ORTHOPEDICS HYPERGUIDE MCQ 101-150

After removing a femoral stem, the best way to prevent fracture of the femur is:

Metaphyseal cement tends to be bulky, and the bone tends to be thin and weak. Initial debulking of the cement with a high-speed burr prevents fracture during attempts at removal of the cement

■Correct Answer: Debulk the metaphyseal cement

When removing the cement mantle by cementing a threaded extractor into the mantle, the polymethylmethacrylate (PMMA) can be removed because:

Because the bond of the PMMA to PMMA is stronger then the bond of PMMA to bone, the mantle can be removed in a piecemeal fashion using a threaded extractor. It is often necessary to cement in the extractor multiple times when performing this removal technique

■Correct Answer: The bond of the new PMMA to the old PMMA is stronger than the bond of PMMA to bone.

Which of the following statements is not true of polymethylmethacrylate  (PMMA):

PMMA is a grout and is strong in compression and weak in tension. Tension forces ultimately cause failure of PMMA.

CorrectAnswer: PMMA is strongest in tension and weakest in compression.

When making perforations in the cortex of the femur, the perforations should be placed:

Perforations of the femur should be placed anteriorly or anterolaterally. The axis of neutral stress for the proximal femur is in a sagittal plane in the anterior femur

■Correct Answer: Anteriorly

When making a femoral window, the tip of the new stem must bypass the window by:

In the femoral window technique and the extended trochanteriCtechnique, the revision stem must bypass the defect in the femoral cortex by at least two femoral diameters to prevent fracture adjacent to the osteotomy

■Correct Answer: Two femoral diameters

When making perforations in the cortex of the femur, the perforations should be placed how far apart:

The holes placed in the anterior cortex in this article were 9 mm in diameter. This study showed that placing the hole less than two diameters apart increased the stress in the area between the holes, which could lead to an increased incidence of fracture

■Correct Answer: Two hole diameters

Reconstructive open methods to obtain femoral neck union of failed femoral neck fractures include all of the following except:

The Meyers pedicle graft revascularizes the nonunion site. The valgus intertrochanteriCosteotomy converts shear forces at the nonunion site to compressive forces and promotes fracture healing. These are the two most common reconstructive open methods. Varus osteotomy is not an open reconstructive method to obtain femoral neck union of a failed femoral neck fracture

■Correct Answer: Varus osteotomy

When deciding between a hemiarthroplasty and total hip replacement (THR) to serve as a salvage procedure for femoral neck nonunions, one may choose a THR because:

THR provides better pain relief then a hemiarthroplasty, but THR is a bigger procedure with more risk of dislocation. There is an increased chance of leg length inequality with a THR, and reimbursement should never be a deciding factor for a particular surgery

■Correct Answer: There is better pain relief.

Which of the following is the preferred method for treating intertrochanteriCnonunions in young patients:

Blade plate and autogenous bone graft is the preferred method for treating intertrochanteriCnonunions in young patients. The femoral head will retain its vascularity and remain viable, so solutions such as hemiarthroplasty and THR should be reserved for older patients

■Correct Answer: Blade plate and autogenous bone graft

Which of the following is the best treatment for older patients with a failed intertrochanteriCfracture and bone loss near the lesser trochanter:

A calcar replacement implant is required to provide leg length and gain hip stability, and a long-stem implant is often required to bypass screw holes in the femur

■Correct Answer: Calcar replacement implant with long stem

Which of the following factors is of least importance when considering the preoperative planning of a revision total knee replacement:

Adequate imaging and planning must include an assessment of the size and location of bone defects, the integrity of the extensor mechanism collateral ligaments, and the soft tissue envelope including the skin

■Correct Answer: Bone density

According to Enghâs classification of bone defects in failed total knee arthroplasty, type 2 defects usually require:

Cement and morcelized bone graft are usually reserved for type 1 defects. Type 2 defects usually require an augmented femoral or tibial component, whereas type 3 defects require a structural bone graft and often a hinged component

■Correct Answer: Augmented femoral or tibial components

When using a structural bone graft in type 3 bone defects (Enghâs classification), which of the following statements is incorrect:

In type 3 defects (F3 or T3), it is necessary to step cut the allograft and gain stability by using plates and screws or cerclage wires. The stem between host bone and graft must bypass the junction by at least 2 cortical diameters

■Correct Answer: Use a stem to bypass the junction between host bone and graft by 1 cortical diameter.

Hip fusion is indicated for all of the following except:

Hip fusion is best indicated for the young and active, or heavy patient who does not have bilateral hip disease. Secondary pain occurs in the lumbosacral area in later years, but a good fusion obviates the possible need for multiple revision total hip replacements

■Correct Answer: Patients with bilateral hip disease

After at least 15 years of follow-up, what percent of patients with hip arthrodesis will have significant back or ipsilateral knee pain:

At 17 to 50 yearsâ follow-up, approximately 60% of patients with arthrodesis will have significant back or ipsilateral knee pain. Significant back or knee pain at 15 years must be balanced against revision total hip replacement at 15 years

■Correct Answer:

60%

For a successful hip arthrodesis, the hip should be fused in:

A successful hip arthrodesis depends on rigid fixation and proper positioning of the limb at 20° to 30° of flexion relative to the torso, neutral abduction/adduction, and 0° to 5° external rotation

■Correct Answer: 20° flexion, neutral abduction/adduction,

0° of external rotation

The most important factor in achieving a satisfactory result when converting a fused hip to a total hip arthroplasty is:

Preservation of the abductor mechanism is the most important factor when converting an arthrodesis to a total hip arthroplasty

■Correct Answer: Preserving the abductor mechanism at time of fusion

Surgical exposure in total knee replacement is best facilitated by all of the following except:

Performing the surgery with the knee flexed, externally rotating the flexed knee and peeling off medial tissues subperiosteally, removing a significant portion of the fat pad, and cutting the patellofemoral ligament facilitate surgical exposure when performing a total knee replacement

■Correct Answer: Keeping the fat pad intact

To obtain good patellar tracking during total knee replacement, a surgeon must not:

A lateral release is not always required. The femoral component must be slightly externally rotated instead of internally rotated. The patella will track better if the patellar implant is positioned slightly medial

■Correct Answer: Place the femoral component in slight internal rotation

Bone cuts are more important than soft tissue balancing when performing a total knee replacement. The consideration least important in your decision making is

Soft tissue balancing and flexion-extension space balancing are as important as the bone cuts

■Correct Answer: Gender specifiCknee replacement

In reviewing instability patterns of nonseptiCrevision total knee replacements, most total knee replacements required revision because of:

Most nonseptiCrevision total knee replacements are a result of soft tissue problems (41%), followed by flexion-extension space mismatch (34%), and insufficient correction of an initial fixed deformity (21%). Only 4% were secondary to bony cut malalignment

■Correct Answer: Soft tissue problems

Which of the following is the best way to predict that a patient is able to obtain full extension after total knee replacement:

Performing the âbounceâ or âpushâ test is the best test, performed at the time of trial reduction, to predict if a patient will achieve full extension postoperatively. One lifts the leg by the ankle in the extended position while pressing proximally on the sole of the foot

■Correct Answer: Lifting the leg by the ankle in the extended position while pressing proximally on the sole of the foot

Which of the following patients are least at risk for extensor-mechanism disruption after total knee replacement:

Obese patients, patients with patellar baja, and patients with previous extensor-mechanism realignment, as well as patients with markedly diminished range of motion, are most at risk for extensor-mechanism disruption

■Correct Answer: Thin patients

Component factors associated with increased stress on the extensor mechanism include all of the following except:

Increased stress on the extensor mechanism involves an oversized femoral component, anterior translation of the femoral component, a thick patella, and elevation of the joint line. An undersized femoral component does not increase the stress on the extensor mechanism

■Correct Answer: An undersized femoral component

Which of the following is the most common level of extensor-mechanism disruption after total knee replacement:

Patellar fracture is the most common level of extensor-mechanism disruption after total knee replacement; however, all of the above have been observed. This is often related to excessive resection of the patella when placing the patella component

■Correct Answer: Patellar fracture

Which of the following statements is not true regarding chroniCpatellar tendon ruptures:

ChroniCpatellar tendon ruptures can severely interfere with the extensor mechanism after total knee replacement. They are usually associated with an abnormal tendon and abnormal histology. Often, chroniCpatellar tendon ruptures must be substituted with an allograft to obtain reasonable function

■Correct Answer: The patellar tendon is histologically normal.

Which of the following is the best indication for hip arthroscopy:

Indications for hip arthroscopy include labral tears, loose bodies, synovial chondromatosis, chondral flap lesions, and foreign body removal. Hip arthroscopy is less important as a diagnostiCtool for a disease entity, such as rheumatoid arthritis or osteonecrosis, because laboratory studies are more specific

■Correct Answer: Labral tears

Conventional magnetiCresonance imaging can detect a labral tear of the hip what percent of the time:

Conventional magnetiCresonance imaging is only 5% effective in detecting labral tears, but, if combined with gadolinium, its sensitivity is increased to 49%. The dye can more easily identify a labral tear, but it does not approach 100% effectiveness. Clinical symptoms and history are also important when considering hip arthroscopy

■Correct Answer: 5%

In dysplastiChips, labral tears most often occur in which of the following locations:

Seventy-two percent of dysplastiChips had labral tears. Sixty-six percent of the tears were anterior, 5% were posterior, and 0.6% were lateral. In dysplastiChips, abnormal pressure is placed on the anterior labrum because of subluxation

■Correct Answer: Anterior

In terms of design for posterior stabilized implants, it is important for the components to incorporate                  before impingement occurs.

It is important to incorporate some hyperextension in the posterior stabilized prosthesis because there is a tendency to place the femoral component in flexion and the tibial component in some posterior slope, which creates overall hyperextension

■Correct Answer: Some hyperextension

When using a primary total knee replacement implant in a patient with distal femoral bone loss:

One moves the joint line proximally with distal femoral bone loss resulting in extension instability and loss of flexion. Tibial bone loss moves the joint line distally. There is no flexion instability in a patient with distal femoral bone loss

■Correct Answer: The joint line will be moved proximally.

In revision total knee replacement, if one uses a revision femoral component that is thicker than the distal femoral bone loss, then:

The joint line is moved distally. The knee does not extend fully and there will be resultant flexion instability

■Correct Answer: The joint line will move distally.

In a total knee replacement, when sizing the femur from posterior up, if the patient is between sizes and the larger size is implanted, then:

Implanting the larger size component will limit both quadriceps excursion and range of motion because it will âstuffâ the joint. The knee will have limited range of motion

■Correct Answer: Range of motion will be limited

In a total knee replacement, one of the consequences of sizing from anterior down, when in between sizes is that:

Sizing from anterior down will increase resection of the posterior condyle. This results in a flexion gap and flexion instability

■Correct Answer: It creates a flexion gap.

A flexion gap observed when trialing for a total knee replacement can be corrected by:

Without going to a posterior stabilized total knee replacement, one can put in a thicker tibia insert and increase the femoral resection to correct a flexion gap. Resecting more tibia increases the flexion gap. Resecting more femur without a thicker tibia insert creates more instability

■Correct Answer: A thicker tibia insert and increased femoral resection

136. (1693) Q1-2089:

It is possible to downsize without notching by cutting the distal femur in:

1) 5° varus

3) 3° flexion

2) 5° valgus

5) 3° extension

4) 10° flexion

The normal trochlear flange of most components diverges approximately 3°. Therefore, if one recuts the distal femur in slight

(3°) flexion, then, because the trochlear now diverges 6°, one can use a smaller component

■Correct Answer: 3° flexion

137. (1694) Q1-2090:

The consequence of flexing the femoral component of a posterior cruciate-retaining system is:

1) Flexion contracture

3) Extension contracture

2) Flexion gap

5) No consequences

4) Decreased range of motion

There are no consequences of slightly flexing the femoral component in most cruciate-retaining systems because most prosthetiCdesigns allow for hyperextension of the articulating surfaces. This is not the case with posterior cruciate-substituting systems

■Correct Answer: No consequences

138. (1695) Q1-2091:

Mathematical modeling shows that a round stem versus a rectangular stem in the mid and distal cross-section can increase cement stress up to:

1) 50%

3) 150%

2) 100%

5) 250%

4) 200%

Mathematical modeling of cement stress predicted that a stem with a circular cross-sectional geometry transmits stresses to the cement mantle up to three times greater than stems with a rectangular cross-section

■Correct Answer: 250%

139. (1696) Q1-2092:

Place the following strategies for treating deep infection in total hip replacement in order of their effectiveness from 1 to 4, with

1 being the most effective. 1. No antibiotics 2. SystemiCantibiotics alone 3. AntibiotiCbone cement alone 4. AntibiotiCbone cement plus systemiCantibiotics

1) 1,2,3,4

3) 4,2,3,1

2) 2,4,3,1

5) 4,3,2,1

4) 3,2,4,1

According to Espehaug and colleagues in their assessment of 10,905 primary cemented total knee replacements, the most effective strategy is antibiotic-bone cement plus systemiCantibiotics followed by systemiCantibiotics alone, antibiotic-bone cement alone, and no antibiotics

■Correct Answer: 4,2,3,1

140. (1697) Q1-2093:

Which of the following bone cements is associated with the lowest risk ratio in assessing the risk of deep infection in revision total hip replacement:

1) Simplex (Howmedica, Allendale, NJ) bone cement

3) Palacos bone cement

2) Palacos gentamicin bone cement

5) Vancomycin in bone cement

4) CMW bone cement

According to Malchau and colleagues, Palacos gentamicin bone cement is associated with the lowest risk ratio for revision total hip replacement. Adding other antibiotics are not as effective as Palacos with gentamicin

■Correct Answer: Palacos gentamicin bone cement

141. (1698) Q1-2094:

A midline skin incision is the preferred skin incision in total knee replacement because:

1) A midline skin incision is less disruptive of the arterial network.

3) A midline skin incision gives better exposure.

2) A midline skin incision is less disruptive of the sensory nerves.

5) A midline skin incision is less disruptive of the lymphatiCsystem.

4) A midline skin incision preserves the extensor mechanism.

The blood supply arises from the terminal branches of the peripatellar anastomotiCarterial ring and a midline skin incision is the least disruptive to the arterial network. This results in better wound healing and, therefore, less chance for an infection

■Correct Answer: A midline skin incision is less disruptive of the arterial network.

142. (1699) Q1-2095:

When performing a total knee replacement, posterior stability can be achieved by all of the following except:

1) Soft tissue

3) Retention of posterior cruciate ligament

2) The implant

5) Resection of the anterior cruciate ligament

4) Resection of the posterior cruciate ligament

Posterior stability can be achieved through the soft tissues or the implant. The posterior cruciate ligament can be retained and posterior instability can still be achieved. The anterior cruciate ligament plays no role in posterior stability and is always resected during a total knee replacement

■Correct Answer: Resection of the posterior cruciate ligament

143. (1700) Q1-2096:

Recurrent hemarthrosis of the knee following total knee replacement may be secondary to all of the following except:

1) Entrapment of the synovium between the tibiofemoral articulation

3) A lax knee

2) Entrapment of the fat pad between the tibiofemoral articulation

5) Contracted knee

4) Entrapment of the synovium between the patellofemoral articulation

Entrapment of synovium or the fat pad between the tibiofemoral and patellofemoral articulation, and a lax knee have been associated with hemarthrosis following total knee replacement and can be treated by synovectomy or by inserting a thicker component

■Correct Answer: Contracted knee

144. (1701) Q1-2097:

After total knee replacement, posterolateral knee pain is due to all of the following except:

1) Component overhang

3) Posterolateral osteophytes

2) Scarring, more commonly seen in a valgus knee

5) Popliteus tendonitis

4) Undersized component

Component overhang, scarring, and posterolateral osteophytes can cause popliteal impingement and a persistent synovitis resulting in popliteus tendinitis and posterolateral pain. An undersized component may present some other problems but not posterolateral knee pain

■Correct Answer: Undersized component

145. (1702) Q1-2098:

Pes anserine bursitis that occurs after total knee replacement can be associated with all of the following except:

1) Anteromedial overhang of the component

3) Inadequate removal of medial osteophytes

2) Residual varus alignment

5) Anterolateral overhang of the component

4) Pes anserine bursitis is an idiopathiCoccurrence and not related to total knee replacement

Pes anserine bursitis is usually associated with anteromedial component overhang with residual varus alignment or inadequate removal of medial osteophytes

■Correct Answer: Anterolateral overhang of the component

146. (1703) Q1-2099:

All of the following statements are true regarding the Bernese osteotomy except:

1) The Bernese osteotomy was popularized by Ganz.

3) The Bernese osteotomy allows for unrestricted correction while keeping the pelviCring intact.

2) The Bernese osteotomy is a reorientation osteotomy.

5) The Bernese osteotomy can be used only in anteverted dysplastiChips.

4) The Bernese osteotomy can be used in approximately 15% of dysplastiChips.

The Bernese periacetabular osteotomy, which was popularized by Ganz, is a reorientation osteotomy that allows for unrestrained correction while keeping the pelviCring intact and can be used in approximately 17% of dysplastiChips. The Bernese osteotomy can be used in anteverted and retroverted dysplastiChips

■Correct Answer: The Bernese osteotomy can be used only in anteverted dysplastiChips.

147. (1704) Q1-2100:

The two most commonly used scoring techniques to assess and report the results of knee arthroplasty are the Hospital for Special Surgery knee score and the Knee Society score. Although they are the most commonly used scoring techniques, their main weakness is:

1) Examiner and intraobserver bias

3) Based on questionairre completed by the patient

2) Can only be used in patients with osteoarthritiCknees

5) Has no intervention of a health care provider

4) Derived from patient outcomes

The Hospital for Special Surgery knee score and the Knee Society score have examiner and intraobserver bias. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score is based on a questionnaire completed by the patient and is derived from patient outcomes without intervention of a healthcare provider

■Correct Answer: Examiner and intraobserver bias

148. (1705) Q1-2101:

Which of the following scoring techniques is the weakest when used to compare specifiCphysical dynamics of a prosthesis:

1) Hospital for Special Surgery knee score

3) Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score

2) Knee Society score

5) Mayo CliniCknee score

4) Iowa knee score

The Hospital for Special Surgery knee score and the Knee Society score provide more detailed information about the physical dynamics of a prosthesis than the WOMACscore. A combination of the three scores correlate well in their measurement of total knee replacement outcomes

■Correct Answer: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score

149. (1706) Q1-2102:

What percentage of nonsteroidal anti-inflammatory drug (NSAID) users annually develop a serious gastrointestinal (GI)

complication:

1) 2%

3) 10%

2) 4%

5) 20%

4) 15%

Annually, 1% to 2% of NSAID users develop a serious GI complication. The risk of bleeding, perforation, hospitalization, or death is three times higher among NSAID users than non-NSAID users

■Correct Answer: 2%

150. (1707) Q1-2103:

Nonsteroidal anti-inflammatory drugs (NSAIDs) work by:

1) Inhibiting the conversion of arachidoniCacid to prostaglandin

3) Increasing the level of prostaglandin in the joint

2) Increasing prostaglandin synthesis

5) Decreasing glycosaminoglycan synthesis

4) Increasing glycosaminoglycan synthesis

Prostaglandins are the key components of the inflammatory process and work by inhibiting the conversion of arachidoniCacid to prostaglandin

■Correct Answer: Inhibiting the conversion of arachidoniCacid to prostaglandin