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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 247 of 326

This practice set contains high-yield board review questions covering key concepts in 3. Adult Reconstruction (Hip & Knee). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 4921

Topic: Total Hip Arthroplasty (THA)
The anteroposterior hip radiograph of a 74-year-old healthy and active man who was seen in the office 18 months after a primary uncemented total hip replacement with a history of 3 hip dislocations. The last dislocation occurred 1 week ago and he was treated in the emergency department with a closed reduction and application of a hip abduction brace. All episodes of dislocation occurred when bending forward. Aside from the episodes of dislocation, his hip functions well. Examination revealed a normal gait with good abductor strength and pain-free hip movement. What is the most appropriate next treatment step?
. Prescribe physical therapy to work on abductor strengthening and reinforce hip position precautions.
. Recommend revision of the acetabular component to change cup position and increase the head and liner size.
. Recommend revision of the head and liner to a larger size using an elevated or oblique liner.
. Continue use of the hip abduction brace for 6 weeks and follow with physical therapy.

Correct Answer & Explanation

. Recommend revision of the acetabular component to change cup position and increase the head and liner size.

Explanation

This patient has had 3 hip dislocations since his hip replacement, and the radiograph shows an under-anteverted cup. He will likely continue to dislocate and surgery is indicated. The anteroposterior radiograph indicates that the cup is vertically oriented and not anteverted. His acetabular component is malpositioned and should be revised to provide the highest likelihood for success. A simple head and liner exchange with a malpositioned implant is less likely to succeed. Additionally, the radiograph shows sufficient acetabular bone stock medial to the cup. The addition of acetabular revision carries a low risk for increased morbidity and will allow a large cup with a larger femoral head with sufficient polyethylene thickness.

Question 4922

Topic: 3. Adult Reconstruction (Hip & Knee)

A 67-year-old man who underwent an uncomplicated hip arthroplasty 9 years ago has had a 1-week history of groin pain with movement. Radiographs reveal a well-positioned, well-fixed cementless arthroplasty with mild eccentricity of the femoral head within the polyethylene. His serum C-reactive protein (CRP) level is 3.0 mg/L (reference range, 0.08-3.1 mg/L) and erythrocyte sedimentation rate(ESR) is 5 mm/h (reference range, 0-20 mm/h). What is the most appropriate next step in management of the patient?

. Aspiration of the hip to rule out an infectious process
. Complete blood count with differential
. Observation
. Bone scan

Correct Answer & Explanation

. Aspiration of the hip to rule out an infectious process

Explanation

Both CRP and ESR results are negative, so aspiration of the hip to rule out periprosthetic hip infection is not recommended. The pain may be the result of a noninfectious process such as polyethylene wear with lysis or a muscle strain. A bone scan is of limited value, as is any further bloodwork. If the symptoms continue, further imaging may be of value.

Question 4923

Topic: 3. Adult Reconstruction (Hip & Knee)
Cryotherapy has been demonstrated to achieve what effect after total knee replacement?
. Decreased transfusion requirement
. Improved pain, swelling, and analgesia
. Improved range of motion at the time of discharge
. Better long-term knee range of motion

Correct Answer & Explanation

. Improved range of motion at the time of discharge

Explanation

In a meta-analysis of randomized controlled trials on the efficacy of cryotherapy after total knee arthroplasty, patients treated with cryotherapy had less blood loss but no difference in transfusion requirements. There was better range of motion at the time of discharge from the hospital. There was no improvement in pain, swelling, or analgesia requirements. Patients treated with cryotherapy did not have better long-term range of motion.

Question 4924

Topic: 3. Adult Reconstruction (Hip & Knee)
Compared to retention of the native patella in primary total knee arthroplasty, routine patella resurfacing is associated with:
. no patellar complications.
. an increased occurrence of anterior knee pain.
. a decreased patellar fracture rate.
. a decreased risk for revision surgery.

Correct Answer & Explanation

. a decreased risk for revision surgery.

Explanation

Despite concerns regarding fracture, osteonecrosis, and patellar clunk, the routine retention of the native patella during primary total knee replacement is associated with a 20% to 30% increased revision risk in large joint registries. In addition, the retention of the native patella results in a 5.7 revision surgery rate in patients with anterior knee pain.

Question 4925

Topic: Total Hip Arthroplasty (THA)
What clinical outcome is associated with total hip replacements that have metal-metal bearings (compared to total hip replacements with metal-polyethylene bearings)?
. Soft-tissue sarcomas
. Similar revision rates at 5 years
. Increased nephrotoxicity
. Pseudotumors

Correct Answer & Explanation

. Pseudotumors

Explanation

Patients with metal-metal total hip bearings have higher levels of cobalt and chromium in the bloodstream, but systemic migration of wear debris from total hip bearings is also common to total hip arthroplasties with polyethylene bearings. There is no direct evidence that patients with metal-metal total hip arthroplasties experience a higher incidence of cancer. Chromosome abnormalities have been detected in patients with metal-metal hip bearings, and the clinical consequences of this finding remain unknown. Also, pseudotumors can form around the periprosthetic joint space in response to localized metal ion debris and the host inflammatory response, although these tumors are not specific for failed metal-metal total hip arthroplasties. Metal-on-metal hip replacements have higher revision rates compared to conventional hip replacements in multiple registry studies. Although metal-on-metal articulations have not been shown to cause renal failure, they are not recommended in patients with chronic renal insufficiency.

Question 4926

Topic: 3. Adult Reconstruction (Hip & Knee)
A 55-year-old man with unilateral osteoarthritis of the hip underwent a total hip arthroplasty using cementless fixation. The acetabular cup was 52 mm and the femoral head was 28 mm and made of cobalt-chromium alloy. The bearing surface was made of annealed highly cross-linked polyethylene, with an estimated thickness of 6.5 mm. What should the orthopaedic surgeon tell the patient regarding wear of the bearing surface?
. A highly cross-linked polyethylene bearing has superior wear characteristics compared to a conventional polyethylene bearing.
. A highly cross-linked polyethylene bearing has similar wear characteristics compared to a conventional polyethylene bearing.
. The incidence of osteolysis is expected to be higher with highly cross-linked polyethylene than with conventional polyethylene.
. The volumetric wear rate would be lower if a 36-mm femoral head were used.

Correct Answer & Explanation

. A highly cross-linked polyethylene bearing has superior wear characteristics compared to a conventional polyethylene bearing.

Explanation

In a prospective, randomized clinical trial of 100 patients undergoing cementless total hip arthroplasties, the investigators compared highly cross-linked polyethylene to conventional polyethylene. All of the femoral heads were 28 mm. The mean follow-up was 6.8 years. The mean head penetration was 0.003 mm/year for the highly cross-linked polyethylene group in comparison to 0.051 mm/year for the conventional polyethylene group (P = .006). The improved wear is seen with larger-diameter heads as well. The volumetric wear rate of highly cross-linked polyethylene is equivalent to slightly higher with a larger head than a 28-mm head. Incidence of periarticular osteolysis is lower with highly cross-linked polyethylene.

Question 4927

Topic: Total Hip Arthroplasty (THA)

A 49-year-old active man has groin pain 3 years after undergoing an uneventful total hip replacement using a cobalt-chrome femoral head articulating against a cobalt-chrome acetabular insert. The pain intensifies with activity and travels down his thigh. Examination and radiographic evaluation are not particularly helpful; there is no evidence of spinal or vascular disease. What is the next step in the evaluation of this patient?

. A 3-phase bone scan
. Measurement of synovial metal ions levels
. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and possible hip aspiration
. Bearing exchange to a metal-polyethylene combination

Correct Answer & Explanation

. A 3-phase bone scan

Explanation

ESR, CRP, and possible hip aspiration is the most logical next step even though at some point, bearing exchange may emerge as the ultimate treatment for a metal-metal adverse reaction in this patient. But the initial workup of a patient with a painful total hip that was otherwise functioning well must include the differential diagnosis of infection, which must be excluded with an appropriate laboratory workup, clinical history, and hip aspiration. The latter study may also help to diagnose a reaction to the metal bearing;cobalt and chromium levels in the aspirate can be investigated, and the color and quantity of the aspirate can be examined along with the cell count. Serum levels of metal ions at this stage could be both helpful and difficult to interpret.

Question 4928

Topic: 3. Adult Reconstruction (Hip & Knee)
These are the radiographs of a 25-year-old woman whose pain has progressed during the last several years to pain with any activity and pain at night. What is the most appropriate treatment?
. Proximal tibial osteotomy
. Distal femoral osteotomy
. Lateral unicompartmental arthroplasty
. Total knee arthroplasty

Correct Answer & Explanation

. Distal femoral osteotomy

Explanation

This patient is a good candidate for a joint-preserving procedure. Her symptoms and radiographic findings reveal valgus malalignment of the knee with narrowing of the lateral joint space. The alignment can be corrected with a varus-producing distal osteotomy as shown in Figure 32c. Most patients do not proceed to knee arthroplasty for at least 10 years after this procedure. Osteotomy is preferred over partial or total knee arthroplasty because of the patientโ€™s young age. Varus proximal tibial osteotomy would result in joint line obliquity.

Question 4929

Topic: 3. Adult Reconstruction (Hip & Knee)

An orthopaedic surgeon noticed a displaced calcar fracture during stem insertion when performing total hip arthroplasty using cementless fixation. What is the most appropriate course of action?

. Intraoperative exploration to determine the extent of the fracture
. Use of a longer stem without fixation of the calcar fracture
. Complete insertion of the stem and measures to protect the patient against full weight bearing for 4 weeks
. Removal of the stem, internal fixation of the fracture, and definitive reconstruction at a later stage after the fracture has healed

Correct Answer & Explanation

. Intraoperative exploration to determine the extent of the fracture

Explanation

Calcar fractures can occur with both cemented and cementless stem fixation during surgery. The dista extent of the fracture must be identified either by direct visualization or intraoperative radiograph prior to fixation or implantation of the femoral component. The recommended treatment is to fix the calcar fracture with cerclage wires/cables to restore the mechanical stability of the femoral metaphysis. The same stem can be inserted successfully. The majority of these fractures unite without adverse stem fixation problems.

Question 4930

Topic: 3. Adult Reconstruction (Hip & Knee)

is the postoperative photograph of a patient who underwent a total knee arthroplasty 10 days after surgery. Knee aspiration suggests a Streptococcus infection.

. Stop physical therapy and institute oral antibiotics.
. Stop physical therapy and institute intravenous (IV) antibiotics.
. Open irrigation and debridement, polyethylene spacer exchange, and IV antibiotics
. Remove components and insert an antibiotic spacer.For each question below, please select the most appropriate treatment from the list above.

Correct Answer & Explanation

. Stop physical therapy and institute oral antibiotics.

Explanation

An acute postoperative infection during the first 2 to 4 weeks should be treated with a return to the operating room for open irrigation and debridement of the wound. Polyethylene spacer exchange aides in washing out the entire knee joint. IV antibiotics are also indicated in this situation. To address persistent wound drainage, there is no role for oral or IV antibiotics alone. Removal of the arthroplasty components is recommended for infections after the initial 2- to 4-week postoperative period.However,several recent publications demonstrate a failure rate higher than 50% when the organism is a methicillinresistant Staphylococcus aureus. Six weeks after surgery, this scenario is no longer considered an acute postoperative infection, and most authors recommend a 2-stage protocol with removal of components and placement of an antibiotic-impregnated cement spacer and 4 to 6 weeks of IV antibiotics.

Question 4931

Topic: 3. Adult Reconstruction (Hip & Knee)

Seven weeks after total knee replacement surgery, a patient has a painful swollen knee. Knee aspiration reveals coagulase-negative Staphylococcus aureus.

. Stop physical therapy and institute oral antibiotics.
. Stop physical therapy and institute intravenous (IV) antibiotics.
. Open irrigation and debridement, polyethylene spacer exchange, and IV antibiotics
. Remove components and insert an antibiotic spacer.For each question below, please select the most appropriate treatment from the list above.

Correct Answer & Explanation

. Stop physical therapy and institute oral antibiotics.

Explanation

An acute postoperative infection during the first 2 to 4 weeks should be treated with a return to the operating room for open irrigation and debridement of the wound. Polyethylene spacer exchange aides in washing out the entire knee joint. IV antibiotics are also indicated in this situation. To address persistent wound drainage, there is no role for oral or IV antibiotics alone. Removal of the arthroplasty components is recommended for infections after the initial 2- to 4-week postoperative period.However,several recent publications demonstrate a failure rate higher than 50% when the organism is a methicillinresistant Staphylococcus aureus. Six weeks after surgery, this scenario is no longer considered an acute postoperative infection, and most authors recommend a 2-stage protocol with removal of components and placement of an antibiotic-impregnated cement spacer and 4 to 6 weeks of IV antibiotics.

Question 4932

Topic: Total Knee Arthroplasty (TKA)
What is the difference in outcome when comparing high tibial osteotomy (HTO) to total knee arthroplasty (TKA)?
. TKA has a longer recovery period than HTO.
. HTO provides more complete pain relief than TKA.
. HTO is more reliable in older patients than TKA.
. HTO outcomes among thin, active, young patients who undergo this procedure approach outcomes associated with TKA.

Correct Answer & Explanation

. HTO outcomes among thin, active, young patients who undergo this procedure approach outcomes associated with TKA.

Explanation

The ideal candidate for HTO is a thin, active person with a stable knee, unicompartmental knee symptoms, and age younger than 60. TKA offers a shorter recovery period and more complete pain relief than HTO. TKA is believed to be more reliable than HTO for patients older than age 60.

Question 4933

Topic: Total Hip Arthroplasty (THA)
This is a radiograph of a 72-year-old man who underwent an open reduction and internal fixation of a right femoral neck fracture. After 3 months he started to develop pain, and during the next 8 months he complained of progressive pain and shortening of the hip. What is the most appropriate treatment?
. Girdlestone
. Total hip replacement
. Hardware removal
. Hardware removal with revision open reduction and internal fixation

Correct Answer & Explanation

. Total hip replacement

Explanation

Even though a relatively short amount of time has passed since the index surgery, this patient has developed significant osteonecrosis that has caused collapse of the bony structures and the hardware to become prominent. Total hip replacement gives the most efficient pain relief. Hardware removal with or without re-reduction does not provide reliable pain relief. A Girdlestone procedure does not allow the patient to function.

Question 4934

Topic: 3. Adult Reconstruction (Hip & Knee)
This is the radiograph of a 68-year-old woman who has right knee pain that is limiting her activity and severe preoperative valgus deformity. During total knee arthroplasty, what pathologic features are typically encountered?
. Lateral femoral hypoplasia
. Internal rotation of the tibia relative to the femur
. Medial patella tracking
. Tight medial collateral ligament

Correct Answer & Explanation

. Lateral femoral hypoplasia

Explanation

In patients with severe valgus deformity, problems frequently encountered include loose or attenuated medial collateral ligament, tight lateral retinaculum and lateral ligamentous structures (lateral collateral, posterolateral corner), atrophic lateral femoral condyle, lateral patella tracking, and external rotation of the tibia relative to the femur. The hypoplastic lateral condyle can cause internal rotation of the anteroposterior cutting block if the posterior condylar line is used for rotational alignment. The medial soft tissues are typically attenuated and stretched.

Question 4935

Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old man with previous total hip arthroplasty developed hip pain of 1 monthโ€™s duration. He underwent dental work 6 weeks ago. Aspiration showed a white blood cell count of > 6000 cells/ยตL (reference range, 4500-11000/ยตL) and presence of gram-positive cocci in clusters on gram stain. The orthopaedic surgeon recommended urgent debridement and irrigation. The components were judged to be stable with regard to fixation, and the surgeon elected to retain the implants. What is this patientโ€™s prognosis for infection resolution?
. Good because it is a gram-positive organism
. Good because it is an acute infection
. Poor because it is a gram-positive organism
. Poor because it is a late infection

Correct Answer & Explanation

. Poor because it is a late infection

Explanation

This is a late infection of at least 4 weeks symptomatic duration that most probably is hematogenous in etiology. This is not an acute hematogenous infection that can successfully be treated with irrigation and debridement. Retention of the implants with debridement and irrigation alone has been associated with poor prognosis. In a recent study, the success rate was only 44% in a series of 104 patients at a mean 5.7 years of follow-up.

Question 4936

Topic: Total Hip Arthroplasty (THA)

A 59-year-old active woman underwent elective total hip replacement using a posterior approach. She had minimal pain and was discharged to home 2 days after surgery. Four weeks later she dislocated her hip while shaving her legs. She underwent a closed reduction in the emergency department. Postreduction radiographs show a reduced hip with well-fixed components in satisfactory alignment. What is the most appropriate management of this condition from this point forward?

. Observation and patient education regarding hip dislocation precautions
. Revision to a larger-diameter femoral head
. Revision to a constrained acetabular component
. Application of a hip orthosis for 3 months

Correct Answer & Explanation

. Observation and patient education regarding hip dislocation precautions

Explanation

First-time early dislocations are often successfully treated without revision surgery, especially when there is no component malalignment. In this clinical scenario, it appears the patient would benefit from better education about dislocation precautions. Hip orthoses are of questionable benefit unless the patient is cognitively impaired. Revision surgery can be successful, but is usually reserved for patients with recurrent dislocations. Question 43

Question 4937

Topic: 3. Adult Reconstruction (Hip & Knee)
Patellar pain, subluxation, or dislocation after total knee arthroplasty can result from which of the following component orientations?
. Internal rotation of the tibial component
. Lateralization of the tibial component
. Lateralization of the femoral component
. External rotation of the femoral component

Correct Answer & Explanation

. Internal rotation of the tibial component

Explanation

Internal rotation of the components of a total knee arthroplasty, both the tibial and femoral components, can lead to symptoms ranging from patellar pain to dislocation. Most researchers agree that proper external rotation of the femoral component is parallel or nearly so to the femoral epicondylar axis with the knee in the 90-degree flexed position. Proper rotational positioning of the tibial component places the midportion of the tibial component rotationally aligned within the medial one-third of the tibial tubercle. Internal rotation of the tibial component causes relative lateralization of the tibial tubercle and the extensor mechanism.

Question 4938

Topic: 3. Adult Reconstruction (Hip & Knee)
How does the risk for periprosthetic infection after total knee arthroplasty compare to risk for infection after total hip arthroplasty?
. Higher in primary arthroplasty
. Lower in primary arthroplasty
. Lower in revision arthroplasty
. Equivalent in both primary and revision arthroplasty

Correct Answer & Explanation

. Higher in primary arthroplasty

Explanation

Risk for periprosthetic infection is higher in the knee (1%-2%) than it is in the hip (0.3%-1.3%). The risk for infection is higher after revision joint replacement surgery compared to primary joint replacement surgery.

Question 4939

Topic: 3. Adult Reconstruction (Hip & Knee)
What factor is associated with a higher risk for dislocation after total hip arthroplasty?
. Male gender
. Previous hip surgery
. A direct lateral surgical approach
. Metal-on-metal bearing surfaces

Correct Answer & Explanation

. Previous hip surgery

Explanation

Dislocation after total hip arthroplasty is a multifactorial problem. Numerous risk factors may act independently or cumulatively to increase risk for this complication. Previous hip surgery of any kind is associated with a twofold increased risk for dislocation. Other risk factors include female gender, impaired mental status, inflammatory arthritis, and older age.

Question 4940

Topic: 3. Adult Reconstruction (Hip & Knee)
What surgical technique has been associated with increased risk for recurrent dislocation after revision total hip arthroplasty?
. Posterior capsulorrhaphy
. Use of a jumbo cup
. Use of a lateralized liner
. Use of a larger femoral head diameter

Correct Answer & Explanation

. Use of a jumbo cup

Explanation

When addressing recurrent dislocation after total hip arthroplasty, surgical considerations that must be addressed include approach, soft-tissue tension, component positioning, impingement, head size, and acetabular liner profile. These considerations most often involve tensioning or augmentation of soft tissues, as in capsulorrhaphy or trochanteric advancement; correction of malpositioned components; use of larger femoral head sizes that increase motion before impingement; improving the head-to-neck ratio; and increasing femoral offset. The use of a larger-diameter acetabular component may lead to soft-tissue overgrowth around the liner, causing impingement and increasing the risk for recurrent dislocation.

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