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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 271 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 5401

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old patient fell 3 weeks after undergoing a total hip arthroplasty using cementless fixation of

the femoral component. She sustained a comminuted Vancouver type B-2 fracture with displacement of the calcar fragment. What is the best treatment option?

. Revision using a proximal femoral replacement prosthesis
. Revision using a diaphyseal engaging femoral prosthesis along with cerclage fixation
. Open reduction internal fixation using a locking plate with strut graft
. Protected weight bearing with abduction bracing

Correct Answer & Explanation

. Revision using a proximal femoral replacement prosthesis

Explanation

The patient has an acute postoperative fracture of the proximal femur with subsidence. It is also common that the stem retroverts relative to the femur. It is most often seen in proximally porous coated stems within 90 days of surgery, one paper found it to occur 0.7% of the time in modern implants. There is always a debate whether this is a missed intraoperative fracture, or a new fracture that has resulted from an event of increased hoop stresses. Removal of the primary stem, placement of a diaphyseal engagingstem (most frequently a tapered-fluted stem), and cabling of the fracture is the most successful treatment.

Question 5402

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the most important preoperative factor predicting conversion to total hip arthroplasty after

arthroscopic surgery of the hip?

. Age over 60 years
. Morbid obesity
. Diagnosis of osteoarthritis
. Tobacco use

Correct Answer & Explanation

. Age over 60 years

Explanation

---The authors cited in theScientific Referencesexamined large databases to determine the risk factors for conversion to total hip arthroplasty after arthroscopic surgery of the hip. In the study by Kester and associates, obesity had an odds ratio (OR) of 5.6 for conversion to hip arthroplasty, whereas age over 60 years had an OR of3.4, osteoarthritis had an OR of 2.4, and tobacco use had an OR of 1.9.

Question 5403

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old woman with a body mass index (BMI) of 34 and a history of hypercholesterolemia has elected

to undergo total hip arthroplasty. Her son recently learned he has factor V Leiden following an episode of pulmonary embolism. What are this patient's risk factors for thromboembolic disease?

. Type of surgery, age, and BMI
. Type of surgery, hypercholesterolemia, and age
. Age, BMI, and hypercholesterolemia
. BMI, type of surgery, and hypercholesterolemia

Correct Answer & Explanation

. Type of surgery, age, and BMI

Explanation

Risk stratification is one of the most critical clinical evaluations to undertake before performing total joint arthroplasty. Many factors have been identified that increase the risk for venous thromboembolism (VTE) The major factors include previous VTE, obesity, type of surgery (such as total joint arthroplasty), hypercoagulable states, myocardial infarction, congestive heart failure, family history of VTE, andhormone replacement therapy. Hypercholesterolemia is not a risk factor for thromboembolic disease.

Question 5404

Topic: 3. Adult Reconstruction (Hip & Knee)

Figures below depict the radiographs obtained from a 76-year-old woman who comes to the emergency

department after experiencing a fall. She is an unassisted community ambulator with a history of right hip pain. What is the most appropriate surgical treatment for this fracture?

. Cemented unipolar hemiarthroplasty
. Cemented bipolar hemiarthroplasty
. Total hip replacement
. Open reduction and internal fixation

Correct Answer & Explanation

. Cemented unipolar hemiarthroplasty

Explanation

This patient has pre-existing right hip osteoarthritis. The most correct option for the treatment of this active patient is a right total hip arthroplasty. Hemiarthroplasty would not address the patient's pain from osteoarthritis, and open reduction and internal fixation would not fix the femoral head issue or theosteoarthritis.

Question 5405

Topic: 3. Adult Reconstruction (Hip & Knee)

Figures below show the clinical photograph and radiograph obtained from a 62-year-old man who has

deformity and pain 1 year after primary total hip arthroplasty. What is the reason for the observed deformity?

. A Vancouver type B1 fracture
. Residual leg-length discrepancy
. Loosening and subsidence of the femoral stem into anteversion
. Loosening and subsidence of the femoral stem into retroversion

Correct Answer & Explanation

. A Vancouver type B1 fracture

Explanation

Figure 1 reveals an external rotation deformity of the right lower extremity. This deformity can have numerous causes, including extra-articular deformity. Figure 2 reveals a loose, subsided femoral component. Femoral stems typically subside into retroversion due to proximal femoral biomechanics, which cause a compensatory external rotation deformity. The combined findings from both images suggest an external rotation deformity most likely related to subsidence into retroversion.

Question 5406

Topic: 3. Adult Reconstruction (Hip & Knee)

Figures below show the radiographs obtained from an 86-year-old-woman who has had chronic left hip

pain for several years. She now uses a walker and a wheelchair for ambulation. She is medically healthy. What is the most appropriate surgical intervention?

. Cemented left total hip arthroplasty (THA)
. Cementless left THA with a proximally porous coated femoral stem
. Hybrid left THA
. Cementless left THA with a diaphyseal engaging conical femoral stem

Correct Answer & Explanation

. Cemented left total hip arthroplasty (THA)

Explanation

This 86-year-old woman has poor bone quality and osteoarthritis of the left hip. Her lateral radiograph confirms Dorr type C bone quality. A hybrid left THA with a cemented femoral stem would be the treatment of choice.

Question 5407

Topic: 3. Adult Reconstruction (Hip & Knee)

Figure below shows the radiograph obtained from a 76-year-old woman who has sharp pain in her groin,

thigh, and buttocks that worsens with activity. She has been dealing with this pain for more than a year but is otherwise healthy. Recently, she has begun to notice night pain. The pain no longer responds to NSAIDs. She would like to be able to dance at her daughter's wedding in 4 months and wonders how best

to proceed. What is the best next step?

. Radiograph-guided steroid injection followed by total hip arthroplasty 6 weeks later
. Total hip arthroplasty
. Physical therapy
. Referral back to her spine surgeon

Correct Answer & Explanation

. Radiograph-guided steroid injection followed by total hip arthroplasty 6 weeks later

Explanation

The next best course of action is total hip arthroplasty. The patient is an otherwise healthy woman requesting pain relief and expresses a desire to be dancing in 4 months. She has had more than 6 months of symptoms that are classic hip osteoarthritis symptoms, with pain in the groin and thigh. Severe osteoarthritis is seen in the radiograph as well. NSAIDs are no longer working. Given the objective findings, the subjective reports, and the duration of symptoms, this patient merits surgery. Consideration for steroid injection is reasonable, but given her desire to be dancing in 4 months, an injection would increase her risk of infection if total hip arthroplasty were to be performed within 3 months of theinjection.

Question 5408

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old woman underwent an uncemented medial/lateral tapered femoral placement during a total

hip arthroplasty. The orthopaedic surgeon noticed a nondisplaced vertical fracture in the calcar region of the femoral neck during final implant insertion. What is the most appropriate treatment?

. Removal of the press-fit implant and cementing of the same femoral stem
. Removal of the uncemented femoral component and placement of a revision modular taper- fluted femoral stem
. Removal of the implant, placement of a cerclage wire around the femoral neck above the lesser trochanter, and reinsertion of the implant
. Final seating of the uncemented femoral component without additional measures

Correct Answer & Explanation

. Removal of the press-fit implant and cementing of the same femoral stem

Explanation

The recognized treatment for a proximal periprosthetic fracture is to first identify the extent and then optimize the correction of the fracture. Several studies indicate that proximal cerclage wiring is adequate to create "barrel hoop" stability of the proximal femur. Braided cables offer superior stability compared with twisted wires or Luque wires. Finally, the appropriate postoperative treatment is protectedweight bearing for 6 weeks, with periodic radiographs taken at 2-week intervals. Other options such ascementing the femoral stem and using a revision arthroplasty device are indicated for unstable fractures.

Question 5409

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old woman has a 3-year history of gradually increasing diffuse and global right knee pain. Her

main issues are difficulty with stairs, stiffness with prolonged sitting, and swelling. She has taken NSAIDs and has received intra-articular steroid injections, all with decreasing efficacy. Her right knee examination reveals a range of motion of 15° to 80° with a fixed deformity to varus and valgus stress. Her symptoms are no longer manageable nonsurgically. Radiographs reveal a 30-degree mechanical axis deformity. When using the measured resection technique during total knee arthroplasty (TKA), the best way to avoid femoral malrotation is to reference the

. anteroposterior axis.
. tibial intramedullary axis.
. posterior condylar axis.
. femoral intramedullary axis.

Correct Answer & Explanation

. anteroposterior axis.

Explanation

In the setting of valgus deformities, TKA poses different challenges than those encountered when varus deformities are present. Most valgus alignment is attributable to a deformity of the distal femur rather than of the proximal tibia, as seen in varus knees. One of the major anatomical differences is a hypoplastic lateral femoral condyle which, when not recognized and used as a rotational reference point, can lead to internal rotation of the femoral component. This malrotation in turn leads to patellofemoral maltrackingor instability, which is a common complication associated with primary TKA.

Question 5410

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old woman has a 3-year history of gradually increasing diffuse and global right knee pain. Her

main issues are difficulty with stairs, stiffness with prolonged sitting, and swelling. She has taken NSAIDs and has received intra-articular steroid injections, all with decreasing efficacy. Her right knee examination reveals a range of motion of 15° to 80° with a fixed deformity to varus and valgus stress. Her symptoms are no longer manageable nonsurgically. Radiographs reveal a 30-degree mechanical axis deformity. The deformity shown in Figure below is predominantly associated with

. a hypoplastic lateral femoral condyle.
. a contracted medial collateral ligament.
. an excessive proximal tibial slope.
. trochlear dysplasia.

Correct Answer & Explanation

. a hypoplastic lateral femoral condyle.

Explanation

In the setting of valgus deformities, TKA poses different challenges than those encountered when varus deformities are present. Most valgus alignment is attributable to a deformity of the distal femur rather than of the proximal tibia, as seen in varus knees. One of the major anatomical differences is a hypoplastic lateral femoral condyle which, when not recognized and used as a rotational reference point, can lead to internal rotation of the femoral component. This malrotation in turn leads to patellofemoral maltrackingor instability, which is a common complication associated with primary TKA.

Question 5411

Topic: Total Knee Arthroplasty (TKA)

When balancing gaps in the coronal plane, what structure preferentially impacts the flexion space more

than the extension space?

. Iliotibial band
. Popliteus tendon
. Lateral collateral ligament
. Lateral head of the gastrocnemius

Correct Answer & Explanation

. Iliotibial band

Explanation

In the setting of valgus deformities, TKA poses different challenges than those encountered when varus deformities are present. Most valgus alignment is attributable to a deformity of the distal femur rather than of the proximal tibia, as seen in varus knees. One of the major anatomical differences is a hypoplastic lateral femoral condyle which, when not recognized and used as a rotational reference point,can lead to internal rotation of the femoral component. This malrotation in turn leads to patellofemoral maltracking or instability, which is a common complication associated with primary TKA.

Question 5412

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old woman has severe anterior knee pain. Her radiographs indicate end-stage patellofemoral

compartment osteoarthritis. The tibiofemoral compartments are preserved. Extensive nonsurgical treatment has failed to provide relief, and she is offered patellofemoral arthroplasty (PFA). What is the most common long-term mode of failure for PFA using an implant with an onlay prosthesis design?

. Infection
. Patellar instability
. Aseptic loosening
. Progression of tibiofemoral arthritis

Correct Answer & Explanation

. Infection

Explanation

Contemporary onlay-design trochlear prostheses in PFA replace the entire anterior trochlear surface. Previous inlay designs were inset within the native trochlea and carried a higher risk of catching and patellar instability, particularly in patients with trochlear dysplasia; they also generally have higher failure rates. The current most common mode of failure is progression of arthritis throughout the knee, in some series as high as 25% at 15 years. Aseptic loosening, particularly of cemented implants, is less common. Infection is an uncommon long-term complication. Patients considering PFA should be advised of the risk of arthritis progression. Many authors routinely obtain a preoperative MRI to assess the status of the tibiofemoral compartments.

Question 5413

Topic: 3. Adult Reconstruction (Hip & Knee)

Figures below show the radiographs obtained from a 79-year-old woman who has been experiencing

increasing tibial pain 10 years after undergoing revision total knee arthroplasty. No evidence of infection is seen. What is the most appropriate treatment?

. Retain the components, and implant a tibial strut allograft.
. Revise the tibial component with a metaphyseal cone and metaphyseal uncemented stem.
. Revise the tibial component with a metaphyseal cone and a press-fit diaphyseal-engaging stem.
. Revise the tibial component with a long cemented diaphyseal-engaging stem.

Correct Answer & Explanation

. Retain the components, and implant a tibial strut allograft.

Explanation

---Stems are available for cemented and press-fit implantation. To be effective, press-fit stems should engage the diaphysis, as shown in Figures 3 and 4. They also assist in obtaining correct limb alignment. Short metaphyseal-engaging stems are associated with failure rates that range between 16% and 29%. Cemented stems may be shorter than press-fit stems, because they do not have to engage the diaphysis. Short, fully cemented stems offer the advantage of metaphyseal fixation. Hybrid stem fixation makes use of the metaphysis for cement fixation with metaphyseal cones or sleeves and diaphyseal-engaging press-fit stems.

Question 5414

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old man reports symptomatic medial knee pain that has become progressively worse during

the past year. MRI reveals a complex, posterior horn medial meniscus tear with associated medial lateral and patellofemoral cartilage defects. Radiographs reveal medial joint space narrowing and osteophytes in the other compartments. What treatment is most likely to provide long-term, durable relief of symptoms?

. High tibial osteotomy
. Total knee replacement
. Unicondylar knee replacement
. Arthroscopic partial meniscectomy

Correct Answer & Explanation

. High tibial osteotomy

Explanation

Total knee replacement is a well-established surgery for diffuse, symptomatic osteoarthritis of the knee joint, and its efficacy has been shown in many studies. According to the 2008 AAOS Clinical Practice Guideline, Treatment of Osteoarthritis of the Knee, arthroscopy in the setting of existing osteoarthritis is efficacious for relieving the signs and symptoms of a torn meniscus but not for osteoarthritis. Likewise, in young and active patients, clinical outcomes show improvement after realignment osteotomy for single- compartment osteoarthritis. Unicondylar knee replacement is not indicated for tricompartmental diseaseof the knee.

Question 5415

Topic: 3. Adult Reconstruction (Hip & Knee)

A 58-year-old man with insulin-dependent diabetes mellitus underwent primary total knee arthroplasty

(TKA). A full-thickness skin slough measuring 3 cm by 4 cm developed, with postsurgical exposure of the patellar tendon. No change is observed in the appearance of the wound after 2 weeks of wet-to-dry dressing changes. What is the best next treatment step for the soft-tissue defect?

. Continued dressing changes
. Split-thickness skin graft
. Full-thickness skin graft
. Local rotational flap

Correct Answer & Explanation

. Continued dressing changes

Explanation

If wound healing does not occur and deep soft tissues such as the patellar tendon are exposed following TKA, local rotational flap is the procedure of choice. The procedure should be performed relatively early after the recognition of a soft-tissue wound-healing problem. In the setting of TKA, the gastrocnemius muscle is an excellent source of flaps for wound coverage of the proximal tibia.

Question 5416

Topic: Total Knee Arthroplasty (TKA)

A 47-year-old obese man with a body mass index of 42 comes into the office with left knee pain 1 year

after undergoing an uncomplicated left medial unicompartmental knee arthroplasty (UKA). Radiographs show a loose tibial component in varus. What is the most appropriate next step to treat this failed construct?

. Aspiration of joint fluid to obtain a cell count
. Revision of the UKA using primary total knee arthroplasty (TKA) components
. Revision of the UKA using a revision TKA with augments
. Procurement of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level

Correct Answer & Explanation

. Aspiration of joint fluid to obtain a cell count

Explanation

This patient likely is experiencing failure of the UKA secondary to poor patient selection. In this young, heavy man, the component likely loosened due to the ongoing varus alignment of the knee and his elevatedweight. Despite this likely scenario, the next step is determining whether an infection is the cause of his pain. Prior to obtaining an aspiration, the surgeon can order ESR and CRP studies to determine whether aspiration is warranted. If the laboratory studies are unremarkable, the surgeon likely can forgo theaspiration and proceed to a revision TKA with possible augments on standby.

Question 5417

Topic: Total Knee Arthroplasty (TKA)

Figure below shows the standing AP radiograph obtained from a 55-year-old man who has a 5-year history of

daily left knee medial joint line pain with weight-bearing activities. He denies night pain or symptoms of instability. On examination, his range of motion is 0° to 140°. He has a mild, fully correctable varus deformity and a negative Lachman test result. Nonsurgical treatment has failed. What is the UKA survivorship for a 55- year-old patient, compared with the survivorship for total knee arthroplasty?

. Equal at 10 years
. Lower at 10 years
. Higher at 10 years
. Not known when using a mobile-bearing UKA

Correct Answer & Explanation

. Equal at 10 years

Explanation

A patient with medial compartment arthritis and a correctable varus deformity with no clinical or examination findings of knee instability most likely has an intact anterior cruciate ligament (ACL). The pattern of medial compartment osteoarthritis most commonly associated with an intact ACL is that of anteromedial osteoarthritis. An incompetent ACL is commonly associated with a fixed varus deformity and radiographic signs of posteromedial wear. An incompetent ACL is a relative contraindication to a mobile-bearing UKA. When evaluating patients for a mobile-bearing UKA, a stress radiograph aids the orthopaedic surgeon in determining the correction of the varus deformity and assessing the lateral compartment. An inability to fully correct the deformity or narrowing of the lateral compartment with valgus stress should influence the surgeon against UKA. Joint registries across the world have shown decreased survivorship associated with TKA and UKA in men compared with other age groups, but survivorship is lower for UKA than for TKA. No studies to date have shown any differences in survivorship between fixed-bearing and mobile-bearing UKAs. The complication that is unique to mobile-bearing UKA is bearing spinout, which occurs in less than 1% of mobile-bearing UKA procedures. In vivo and in vitro polyethylene wear in mobile-bearing UKA are low. Arthritis may progressfaster in patients with mobile-bearing UKAs than in those with fixed-bearing UKAs.

Question 5418

Topic: 3. Adult Reconstruction (Hip & Knee)

A 57-year-old woman experiences pain 1 year after total knee arthroplasty (TKA). She reports sharp

anterior pain and a painful catching sensation that is aggravated by rising from a chair or climbing stairs. Physical examination reveals a mild effusion and a range of motion of 2° to 130°, with patellar crepitus.

The symptoms are reproduced by resisted knee extension. Radiographs show a well-aligned posterior- stabilized TKA without evidence of component loosening. What is the most likely cause of this patient's pain?

. Patellar clunk syndrome
. Flexion gap instability
. Polyethylene wear
. Femoral component malrotation

Correct Answer & Explanation

. Patellar clunk syndrome

Explanation

Patellar clunk syndrome is caused by the development of a fibrous nodule on the posterior aspect of the quadriceps tendon at its insertion into the patella. It causes a painful catching sensation when the extensor mechanism traverses over the trochlear notch as the knee extends from 45° of flexion to 30° from full extension. It characteristically occurs in posterior stabilized total knee arthroplasties and appears to be related to femoral component design. The syndrome can usually be prevented by excising the residual synovial fold just proximal to the patella. Flexion gap instability can also cause a painful total knee arthroplasty but is less common in posterior stabilized implants. Femoral component malrotation can cause pain attributable to a flexion gap imbalance or patellar tracking problems. Polyethylene wear would be unlikely after just 1 year. Patellar clunk syndrome can usually be addressed successfully with arthroscopic synovectomy. Recurrence is uncommon. Physical therapy may help to strengthen the quadriceps following synovectomy but would not resolve the clunk syndrome symptoms. Femoral or tibial insert revision is not indicated if patellar clunk syndrome is the only problem resulting in a painfultotal knee arthroplasty.

Question 5419

Topic: 3. Adult Reconstruction (Hip & Knee)

In total knee arthroplasty, in vitro testing has shown that cross-linking can diminish the rate of

polyethylene wear by 30% to 80%. What other change in material properties is possible when polyethylene is highly cross-linked?

. Increased ductility
. Increased wettability
. Diminished fatigue strength
. Decreased resistance to abrasive wear

Correct Answer & Explanation

. Increased ductility

Explanation

The most important concern regarding highly cross-linked polyethylene relates to decreased mechanical properties. Cross-linking results in reduced ductility, tensile strength, and fatigue crack propagation resistance. These problems have not been shown to cause implant failure in the most recent clinical trials, but they remain the most important mechanical issues associated with current material processing methods.

Question 5420

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old woman who underwent total knee replacement 18 months ago has had 3 weeks of moderate

drainage from a previously healed wound. What is the most appropriate treatment?

. Vacuum-assisted wound closure dressing
. Intravenous antibiotics for 6 weeks, followed by long-term oral antibiotic administration
. Irrigation and debridement, followed by polyethylene exchange
. Two-stage debridement and reconstruction

Correct Answer & Explanation

. Vacuum-assisted wound closure dressing

Explanation

This situation represents a definitively and chronically infected knee replacement. Antibiotic therapy alone might suppress the infection but would not eradicate it. Debridement and polyethylene exchange would be appropriate treatment for an early postoperative infection. The treatment of choice is to perform a two-stage debridement and reconstruction. Although not among the listed choices, an aspiration or culture could be done presurgically and might help clinicians identify the best antibiotics to treat the condition. Antibiotic selection would not affect the need for the two-stage reconstruction, however.

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