation
2) Bracing
5) Anterior and posterior fusion with instrumentation
4) Posterior fusion and instrumentation
Posterior fusion and instrumentation is the best-documented treatment. Although this form of treatment is followed by an increased incidence of wound healing problems, the problems can be treated.
Observation is not recommended because the curve is highly likely to increase and cause a decrease in pulmonary function.
Bracing has no role in large curves, and it is not known if bracing is successful in Ehlers-Danlos syndrome.
Anterior fusion with instrumentation would be difficult with a double curve. Anterior fusion carries an increased risk due to vascular fragility. It is not necessary because there is no increased risk of crankshaft or pseudarthrosis.
There is no particular reason for adding an anterior procedure in this situation in view of the vascular risk.
■Correct Answer:Posterior fusion and instrumentation
1871. (833) Q5-1095:
Scoliosis in osteogenesis imperfecta is characterized by which of the following:
1) Scoliosis is due primarily to vertebral fractures.
3) Scoliosis is due primarily to associated neurologic problems.
2) Scoliosis is due primarily to ligamentous laxity.
5) Scoliosis rarely impairs quality of life.
4) Scoliosis usually responds to brace treatment.
Scoliosis in osteogenesis imperfecta (OI) is due primarily to ligamentous laxity.
Scoliosis in OI is due primarily to ligamentous laxity, not bony fractures. There is no association between brainstem impression and scoliosis. Scoliosis in OI rarely responds to brace treatment.
Scoliosis, when present in OI, is a major impairment of quality of life.
■Correct Answer:Scoliosis is due primarily to ligamentous laxity.
1872. (834) Q5-1096:
Which of the following is not a specific feature in making the diagnosis of a dystrophic curve in neurofibromatosis 1:
1) Penciling of the ribs
3) Widening of the foramen
2) Scalloping of the vertebrae
5) Right convex apex
4) Thinning of the transverse processes
Right convex apex is not a specific characteristic of dystrophic curves. It is more common in dystrophic curves than in nondystrophic curves, but it is commonly present in both types of curves.
Penciling of the ribs is one of the features specific for dystrophic curves in neurofibromatosis 1.
Scalloping of the vertebrae anteriorly and posteriorly is characteristic of dystrophic curves in neurofibromatosis 1. Widening of the neural foramen is specific for dystrophic curves in neurofibromatosis 1. Widening of the neural foramen is due to tumorous masses passing through the foramen.
Thinning of the transverse process is a characteristic of dystrophic curves in neurofibromatosis 1.
■Correct Answer:Right convex apex
1873. (835) Q5-1097:
The spine in familial dysautonomia is characterized by which of the following:
1) Rare scoliosis
3) Dense bone
2) Flexible scoliosis
5) Spinal stenosis
4) Increased risk of loss of fixation after surgery
There is an increased risk of loss of fixation in familial dysautonomia curves due to decreased bone density and curve rigidity.
Scoliosis is common in patients with familial dysautonomia and affects up to one-half of patients with the disorder. The curves in familial dysautonomia are rigid, leading to limited correction.
The bone density in familial dysautonomia is decreased.
Spinal stenosis is not reported in patients with familial dysautonomia.
■Correct Answer:Increased risk of loss of fixation after surgery
1874. (836) Q5-1098:
Which of the following spinal problems is most common in achondroplasia:
1) Atlantoaxial instability
3) Symptomatic kyphosis
2) Basilar invagination
5) Spondylolisthesis
4) Thoracolumbar stenosis
Symptomatic stenosis of the thoracic and lumbar spine is seen in almost half of all achondroplastic patients, although not all patients require surgery.
Atlantoaxial instability is rare in achondroplasia, although it is not uncommon in other dysplasias. Basilar invagination is not present in achondroplasia.
Kyphosis is often transient in achondroplasia and rarely persists beyond the second year. Kyphosis is rarely symptomatic. Spondylolisthesis is rare in achondroplasia.
■Correct Answer:Thoracolumbar stenosis
1875. (837) Q5-1099:
A 2-year-old girl with diastrophic dysplasia is brought into the office for an overall examination. A lateral radiograph of the spine shows a kyphosis of 35° from C 3 to C 6. A neurologic exam is normal, although she does have stiff joints. The patient is not yet walking. For management of this kyphosis, recommended treatment includes:
1) Observation
3) Halo traction
2) C ervicothoracic orthosis
5) Anterior and posterior fusion
4) Posterior fusion
Many diastrophic cervical kyphoses will correct spontaneously if the curve does not exceed 50°. In this patient, the lack of walking is most likely due to other skeletal factors.
There is no evidence that orthosis will change the natural history of the disorder.
There is no need for traction given the high chance of spontaneous resolution and the dangers of traction.
Posterior fusion is only indicated if the kyphosis is continually progressive, or if neurologic signs or symptoms develop. Anterior and posterior surgery is only indicated in cases with severe pre-existing neurologic deficit.
■Correct Answer:Observation
1876. (838) Q5-1100:
A baby born with diastrophic dysplasia today may eventually require all of the following orthopedic procedures during childhood or adulthood except:
1) C orrection of equinus or varus feet
3) Posterior spinal fusion for scoliosis
2) Arthrodesis from the occiput to the atlas or axis
5) Arthroplasty of the knees
4) Arthroplasty of the hips
Patients with diastrophic dysplasia rarely have instability of the upper cervical spine.
Babies with diastrophic dysplasia often have rigid equinovarus feet that require surgery to become plantigrade and wear normal shoes.
A number of patients with diastrophic dysplasia develop progressive scoliosis that requires surgical treatment. Degenerative disease of the hips is common and often requires arthroplasty in early adulthood.
Degenerative disease of the knees is common and often requires arthroplasty in early adulthood.
■Correct Answer:Arthrodesis from the occiput to the atlas or axis
1877. (839) Q5-1101:
A patient with spondyloepiphyseal dysplasia congenita reaches the age of 5 without being able to walk with a walker. She has five beats of clonus in both ankles. Her reflexes are brisk and her toes are upgoing. The most likely problem that accounts for these findings is:
1) Severe scoliosis of the thoracic spine
3) Lumbar stenosis
2) Foramen magnum stenosis
5) Atlantoaxial instability
4) Thoracolumbar kyphosis
Atlantoaxial instability, sometimes combined with stenosis of the atlas, is a frequent cause of myelopathy in spondyloepiphyseal dysplasia congenita.
Scoliosis does not account for developmental delay or myelopathy.
Foramen magnum stenosis is rare in spondyloepiphyseal dysplasia congenita.
Lumbar stenosis is rare with spondyloepiphyseal dysplasia congenita and would not account for myelopathy. Thoracolumbar kyphosis severe enough to cause myelopathy is rare in spondyloepiphyseal dysplasia congenita condition.
■Correct Answer:Atlantoaxial instability
1878. (840) Q5-1102:
Scoliosis in cleidocranial dysplasia is frequently associated with which of the following conditions:
1) Syringomyelia
3) Spondylolisthesis
2) Atlantoaxial instability
5) Spinal decompensation
4) Spinal stenosis
Scoliosis with cleidocranial dysplasia (C C D) is frequently associated with syringomyelia.
C ervical instability is rare in C C D. Spondylolisthesis is rare in C C D. Spinal stenosis is rare in C C D.
Spinal decompensation is rare in C C D.
■Correct Answer:Syringomyelia
1879. (841) Q5-1103:
A 3-year-old girl with Larsen syndrome is brought into the office for examination. A spinal radiograph demonstrates a 50°
kyphosis of the cervical spine. Her neurologic examination is normal. Recommended treatment includes:
1) Observation
3) C ervical-thoracic orthosis
2) Halo traction
5) Anterior and posterior fusion
4) Posterior cervical fusion
Posterior cervical fusion has been proven effective in curves of 60°or less in Larsen syndrome, in preventing progression, and allowing correction with anterior growth.
This curve is much more likely to worsen than to spontaneously improve, so preventive surgery is indicated. There is no role for halo traction in this situation.
Bracing has not been proven effective in helping patients with Larsen syndrome.
Addition of anterior fusion is not needed for this degree of curve in a neurologically normal child.
■Correct Answer:Posterior cervical fusion
1880. (842) Q5-1104:
A 10-year-old patient with Hurler syndrome has undergone a bone marrow transplant and is currently medically stable. He has developed a painful thoracolumbar kyphosis that measures 50° with 25% subluxation T12 on L1. Recommended treatment includes which of the following:
1) Exercise program for the trunk extensor muscles
3) Halo traction followed by orthosis
2) Thoracolumbar orthosis
5) Anterior and posterior spinal fusion
4) Anterior spinal fusion
Anterior and posterior fusion will correct the translation, instability, and ensure a solid fusion. In some cases, posterior fusion alone will suffice if pedicle fixation is good.
Exercises will not correct the subluxation, which is the cause of the pain. A thoracolumbar orthosis is not corrective or well tolerated.
There is no need for halo traction.
Anterior fusion alone is not enough to control this focal instability if the patient is well enough to tolerate a more involved procedure.
■Correct Answer:Anterior and posterior spinal fusion
1881. (843) Q5-1105:
Aneurysmal bone cyst of the spine is most common in which of the following regions:
1) C ervical
3) Lower thoracic
2) Upper thoracic
5) Sacral
4) Lumbar
Aneurysmal bone cyst of the spine is most common in the lumbar spine, followed by the cervical spine. Aneurysmal bone cyst most commonly involves the anterior elements but later may expand into the posterior elements.
■Correct Answer:Lumbar
1882. (844) Q5-1106:
Aneurysmal bone cyst of the spine is most likely in this age group:
1) First decade
3) Third decade
2) Second decade
5) Fifth decade
4) Fourth decade
The most common age is the second decade; the mean age is 13 years old for patients with this disorder.
■Correct Answer:Second decade
1883. (845) Q5-1107:
A 14-year-old girl is examined because of a pain in her left flank. The radiographs of the lumbar spine show loss of the pedicle with expansion of the lateral wall of the third lumbar vertebral body. Magnetic resonance imaging shows multiple fluid levels with no additional areas of involvement. She is neurologically normal. Recommended treatment includes:
1) Observation
3) Selective arterial embolization
2) Radiation therapy
5) C urettage plus radiation therapy
4) Radical en bloc resection
This patient has an aneurysmal bone cyst. Selective arterial embolization is a minimally invasive treatment that often succeeds in arresting the lesions. Many times it is the only treatment needed. Selective arterial embolization can also be used as part of a strategy to be followed by curettage and reconstruction to decrease operative bleeding.
This lesion will continue to expand and might cause neurologic compromise or mechanical instability. Radiation therapy poses risks of later malignant degeneration. There are other ways of treating this lesion. Radical en bloc resection may unnecessarily injure neurologic structures.
While curettage is often necessary, there is no reason to introduce the risk of radiation therapy.
■Correct Answer:Selective arterial embolization
1884. (846) Q5-1108:
A 15-year-old girl has severe hip pain following slipped capital femoral epiphysis that was complicated by avascular necrosis. Recommended treatment is a hip arthrodesis. In response to questions about late effects, after surgery the patient should be told that she is most likely to experience:
1) Low back pain
3) Marked limitation of activity
2) C ontinued severe pain in the ipsilateral hip
5) Pain in the contralateral hip
4) Significant continued limp
Low back pain, followed closely by ipsilateral knee pain, is the most common late effect of hip arthrodesis in young patients. The tolerable pain usually occurs much later but may be treated by conversion to arthroplasty, if needed.
Ipsilateral hip pain should be minimal or absent if the fusion is successful.
Activity following arthrodesis is not significantly limited. Sports and heavy physical activities are feasible. The limp is usually minimal because the loss of hip motion is masked by lumbar motion.
Pain in the contralateral hip is rare and is often minimal after hip arthrodesis.
■Correct Answer:Low back pain
1885. (847) Q5-1109:
Which of the following is a parameter that should be used in positioning arthrodesis of the hip in a young person:
1) Flexion of 45°
3) Adduction of 0°
2) Abduction of 15° if there is shortening
5) Shortening of at least 3 cm
4) External rotation of 25°
Neutral abduction is important in preventing back pain.
The flexion should be between 25° and 35°.
Any abduction beyond neutral poses increases risk of back pain. External rotation beyond approximately 5° is not needed.
Arthrodesis often produces some mandatory shortening; therefore, intentional shortening is not needed.
■Correct Answer:Adduction of 0°
1886. (848) Q5-1111:
A 9-year-old boy with cerebral palsy has trouble sitting. His mother states that whenever his diapers are changed or his hips are moved, he begins to cry. Radiographs demonstrate high dislocations of both femoral heads. The femoral heads have an ovoid shape and superolateral flattening. Recommended treatment includes:
1) Botulinum toxin injected into the adductors
3) Bilateral femoral osteotomies with acetabuloplasty
2) Bilateral open adductor tenotomy
5) Bilateral C olonna arthroplasty
4) Bilateral proximal femoral resection
Bilateral proximal femoral resection is the recommended treatment.
Femoral head dislocations may become painful in cerebral palsy at a much earlier age than in nonspastic individuals. Botulinum toxin or adductor tenotomy will not solve the problem.
Replacing the deformed femoral heads into the acetabulum will not achieve the long-term goal of good hip range of motion.
A 9-year-old boy is examined due to a closed distal forearm fracture. The radius and ulna are both fractured and translated
100%. After manipulation twice with sedation, the translation cannot be reduced. There is 10-mm shortening of the radius and 5- mm shortening of the ulna. The distal radial angulation on the anteroposterior view is 5° less than normal. The next step in treatment should include:
1) C losed reduction in the operating room under general anesthesia
3) Open reduction and percutaneous pin fixation
2) Open reduction and cast application
5) Acceptance of the reduction and maintenance with a cast
4) Open reduction and plate fixation
The translation and shortening are not problems and the amount of angulation will easily remodel with this fracture. There is nothing to be gained from operative reduction.
■Correct Answer:Acceptance of the reduction and maintenance with a cast
1888. (850) Q5-1113:
When applying a halo for postoperative immobilization in a skeletally mature teenager, which of the following is the proper torque for the pins:
1) 2 inch-pounds
3) 8 inch-pounds
2) 4 inch-pounds
5) 12 inch-pounds
4) 10 inch-pounds
Eight inch-pounds is the currently recommended torque to provide optimal biomechanical fixation while minimizing pin penetration. This is also recommended for adults. In young children, 4- to 6-inch-pounds are preferred.
■Correct Answer:8 inch-pounds
1889. (851) Q5-1114:
A posterior spine fusion with segmental hook fixation from T4-L4 is performed for idiopathic scoliosis in a 15-year-old girl. Somatosensory evoked potential monitoring is normal throughout the procedure. The patient awakens and is unable to move either lower extremity, but she does have some sensation in the lower extremities. Recommended treatment includes:
1) Removal of instrumentation
3) Laminectomy above the conus medullaris
2) Myelogram
5) Full heparinization of the patient
4) Administration of corticosteroids and observation for 6 hours
Spinal cord injury occurs in approximately 0.1% of patients operated upon for idiopathic scoliosis. In some cases, sensory spinal cord monitoring may be unchanged, especially if the injury preserves the dorsal columns. The instrumentation should be removed as soon as possible in case spinal traction or derotation or implant protrusion is producing effects on the cord or its blood supply.
C orticosteroids should be administered at spinal cord injury doses, but this should not be the only measure. Obtaining a myelogram may delay the removal of instrumentation and should not be the first step. Heparinization has no proven effect.
■Correct Answer:Removal of instrumentation
1890. (852) Q5-1115:
A 12-year-old boy with achondroplasia has a gradual 40° thoracolumbar kyphosis. He is unable to walk more than two blocks. Magnetic resonance imaging reveals spinal stenosis, and the patient is scheduled to undergo posterior decompression from T12- S1. In addition to this procedure, you recommend:
1) Observation with serial radiographs every 4 months
3) In situ fusion with bone graft
2) Postoperative brace for 6 months
5) Anterior corpectomy and fusion of T12
4) Posterior fusion across the kyphosis with instrumentation
Extensive posterior decompression poses a high risk of postoperative increase in kyphosis because of both the patientâs age and pre-existing kyphosis.
Observation would not be a good idea because the risk is already known to be high.
Neither a brace nor an uninstrumented fusion would prevent the deformity from developing. C orpectomy is not indicated because the kyphosis is not focal.
Posterior instrumented fusion at the time of decompression is indicated.
■Correct Answer:Posterior fusion across the kyphosis with instrumentation
1891. (853) Q5-1116:
Which of the following is true regarding brace treatment for Scheuermann kyphosis:
1) The Milwaukee brace is not indicated.
3) Bracing is effective in curves over 75°.
2) Permanent correction is usually obtainable.
5) The brace should be worn for 1 year after starting brace treatment.
4) Bracing is ineffective in curves having an apex at or above T8.
Brace treatment is effective for Scheuermann kyphosis. Unlike idiopathic scoliosis, permanent correction of the deformity is the goal.
The Milwaukee brace is often indicated.
Brace treatment is ineffective for curves over 74°. The brace should be worn until skeletal maturity.
■Correct Answer:Permanent correction is usually obtainable.
1892. (854) Q5-1117:
Which of the following statements is true about bone marrow transplantation in mucopolysaccharidoses:
1) Bone marrow transplantation is contraindicated.
3) Bone marrow transplantation reverses the orthopedic manifestations.
2) Bone marrow transplantation does not affect the orthopedic problems.
5) Bone marrow transplantation should be deferred until skeletal maturity.
4) Graft-versus-host disease is rare.
Bone marrow transplantation is effective in preventing the deposition of mucopolysaccharides in solid organs. Transplantation should be done early to prevent organ damage. Because the lysosomal enzyme does not cross the cell membrane of osteocartilaginous cells, it does not affect the orthopedic aspects. The risk of graft-versus-host disease is high but may be treated in most cases. Survival rate is 61% at 2 years for Hurler disease, which is otherwise fatal before maturity.
■Correct Answer:Bone marrow transplantation does not affect the orthopedic problems.
1893. (855) Q5-1118:
A 3-year-old girl with spina bifida is able to flex and adduct her hips, but she cannot extend her knees. The hips are both dislocated. The patientâs parents ask how the hips must be treated to optimize function. The recommended treatment is:
1) Observation
3) Bilateral open reduction
2) Bilateral closed reduction
5) Bilateral open reduction with femoral osteotomies and muscle transfers
4) Bilateral open reduction and femoral osteotomies
Nonoperative treatment will allow the patient to retain maximum mobility of the hips.
Operative treatment carries substantial risk of avascular necrosis, stiffness, and redislocation. These risks are not worth taking in view of the patientâs limited muscle strength about the hips. In addition, the motor level alluded to (L2-L3) means that she will not have sensation of pain from the hips.
■Correct Answer:Observation
1894. (856) Q5-1119:
A patient with spina bifida and L5 motor level undergoes tendon transfers about the ankle. After cast removal, he is lost to follow-up for 3 years. Upon re-examination, the patient has no motor power on either side below the knee. The most likely explanation is:
1) The tendon transfers have all pulled out.
3) His spinal cord has become tethered.
2) His ventriculoperitoneal shunt has malfunctioned.
5) He has sustained a silent compartment syndrome because of lack of sensation.
4) His muscles have fatigued.
This scenario is common. The most likely explanation of the patientâs loss of motor power on either side below the knee is a result of a tethered spinal cord.
It is unlikely that all transferred tendons have pulled out and that he has lost function in all of the other L5 muscles that should be active.
Shunt malfunction is a common occurrence in patients with spina bifida, but shunt malfunction does not present with a focal deficit at a distal level.
Muscle fatigue is not a recognized phenomenon in spina bifida.
■Correct Answer:His spinal cord has become tethered.
1895. (857) Q5-1120:
A 6-year-old boy with spina bifida and L3 motor level presents to the clinic with bilateral swollen legs (below the knees). His legs have been swollen for the past 3 days and his knees are warm. The patient has an oral temperature of 38.1°C . He denies any pain. There is no history of systemic infection or of any other trauma. The problem may be most likely diagnosed by ordering:
1) A venogram of both lower extremities
3) C ell count, gram stain, and culture of synovial fluid of both knees
2) A duplex ultrasound of both lower extremities and the pelvic veins
5) Plain and stress varus-valgus radiographs of both knees
4) Aspirate of both distal femoral metaphyses
Low-energy fractures are the most likely cause of the patientâs bilateral swollen legs. The fractures may occur with everyday activities, and they do not cause pain because of the patientâs high neurologic level. If plain radiographs do not give the diagnosis, stress radiographs should be obtained to detect undisplaced physeal fractures.
Deep vein thrombosis is rare in this age group, especially bilaterally.
Spontaneous joint infection and spontaneous osteomyelitis are not any more likely in patients with spina bifida than in the general population.
■Correct Answer:Plain and stress varus-valgus radiographs of both knees
1896. (858) Q5-1121:
A patient with spina bifida has significant symmetrical calcaneus positioning of both ankles. This is most likely due to:
1) Lack of ambulatory experience
3) Motor level at L3
2) Braces that are set in too much dorsiflexion
5) Motor level at S1
4) Motor level at L5
At motor level L5, dorsiflexors overpower plantarflexors to cause a calcaneus position.
This condition occurs from muscle imbalance. Even with significant ambulation, it will persist. Brace properties do not cause fixed deformity.
At L3, neither dorsiflexors nor plantarflexors of the ankle work. At S1, both dorsiflexors and plantarflexors are well innervated.
■Correct Answer:Motor level at L5
1897. (859) Q5-1122:
C orrection of the congenital gibbus in spina bifida must follow which of these surgical principles:
1) Long instrumentation
3) Avoidance of instrumentation
2) Short instrumentation
5) Anterior approach to deformity
4) Avoidance of bony resection
The leverage provided by long instrumentation prevents loss of correction and junctional deformity.
Short instrumentation poses a risk of junctional kyphosis or loss of fixation.
Because of the severe angular deformity, fusion in situ without correction will be followed by increasing deformity. Resection of one to three of the vertebrae on the lower limb of the kyphosis is essential to allow safe correction without excessive tension on vessels and viscera.
The anterior approach to the gibbus is deep and impractical. This approach does not allow mechanically efficient instrumentation.
■Correct Answer:Long instrumentation
1898. (860) Q5-1123:
A patient with L4 level myelomeningocele has developed a full-thickness pressure sore on the heel that has a central necrosis and is draining. While undergoing debridement in the local emergency department, the patient develops labored respiration and a nondetectable blood pressure. The most likely cause is:
1) Latex allergy
3) Septic shock
2) Aortic dissection
5) Shunt failure
4) Spontaneous tension pneumothorax
Latex sensitivity is common in patients with spina bifida because of frequent exposure through catherizations and procedures. Latex avoidance is becoming the standard in institutions that commonly treat patients with spina bifida, but community hospitals that rarely see such patients may not always be aware of this problem.
Dissection is not likely unless the patient has a connective tissue disorder. Septic shock is not likely to develop from a freely draining peripheral ulcer.
Tension pneumothorax is not any more likely in patients with spina bifida than in the general population.
Although it is important to be aware of shunt failure, it is not likely in this procedure which is done without anesthetic.
■Correct Answer:Latex allergy
1899. (884) Q5-1151:
The most common benign tumor of vertebral bodies is:
1) Osteoid osteoma
3) Osteochondrom
2) Osteoblastoma
5) Aneurysmal bone cyst
4) Giant cell tumor
Aneurysmal bone cyst is the most common benign bone tumor of the vertebral body. Aneurysmal bone cysts sometimes extend into the posterior elements.
Osteoid osteoma, osteoblastoma, and osteochondroma are primarily found in the posterior elements of the vertebrae. Giant cell tumor is rare in the spine.
■Correct Answer:Aneurysmal bone cyst
1900. (885) Q5-1152:
A magnetic resonance image of a 7-year-old girl shows a line of high-signal intensity within the cord on T2 sequences that parallels the ventral surface of the cord and appears as a syrinx. However, on the axial images and on the T1 sequences, this finding is not evident. The most likely diagnosis is:
1) C ollapsing syrinx
3) Motion artifact
2) Gibbs artifact
5) Astrocytoma
4) Ependymoma
A Gibbs artifact is a linear focus in the cord on T2-weighted images that parallels the ventral aspect of the cord and mimics a syrinx. The Gibbs artifact is due to the linear interface between two tissues of differing signal intensity. It is not seen on axial images or T1-weighted images.
Motion artifact is a blurring of the image due to patient motion, respiration, or cerebral spinal fluid pulsation. Ependymoma and astrocytoma are seen on both the axial and the sagittal images.
