ORTHOPEDICS HYPERGUIDE MCQ 251-300

251. (1843) Q1-2245:

C-reactive protein (CRP) peaks 48 hours postoperatively and rapidly declines to normal in           weeks without persistent infection or inflammation.

1) 1 to 2

3) 4 to 6

2) 2 to 3

5) 8 to 10

4) 5 to 7

The CRP returns to normal in 2 to 3 weeks without persistent infection or inflammation. High levels beyond 2 to 3 weeks suggest persistent infection

■Correct Answer: 2 to 3

252. (1844) Q1-2246:

As the most direct and predictable preoperative diagnostiCtest for hip infection, the false-positive rate for hip aspiration is:

1) 0%

3) 15% to 25%

2) 0% to 15%

5) 40% to 50%

4) 25% to 40%

Hip aspiration has a false-positive rate of 0% to 15%. Many authors have warned against its routine use before revision surgery

■Correct Answer: 0% to 15%

253. (1845) Q1-2247:

What levels of polymorphonuclear leukocytes (PMN) per high-power field (HPF) are inconsistent with infection when performing intraoperative frozen sections of total joint replacement:

1) No value as predictor

3) <8 PMN/HPF

2) <5 PMN/HPF

5) <15 PMN/HPF

4) <10 PMN/HPF

When using <5 PMN/HPF as a cut off for an infected total joint, the sensitivity was 100% and specificity was 96%

■Correct Answer:

<5 PMN/HPF

254. (1846) Q1-2248:

False-positive results with intraoperative culture as confirmation of periprosthetiCjoint infection are reported to be:

1) 5%

3) 15%

2) 10%

5) 25%

4) 20%

The false-positives results are reported to be between 6% and 13% and are probably related to break in sterility while obtaining, transferring, and plating the specimen

■Correct Answer: 10%

255. (1847) Q1-2249:

It is recommended to use which of the following drugs in patients who are too sick for a surgical procedure and antibiotiCsuppression:

1) Amikacin

3) Imipenem

2) Ofloxacin

5) Rifampin

4) Vancomycin

Amikacin, ofloxacin, imipenem, and vancomycin are only effective against growing bacteria. Rifampin, which affects messenger RNA synthesis, is the only drug capable of inducing strong enough pharmacodynamiCeffects to inhibit both growing and nongrowing Staphylococcus epidermidis

■Correct Answer: Rifampin

256. (1848) Q1-2250:

The highest dislocation rate for total hip arthroplasty is associated with which of the following surgical approaches:

1) Anterior approach

3) TranstrochanteriCapproach

2) Posterior approach

5) All of the approaches have the same incidence of dislocation.

4) Hardinge approach

The anterior approach has a dislocation rate of 3.5%, posterior approach 4.6%, and transtrochanteriCapproach 7.6%.Correct

Answer: TranstrochanteriCapproach

257. (1849) Q1-2251:

The prevalence of dislocation following a primary bipolar hemiarthroplasty is:

1) The same as primary total hip arthroplasty

3) Lower than primary total hip arthroplasty

2) Higher than primary total hip arthroplasty

5) Not dependent on the surgical approach

4) Higher than semipolar hemiarthroplasty

The prevalence of dislocation following a primary bipolar hemiarthroplasty is 1.5% compared to 3.5% or higher (depending on the surgical approach) for a total hip arthroplasty

■Correct Answer: Lower than primary total hip arthroplasty

258. (1850) Q1-2252:

Which of the following patient-related factors is a risk factor for dislocation after total hip arthroplasty:

1) Gender

3) Acute femoral neck fracture

2) Height

5) Previous knee surgery

4) Weight

In addition to an acute femoral neck fracture, other patient-related factors associated with dislocation after total hip arthroplasty include patients older than 80 years and previous hip surgery

■Correct Answer: Acute femoral neck fracture

259. (1851) Q1-2253:

Which of the following factors is associated with the highest incidence of total hip dislocation after surgery:

1) Acetabular component malposition in a vertical position

3) Acetabular component in a retroverted position

2) Femoral component malposition in a varus position

5) Femoral component malposition in a valgus position

4) Muscular imbalance

A computed tomography study of dislocated total hip arthroplasties (THAs) compared to uncomplicated THAs showed no difference between the alignment of the components in either group. Muscular imbalance rather than malposition of components was the major factor in determining dislocation

■Correct Answer: Muscular imbalance

260. (1852) Q1-2254:

Which of the following is associated with an increased risk of dislocation after a total hip arthroplasty:

1) Elevated rim liner

3) 32-mm femoral head

2) Skirt (reinforcement of the bone at the neck)

5) Ceramic-on-ceramiChip arthroplasty

4) Metal-on-metal hip arthroplasty

There is an increased risk of dislocation with a skirt. The elevated rim liner decreases the risk of a dislocation, and a 32-mm femoral head may or may not have a decreased rate of dislocation

■Correct Answer: Skirt (reinforcement of the bone at the neck)

261. (1853) Q1-2255:

Which of the following factors is not associated with dislocation of a total hip arthroplasty:

1) Infection

3) Profound weight loss

2) Trauma

5) Gender

4) ChroniCillness

Infection, trauma, and profound weight loss are associated with an increased risk of dislocation. Infection with septiCfluid accumulation stretches the capsule. Trauma from a fall is a direct cause of dislocation, and profound weight loss with its accompanying loss of muscle mass (as a result of cancer or chroniCillness)

■Correct Answer: Gender

262. (1854) Q1-2256:

What percentage of patients with an initial dislocation of the hip will have recurrent dislocation:

1) 5%

3) 20%

2) 10%

5) 50%

4) 33%

One-third of patients with a dislocated total hip arthroplasty will have recurrent dislocations. This number is potentially minimized by having patients wear an abduction splint for 6 to 12 weeks after the initial dislocation

■Correct Answer: 33%

263. (1855) Q1-2257:

The highest incidence of deep infection in total hip arthroplasty is associated with what patient group:

1) Patients with rheumatoid arthritis

3) Patients with diabetes mellitus

2) Patiens with psoriatiCarthritis

5) Women

4) Patients with avascular necrosis

The highest incidence of deep infection is in patients with diabetes mellitus (5.6%) compared to patients with rheumatoid arthritis (1.2%) and patients with psoriatiCarthritis (5.5%). Any immune-compromised  patient is at a higher risk for infection following total hip arthroplasty

■Correct Answer: Patients with diabetes mellitus

264. (1856) Q1-2258:

The most common complication after total hip arthroplasty is:

1) Infection

3) Deep vein thrombosis

2) Dislocation

5) Urinary tract infection

4) Pulmonary embolism

The incidence of deep vein thrombosis is as high as 70% and as low as 8%

■Correct Answer: Deep vein thrombosis

265. (1857) Q1-2259:

The incidence of deep vein thrombosis is reported to be highest on postoperative day:

1) 1

3) 3

2) 2

5) 5

4) 4

The incidence of deep vein thrombosis is reported to be highest on postoperative day 4

■Correct Answer: 4

266. (1858) Q1-2260:

Which of the following is the gold standard to rule out a pulmonary embolism:

1) Radiograph

3) Electrocardiogram

2) Ventilation perfusion scan

5) Pulmonary angiogram

4) Ultrasonography

The gold standard for detecting pulmonary embolus is the pulmonary angiogram, although a combination chest radiograph, ventilation perfusion scan, and electrocardiogram is usually performed

■Correct Answer: Pulmonary angiogram

267. (1859) Q1-2261:

What incidence of bleeding complications is attributed to the treatment of postoperative thomboemboliCdisease with heparin when it is administered intravenously in the first 6 days after total hip arthroplasty:

1) 5%

3) 25%

2) 15%

5) 60%

4) 45%

The risk of bleeding complications from therapeutiCanticoagulation is high in the immediate postoperative period with a 45%

incidence

■Correct Answer: 45%

268. (1860) Q1-2262:

All of the following conditions are associated with an increased risk of heterotopiCossification after total hip arthroplasty except:

1) Ankylosing spondylitis

3) PosttraumatiCarthritis

2) Forestier disease

5) Rheumatoid arthritis

4) Men with bilateral osteophytiCosteoarthritis

Ankylosing spondylitis, Forestier disease, posttraumatiCarthritis, and men with bilateral osteophytiCosteoarthritis are associated with an increased risk of heterotopiCossification following total hip arthroplasty

■Correct Answer: Rheumatoid arthritis

269. (1861) Q1-2263:

What is the lowest dose of radiation that is effective in preventing heterotopiCbone formation after total hip arthroplasty:

1) 1000 Rads

3) 3000 Rads

2) 2000 Rads

5) 5000 Rads

4) 4000 Rads

A protocol of 1000 Rads is as effective as 2000 Rads

■Correct Answer: 1000 Rads

270. (1862) Q1-2264:

The incidence of trochanteriCnonunion after greater trochanteriCosteotomy in primary total hip arthroplasty is:

1) 5%

3) 15%

2) 10%

5) 25%

4) 20%

There is a 5% incidence of trochanteriCnonunion after greater trochanteriCosteotomy in primary total hip arthroplasty.Correct

Answer: 5%

271. (1863) Q1-2265:

The main purpose of a trochanteriCosteotomy is to:

1) Decrease the operative time

3) Lateralize the adduction mechanism

2) Enhance exposure

5) Decrease the blood loss

4) Prevent dislocation

Enhancing exposure and lateralizing the abductor mechanism are the main reasons for performing an osteotomy. The osteotomy must be balanced against the increased blood loss, operative time, and slower rehabilitation

■Correct Answer: Enhance exposure

272. (1864) Q1-2266:

Breakage of stems in total hip arthroplasty is related to all of the following except:

1) Excessive head-stem offset

3) Size of stem

2) Modularity

5) Inadequate cross-sectional area

4) Material strength

All of the factors, except modularity, contribute to early stem breakage in the first generation of total hips

■Correct Answer: Modularity

273. (1865) Q1-2267:

In early first-generation total hip implant designs, fatigue fractures occurred in which of the following areas of the femoral stem:

1) Posterolateral

3) Anterolateral

2) Posteromedia

5) Anterior

4) Anteromedial

In early first-generation total hip implant designs, fatigue fractures occurred anterolaterally because that was the area of greatest tension. Fatigue fractures are less common in compression

■Correct Answer: Anterolateral

274. (1866) Q1-2268:

Total hip arthroplasty for a congenital dislocated hip has a nerve injury incidence of:

1) 5%

3) 15%

2) 10%

5) 25%

4) 20%

The incidence of nerve injury following congenital dislocated hip is 5.2% compared to 0.6% to 3.7% for routine total hip arthroplasty

■Correct Answer: 5%

275. (1867) Q1-2269:

Which of the following arteries is at the greatest risk for vascular injury during a total hip arthroplasty for protrusio acetabuli:

1) Femoral artery

3) Common iliaCartery

2) Obturator artery

5) Popliteal artery

4) Peroneal artery

The common and superficial iliaCarteries are most at risk in patients with protrusio acetabuli. The obturator is not at risk when removing the transverse ligament from the inferior margin of the cup

■Correct Answer: Common iliaCartery

276. (1868) Q1-2270:

Debonding (separation of the femoral stem from the surrounding cement mantle) is caused by:

1) Tension forces from muscle contraction

3) Torsional forces in retroversion

2) Strain at the cement-metal interface

5) Compression forces from muscle contraction

4) Rotational forces in anteversion

When arising from a chair or climbing the stairs, the stem shifts to a more retroverted position within the cement mantle secondary to the peak torsional forces in retroversion

■Correct Answer: Torsional forces in retroversion

277. (1869) Q1-2271:

Which of the following terms is defined as a fundamental wear mechanism in joint replacement known as bonding of the surfaces when they are pressed together under load:

1) Abrasion

3) Adhesion

2) Fatigue

5) Compression

4) Cohesion

Abrasion, fatigue, and adhesion are fundamental wear mechanisms. Adhesion is the binding of the surfaces when they are pressed together under load

■Correct Answer: Adhesion

278. (1870) Q1-2274:

The volumetriCwear of polyethylene is greatest with what size head:

1) 32 mm

3) 26 mm

2) 28 mm

5) 20 mm

4) 22 mm

The volumetriCwear of polyethylene is proportional to the size of the femoral head and larger femoral heads have a longer sliding distance that results in greater wear

■Correct Answer: 32 mm

279. (1871) Q1-2275:

Preparing and sterilizing polyethylene with gamma radiation:

1) Increases the molecular weight of the material

3) Increases recombination of the polyethylene particles

2) Decreases free radicals that can react with carbon dioxide

5) Increases free radicals that react with carbon dioxide

4) Stabilizes free radicals that react with carbon dioxide

Gamma radiation prevents recombination, decreases the molecular weight of the material, and increases free radicals that react with carbon dioxide to form ketone esters and carboliCacid groups

■Correct Answer: Increases free radicals that react with carbon dioxide

280. (1872) Q1-2276:

In osteolysis, small wear debris is broken down and ingested by:

1) Polymorphonuclear neutrophils

3) Macrophages

2) Foreign body giant cells

5) Osteoblasts

4) Histiocytes

Small wear debris is phagocytosed by macrophages. Large wear debris is surrounded by foreign body giant cells

■Correct Answer: Macrophages

281. (1873) Q1-2278:

Based on the volume of polyethyelene wear in some total hip arthoplasties and the average portal size, the number of particles generated with each gait cycle is:

1) 500

3) 100,000

2) 50,000

5) 500,000

4) 300,000

The average number of particles generated with each gait cycle is approximately 500,000

■Correct Answer: 500,000

282. (1982) Q1-2396:

All of the following are consequences of using too large of a femoral component in total knee replacement except:

1) Overstuffing the joint

3) Decreasing range of motion

2) Limitation of quadriceps excursion

5) Increasing range of motion

4) A cause of postoperative knee pain

Too large of a femoral component in total knee replacement may result in overstuffing the joint, limiting quadriceps excursion, and decreasing range of motion

■Correct Answer: Increasing range of motion

283. (1983) Q1-2397:

It is acceptable for the joint line to be elevated how many millimeters during total knee replacement surgery:

1) 0 mm

3) 2 mm

2) 1 mm

5) 4 mm

4) 3 mm

It is acceptable for the joint line to be raised approximately 2 mm during total knee replacement, but any higher elevation may create mid-flexion laxity

■Correct Answer: 2 mm

284. (1984) Q1-2399:

When performing a total knee replacement and you are in between sizes, it is best to:

1) Downsize the femoral component and recut the femur in 3° of flexion

3) Upsize the prosthesis

2) Downsize the femoral component and recut the femur in 6° of flexion

5) Upsize the prosthesis and recut the femur in 6° of extension.

4) Downsize the femoral component and minimalize notching the anterior cortex

An option for downsizing without notching is to recut the distal femur in slight flexion, applying a modified distal cutting block that will add several degrees of flexion to the distal cut. Recutting the distal femur in slight (3°) flexion has the following rationale: the normal trochlear flange of most components already diverges approximately 3°. By adding another 3° of flexion one can use a smaller component because the trochlear flange will now diverge 6°, avoiding a notch in the anterior cortex. The advantage is that the posterior condylar resection remains anatomiCand the level of the joint line is preserved

■Correct Answer: Downsize the femoral component and recut the femur in 3° of flexion

285. (1985) Q1-2400:

The primary features of a posterior stabilized total knee replacement include all of the following except:

1) Femoral cam

3) Conforming articular geometry

2) Polyethylene post on the tibial component

5) Constrained hinge

4) Use of cement

The primary features of posterior stabilized total knee devices include femoral cam, polyethylene post on the tibial component, conforming articular geometry, and use of cement. These characteristics have produced total knee prostheses with unsurpassed clinical survivorship and patient function

■Correct Answer: Constrained hinge

286. (1986) Q1-2401:

The clinical survivorship of posterior stabilized prostheses at 10 years is:

1) 80%

3) 90%

2) 85%

5) 98%

4) 95%

The clinical survivorship of posterior stabilized prostheses is spectacular by any standards with a success rate of approximately

95% of prostheses that were free from revision due to aseptiCloosening at 10 to 15 years

■Correct Answer: 95%

287. (1987) Q1-2402:

If the posterior cruciate ligament (PCL) is too loose in flexion in a cruciate-retaining prosthesis, the result is:

1) Flexion gap

3) Increased posterior sliding of the femorotibial contact point

2) Extension gap

5) Hyperextension deformity

4) Restricted flexion

If the PCL is too loose, anterior translation of the femorotibial contact point will occur, whereas if the PCL is too tight, flexion will be restricted

■Correct Answer: Flexion gap

288. (1988) Q1-2403:

If the posterior cruciate ligament (PCL) is too tight in flexion in a cruciate-retaining total knee replacement, the result is:

1) Flexion gap

3) Restricted flexion

2) Restricted extension

5) Increased flexion

4) Hyperextension deformity

If the PCL is too loose, anterior translation of the femorotibial contact point will occur, whereas if the PCL is too tight, flexion will be restricted

■Correct Answer: Restricted flexion

289. (1989) Q1-2404:

If a flexion gap is observed while performing a trial reduction of components before cementing a total knee replacement, a surgeon should consider:

1) Using a smaller tibial insert

3) Resecting more femur in extension

2) Resecting more tibial bone

5) Increasing the size of the femoral component

4) Using a deep dish insert

Hofmann and colleagues reviewed their use of ultracongruent polyethylene over 7 years in 100 patients who underwent PCL- substituting total knee arthroplasties. Fifty-three cases were primary and 47 were revisions. There were no cases of anteroposterior (AP) instability in either revision or primary cases when a deep-dish polyethylene was inserted. The incidence of AP instability using standard inserts was 2% to 3%

■Correct Answer: Using a deep dish insert

290. (1990) Q1-2405:

Patellar clunk syndrome is caused by:

1) Too large a patellar component

3) Fibrous tissue build-up occurring in a large intercondylar notch of the prosthesis

2) Too small a patellar component

5) Dislocation of the quadriceps mechanism over a malrotated femoral component

4) Too large a femoral component

Patellar clunk occurs from a large intercondylar notch of the prosthesis, which causes fibrous tissue build-up proximally and can result in 1% to 2% of patients requiring arthroscopiCdebridement

■Correct Answer: Fibrous tissue build-up occurring in a large intercondylar notch of the prosthesis

291. (1991) Q1-2406:

All of the following is a reported complication of posts in posterior cruciate-retaining prostheses except:

1) Patellar fracture

3) Patellar clunk syndrome

2) Knee dislocation

5) Flexion instability

4) Post fracture

Complications reported with the use of posts include patellar fractures, knee dislocations, and patellar clunk syndrome.Correct

Answer: Flexion instability

292. (1992) Q1-2407:

In a posterior cruciate-retaining prosthesis, most stress at the posterior cruciate ligament occurs in:

1) Extension

3) 30° flexion

2) 15° flexion

5) 90° flexion

4) 45° flexion

A consequence of the kinematics of a crossed four-bar link is the phenomenon of rollback, that is, the progressive movement of the femoral condyle posteriorly relative to the tibia with increasing flexion

■Correct Answer: 90° flexion

293. (1993) Q1-2408:

Cruciate ligament deficiency can lead to abnormalities during all of the following except:

1) Stair climbing

3) Walking on uneven ground

2) Rising from a chair

5) Full extension

4) Stepping up a curb

Cruciate ligament deficiency can lead to abnormalities during stair climbing, rising from a chair, and walking on uneven ground

■Correct Answer: Full extension

294. (1994) Q1-2410:

C-reactive protein should return to normal how many weeks after a total knee replacement surgery:

1) 1 week

3) 3 weeks

2) 2 weeks

5) 12 weeks

4) 6 weeks

C-reactive protein should return to normal within 3 weeks of surgery

■Correct Answer: 3 weeks

295. (1995) Q1-2411:

One can best avoid bone stiffness after total knee replacement (TKR) by:

1) Careful attention to proper sizing of the components

3) Maintenance of physiologiCsoft tissue tension in complete extension and at 90° of flexion

2) Restoration of the mechanical axis and anatomiCjoint line

5) None of the above

4) All of the above

Avoiding stiffness after TKR is easier than managing the stiff total knee. Careful attention to proper sizing of components, restoration of the mechanical axis and anatomiCjoint line, and maintenance of physiologiCsoft-tissue tension in complete extension and at 90° of flexion will minimize the risk of stiffness following TKR

■Correct Answer: All of the above

296. (1996) Q1-2412:

Flexion contractures after total knee replacement are best treated by:

1) Manipulation

3) DynamiCextensor splint

2) Physical therapy

5) All of the above

4) Physical therapy, and dynamiCextensor splint

Flexion contractures are treated with physical therapy and the use of a dynamiCextension splint at night

■Correct Answer: Physical therapy, and dynamiCextensor splint

297. (1997) Q1-2413:

The incidence of periprosthetiCfracture about total knee replacement is:

1) 0.2%

3) 5%

2) 3%

5) 9%

4) 7%

PeriprosthetiCfractures about total knee arthoplasty (TKA) are relatively rare (0.5% to 3%)

■Correct Answer: 3%

298. (1998) Q1-2414:

Wear debris particles in cross-linked polyethylenes are:

1) Less than 0.1 µm

3) 1 µm to 2 µm

2) 0.1 µm to 0.5 µm

5) Larger than 3 µm

4) 2 µm to 3 µm

Studies have shown that cross-linked polyethylenes are stiffer and weaker than conventional polyethylene, and wear debris particles generated usually are less than 1 µm (0.1 µm to 0.5 µm), which is the most biologically active particle size

■Correct Answer: 0.1 µm to 0.5 µm

299. (1999) Q1-2415:

Which of the following is the most common cause for revising a total hip arthroplasty (THA) when polyethylene is used:

1) Infection

3) Debris-associated osteolysis

2) Thigh pain

5) ChroniCdislocation

4) Wear

Debris-associated osteolysis is the most common cause for revision THA when polyethylene is used. ChroniCdislocation, thigh pain, wear, and infection are less common causes for revision

■Correct Answer: Debris-associated osteolysis

300. (2000) Q1-2416:

Which of the following bearing surfaces has the lowest rate of wear in total hip arthroplasty:

1) Polyethylene-metal bearings

3) Ceramic-metal bearings

2) Metal-metal bearings

5) Alumina ceramic-ceramiCbearings

4) Ceramic-polyethylene  bearings

According to retrieval studies of Clarke and colleagues, alumina ceramic-ceramiCbearings have the lowest rate of wear of any bearing surface

■Correct Answer: Alumina ceramic-ceramiCbearings

301. (2001) Q1-2417:

Staphylococcus epidermidis adheres:

1) More strongly to polyethylene

3) Similarly to both polyethylene and alumina ceramic

2) More strongly to alumina ceramic

5) More strongly to polymethylmethacrylate

4) This has not been studied in a laboratory setting.

Staphylococcus epidermidis adheres 2.5 times more strongly to high density polyethylene than alumina ceramic

■Correct Answer: More strongly to polyethylene