ORTHOPEDICS HYPERGUIDE MCQ 401-450

 

401. (3244) Q1-4067:

In patients with sickle cell disease, what are the most commonly affected locations for osteonecrosis:

1) Distal radial and distal humerus

3) Distal femur and proximal tibia

2) Head of femur and head of humerus

5) Metacarpals and phalanges

4) Head of humerus and proximal tibia

The prevalence of osteonecrosis in patients with sickle cell disease is as high as 37% to 50%. Osteonecrosis most commonly occurs in the humeral and femoral heads, due to their limited arterial network, which can easily succumb to occlusion by sickled cells

■Correct Answer: Head of femur and head of humerus

402. (3245) Q1-4068:

Appropriate indications for preoperative transfusion therapy in patients with sickle cell include:

1) Hemoglobin <5g/dL with clinical signs/symptoms of anemia.

3) Acute chroniCanemia with severe aplastiCanemia.

2) Pulmonary acute chest syndrome with multisegmental disease or hypoxia.

5) Hemoglobin <5g/dL with clinical signs/symptoms of anemia, acute chroniCanemia with severe aplastiCanemia, and pulmonary acute chest syndrome with multisegmental disease or hypoxia.

4) Hemoglobin <5g/dL with clinical signs/symptoms of anemia, and acute chroniCanemia with severe aplastiCanemia.

The need for transfusion therapy is based on the overall clinical history of the individual patient. Commonly cited indications include:

Patients with hemoglobin <5 g/dL and significant signs of anemia Pulmonary acute chest syndrome with multisegmental disease or hypoxia Acute or chroniCanemias with severe aplastiCanemias

Correct Answer: Hemoglobin <5g/dL with clinical signs/symptoms of anemia, acute chroniCanemia with severe aplastiCanemia, and pulmonary acute chest syndrome with multisegmental disease or hypoxia.

403. (3246) Q1-4069:

What is the most common postoperative complication in patients with sickle cell disease:

1) Acute chest syndrome

3) Neurological events

2) Vaso-occulsive crisis

5) None of the above

4) Renal events

Postoperative management consists of intravenous hydration, supplemental oxygen, intravenous antibiotics, chest physiotherapy, and incentive spirometry. Common complications encountered in the early postoperative period include acute chest syndrome (12%), vaso-occlusive crisis (9%), and less commonly, neurological and renal events

■Correct Answer: Acute chest syndrome

404. (3247) Q1-4070:

Intraoperatively, all patients with sickle cell disease require which of the following:

1) CardiaCrhythm monitoring

3) Active warming

2) Oxygen saturation monitoring

5) All of the above

4) Blood pressure monitoring

The most common intraoperative complications are excessive blood loss (53%), followed by hypothermia (11%). Therefore, patients require extensive monitoring of cardiaCrhythm, blood pressure, temperature, and oxygen saturation. They also need active intraoperative warming, which usually consists of a combination of a warming blanket, humidifier, blood/fluid warmer, and heat lamp

■Correct Answer: All of the above

405. (3248) Q1-4071:

Which of the following postoperative thromboemboliCprophylaxis options is of greatest benefit in patients with sickle cell disease:

1) Low-molecular-weight heparin

3) Warfarin

2) Low-dose heparin

5) Aspirin

4) Warfarin and foot pumps

Few published reports exist on the risk of deep vein thrombosis (DVT) in patients with sickle cell disease following orthopediCprocedures. In sickle cell disease, platelets do not contribute to the pathophysiology of microvascular occlusion. However, due to spleniCsequestration, patients with sickle cell disease often have thrombocytopenia. Factors associated with vaso-occlusion include the increased adhesion of the sickle cells to the endothelium and the activation of the clotting cascade with thrombin formation. Thrombin induces endothelial retraction resulting in the exposure of proadhesive extracellular components. It also upregulates endothelial expression of P-selectin, which increases binding among erythrocytes, white cells, platelets, and

endothelial cells. Both of these events can facilitate thrombus formation. Following hip surgery, there is already a definable risk of

DVT attributable to surgical trauma and immobility.

The goal of lower limb arthroplasty is optimal pain control with early mobilization to minimize the risk of respiratory and thromboemboliCcomplications. Results of a meta-analysis of DVT after hip surgery suggest that patients with sickle cell disease undergoing THR are best managed with foot pumps and warfarin postoperatively to decrease the likelihood of thromboses in these patients.

Correct Answer: Warfarin and foot pumps

406. (3249) Q1-4072:

Which of the following is the most common indication for total hip arthroplasty in patients with sickle cell disease:

1) SeptiCarthritis

3) Osteoarthritis

2) Avascular necrosis

5) Fracture

4) Pain crisis

The mean age of patients with sickle cell disease undergoing hip surgery is approximately 34 years, with the most frequent procedure being THR for avascular necrosis. Some patients undergo bipolar hemiarthroplasty, which can be complicated by acetabular protrusio. Because hip surgery often is more complex in patients with sickle cell disease, it often is associated with longer anesthesia time and greater blood loss. Mean blood loss in THR in patients with sickle disease is approximately 1200 mL, which is significantly greater than in patients without sickle cell disease

■Correct Answer: Avascular necrosis

407. (3250) Q1-4073:

The common genetiCbasis of sickle cell disease is a mutation on what chromosome:

1) Chromosome 2

3) Chromosome 11

2) Chromosome 8

5) Chromosome 14

4) Chromosome X

The common genetiCbasis of sickle cell disease is a mutation on chromosome 11 that results in an amino-acid substitution of valine for glutamiCacid at the sixth position of the beta-globin subunit of hemoglobin that results in hemoglobin S (HbS). In the heterozygote carrier, this sickle gene mutation offers potential resistance to endemiCPlasmodium falciparum malaria infections. Diagnosis of the disease is confirmed by hemoglobin electrophoresis

■Correct Answer: Chromosome 11

408. (3251) Q1-4074:

In the heterozygote carrier, the presence of this sickle gene mutation offers potential resistance to:

1) Bartonella infections

3) Pneumococcal infections

2) Clostridium infections

5) Typhoid fever

4) Plasmodium falciparum malaria infections

The common genetiCbasis of sickle cell disease is a mutation on chromosome 11 that results in an amino-acid substitution of valine for glutamiCacid at the sixth position of the beta-globin subunit of hemoglobin that results in hemoglobin S (HbS). In the heterozygote carrier, this sickle gene mutation offers potential resistance to endemiCPlasmodium falciparum malaria infections. Diagnosis of the disease is confirmed by hemoglobin electrophoresis

■Correct Answer: Plasmodium falciparum malaria infections

409. (3252) Q1-4076:

The minimally invasive surgical technique for unicondylar knee arthroplasty (UKA):

1) Everts the patella

3) Subluxes the patella

2) Resurfaces the patella

5) Violates the suprapatellar synovial pouch

4) Removes a portion of the patella

New surgical technique and instrumentation leads to less invasion of the extensor mechanism. The patella is not everted, and the suprapatellar synovial pouch remains untouched

■Correct Answer: Subluxes the patella

410. (3253) Q1-4077:

The early failures of unicondylar knee arthroplasty (UKA) were due to:

1) Patient selection

3) Surgical technique

2) Implant design

5) Patient selection, implant design, and surgical technique

4) Implant design and surgical technique

The initial high failure rate of UKA in early reports was related to improper patient selection, incorrect surgical technique, and poor implant design

■Correct Answer: Patient selection, implant design, and surgical technique

411. (3254) Q1-4078:

In unicondylar knee arthroplasty (UKA) for a varus knee:

1) The medial collateral ligament should be released

3) The medial collateral ligament should not be changed

2) The medial collateral ligament should be tightened

5) Knee alignment is corrected to 6° of valgus

4) The lateral collateral ligament should be tightened

In total knee arthroplasty (TKA), knee alignment is corrected to an anatomiC6º or 7º of valgus. In UKA, this alignment leads to excessive medial compartment tightness and overload of the opposite lateral compartment. A varus knee in UKA should remain in neutral or a few degrees of varus. In TKA, a flexion contracture can be readily corrected with additional resection of both femoral condyles. In UKA, resection of the single distal femoral condyle helps to correct the flexion contracture but also changes the distal femoral valgus. Ligament releases in UKA are not as predictable as in TKA because only one compartment is replaced in the UKA, and the forces on the opposite compartment are more difficult to balance

■Correct Answer: The medial collateral ligament should not be changed

412. (3255) Q1-4079:

In comparing high tibial osteomtomy to unicondylar knee arthroplasty (UKA):

1) Patients with high tibial osteotomy recover faster than patients with UKA.

3) High tibial osteotomy has better early results than UKA.

2) High tibial osteotomy has better 10-year results than UKA.

5) High tibial osteotomy has fewer operative complications than UKA.

4) High tibial osteotomy is better for patients who work as heavy laborers.

Although a successful UKA can eliminate pain and improve the patientâs function, heavy labor and high impact athletiCactivities are not encouraged. High tibial osteotomy allows a patient to perform more aggressive activities

■Correct Answer: High tibial osteotomy is better for patients who work as heavy laborers.

413. (3256) Q1-4080:

Contraindications to unicondylar knee arthroplasty (UKA) includes all of the following except:

1) Bilateral knee disease

3) Varus deformity >15°

2) Tibial subluxation

5) >10° flexion contracture

4) Inflammatory arthritis

A patientâs symptoms and physical findings should be isolated to one tibiofemoral compartment, but disease can be present in both the right and left knee as long as its just one compartment. Patient history must be thoroughly evaluated to ensure that there are no associated patellofemoral symptoms in the opposite compartment

■Correct Answer: Bilateral knee disease

414. (3257) Q1-4082:

Patellofemoral arthritis in the knee undergoing unicondylar knee arthroplasty (UKA):

1) Is an absolute contraindication

3) Does not affect the result of UKA

2) Is a relative contraindication

5) Is more symptomatiCthan patellar impingement

4) Is always present in UKA

Kozinn and Scott have emphasized that pain in the patellofemoral joint is a relative contraindication for UKA surgery. Degenerative changes of the patellofemoral joint also affected patient function, but the symptoms were less severe than in patients with patellar impingement. If patients report significant symptoms related to the patellofemoral joint, then UKA is contraindicated

■Correct Answer: Is a relative contraindication

415. (3258) Q1-4083:

When performing unicondylar knee arthroplasty (UKA), it is best to use polyethylene:

1) With a thickness of >10 mm

3) With a thickness of >6 mm

2) With a thickness of >8 mm

5) With a thickness of >2 mm

4) With a thickness of >4 mm

Manufacturing of polyethylene is improving, and cross-linking processes are increasing the wear properties. Most surgeons believe that it is safest to use a thickness of at least 6 mm with conventional polyethylene

■Correct Answer: With a thickness of >6 mm

416. (3259) Q1-4085:

Radiographs of the UKA over a period of years after surgery show:

1) Some progression of arthritis in the opposite compartment

3) Advanced arthritis in the opposite compartment

2) No arthritis in the opposite compartment

5) Unacceptable rate of subsidence of the tibial compartment

4) No arthritis in the patellofemoral joint

Marmor reported no significant increase in the opposite compartment. Kozinn and Scott reported failures due to progression in the opposite compartment; however, this may have been due to over correction of the knee. Berger and colleagues reported minimal change in the opposite compartment with 12-year follow-up radiographs

■Correct Answer: Some progression of arthritis in the opposite compartment

417. (3260) Q1-4086:

The minimally invasive surgical technique for unicondylar knee arthroplasty(UKA)

1) Everts the patella

3) Subluxes the patella

2) Resurfaces the patella

5) Violates the suprapatellar pouch

4) Removes a portion of the patellar

The minimally onvasive surgical technique for UKA subluxes the patella and leads to less invasion of the extensor mechanism. The patella is not everted and the suprapatellar synovial pouch remains untouched

■Correct Answer: Subluxes the patella

418. (3450) Q1-4377:

The most common organism identified in bone cultures taken from patients with sickle cell disease with osteomyelitis is:

1) Salmonella typhimurium

3) Haemophilus influenzae

2) Staphylococcus aureus

5) Staphylococcus epidermis

4) Plasmodium falciparum

Although Salmonella infections are highly specifiCto patients with sickle cell disease, the most common organism identified in bone cultures taken from patients with sickle cell disease with osteomyelitis is S aureus. Due to autoinfarction, 95% of individuals develop functional asplenia by age 5 years. This condition has been associated with a decrease in opsonin production and phagocytiCactivity. Thus, in infants with sickle cell disease the major cause of death is pneumococcal sepsis. It has been recommended that patients with sickle cell disease have pneumococcal vaccine administered every 3 to 5 years

■Correct Answer: Staphylococcus aureus

419. (3451) Q1-4378:

Second-generation cement technique implies which of the following:

1) Cement is hand-packed in the shaft of the femur.

3) Cement is hand-mixed, medullary lavage is performed, and a canal plug is used.

2) The medullary canal is rinsed out by medullary lavage.

5) External pressurization is used.

4) The canal is brushed, jet lavage is performed, and a vacuum or centrifuge machine is used.

First-generation cement technique implies that cement is hand-packed in the shaft of the femur. A cement plug is not used and a lavage of the femoral canal is not performed. Second-generation technique implies that cement is hand-mixed in a bowl,

medullary lavage is performed, and a canal plug is used. Third-generation technique refers to performing high-pressure jet lavage of the femoral canal, brushing the canal of all particles, using a vacuum or centrifuge machine in the mixing procedure, and using external pressurization on a closed canal

■Correct Answer: Cement is hand-mixed, medullary lavage is performed, and a canal

plug is used.

420. (3464) Q1-4399:

When comparing syringe-mixing versus bowl-mixing of bone cement, which of the following is not true:

1) Syringe-mixed bone cement has a greater density.

3) Syringe-mixed bone cement has a lesser bending modulus.

2) Syringe-mixed bone cement has a greater bending modulus.

5) Centrifuged or syringe-mixed bone cement, under vacuum conditions, is of greater strength than aerated bowl-mixed cement.

4) Syringe-mixed bone cement has a higher bending strain.

When analyzing bone cement for void content and failure in four-part bending, the results show that syringe-mixed bone cement has a greater density and a greater bending modulus and is of greater strength than aerated bowl-mixed cement

■Correct Answer: Syringe-mixed bone cement has a lesser bending modulus.

421. (3486) Q1-4426:

In an obese patient undergoing unicondylar knee arthroplasty (UKA):

1) The results are worse than in a normal weight patient.

3) The results are not predictably better or worse.

2) The results are better than in a normal weight patient.

5) Results are gender dependent.

4) The results depend on the design of the prosthesis.

The knee should have less than 15° of deformity in varus or valgus and less than 10° flexion contracture. Inflammatory or crystalline-induced arthritis, knee subluxation, gross ligamentous laxity, and obesity are relative contraindications to the procedure. Scott and colleagues found that increased body weight contributed to failure in UKA and suggested that the best candidates are less than 180 lb

■Correct Answer: The results are worse than in a normal weight patient.

422. (3489) Q1-4431:

The percentage of patients with a natural history of untreated asymptomatiCosteonecrosis of the femoral head with sickle cell disease that will develop progression to pain is:

1) 10%

3) 50%

2) 30%

5) 90%

4) 70%

In a study involving 121 patients with untreated asymptomatiCosteonecrosis of the femoral head, 110 of the patients went on to develop significant hip pain. Spontaneous resolution of osteonecrosis of the femoral head was not observed in asymptomatiChips

■Correct Answer: 90%

423. (3503) Q1-4454:

Which of the following statement is true regarding osteonecrosis and sickle cell disease:

1) Sickle cell patients with total hip replacement have outcomes equivalent to patients with osteonecrosis secondary to steroid use.

3) Core decompression alone is the most effective means of treatment in sickle cell patients with osteonecrosis.

2) Physical therapy alone is the most effective means of treatment in sickle cell patients with osteonecrosis.

5) Bone grafting has the best outcome for sickle cell patients.

4) Physical therapy alone is as effective as hip core decompression followed by physical therapy.

In a randomized prospective study performed by Neumayr and colleagues, physical therapy alone appeared to be as effective as hip core decompression followed by physical therapy in improving hip function and postponing the need for additional surgical intervention at a mean of 3 years after treatment

■Correct Answer: Physical therapy alone is as effective as hip core decompression followed by physical therapy.

424. (3505) Q1-4456:

In the varus knee, unicondylar knee arthroplasty (UKA) should correct the deformity:

1) 7° of anatomiCvalgus

3) 0°

2) 10° of anatomiCvalgus

5) 5° of anatomiCvarus

4) Permit implant positioning with 2 mm of laxity in flexion and full extension

In the medial UKA with preoperative varus, most of the reviews suggest an alignment of 0° with reference to the anatomiCaxis of the lower extremity or slightly less than 0° with reference to the mechanical axis. In the study by Kennedy and White on 100

UKAs, they reported that superior results were obtained when the postoperative mechanical axis of the operated limb fell in the center of the knee or slightly medial to the center

■Correct Answer: 0°

425. (3547) Q1-4542:

The most common risk factors for stress fractures is:

1) Leg length discrepancy

3) Muscle strength

2) Training regimen

5) Footwear

4) Low bone mineral density

Numerous risk factors for stress fracture exist. Most commonly, the scenario is doing âtoo much too soon.â Survey data have shown 86% of runners suffering stress fracture have had a change in duration, frequency, or intensity of training immediately prior to injury. The best independent predictors for stress fracture development in women appear to be age of menarche and calf girth

■Correct Answer: Training regimen

426. (3548) Q1-4543:

Which of the following exerts protective effects on bone:

1) Ligaments

3) Muscle-tendon unit

2) Muscle flexibility

5) Hormonal factors

4) Articular cartilage

The muscle-tendon unit exerts a protective effect on cortical bone by acting as the major shock absorber. With muscle contraction, cortical bone surface bending strains are reduced. In most weight-bearing bones it is believed that with muscle fatigue, the shock-absorbing effect is lessened and more force is transmitted directly to bone, increasing the likelihood of microdamage accumulation

■Correct Answer: Muscle-tendon unit

427. (3549) Q1-4545:

Which of the following is not associated with increased risk of stress fractures:

1) Eating disorder

3) Prolonged corticosteroid use

2) Hyperthyroidism

5) CeliaCsprue

4) Hypothyroidism

Any history of frequent or prolonged corticosteroid use, hyperparathyroidism, rheumatoid arthritis, hyperthyroidism, celiaCsprue, previous stress fractures or overuse injuries as well as signs or symptoms of an eating disorder also should draw oneâs attention to the possibility of a reduced bone mass

■Correct Answer: Hypothyroidism

428. (3550) Q1-4546:

Which of the following are both markers of bone formation:

1) Osteocalcin and bone specifiCalkaline phosphatase

3) IGF-1 and serum C-telopeptide

2) Collagen degradation products and leptin

5) IGF-1 and leptin

4) Urine N-telopeptide and serum C-telopeptide

Several metaboliChormones that influence bone formation (IGF-1, T3, leptin) as well as bone formation markers (serum Type I procollagen carboxyl and amino terminal propeptides, osteocalcin, bone specifiCalkaline phosphatase) and bone resorption markers (collagen degradation products, urine N-telopeptide, and serum C-telopeptide) can be followed to form an impression on the overall bone turnover status

■Correct Answer: Osteocalcin and bone specifiCalkaline phosphatase

429. (3551) Q1-4547:

Which of the following is not a component of the female athlete triad:

1) Disordered eating

3) Menstrual dysfunction

2) Osteopenia

5) Excessive training

4) Low bone density

The female athlete triad, first described in 1993, initially consisted of three interrelated conditions: eating disorders, amenorrhea, and osteoporosis. The definition has since been broadened to disordered eating, menstrual dysfunction, and low bone density (osteopenia or osteoporosis) to include all those at risk for the detrimental effects to bone

■Correct Answer: Excessive training

430. (3552) Q1-4548:

Which of the following is not appropriate in the conservative management of stress fractures:

1) Relative rest

3) Modification of training errors

2) Maintenance of athletiCfitness

5) Gradual return to activity

4) Pain relief with nonsteroidal anti-inflammatory drugs (NSAIDs)

Literature regarding nonsteroidal anti-inflammatory drug (NSAID) use in stress fracture healing is lacking; however, there has been research into its risks associated with complete fractures and nonunion after surgery. Prostaglandins play a crucial role in bone metabolism and repair. Cyclooxygenase-2 (COX-2) products have been found to be essential to bone repair in animal studies. Animal studies have shown that NSAIDs including indomethacin, aspirin, ibuprofen, and COX-2 inhibitors cause delayed fracture healing that may or may not be reversible on cessationCorrect Answer: Pain relief with nonsteroidal anti-inflammatory drugs (NSAIDs)

431. (3553) Q1-4549:

How much should training time and intensity be increased per week to avoid bone stress injury:

1) 10%

3) 30%

2) 20%

5) 50%

4) 40%

Generally, it is best to increase training time and intensity by <10% per week to avoid bone stress injury. Particularly important to female athletes are intrinsiCconditions such as disordered eating and menstrual dysfunction resulting in low bone density

■Correct Answer: 10%

432. (3554) Q1-4550:

Which of the following sites are not at increased risk for complications following stress fractures (i.e., delayed union, nonunion, or progression to complete fracture):

1) Olecranon

3) Mid tibia

2) Sesamoids of the great toe

5) Navicular

4) Radius

Delayed union and nonunion are seen in approximately 10% of all stress fractures and occur more commonly in sesamoids of the great toe, proximal and mid tibia, base of the fifth metatarsal, navicular, and olecranon

■Correct Answer: Radius

433. (3555) Q1-4551:

Which of the following stress fractures is associated with a particularly high level of morbidity:

1) Vertical patellar stress fracture

3) Lateral femoral neck

2) Second metatarsal

5) Proximal tibia

4) Fibula

Lateral- or tension-sided femoral neck fractures are most commonly associated with a high level of morbidity following completion of fracture. In fact, one study found 60% of appropriately treated displaced femoral neck fractures were still unable to return to their preinjury level of participationCorrect Answer: Lateral femoral neck

434. (3556) Q1-4552:

Metal-on-metal articulations generate how much more wear than metal-on-polyethylene  articulations:

1) Less wear

3) 10 times less wear

2) 10 times more wear

5) 10,000 times less wear

4) 10,000 times more wear

Metal-on-metal articulations generate approximately 6.7x101 2 to 2.5 x 101 4 particles every year, which is 13,500 times the number of particles produced from a typical metal-on-polyethylene  bearing

■Correct Answer: 10,000 times more wear

435. (3557) Q1-4553:

The volumetriCwear of a metal-on-metal articulation compared to polyethylene particles is:

1) Lower

3) Higher

2) Approximately the same

5) Depends on the metal involved

4) Not comparable

The actual volumetriCwear of a metal-on-metal articulation is lower because of the nano-scale size of the particles (generally <

50 nm) when compared with polyethelene particles, which are rarely <0.1 µm

■Correct Answer: Lower

436. (3558) Q1-4554:

Prosthesis-derived metal wear products are found in:

1) Synovial fluid

3) Liver and spleen

2) Synovial fluid and periprosthetiCtissues

5) Synovial fluid, periprosthetiCtissues, lymph nodes, and liver and spleen

4) Lymph nodes

Prosthesis-derived metal wear products are found extensively within the synovial fluid and periprosthetiCtissues of arthroplasty patients. At post-mortem further accumulation has been identified in the regional lymph nodes, liver and spleen. Because metal particles are very small (nano scale), the true extent of dissemination is not yet known

■Correct Answer: Synovial fluid, periprosthetiCtissues, lymph nodes, and liver and spleen

437. (3559) Q1-4555:

When metal nanoparticles are taken up by cells the biological response to the metal wear particles:

1) Induces cytotoxicity

3) Stabilizes the cell membrane

2) Causes oxidative stress

5) Induces chromosomal damage, cytotoxicity, and causes oxidative stress

4) Induces chromosomal damage

The uptake of metal nanoparticles(<150 nm) by cells occurs by endocytotiCprocesses, particularly nonspecifiCreceptor-mediated endocytosis and pinocytosis. Larger particles (>150 nm) can stimulate phagocytosis in specialized cells such as macrophages. Once internalized, metal particles can induce cytotoxicity, chromosomal damage, and oxidative stress. The toxicity of particles is modified by passivation and particle size. These factors both influence the dissolution of metal from the surface, which may account for biological activity. Evidence of cell damage, such as irregular cell membranes and enlarged mitochondria, may be induced by the physical properties of the particles

■Correct Answer: Induces chromosomal damage, cytotoxicity, and causes oxidative stress

438. (3560) Q1-4556:

The pattern of inflammation in the periprosthetiCtissue of loose metal-on-metal articulations is characterized by:

1) Perivascular infiltration of eosinophils

3) Perivascular infiltration of plasma cell

2) Perivascular infiltration of lymphocytes

5) Perivascular infiltration of lymphocytes and accumulation of plasma cells

4) Perivascular infiltration of polymorphonuclears

The pattern of inflammation in the periprosthetiCtissue of loose metal-on-metal articulations is significantly different to that of metal-on-metal polyethylene articulations, and is characterized by perivascular infiltration of lymphocytes and the accumulation of plasma cells. Experimental data suggest that orthopediCmetals induce immunological effects that support a cell-mediated hypersensitivity response

■Correct Answer: Perivascular infiltration of lymphocytes and accumulation of plasma cells

439. (3561) Q1-4557:

The International Agency for Research on Cancer classified Cr (VI) and Ni (II) as:

1) Non carcinogenic

3) Possibly carcinogenic

2) Carcinogenic

5) Moderately carcinogenic

4) Moderately carcinogenic

The International Agency for Research on Cancer, which publishes information on the risks posed by chemicals on the development of human cancers, has classified Cr (VI) and Ni (II) as carcinogenic, metalliCNi and soluble Co as possibly carcinogenic, and metalliCCr, Cr (III) compounds and implanted orthopediCalloys as unclassifiable

■Correct Answer: Carcinogenic

440. (3562) Q1-4558:

Which of the following metals is likely to induce developmental toxicity in pregnancy as suggested by animal studies:

1) Cr

3) Ni and V

2) Co

5) Cr, Co, NI, V and Al

4) Cr and Co

Experimental animal studies suggest that several metals, including Cr, Co, Ni, V and Al, may induce development toxicity. For example, Cr (VI) exposure in male and/or female mice either before or during gestation can affect the number of implantations and viable fetuses resulting from conception. Many metals can also induce teratogeniCmalformations, including Cr, Ni, and V

■Correct Answer: Cr, Co, NI, V and Al

441. (3563) Q1-4559:

The accumulation of what metal was attributed to the 1996 episode of âbeer-drinkersâ cardiomyopathy:

1) Al

3) Cr

2) Co

5) Ni

4) V

The accumulation of Co in the myocardium can induce cardiomyopathy, which was particularly evident after the 1996 episode of âbeer-drinkersâ cardiomyopathy, during which Co was used as a foam-stabilizing agent in beer

■Correct Answer: Co

442. (3564) Q1-4560:

The deposition of what metal in bone has been linked to osteomalacia, bone pain, and pathological fractures:

1) Al

3) Cr

2) Co

5) Ni

4) V

Deposition of A1 in the bone occurs as a consequence of chroniCexposure and has been linked to osteomalacia, bone pain, pathological fractures, proximal myopathy, and the failure to respond to vitamin D therapy

■Correct Answer: Al

443. (3565) Q1-4561:

Which of the following metals has been documented to cause serve retinal degeneration:

1) Al

3) Ni

2) Co

5) Al, Co, and Ni

4) Al and Co

Al, Co, and Ni can cause severe retinal degeneration at high-concentrations in experimental animals

■Correct Answer: Al, Co, and

Ni

444. (3566) Q1-4562:

The incidence of dermal reactions and positive skin-patch testing to Co, Ni, and Cr in patients with total joint replacement with stable prostheses is:

1) 5% above those of the general population

3) 15% above those of the general population

2) 10% above those of the general population

5) 50% above those of the general population

4) 30% above those of the general population

Metal-induced skin reactions can include contact dermatitis, urticaria, and/or vasculitis. The incidence of dermal reactions and positive skin-patch testing to Co, Ni, and Cr in patients with total joint replacement with stable and loose prostheses increases by

15% and 50% respectively, above those of the general population

■Correct Answer: 15% above those of the general population

445. (3567) Q1-4563:

The incidence of dermal reactions and positive skin-patch testing to Co, Ni, and Cr in patients with total joint replacement with unstable prostheses is:

1) 5% above those of the general population

3) 15% above those of the general population

2) 10% above those of the general population

5) 50% above those of the general population

4) 30% above those of the general population

Metal-induced skin reactions can include contact dermatitis, urticaria ,and/or vasculitis. The incidence of dermal reactions and positive skin-patch testing to Co, Ni, and Cr in patients with total joint replacement with stable and loose prostheses increases by

15% and 50% respectively, above those of the general population

■Correct Answer: 50% above those of the general population

446. (3568) Q1-4564:

Hepatocellular necrosis has been observed with high levels of             in the body.

1) Al

3) Cr

2) Co

5) Ni

4) V

Hepatocellular necrosis often occurs in response to high levels of metal in the body, as observed after acute ingestion of Cr (VI) in humans

■Correct Answer: Cr

447. (3569) Q1-4565:

Which metal ion concentrates in the epithelial cells of the proximal tubules and can impair renal function, induce tubular necrosis, and cause marked interstitial changes in experimental animals and humans:

1) Al

3) Cr

2) Co

5) Ni

4) V

Cr is concentrated in the epithelial cells of the proximal renal tubules and can impair renal function, induce tubular necrosis, and cause marked interstitial changes in experimental animals and humans. Indicators of tubular dysfunction have been identified in human objects exposed to Cr (VI) through occupation. Al, Ni, and Co are all rapidly excreted by the kidney, hence renal toxicity tends to require significantly larger doses

■Correct Answer: Cr

448. (3570) Q1-4566:

Severe neurological manifestations have been attributed with accumulation of what metal ion in the brain:

1) Al

3) Cr

2) Co

5) Ni

4) V

Several neurological manifestations have been attributed to Al intoxication in humans, including memory loss, jerking, ataxia, and neurofibrillary degeneration. The development of some neuropathological conditions, including amyotrophiClateral sclerosis, Parkinsonian, dementia, dialysis encephalopathy, and senile plaques of Alzheimerâs disease, may be related to the accumulation of Al in the brain

■Correct Answer: Al

449. (3637) Q1-7414:

What is the preferred imaging modality to determine the glenoid wear pattern in a patient with rheumatoid arthritis:

1) Plain radiographs

3) MagnetiCresonance image

2) Fluoroscopically positioned plain radiographs

5) Computed tomography scan

4) Tomograms

A computed tomography scan provides important information in regard to the version of the glenoid, wear pattern, amount of wear, glenohumeral subluxation, as well as desired entry point

■Correct Answer: Computed tomography scan

450. (3638) Q1-7415:

What is the most common reason for revision among patients who undergo shoulder arthroplasty for rheumatoid arthritis:

1) Infection

3) Humeral component loosening

2) Instability

5) Painful glenoid arthritis

4) Glenoid component loosening

The most common reason for revision surgery among patients with rheumatoid arthritis is painful glenoid arthritis. The rate of revision for painful glenoid arthritis is higher than that for glenoid component loosening

■Correct Answer: Painful glenoid arthritis