ORTHOPEDICS HYPERGUIDE MCQ 351-400

351. (4054) Q1-3025:

The disadvantages of a complete arthroscopiCrepair of a rotator cuff include all of the following except:

1) Complete arthroscopiCrepair limits some suture configuration options in the tendon.

3) Complete arthroscopiCrepair is technically difficult to perform.

2) Postoperative pain is increased.

5) Operative time is longer.

4) Complex instrumentation is required.

ArthroscopiCrepair techniques generally require the use of suture anchors and limit some suture configuration options in the tendon. Complete arthroscopiCrepair is technically difficult, requires significantly greater and more complex instrumentation, and has a potentially longer operative time. However, it decreases postoperative pain

■Correct Answer: Postoperative pain is increased.

352. (2553) Q1-3026:

The types of rotator cuff tear patterns are:

1) Crescent-shaped and massive contracted immobile tears

3) Vertical and horizontal cleavage tears

2) U-shaped and L-shaped tears

5) Vertical cleavage, U-shaped, and L-shaped tears

4) Crescent-shaped, U-shaped, L-shaped, and massive contracted immobile tears

Four major types of rotator cuff tear patterns have been described and are based on the shape and mobility of the tear margins: crescent-shaped, U-shaped, L-shaped, and massive contracted immobile tears. Vertical and horizontal cleavage tears are related to meniscal tears in the knee

■Correct Answer: Crescent-shaped, U-shaped, L-shaped, and massive contracted immobile tears

353. (2554) Q1-3027:

Which of the following rotator cuff tears is the simplest to repair:

1) U-shaped tear

3) Crescent-shaped tear

2) L-shaped tear

5) Parrot-beak tear

4) Vertical cleavage tear

Crescent-shaped tears are the simplest of all tears to repair and demonstrate minimal retraction and excellent mobility. They can be repaired directly to the bone with minimal tension. The anchors are placed percutaneously using a spinal needle. Suture passing techniques are then used and the rotator cuff is tied down. Vertical cleavage and parrot-beak tears refer to meniscal injuries in the knee

■Correct Answer: Crescent-shaped tear

354. (2555) Q1-3028:

Slide 1

The following image depicts:

1) An arthroscopiCview of a massive rotator cuff tear

3) An arthroscopiCview of a U-shaped rotator cuff tear

2) An arthroscopiCview of an L-shaped rotator cuff tear

5) An arthroscopiCview of a medial meniscus tear of the knee

4) An arthroscopiCview of a crescent-shaped rotator cuff tear

The image depicts a lateral arthroscopiCview of a crescent-shaped tear, which demonstrates minimal retraction and excellent mobility, and is easily repaired

■Correct Answer: An arthroscopiCview of a crescent-shaped rotator cuff tear

355. (2556) Q1-3029:

Slide 1

The following image depicts:

1) A lateral arthroscopiCview of a massive U-shaped tear of the rotator cuff

3) A lateral arthroscopiCview of an L-shaped tear of the rotator cuff

2) A lateral arthroscopiCview of a crescent-shaped tear of the rotator cuff

5) A bucket-handle tear of the medical meniscus

4) A degenerative posterior horn tear of the medial meniscus

The image depicts a lateral arthroscopiCview of a massive U-shaped tear. U-shaped rotator cuff tears extend much farther medially than crescent-shaped tears, with the apex of the tear adjacent to or medial to the glenoid rim

■Correct Answer: A lateral arthroscopiCview of a massive U-shaped tear of the rotator cuff

356. (2557) Q1-3030:

All of the following are statiCrestraints providing stability for the shoulder except:

1) Labrum

3) Glenohumeral ligaments

2) Glenoid

5) Joint capsule

4) Rotator cuff and scapular muscles

The shoulder allows more range of motion than any other joint in the body and is susceptible to injury. It has both statiCand dynamiCrestraints. The rotator cuff and scapular muscles are the dynamiCrestraints. The glenoid, labrum, glenohumeral ligaments, and joint capsule are the statiCrestraints

■Correct Answer: Rotator cuff and scapular muscles

357. (2558) Q1-3031:

Which of the following provides the greatest restraint to anterior dislocation of the shoulder:

1) Superior glenohumeral ligament

3) Infraspinatus

2) Supraspinatus

5) Joint capsule

4) Inferior glenohumeral ligament

The inferior glenohumeral ligament provides the greatest restraint to dislocation of the shoulder. The inferior glenohumeral ligament is under the most stress at 90° of abduction with external rotation and extension. Bracing to restrict this position benefits a patient with instability

■Correct Answer: Inferior glenohumeral ligament

358. (2559) Q1-3032:

The percentage of patients 20 to 40 years of age who have recurrent shoulder instability is:

1) 10%

3) 40%

2) 20%

5) 60%

4) 50%

Suffering from recurrent instability in the shoulder joint depends on a patientâs age and activity level. Ninety percent of patients younger than 20 years of age have recurrent instability. In patients 20 to 40 years of age, 40% have recurrent instability

■Correct Answer: 40%

359. (2560) Q1-3033:

The percentage of athletes with recurrent instability choosing to return to collision sports after an anterior shoulder dislocation is:

1) 20%

3) 60%

2) 40%

5) 100%

4) 80%

A patientâs activity level is the predicting factor for recurrent instability. Eighty-two percent of athletes suffer from recurrent instability compared with 30% of nonathletes. The percentage approaches 100% for athletes choosing to return to collision sports

■Correct Answer: 100%

360. (2561) Q1-3034:

The most frequently transplanted human tissue is:

1) Bone

3) Kidney

2) Blood

5) Skin

4) Cornea

After blood, bone is the most frequently transplanted human tissue. However, bone autografting may eventually become a thing of the past. Bone replacement with synthetiCmaterials and growth factors is becoming common procedure in the orthopedic

operating room

■Correct Answer: Blood

361. (2562) Q1-3035:

The first documented bone transplant was performed by:

1) Van Meekeren

3) Phemister

2) Macewan

5) Albee

4) Ferguson

The first documented bone transplant was performed in 1668 by Dutch surgeon Job van Meekeren, when he used a dog cranium (a xenograft) to repair a soldierâs skull defect. Scottish surgeon William Macewan performed the first bone allograft in 1880 when he replaced the infected humerus of a 4-year-old boy with a tibia graft taken from a child with rickets. In his 1914 publication, Phemister noted the importance of âhemostasis, asepsis, and coaptation of partsâ in successful bone grafting. Phemister and Albee elucidated the important factors in bone grafting in the early 20th century, paving the way for the recent work that has delineated the importance of osteoconductive scaffolding, osteoinductive growth factors, and osteogeniCprogenitor stem cells in bone graft healing

■Correct Answer: Van Meekeren

362. (2563) Q1-3036:

In most clinical applications, a bone autograft is preferable to a bone allograft because:

1) A bone autograft is more osteoconductive, osteoinductive, and osteogeniCthan a bone allograft.

3) A bone autograft incorporates more slowly than a bone allograft.

2) A bone autograft has a higher risk of infection than a bone allograft.

5) There are more immunological considerations.

4) Bone autografts are in limitless supply.

Autografting is the standard method used to replace bone loss due to trauma, infection, tumor resection, revision arthroplasty, and arthrodesis. Rapid incorporation and consolidation with the lack of immunological considerations make bone harvested from the patient ideal. Bone autografts are osteoconductive and contain osteoinductive proteins and cells, which are able to give rise to bone-forming cells. Because of its lower risks, a bone autograft (especially of cancellous bone) is preferable to a bone allograft. Bone autografts, however, are in limited supply, particularly in children

■Correct Answer: A bone autograft is more osteoconductive, osteoinductive, and osteogeniCthan a bone allograft.

363. (2564) Q1-3037:

When nonvascularized cortical allografts lose mechanical strength during the first year following surgery, it is most likely due to:

1) Revascularization

3) Infection

2) Failure of the graft to incorporate

5) Failure to provide initial structural support

4) Complex regional pain syndrome

Nonvascularized cortical grafts may provide immediate structural support but lose mechanical strength over the first few months. Loss of mechanical strength is due to the revascularization process, which causes osteoporosis and subsequent graft weakening. The process requires resorption of at least some graft bone to allow ingrowth of blood vessels and takes a significantly longer period of time in cortical bone than in cancellous bone

■Correct Answer: Revascularization

364. (2565) Q1-3038:

What percentage of osetocytes present in a vascularized cortical autograft survive:

1) 24%

3) 60%

2) 40%

5) 90%

4) 80%

Vascularized cortical autografts are effective structural grafts that heal quickly without the revascularization process and consequent mechanical compromise found in avascular cortical autografts and allografts. Typically, more than 90% of osteocytes present in a vascularized cortical allograft survive transplantation and bring their own blood supply, perhaps making the contribution of the recipient bed tissues less important than healing

■Correct Answer: 90%

365. (2566) Q1-3039:

Vascularized free fibular grafts have been used to treat all of the following except:

1) Congenital pseudoarthrosis of the tibia

3) Osteonecrosis of the femoral head

2) Tumor-related defects in the proximal humerus

5) Nonunions of the femur

4) Pseudoarthrosis of the scaphoid

Vascularized free fibula grafts have been used in numerous locations for a variety of difficult problems. Potential situations in which a patient might benefit from vascularized autografts include osteonecrosis of the femoral head, reconstruction of tumor- related defects in the proximal humerus and lower extremity, treatment of congenital tibial pseudoarthrosis, and nonunions of the femur, tibia, and femoral neck

■Correct Answer: Pseudoarthrosis of the scaphoid

366. (2567) Q1-3040: Demineralized bone matrix is:

1) Osteogenic

3) Osteoinductive, osteogenic, and osteoconductive

2) OsteogeniCand osteoconductive

5) Only osteoconductive

4) Osteoconductive and osteoinductive

Demineralized bone matrix is recognized as having a variable amount of osteoinductive capacity and some osteoconductive properties. The biologiCactivity varies with specifiCprocessing and storage methods, in addition to variation among donors

■Correct Answer: Osteoconductive and osteoinductive

367. (2568) Q1-3041:

Which of the following has the highest risk of disease transmission:

1) Cortical allograft

3) Cancellous allograft

2) Cortical autograft

5) Cortical allograft and cancellous allograft have the same risk of disease transmission.

4) Cancellous autograft

Cortical bone is of greater density than cancellous bone, and it is believed that the density accounts for the slightly higher risk of disease transmission, as pathogens are less easily destroyed when embedded in a more dense tissue bed. Two cases of HIV transmission resulting from cortical allografts have been reported

■Correct Answer: Cortical allograft

368. (2569) Q1-3042:

Slide 1                             Slide 2

The following image (Slide 1) depicts:

1) The removal of congenital pseudoarthrosis of the tibia

3) A fibular autograft

2) A vascularized iliaCautograft

5) A fibular autograft for spinal fusion

4) The harvesting of the vascularized fibula from the contralateral leg

The image depicts the harvesting of a vascularized fibula from the contralateral leg, which is then used to move a defect in congenital pseudoarthrosis of the tibia on the opposite side. The following image (Slide 2) shows clinical union 3.5 years later

■Correct Answer: The harvesting of the vascularized fibula from the contralateral leg

369. (2570) Q1-3043:

Vascularized transplantation of the knee and femoral diaphysis is most frequently complicated by:

1) Immunosuppressive medications

3) Bony nonunions

2) Pulmonary emboli

5) Deep venous thrombosis (DVT)

4) Acute infections

Hofmann and Kirschner reported their experiences with transplantation of vascularized diaphyseal femora and vascularized knees. While using an immunosuppressive regimen consisting of antithymocyte globulin, cyclosporine, azathioprine, and methylprednisolone, which was tapered over 6 months to cyclosporine monotherapy, three patients underwent transplantation of vascularized femoral diaphysis and five patients underwent transplantation of the entire knee, including the extensor mechanism and joint capsule. According to their most recent report, four of these eight patients (two from each group) are currently weight bearing on their transplants. As the authors state, these vascularized bone transplants were âfraught with complications,â largely related to the immunosuppressive medications

■Correct Answer: Immunosuppressive medications

370. (2636) Q1-3127:

When treating an infected joint prosthesis with antibiotiCcement, the antibiotiCelution should stay above the minimum inhibitory concentration (MIC) for a minimum of:

1) 1 week

3) 3 weeks

2) 2 weeks

5) 6 weeks

4) 4 weeks

AntibiotiCelutions differ among brands of cement. However, the antibiotiCconcentrations should stay above the MICfor at least 3 weeks. The effect is local and there is no significant absorption of a specifiCantibiotiCout of the bone cement and into the plasma

■Correct Answer: 3 weeks

371. (2637) Q1-3128:

After implantation, the antibiotiCinside bone cement will be present and can be measured for up to:

1) 1 day

3) 2 weeks

2) 1 week

5) Several months

4) 3 weeks

The antibiotiCinside bone cement will be present in the bone cement for months or even years after implantation into a patient. AntibiotiChas been measured present even after 5 years

■Correct Answer: Several months

372. (2638) Q1-3129:

The chances of an arthroplasty revision becoming re-infected by a different organism or the initial infection after a two-stage revision is approximately:

1) 5%

3) 20%

2) 10%

5) 50%

4) 40%

In one series, 23% of arthroplasty revisions became re-infected by a different organism even after a two-stage revision. However, re-infection is usually, although not always, caused by the same microorganism that caused the initial infection. Once the white blood cell count, sedimentation rate, and C-reactive protein count return to normal, it is usually safe to re-implant the prosthesis

■Correct Answer: 20%

373. (2639) Q1-3130:

Slide 1

Which of the following antibiotics has the highest concentration locally from Palacos-R (Biomet, Warsaw, IN) cement:

1) Tobramycin

3) Bacitracin

2) Lincomycin

5) Keflex

4) Gentamicin

The Slide represents different antibiotics that may be used with bone cement and the release of antibiotics over a 10-day period. Gentamicin leads the way with a high concentration locally. Bacitracin, for instance, does not leach in high concentrations from Palacos-R bone cement

■Correct Answer: Gentamicin

374. (2640) Q1-3131:

The maximum amount of antibiotiCpowder that can be added as a temporary spacer to 40 g of cement powder is:

1) 1 g

3) 4 g

2) 2 g

5) 9 g to 10 g

4) 6 g to 8 g

Surgeons should not add more than 6 g to 8 g of antibiotiCpowder per 40 g of cement powder. One also needs to be careful when adding additional antibiotiCpowder of the same type, especially to Palacos-R (Biomet, Warsaw, IN) cement, as an overdose may occur. The cement powder should be mixed with the liquid and then the antibiotiCpowder added to facilitate setting of the cement

■Correct Answer: 6 g to 8 g

375. (2641) Q1-3132:

The optimal depth of cement penetration for prosthesis insertion is:

1) 1 mm

3) 3 mm

2) 2 mm

5) 8 mm

4) 4 mm

Pressure magnitude is the most influential of all factors considered in cement penetration behavior. The optimal depth of cement penetration is 4 mm. The higher the pressure is inside the femoral canal, the more effectively the cement will interdigitate

■Correct Answer: 4 mm

376. (2642) Q1-3133:

Which of the following most effectively provides the strongest fixation when cementing a prosthesis in a femur:

1) A thin cancellous layer

3) A poor quality cancellous layer

2) No cancellous layer at all

5) A straight-stem femoral prosthesis

4) High-quality, radiodense cancellous bone

The most effective way to provide the strongest fixation when cementing a prosthesis in a femur is to insert it into high-quality, radiodense cancellous bone using a tapered femoral stem, which creates higher intramedullary pressures than a straight stem

■Correct Answer: High-quality, radiodense cancellous bone

377. (2643) Q1-3134:

Which of the following is not a risk factor for fracturing cement around a prosthesis:

1) A sharp corner in the metal

3) A thick cement mantle

2) A cement mantle less than 3 mm thick

5) Local debonding of the cement-metal interface

4) Voids or air bubbles in the cement mantle

Sharp corners in the metal act as chisels and, as time goes by, are driven into the cement causing cracks. A cement mantle less than 3 mm thick, voids or air bubbles in the cement mantle, and local debonding of the cement-metal interface are also risk factors. A thick cement mantle of 4 mm or greater is desired because a thin mantle cannot sustain the prosthesis

■Correct Answer: A thick cement mantle

378. (2644) Q1-3135:

To obtain an adequate cement penetration of 4 mm at a pressure of 0.2 MPA to 0.3 MPA in arthritiCbone, one needs to maintain:

1) 10 kg of pressure for 20 seconds

3) 30 kg of pressure for 30 seconds

2) 20 kg of pressure for 30 seconds

5) 50 kg of pressure for 50 seconds

4) 40 kg of pressure for 30 seconds

To extrapolate the above to the clinical situation, one must maintain a force of 40 kg to 60 kg of pressure for at least a period of

40 to 60 seconds. Adequate penetration of less than 40 kg of pressure for less than 40 seconds does not give adequate cement penetration

■Correct Answer: 50 kg of pressure for 50 seconds

379. (2645) Q1-3136:

Which of the following commercially available cements has the lowest tensile strength value:

1) Palacos-R (Biomet, Warsaw, IN)

3) Simplex P (Stryker, Kalamazoo, MI)

2) Sulfix-60 (Sulzer, Austin, TX)

5) Zimmer Dough (Zimmer, Warsaw, IN)

4) CMW3 (Wright Medical Technology, Inc, Arlington, TN)

Zimmer Dough has the lowest value of tensile strength; however, all of the above are FDA-approved cements and of sufficient quality

■Correct Answer: Zimmer Dough (Zimmer, Warsaw, IN)

380. (2646) Q1-3137:

Which of the following bone cements has demonstrated the lowest cycles to failure:

1) Simplex P (Stryker, Kalamazoo, MI)

3) BoneloC(Biomet, Warsaw, IN)

2) Palacos-R (Biomet, Warsaw, IN)

5) Sulfix-60 (Zimmer, Warsaw, IN)

4) Zimmer Dough (Zimmer, Warsaw, IN)

Simplex P and Palacos-R display outstanding results when tested in the cycliCconditions. BoneloCdemonstrated the lowest cycles to failure

■Correct Answer: BoneloC(Biomet, Warsaw, IN)

381. (2647) Q1-3138:

The most significant factor reducing porosity in bone cement is:

1) Storage temperature only

3) Vacuum-mixing medium viscosity

2) Centrifugation of low viscosity cement

5) Vacuum-mixing only

4) A combination of vacuum-mixing and centrifugation

The most significant factor reducing porosity in bone cement is a combination of centrifugation and vacuum-mixing. If cement is centrifuged and vacuum-mixed, then low viscosity cement is not significantly different from medium viscosity cement. A comparison of storage temperatures at 4° Cand 21° Cshows little effect on cement bubbles or cement voids, or porosity of bone cement

■Correct Answer: A combination of vacuum-mixing and centrifugation

382. (2648) Q1-3139:

ProsthetiCplacement in a cement-filled canal creates highest peak elevations in pressure when:

1) Using a cement restrictor

3) Using mechanical pressurization

2) Using a retrograde filling

5) Inserting the prosthesis early, while the cement is extremely soft

4) Inserting the prosthesis late in the setting phase

ProsthetiCplacement in the cement-filled femoral canal creates transiently higher peak elevations in pressure when inserted late in the setting phase. It creates higher pressures than those obtained with a cement restrictor, retrograde filling, or mechanical pressurization

■Correct Answer: Inserting the prosthesis late in the setting phase

383. (2649) Q1-3140:

The time it takes for the polymer/monomer mixing until polymerization is sufficient to maintain the implant in its correct position is known as:

1) Doughing time

3) Setting time

2) Working time

5) Polymerization time

4) Mixing time

The setting process is described by three critical time periods, which include doughing time, working time, and setting time. The doughing time begins when the polymer and the monomer are mixed until the time when the mixture will not adhere to a gloved hand anymore. Working time implies the time from the start of kneading until the cement is too stiff to be delivered in the bone. The setting time implies the time from the polymer/monomer mixing until polymerization is sufficient to maintain the correct implant position

■Correct Answer: Setting time

384. (2650) Q1-3141:

Cement takes longer to set when using a:

1) Roughened stem

3) Polished femoral stem

2) Precoated femoral stem

5) Cement setting time is not affected by the femoral stem.

4) Irregular femoral stem

Cement sets sooner when using a roughened or precoated femoral stem. It sets later when using a finely polished femoral stem because the cement-prosthesis bond is not influenced by the wetness of the cement

■Correct Answer: Polished femoral stem

385. (2651) Q1-3142:

AcryliCbone cement is composed of:

1) A polymer powder and a polymer liquid component

3) A polymer powder and a monomer liquid component

2) A monomer powder and a monomer liquid component

5) Polymethylmethacrylate  (PMMA) only

4) A monomer powder and a polymer liquid component

Polymethylmethacrylate  (PMMA) is one of the ingredients of acryliCbone cement. The two components of bone cement are a polymer powder component and a monomer liquid component. A blend of ingredients in the polymer and monomer (which includes PMMA) gives cement its unique characteristics

■Correct Answer: A polymer powder and a monomer liquid component

386. (2652) Q1-3143:

The chemical composition of acryliCbone cement is:

1) Benzoyl peroxide and barium sulfate

3) Methylmethacrylate-styrene-copolymer and polymethylmethacrylate

2) Methylmethacrylate-styrene-copolymer

5) Polymethylmethacrylate  and dimethyl-p-toluidine

4) Methylmethacrylate-styrene-copolymer, polymethylmethacrylate,  and barium sulfate

When the monomer liquid is added to the polymer powder, the polymer powder dissolves and releases benzoyl peroxide from the polymer. The benzoyl peroxide initiates a reaction with n,n-dimethyl-p-toluidine  in the monomer, which accelerates the chemical reaction and polymerization. When complete, acryliCbone cement is composed of 75% methylmethacrylate-styrene-copolymer,

15% polymethylmethacrylate,  and 10% barium sulfate

■Correct Answer: Methylmethacrylate-styrene-copolymer, polymethylmethacrylate,  and barium sulfate

387. (2653) Q1-3144:

Bone cement was first used commercially:

1) During World War II in the production of airplane windshields

3) By John Charnley for bonding total hip joints to bone

2) In dentistry for filling cavities

5) As a base material for dentures

4) By neurosurgeons for replacement of skull defects

Otto Rohm, MD, developed polymethylmethacrylate  and introduced it into commercial application. In the 1930s, bone cement was first used commercially as a base material for dentures

■Correct Answer: As a base material for dentures

388. (2654) Q1-3145:

The longest period of survival for cemented total joints is associated with which type of cementation technique:

1) Grade A

3) Grade C1

2) Grade B

5) Grade D

4) Grade C2

The grade A cementation technique is the most advantageous and is associated with the longest period of survival in total joint replacement. One cannot clearly distinguish between the edge of the cement and the edge of the surrounding bone

■Correct Answer: Grade A

389. (2655) Q1-3146:

Which of the following prosthetiCareas is classified as a grade 4 Gruen zone radiographiCdefect:

1) The medullary distal tip of the prosthesis and the cement

3) The lateral lower third of the prosthesis

2) The lateral middle part of the prosthesis

5) The middle part, medial of the prosthesis

4) The medial distal third of the prosthesis

Gruen zones are an effective international classification system whereby radiographiCdefects or errors are evaluated and documented according to zones around a prosthesis. The classification begins with grade 1, which is lateral in the area of the greater trochanter to just below the lesser trochanter. Grade 4 is a radiographiCdefect located at the medullary distal tip of the prosthesis and the cement

■Correct Answer: The medullary distal tip of the prosthesis and the cement

390. (2656) Q1-3147:

Which of the following grades classifies the mode of failure of cemented femoral components in which the whole proximal part of the prosthesis is denude of bone cement and rocks back and forth in the distal part that is fixed with bone cement:

1) Grade Ia

3) Grade III

2) Grade II

5) Grade Ib

4) Grade IV

Modes of failure of cemented femoral components are classified into four grades. In a grade Ia, subsidence of the metal prosthesis in the cement mantle is present. Grade Ib implies that the cement and stem are pistoning distalward. Grade II implies medial migration of the proximal stem and lateral migration of the distal stem. Grade III is classified by a pivot of the calcar part of the prosthesis. Grade IV implies that the whole proximal part of the prosthesis is denude of bone cement and rocks back and forth in the distal part that is fixed with bone cement

■Correct Answer: Grade IV

391. (2657) Q1-3148:

Which of the following latex-free gloves are destroyed by bone cement:

1) Allegard latex-free gloves (Johnson & Johnson, New Brunswick, NJ)

3) Neotech (Regent Medical)

2) Biogel (Regent Medical, Norcross, GA)

5) No latex-free gloves are destroyed by bone cement.

4) Duraprene

Not all brands of latex-free gloves are equally effective. Bone cement destroys Allegard latex-free gloves

■Correct Answer: Allegard latex-free gloves (Johnson & Johnson, New Brunswick, NJ)

392. (2658) Q1-3149:

Which of the following is not a factor in the setting time of cement:

1) Storage temperature of bone cement

3) Handling and kneading of bone cement

2) Ambient temperature

5) Introducing bone cement in a warm environment

4) Use of a cement gun

Storage temperature, ambient temperature, handling and kneading of bone cement, and introducing cement in a warm environment are factors of the setting time of cement. Use of a cement gun is not a factor

■Correct Answer: Use of a cement gun

393. (3067) Q1-3575:

With the use of perineural catheters, improvement in all of the following outcomes can be anticipated except:

1) Lower pain scores

3) Reduced incidence of nausea and vomiting

2) NarcotiCsparing effect

5) Shortened length of stay

4) Increased sleep disturbances

Double blind placebo controlled randomized trials the use of perineural catheters led to improved pain scores, decreased narcotiCusage and narcotiCrelated side effects, and fewer sleep disturbances.

Length of stay was shortened by the use of perineural catheters as compared to epidural or IV PCA analgesia in several studies. In pilot studies, the use of perineural catheters in carefully selected patients allowed ambulatory total shoulder arthroplasty and single day admissions for total hip arthroplasty and total knee arthroplasty

■Correct Answer: Increased sleep disturbances

394. (3068) Q1-3576:

The addition of a sciatiCnerve block to a femoral nerve block will:

1) Enhance analgesia following knee surgery

3) Provide complete anesthesia to the knee

2) Improve mobility

5) Decrease DVT formation

4) Increase the likelihood of nerve injury

Pain from the posterior aspect of the knee joint is diminished with the addition of a sciatiCnerve block to complement a femoral nerve block.

The use of combined femoral sciatiCnerve block impairs ambulation because of the degree of extensive motor block of the quadriceps and muscles of the lower leg. In addition, proprioception that aids in balance is diminished with peripheral nerve block.

The obturator nerve, which contributes to the innervation of the knee capsule, is more frequently anesthetized with a lumbar plexus (posterior approach) than an anterior femoral nerve block. Because of the variability of the cutaneous innervation of the obturator nerve, the only reliable test for measuring obturator nerve block is motor block of the adductors of the thigh. The addition of a sciatiCnerve block will not improve obturator nerve blockade.

Nerve injury after peripheral nerve block of lower extremity is uncommon (<1 in 5,000). The incidence is no higher after combined femoral sciatiCnerve blocks than after single nerve blocks.

Theoretically, the likelihood of DVT formation should be decreased in patients receiving a combined femoral and sciatiCnerve blocks compared to patients who receive no regional anesthesia because of the profound degree of vasodilatation induced by the sympathetiCblock to the lower extremity. To date, no large studies have been performed to prove or disprove this theoretical advantage.

Correct Answer: Enhance analgesia following knee surgery

395. (3238) Q1-4060:

What percent of asymptomatiCosteonecrosis (Stage I Steinberg) with steroid use, alcohol abuse, or an idiopathiCetiology progress to painful symptoms:

1) 10%

3) 50%

2) 30%

5) 90%

4) 70%

In several combined studies that involved 83 asymptomatiCstage 1 osteonecrosis of the femoral head associated with steroid use, alcohol abuse, or idiopathiCetiology, only 27 (33%) hips progressed to symptoms after 6 to 36 months.

TABLE II. Review of the Literature of the Evolution for other AsymptomatiCStage-I Hips Treated Nonoperatively

Study              Number of Hips Duration of Follow-up(mo) SymptomatiCProgression

Stulberg et al                         3                                26.8                                     2 of 3

Kopecky et al                        25                                16                                      7 of 25

Takatori et al                        32                               20.9                                   14 of 32

Fordyce and Solomon             5                                 36                                      2 of 5

Mulliken et al                         11                                22                                      0 of 11

Davidson                               7                                 6.5                                      2 of 7

Total                                                                                                                  27 of 83

Correct Answer: 30%

396. (3239) Q1-4061:

In addition to developing pain, what percent of patients with asymptomatiCosteonecrosis and sickle cell disease will have hips that collapse:

1) 10%

3) 50%

2) 30%

5) 90%

4) 70%

Seventy-seven percent of 121 asymptomatiChips studied by Hernigou and colleagues went on to collapse. Their results suggest that patients with sickle cell disease with asymptomatiCstage I and II osteonecrosis is more rapid and frequent than previously assumed with osteonecrosis related to steroid or alcohol use

■Correct Answer: 70%

397. (3240) Q1-4062:

Which of the following percentages represents the number of patients with homozygous sickle cell disease that will develop osteonecrosis of the femoral head by age 35:

1) 10%

3) 50%

2) 30%

5) 90%

4) 70%

Osteonecrosis of the femoral head is a common complication in patients with sickle cell disease, and the prevalence of complications peaks in adolescence. Osteonecrosis of the femoral head develops by the age of 35 in nearly half of all patients with homozygous sickle cell disease

■Correct Answer: 50%

398. (3241) Q1-4063:

Bilateral hip involvement with osteonecrosis is seen in what percent of patients with sickle cell disease:

1) 5%

3) 20%

2) 10%

5) 50%

4) 30%

Bilateral hip involvement in patients with sickle cell disease with osteonecrosis is found in 40% to 90% of all patients. Without intervention, the rate of femoral head collapse in patients with sickle cell disease is 87% within 5 years after initial diagnosis of the osteonecrosis, but it can be as high as 90% within 2 years after the initial diagnosis

■Correct Answer: 50%

399. (3242) Q1-4064:

Failure rates, based on pain and limitation of motion, after total hip replacements (THR) in patients with sickle cell disease is:

1) 10%

3) 50%

2) 25%

5) 90%

4) 75%

Seventy-five percent of patients with sickle cell disease who had undergone THR were found to have ongoing pain and substantial limitation of motion. Because of these unfavorable results, there is considerable interest in evaluating treatment regimens that will postpone the need for THR in this population

■Correct Answer: 75%

400. (3243) Q1-4066:

What is the prevalence of sickle cell disease among African Americans:

1) 1/6

3) 1/600

2) 1/60

5) 1/60,000

4) 1/6000

Sickle cell disease denotes all genotypes containing one sickle cell gene and another variant hemoglobin encoding gene (eg, HbC, HbS, HbD). These result in phenotypes where HbS constitutes at least 50% of the present hemoglobin. It is estimated that 1 of every 600 African Americans has sickle cell disease. Six major subsets of sickle cell disease exist, with mutation type determining disease severity

■Correct Answer: 1/600