Question 1

Which of the following descriptions is more characteristic of tuberculosis than pyogenic spondylitis:

Explanation

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.

Question 2

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 girlâ s spinal problem, recommended treatment includes:

Explanation

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.

Question 3

A dorsal approach has which of the following characteristics with regard to a posteromedial approach in the surgical treatment of congenital vertical talus:

Explanation

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.

Question 4

Which of the following conditions is not associated with an increased incidence of congenital vertical talus:

Explanation

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.

Question 5

Scoliosis in Marfan syndrome is characterized by which of the following:

Explanation

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.

Question 6

Which of the following statements is true of demineralized bone matrix:

Explanation

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.

Question 7

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:

Explanation

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.

Question 8

Scoliosis in osteogenesis imperfecta is characterized by which of the following:

Explanation

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.

Question 9

Which of the following is not a specific feature in making the diagnosis of a dystrophic curve in neurofibromatosis 1:

Explanation

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.

Question 10

The spine in familial dysautonomia is characterized by which of the following:

Explanation

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.

Question 11

Which of the following spinal problems is most common in achondroplasia:

Explanation

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.

Question 12

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:

Explanation

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.

Question 13

A baby born with diastrophic dysplasia today may eventually require all of the following orthopedic procedures during childhood or adulthood except:

Explanation

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.

Question 14

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:

Explanation

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.

Question 15

Scoliosis in cleidocranial dysplasia is frequently associated with which of the following conditions:

Explanation

Scoliosis with cleidocranial dysplasia (C C D) is frequently associated with syringomyelia. Cervical 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.

Question 16

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:

Explanation

Posterior cervical fusion has been proven effective in curves of 60Â°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.

Question 17

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 50Â° with 25% subluxation T12 on L1. Recommended treatment includes which of the following:

Explanation

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.

Question 18

Aneurysmal bone cyst of the spine is most common in which of the following regions:

Explanation

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.

Question 19

Aneurysmal bone cyst of the spine is most likely in this age group:

Explanation

The most common age is the second decade; the mean age is 13 years old for patients with this disorder.

Question 20

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:

Explanation

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.

Question 21

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:

Explanation

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.

Question 22

Which of the following is a parameter that should be used in positioning arthrodesis of the hip in a young person:

Explanation

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.

Question 23

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:

Explanation

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.

Question 24

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 5Â° less than normal. The next step in treatment should include:

Explanation

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.

Question 25

When applying a halo for postoperative immobilization in a skeletally mature teenager, which of the following is the proper torque for the pins:

Explanation

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.

Question 26

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:

Explanation

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. Corticosteroids 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.

Question 27

A 12-year-old boy with achondroplasia has a gradual 40Â° 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:

Explanation

Extensive posterior decompression poses a high risk of postoperative increase in kyphosis because of both the patientâ s 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. Corpectomy is not indicated because the kyphosis is not focal. Posterior instrumented fusion at the time of decompression is indicated.

Question 28

Which of the following is true regarding brace treatment for Scheuermann kyphosis:

Explanation

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.

Question 29

Which of the following statements is true about bone marrow transplantation in mucopolysaccharidoses:

Explanation

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.

Question 30

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 patientâ s parents ask how the hips must be treated to optimize function. The recommended treatment is:

Explanation

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 patientâ s 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.

Question 31

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:

Explanation

This scenario is common. The most likely explanation of the patientâ s 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.

Question 32

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:

Explanation

Low-energy fractures are the most likely cause of the patientâ s bilateral swollen legs. The fractures may occur with everyday activities, and they do not cause pain because of the patientâ s 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.

Question 33

A patient with spina bifida has significant symmetrical calcaneus positioning of both ankles. This is most likely due to:

Explanation

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.

Question 34

Correction of the congenital gibbus in spina bifida must follow which of these surgical principles:

Explanation

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.

Question 35

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:

Explanation

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.

Question 36

The most common benign tumor of vertebral bodies is:

Explanation

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.

Question 37

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:

Explanation

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.

Question 38

Which of the following statements correctly represents the definitions of C hiari I and C hiari II malformations:

Explanation

A Chiari I malformation involves displacement of the cerebellum through the foramen magnum. A C hiari II malformation involves similar displacement of the brainstem, as well. In a C hiari II malformation, there is almost always a myelomeningocele in the lower cord. Sometimes a syrinx is also present.

Question 39

The conus medullaris is always termed abnormal if it terminates below this level:

Explanation

The vertebral bodies grow faster than the spinal cord. A more caudal placement of the conus medullaris is considered normal in an older patient. However, a conus medullaris below L3 at any age is abnormal and may represent a tethered and/or dysplastic cord.

Question 40

Regardless of age, the tonsils of the cerebellum should not extend more than this distance below the foramen magnum:

Explanation

Displacement of the cerebellar tonsils below the foramen magnum is termed a C hiari malfomation. A C hiari I malformation is an isolated malformation; a C hiari II malformation is associated with a syrinx. Symptoms may include headache, vomiting, and nystagmus. Although the normal protrusion allowed decreases with age, 5 mm is abnormal at any age.

Question 41

When applying a halo, the use of six pins instead of four has which of the following effects:

Explanation

With an increase from four to six pins, the load to failure is increased by more than 50%. Additional pins decrease many of the complications, such as loosening and pin tract infection. The risk of dural puncture is not measurably increased because it is a rare complication.

Question 42

Which of the following findings is an indication for the Bernese (Ganz) osteotomy:

Explanation

The Bernese (Ganz) osteotomy is contraindicated in patients with open triradiate cartilages because it crosses the cartilage. The procedure is also contraindicated in complete dislocations, incongruous hips, and advanced osteoarthritis with a joint space of 1 mm or less.

Question 43

The false profile radiographic view of the hip is taken with the patient in which of the following positions:

Explanation

The false profile radiographic view assesses anterior coverage and is obtained with the affected hip against the film and the pelvis rotated 65° away from the plane of the film.

Question 44

A 15-year-old boy has a history of excessive bleeding when he is cut. His maternal uncle passed away during a tonsillectomy. The boy presents with severe hip pain (worse in extension than in flexion) and some weakness in his knee extension. The most likely cause of the patients symptoms is:

Explanation

The patient has features suggesting mild hemophilia A or B including x- linked inheritance and occasional bleeding episodes. Iliopsoas hematoma is a complication of hemophilia. Bleed into the hip or the lumbar epidural space is less common and there are no signs to suggest infection.

Question 45

A patient with hemophilia A has a hematoma of the iliopsoas. He has a partial femoral nerve palsy. Treatment involves continuous factor replacement and:

Explanation

The standard treatment of a psoas abscess is continuous factor replacement. Surgery is usually unnecessary, but it may be considered in cases of acute palsy with severe pain unresponsive to medical therapy. A percutaneous drainage tube is not recommended because the hematoma may be difficult to locate or drain.

Question 46

Which of the following best predicts the risk of nonaccidental injury in young children who sustain a fracture of the femur:

Explanation

Although a spiral fracture is classically consistent with nonaccidental injury, this is not always true. A spiral fracture is often seen in accidental injuries. The location of the fracture in the femur, the socioeconomic status of the family, and the coexistence of other disabilities are all poor predictors. The ability of the child to walk has predictive ability. In one study, nonaccidental injury accounted for 42% of all femur fractures in children before walking age vs. only 2% of fractures after walking age.

Question 47

Which of the following is known about the genetics of multiple hereditary exostosis (MHE):

Explanation

Multiple hereditary exostosis (MHE) is inherited as an autosomal dominant condition. There are three genes known to be involved: EXT 1, 2, and 3. EXT 1 and 2 encode glycosyltransferases needed for biosynthesis of heparan sulfate. Fibroblast growth factor receptor is abnormal in achondroplasia.

Question 48

A 10-year-old patient has a painful lytic lesion replacing 75% of the distal femoral metaphysis. The lesion has indistinct margins, but there is not any periosteal reaction. Biopsy reveals a benign histiocytic tumor with multiple eosinophils. Physical exam and skeletal survey reveal no other abnormalities. Which of the following would be the most appropriate treatment method:

Explanation

This patient has an eosinophilic granuloma, which is an isolated form of Langerhans cell histiocytosis. Patients with isolated involvement may be treated with observation, curettage, bone grafting, or steroid injection. For a lesion of this size, the risk of fracture is high and curettage with bone grafting is recommended. C hemotherapy and/or systemic steroids are reserved for patients with systemic disease.

Question 49

Which of the following methods has the highest sensitivity in detecting skeletal lesions in patients with Langerhans cell histiocytosis:

Explanation

Skeletal survey is the most sensitive means of detecting lesions of eosinophilic granuloma (Langerhans cell histiocytosis). Bone scan detects most, but not all, of the lesions. Some lesions lack enough osteoblastic activity to appear on bone scan. Lesions are not detected on physical exam unless they are large enough to cause pain or tenderness. Indium labeled white cell studies are not used in this condition.

Question 50

A 15-year-old girl presents with pain and a 17°-scoliosis curve. The film suggests an enlargement and sclerosis of the transverse process of L2. The best study to further evaluate the nature and anatomic extent of the lesion is:

Explanation

This lesion is most likely to be an osteoid osteoma or an osteoblastoma. The best study to further evaluate the nature and anatomic extent is with computed tomography. Magnetic resonance imaging may overestimate the lesion because of sensitivity to edema in the marrow and surrounding soft tissue. Bone scintigraphy with or without SPEC T does not provide enough anatomic detail. C oned radiographs do not provide the needed multidimensional detail for this condition, as well as many other spinal problems.

Question 51

A 13-year-old obese boy presents with a 3-month history of right groin pain and a limp. On examination, his right hip obligatory externally rotates when passively flexed to 90 degrees. Radiographs confirm a stable, severe slipped capital femoral epiphysis (SCFE). Which of the following is the most appropriate initial management?

Explanation

In situ percutaneous pinning with a single cannulated screw is the gold standard treatment for a stable SCFE to prevent further slippage. Closed reduction is contraindicated due to a high risk of iatrogenic avascular necrosis.

Question 52

During the percutaneous placement of an iliosacral screw into the S1 vertebral body for a posterior pelvic ring injury, the guidewire inadvertently breaches the anterior cortex of the sacral ala. Which of the following neurological structures is most at risk of injury in this location?

Explanation

The L5 nerve root courses anteriorly over the sacral ala and is highly vulnerable to injury if an S1 iliosacral screw is misdirected anteriorly. The S1 root is typically protected unless the screw enters the sacral foramen.

Question 53

A 65-year-old male with progressive hand clumsiness and gait instability is diagnosed with cervical spondylotic myelopathy. Magnetic resonance imaging (MRI) of the cervical spine reveals severe cord compression at C4-C5. Which of the following MRI findings correlates most strongly with a poor potential for neurological recovery postoperatively?

Explanation

T1-weighted hypointensity in the spinal cord indicates myelomalacia and irreversible cord necrosis, serving as a strong predictor of poor postoperative clinical recovery. While T2 hyperintensity shows edema, T1 hypointensity confirms permanent damage.

Question 54

A 22-year-old female undergoes anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BTB) autograft. During her postoperative rehabilitation, she develops localized pain. What is the most common long-term complication associated with this specific graft choice?

Explanation

Anterior knee pain, particularly with kneeling, is the most common complication and cause of morbidity following BTB autograft ACL reconstruction. Patellar fracture is a known but rare complication.

Question 55

A 72-year-old female presents to the emergency department with a third episode of posterior dislocation of her right total hip arthroplasty (THA). Radiographic evaluation reveals no gross hardware loosening or polyethylene wear. Which of the following component positioning errors is the most likely cause of her recurrent posterior instability?

Explanation

Insufficient acetabular anteversion (retroversion) predisposes a THA to posterior impingement and subsequent posterior dislocation. Excessive anteversion would typically lead to anterior instability.

Question 56

A 28-year-old male sustains a proximal pole scaphoid fracture. Eight weeks later, radiographs demonstrate a lack of healing and nonunion. The high rate of nonunion in proximal pole scaphoid fractures is primarily due to the retrograde blood supply. Which vessel provides the primary blood supply to the proximal pole of the scaphoid?

Explanation

The primary blood supply to the scaphoid enters the distal half of the bone via the dorsal carpal branch of the radial artery. The blood then flows retrogradely to the proximal pole, making proximal fractures highly susceptible to avascular necrosis and nonunion.

Question 57

A 15-year-old boy presents with progressive knee pain. Radiographs reveal a mixed lytic and sclerotic lesion in the distal femoral metaphysis with a sunburst periosteal reaction. Core needle biopsy confirms a high-grade intramedullary osteosarcoma. Staging studies are negative for metastasis. What is the standard of care for this patient?

Explanation

The standard of care for high-grade conventional osteosarcoma is neoadjuvant chemotherapy, followed by wide surgical resection (limb-salvage or amputation), and completed with adjuvant chemotherapy. Osteosarcoma is highly radioresistant.

Question 58

Articular cartilage is a highly specialized tissue divided into distinct structural zones. Which of the following best describes the characteristics of the deep zone of articular cartilage?

Explanation

The deep zone of articular cartilage possesses the lowest water content and the highest proteoglycan concentration. Its collagen fibers are oriented perpendicular to the joint surface, anchoring the cartilage to the subchondral bone.

Question 59

A 55-year-old patient with long-standing, poorly controlled diabetes mellitus presents with a severely swollen, erythematous, and warm but painless left foot. Skin integrity is completely intact. Radiographs show early fragmentation and debris at the midtarsal joints. What is the most appropriate initial management?

Explanation

This patient presents with an acute (Eichenholtz Stage 0 or 1) Charcot arthropathy. The gold standard for initial management is strict offloading utilizing a total contact cast to prevent further deformity and allow the acute inflammatory phase to subside.

Question 60

A 7-month-old infant is referred for developmental dysplasia of the hip (DDH) after failing a 6-week trial of a Pavlik harness. Ultrasound confirms persistent superior and lateral displacement of the femoral head. What is the most appropriate next step in management?

Explanation

In an infant older than 6 months who has failed Pavlik harness treatment, the next appropriate step is an examination under anesthesia, arthrogram, and closed reduction with spica casting. Continuing a failed harness risks "Pavlik harness disease" (posterior acetabular wear).

Question 61

A 40-year-old female complains of sudden loss of active thumb interphalangeal joint flexion 6 months after open reduction and internal fixation of a distal radius fracture with a volar locking plate. Radiographs show the plate is positioned distally, crossing the watershed line. Which tendon is most likely ruptured?

Explanation

The flexor pollicis longus (FPL) tendon lies directly over the volar aspect of the distal radius. Volar plates placed distal to the watershed line can cause attritional wear and eventual rupture of the FPL tendon.

Question 62

A 68-year-old male presents with bilateral buttock and calf pain that worsens after walking two blocks. Which of the following clinical features is most useful in differentiating neurogenic claudication secondary to lumbar spinal stenosis from vascular claudication?

Explanation

Neurogenic claudication is characteristically relieved by lumbar flexion (such as sitting or leaning on a shopping cart), which increases the cross-sectional area of the spinal canal. Vascular claudication is typically relieved simply by resting, regardless of spinal posture.

Question 63

A 28-year-old professional baseball pitcher undergoes shoulder arthroscopy for superior labrum anterior and posterior (SLAP) tear. What is the predominant biomechanical mechanism responsible for Type II SLAP lesions in overhead throwing athletes?

Explanation

The "peel-back" mechanism occurs during the late cocking phase of throwing when the shoulder is in maximal abduction and external rotation. This positioning produces a torsional force at the base of the biceps, peeling the superior labrum off the glenoid.

Question 64

A 66-year-old female presents with an audible and palpable pop in her anterior knee one year after a posterior-stabilized total knee arthroplasty (TKA). She reports the pop is occasionally painful. At what point in the range of motion does "patellar clunk syndrome" typically occur?

Explanation

Patellar clunk syndrome occurs in posterior-stabilized TKA when a fibrous nodule forms at the superior pole of the patella. As the knee actively extends from approximately 45 to 30 degrees of flexion, the nodule catches and then suddenly escapes the femoral intercondylar box.

Question 65

During surgical repair of a zone II flexor tendon laceration, a surgeon must carefully manage the flexor tendon sheath to prevent bowstringing of the repaired tendons. Preservation of which two annular pulleys is most critical for maintaining the biomechanical integrity of the digit?

Explanation

The A2 (located over the proximal phalanx) and A4 (located over the middle phalanx) are the major annular pulleys. Their preservation or reconstruction is absolutely critical to prevent flexor tendon bowstringing and ensure efficient digital flexion.

Question 66

A 12-year-old boy presents with thigh pain and systemic symptoms including low-grade fever and weight loss. Radiographs show a permeative diaphyseal lesion of the femur with "onion-skin" periosteal reaction. Biopsy confirms Ewing sarcoma. Which of the following chromosomal translocations is most characteristic of this diagnosis?

Explanation

Ewing sarcoma is classically associated with the t(11;22) chromosomal translocation, which results in the EWS-FLI1 fusion protein. This finding is highly sensitive and specific for the Ewing sarcoma family of tumors.

Question 67

Bone formation occurs primarily via two distinct developmental pathways: endochondral ossification and intramembranous ossification. Which of the following skeletal structures forms exclusively through intramembranous ossification?

Explanation

The clavicle, mandible, and flat bones of the skull develop via intramembranous ossification, a process where mesenchymal stem cells differentiate directly into osteoblasts without a cartilage model. Long bones develop via endochondral ossification.

Question 68

A 3-year-old girl is brought to the emergency department with a 2-day history of right hip pain, refusal to bear weight, a temperature of 39.0 C, a white blood cell count of 15,000/mm3, and an erythrocyte sedimentation rate of 55 mm/hr. What is the most appropriate definitive management?

Explanation

This child meets all four Kocher criteria, making the probability of septic arthritis >99%. The definitive and limb-saving treatment for a pediatric septic hip is emergent surgical irrigation and debridement to prevent irreversible articular cartilage destruction.

Question 69

A 30-year-old male is admitted after a high-energy closed tibial shaft fracture. Twelve hours later, he develops severe pain out of proportion to the injury, exacerbated by passive stretch of the toes. Intracompartmental pressure monitoring is performed. Which of the following pressure measurements is generally accepted as the threshold for diagnosing acute compartment syndrome and indicating emergent fasciotomy?

Explanation

A delta pressure (diastolic blood pressure minus absolute compartment pressure) of less than 30 mmHg is considered the diagnostic threshold for acute compartment syndrome. Absolute compartment pressures are less reliable because tissue perfusion is dependent on systemic blood pressure.

Question 70

A 24-year-old professional football player suffers a hyperplantarflexion injury to his midfoot. Weight-bearing radiographs reveal widening between the 1st and 2nd metatarsal bases and a "fleck sign" in the first intermetatarsal space. The bony avulsion fragment creating the fleck sign originates from which of the following structures?

Explanation

The "fleck sign" represents an avulsion of the Lisfranc ligament. This strong interosseous ligament connects the lateral aspect of the medial cuneiform to the medial aspect of the base of the 2nd metatarsal, from which the fleck typically avulses.

Question 71

A 32-year-old man presents with a closed tibial shaft fracture. He reports excruciating pain out of proportion to the injury and pain with passive toe stretch. Which of the following pressure measurements is most diagnostic of acute compartment syndrome?

Explanation

The delta pressure (diastolic blood pressure minus compartment pressure) is the most reliable indicator for diagnosing acute compartment syndrome. A delta pressure of less than 30 mm Hg is generally considered the threshold for performing an emergency fasciotomy.

Question 72

A 13-year-old obese boy presents with sudden inability to bear weight on his left leg after a minor trip. Radiographs show a slipped capital femoral epiphysis (SCFE). What is the most significant risk factor for the development of avascular necrosis (AVN) in this patient?

Explanation

Slip stability is the primary prognostic factor for developing AVN in SCFE. Unstable slips, defined clinically by the inability to bear weight even with crutches, carry an AVN risk of up to 47%, compared to less than 10% for stable slips.

Question 73

A 75-year-old man falls from a standing height and sustains a Type II odontoid fracture. Which of the following factors most significantly increases the risk of nonunion with conservative management (e.g., rigid cervical collar) in this patient?

Explanation

Risk factors for nonunion of a Type II odontoid fracture include age greater than 50 years, initial displacement greater than 5 mm, and posterior displacement. Fracture into the C2 body defines a Type III fracture, which has a higher union rate.

Question 74

In the context of modern total hip arthroplasty (THA), which of the following bearing surface combinations exhibits the lowest volumetric wear rate?

Explanation

Ceramic-on-ceramic articulations demonstrate the lowest wear rates of all modern bearing surfaces, typically less than 1 micron per year. However, they carry unique risks such as squeaking and component fracture.

Question 75

A 24-year-old soccer player sustains an acute knee injury with an audible "pop." Plain radiographs reveal a small, elliptic bony avulsion fragment just distal to the lateral tibial plateau. This radiographic finding is pathognomonic for a tear of which anatomical structure?

Explanation

The described radiographic finding is a Segond fracture, which is an avulsion of the anterolateral ligament/capsule. It is highly pathognomonic for an anterior cruciate ligament (ACL) tear.

Question 76

A 14-year-old boy presents with a painful mass in his diaphyseal femur with a "periosteal onion-skin" appearance on X-ray. Biopsy reveals small round blue cells. Cytogenetic analysis is most likely to show which of the following translocations?

Explanation

The clinical, radiographic, and histologic presentation is classic for Ewing sarcoma. The t(11;22) translocation, resulting in the EWS-FLI1 fusion protein, is found in approximately 85% of Ewing sarcoma cases.

Question 77

The Lisfranc ligament is a critical stabilizing structure for the midfoot. This ligament strictly connects which two osseous structures?

Explanation

The Lisfranc ligament courses from the lateral aspect of the medial cuneiform to the medial base of the second metatarsal. There is no direct ligamentous connection between the first and second metatarsal bases.

Question 78

A 22-year-old man sustains a proximal pole scaphoid fracture. The high rate of avascular necrosis associated with this specific fracture pattern is primarily due to the retrograde blood supply originating from which of the following arteries?

Explanation

The primary blood supply to the scaphoid is retrograde, entering the distal pole via branches of the dorsal carpal branch of the radial artery. Fractures of the proximal pole disrupt this supply, significantly increasing the risk of avascular necrosis and nonunion.

Question 79

A 45-year-old male is brought to the trauma bay with an unstable "open book" pelvic fracture (APC-III) and hemodynamic instability. To optimally reduce the pelvic volume and control hemorrhage, a circumferential pelvic binder should be centered directly over which anatomical landmarks?

Explanation

A pelvic binder must be centered over the greater trochanters to effectively close the pelvic ring and reduce internal volume. Placing it over the iliac crests is incorrect and can paradoxically open the pelvis further.

Question 80

A 65-year-old woman presents with a painful total knee arthroplasty 3 years postoperatively. According to the 2018 International Consensus Meeting criteria, which of the following synovial fluid biomarkers is highly specific for confirming periprosthetic joint infection in this setting?

Explanation

Synovial fluid alpha-defensin is a major criterion for diagnosing periprosthetic joint infection (PJI) due to its high sensitivity and specificity. It is an antimicrobial peptide released by neutrophils in response to pathogens.

Question 81

A 6-week-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the first follow-up, the infant shows decreased active knee extension on the treated side. This complication is most commonly caused by:

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hips. Management involves adjusting the harness to decrease flexion and monitoring for spontaneous recovery.

Question 82

A 68-year-old man complains of bilateral leg pain when walking. Which of the following clinical findings best differentiates neurogenic claudication (due to lumbar spinal stenosis) from vascular claudication?

Explanation

Walking uphill places the lumbar spine in slight flexion, which increases the spinal canal cross-sectional area and relieves symptoms of neurogenic claudication. Conversely, walking downhill extends the spine, exacerbating neurogenic symptoms.

Question 83

During an arthroscopic Bankart repair for recurrent anterior shoulder instability, a large Hill-Sachs lesion is noted. This lesion is anatomically described as an impaction fracture of the:

Explanation

A Hill-Sachs lesion is a cortical impaction fracture of the posterolateral humeral head created when it strikes the firm anterior glenoid rim during an anterior shoulder dislocation.

Question 84

Denosumab is frequently used as a neoadjuvant or primary medical management for unresectable giant cell tumors of bone. What is the precise mechanism of action of this medication?

Explanation

Denosumab is a fully human monoclonal antibody that binds to and inhibits RANK ligand (RANKL). This prevents the activation of osteoclast-like giant cells, thereby reducing osteolysis and promoting tumor ossification.

Question 85

A patient sustains a laceration to the volar aspect of the hand, severing the flexor digitorum superficialis and profundus tendons in the region historically known as "no man's land." This anatomic area (Zone II) is defined by which of the following boundaries?

Explanation

Flexor tendon Zone II extends from the proximal edge of the A1 pulley to the insertion of the flexor digitorum superficialis (FDS) on the middle phalanx. Both FDS and FDP travel together in the tight fibro-osseous sheath here, making repairs technically demanding.

Question 86

A 35-year-old recreational athlete sustains an acute Achilles tendon rupture. When comparing open operative repair to non-operative management utilizing early functional rehabilitation protocols, operative repair is historically associated with:

Explanation

Operative repair of the Achilles tendon traditionally reduces the risk of re-rupture compared to non-operative management but carries a significantly higher risk of complications such as wound breakdown and infection.

Question 87

A 13-year-old obese male presents with a 3-week history of groin pain and an antalgic gait. Examination reveals obligatory external rotation of the hip with passive flexion. An AP radiograph of the pelvis shows a widened physis and the 'Klein line' not intersecting the epiphysis. Which of the following complications is most specifically associated with unrecognized penetration of the posterosuperior femoral neck cortex by the screw during in situ fixation?

Explanation

Unrecognized penetration of the posterosuperior femoral neck cortex during in situ pinning of a slipped capital femoral epiphysis (SCFE) risks direct injury to the lateral epiphyseal vessels. This disruption is a primary iatrogenic cause of avascular necrosis in these patients.

Question 88

A 45-year-old male sustains a Schatzker type IV tibial plateau fracture following a high-energy motor vehicle collision. Which of the following neurovascular structures is at the highest risk of injury secondary to the specific fracture pattern and associated displacement?

Explanation

Schatzker type IV fractures (medial tibial plateau) typically result from high-energy trauma and are often associated with knee subluxation or dislocation. Because of the anatomic tethering of the popliteal artery at the adductor hiatus and soleal arch, it is at significant risk of injury in these high-energy fracture patterns.

Question 89

A 22-year-old male falls on an outstretched hand and presents with anatomic snuffbox tenderness. Radiographs show a displaced fracture of the proximal pole of the scaphoid. The high risk of avascular necrosis in this specific location is primarily due to the retrograde intraosseous blood supply from which of the following vessels?

Explanation

The scaphoid receives 70-80% of its blood supply in a retrograde fashion from the dorsal carpal branch of the radial artery, which enters the distal pole and waist. Proximal pole fractures disrupt this intraosseous supply, leading to a predictably high rate of avascular necrosis.

Question 90

A 65-year-old female undergoes a total hip arthroplasty using a ceramic-on-ceramic bearing. Two years postoperatively, she complains of an audible squeaking sound during hip flexion. Which of the following factors is most strongly associated with this specific complication?

Explanation

Squeaking is a known complication specific to ceramic-on-ceramic bearing surfaces in total hip arthroplasty. It is most commonly associated with component malposition, particularly acetabular component anteversion or inclination errors, which lead to edge loading and loss of fluid-film lubrication.

Question 91

A 30-year-old male is involved in a motor vehicle accident and sustains a Levine-Edwards Type II traumatic spondylolisthesis of the axis (Hangman's fracture). The mechanism of injury typically involves hyperextension followed by axial loading and flexion. What is the most appropriate definitive management for this specific injury pattern?

Explanation

A Levine-Edwards Type II Hangman's fracture involves significant translation and angulation but is primarily treated with non-operative management using Halo vest immobilization. Operative management is typically reserved for Type IIa (with severe angulation requiring compression) or Type III (with bilateral facet dislocations).

Question 92

A 12-year-old boy presents with progressive knee pain and a palpable mass in the distal femur. Radiographs reveal a destructive metaphyseal lesion with a 'sunburst' periosteal reaction. Biopsy confirms the diagnosis of osteosarcoma. Which of the following genetic alterations is most consistently associated with the pathogenesis of this tumor?

Explanation

Osteosarcoma is characterized by high genomic instability and is strongly associated with mutations or inactivation of the RB1 (retinoblastoma) and TP53 tumor suppressor genes. In contrast, t(11;22) is characteristic of Ewing sarcoma, and t(X;18) is associated with synovial sarcoma.

Question 93

A 25-year-old elite female soccer player undergoes anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BPTB) autograft. Postoperatively, she successfully returns to sport but complains of localized anterior knee pain, particularly when kneeling. This complication is anatomically related to which of the following?

Explanation

Anterior knee pain, particularly with kneeling, is the most common specific complication associated with bone-patellar tendon-bone autografts. This is directly related to graft site morbidity and donor-site pathology rather than nerve injury, though infrapatellar saphenous nerve injury can cause isolated numbness.

Question 94

A 35-year-old male is crushed by a heavy machine and sustains a pelvic ring injury. Initial radiographs show widening of the pubic symphysis of 3.5 cm with disruption of the anterior sacroiliac, sacrospinous, and sacrotuberous ligaments, but the posterior sacroiliac complex remains intact. Which of the following Young-Burgess classifications best describes this injury?

Explanation

An APC Type II injury is characterized by symphyseal diastasis > 2.5 cm and disruption of the anterior sacroiliac, sacrospinous, and sacrotuberous ligaments, causing rotational instability. The intact posterior sacroiliac ligaments maintain the vertical stability of the hemipelvis.

Question 95

During the evaluation of a 28-year-old runner with midfoot pain after a twisting injury, a weight-bearing AP radiograph of the foot reveals a small avulsion fracture fragment ('fleck sign') in the first intermetatarsal space. This finding represents an avulsion of the Lisfranc ligament from which of the following structures?

Explanation

The Lisfranc ligament connects the medial cuneiform to the base of the second metatarsal, providing critical midfoot stability. The pathognomonic 'fleck sign' represents an avulsion of this ligament specifically from the base of the second metatarsal.

Question 96

In the process of endochondral ossification during secondary fracture healing, the cartilaginous callus is ultimately replaced by woven bone. Which of the following transcription factors is considered the master regulator strictly required for hypertrophic chondrocyte differentiation and subsequent vascular invasion in this pathway?

Explanation

RUNX2 (Cbfa1) is the essential master transcription factor for osteoblast differentiation and is required for the maturation of hypertrophic chondrocytes during endochondral ossification. Without RUNX2, vascular invasion and subsequent replacement of cartilage with bone fail to occur.

Orthopedic Prometric Exam Preparation MCQs - Part 1

Orthopedic Prometric Exam Preparation MCQs - Part 18

Orthopedic Prometric Exam Preparation MCQs - Part 18

Chapter Index