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 1641
Topic: 3. Adult Reconstruction (Hip & Knee)
A 60-year-old male with a metal-on-polyethylene total hip arthroplasty presents with new-onset groin pain and a pseudotumor on MRI. Infection workup is negative. Blood metal ion levels reveal elevated serum cobalt relative to chromium. This clinical picture is most likely driven by mechanically assisted crevice corrosion (MACC) at which interface?
Correct Answer & Explanation
. The femoral head-neck trunnion interface
Explanation
Adverse Local Tissue Reaction (ALTR) in the setting of a metal-on-polyethylene THA is typically caused by trunnionosis. This is mechanically assisted crevice corrosion (MACC) occurring at the modular junction between the metallic femoral head and the femoral neck trunnion. It typically causes higher serum cobalt levels compared to chromium.
Question 1642
Topic: 3. Adult Reconstruction (Hip & Knee)
A 75-year-old female who underwent revision total hip arthroplasty with a dual mobility construct presents with an acute dislocation. Radiographs reveal the 'bubble sign' with eccentric position of the femoral head within the acetabular shell. What is the precise mechanism of this specific type of intraprosthetic dislocation?
Correct Answer & Explanation
. Wear and failure of the polyethylene retentive rim allowing the smaller inner metal head to escape the polyethylene liner
Explanation
Intraprosthetic dislocation (IPD) is a unique complication of dual mobility cups. It occurs when the polyethylene retentive rim wears out or fails, allowing the smaller, inner metallic/ceramic femoral head to 'escape' the large mobile polyethylene head. The small head then articulates directly with the metallic acetabular shell, creating the eccentric 'bubble sign' on radiographs.
Question 1643
Topic: 3. Adult Reconstruction (Hip & Knee)
A 65-year-old female with severe rheumatoid arthritis is considering a semiconstrained (linked) Total Elbow Arthroplasty (TEA). When discussing the long-term prognosis and risks, what should the surgeon quote as the most common long-term complication leading to revision?
Correct Answer & Explanation
. Aseptic loosening
Explanation
Aseptic loosening remains the most common long-term complication and the most frequent reason for revision of a total elbow arthroplasty, especially in linked (semiconstrained) designs, due to the high biomechanical stresses transferred to the bone-cement interface at the bushing hinges.
Question 1644
Topic: Total Hip Arthroplasty (THA)
A patient is undergoing deformity correction for a midshaft tibial malunion. According to Paley's rules of osteotomies, if the osteotomy is performed at a site separate from the Center of Rotation of Angulation (CORA) and the proximal and distal mechanical axes are aligned, what is the inevitable geometric result?
Correct Answer & Explanation
. Translation (displacement) at the osteotomy site
Explanation
According to Osteotomy Rule 2, when the osteotomy is performed outside the CORA and the axes are realigned, the bone ends will translate (displace) at the osteotomy site. This translation must be accommodated to restore the mechanical axis.
Question 1645
Topic: 3. Adult Reconstruction (Hip & Knee)
During a revision total hip arthroplasty, the surgeon encounters a Paprosky Type IIIB acetabular defect. There is complete loss of the medial wall, superior migration of 3.5 cm, and severe ischial lysis. Which reconstructive option provides the most reliable mechanical fixation for this specific defect pattern?
Correct Answer & Explanation
. Cup-cage construct or custom triflange
Explanation
Paprosky Type IIIB defects involve severe pelvic discontinuity or highly compromised inferior bone (ischium) with >3 cm up-migration. Standard cups or jumbo cups have high failure rates here; cup-cage constructs or custom triflange implants are required to span the defect.
Question 1646
Topic: 3. Adult Reconstruction (Hip & Knee)
A 60-year-old woman sustains the injury shown in Figure 75. Prior to her injury, she lived independently and was a community ambulator without need for any assistive devices. What treatment will give her the greatest long-term painless hip function with the lowest reoperation rate?
Correct Answer & Explanation
. Total hip arthroplasty
Explanation
Cemented hemiarthroplasty is typically used to treat displaced femoral neck fractures in elderly patients. Recently, however, there has been a growing realization that many of these patients would be candidates for total hip arthroplasty had they presented with arthritis rather than fracture. Recent randomized studies have demonstrated improved outcomes up to 4 years following total hip arthroplasty compared with hemiarthroplasty in pain and functional scores. The rate of dislocation is higher following total hip arthroplasty. However, some patients with hemiarthroplasties required later conversion to total hip arthroplasty because of acetabular wear. In situ pinning is not recommended for patients with a displaced fracture. Open reduction and internal fixation of displaced femoral neck fractures in elderly patients is not recommended because of the risk of nonunion and osteonecrosis.
Question 1647
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 48a shows the full-leg standing radiograph of a patient with a prior femoral fracture. Figure 48b shows the lateral view of the same joint. The patient is scheduled to undergo total knee arthroplasty. Because the mechanical axis of the lower extremity in patients with a prior femoral fracture may be disrupted, which of the following should be used during surgery to restore the mechanical axis of the lower extremity in this patient?
Correct Answer & Explanation
. Routine knee prosthesis
Explanation
DISCUSSION: The radiograph shows hardware that was used for fixation of a prior femoral fracture. The mechanical axis of the lower extremity in this patient is nearly normal (3 degrees valgus), and the deformity at the healed fracture site (14 degrees) does not appear to affect the joint alignment and is acceptable. Use of a routine knee prosthesis will be possible in this patient. To avoid hardware removal, extramedullary jigs and/or computerized navigation may be used to measure and restore the long axis of the femur. The use of a hinged prosthesis does not influence the mechanical axis directly. Extra-articular osteotomy is occasionally needed to reverse severe deformities. REFERENCES: Papadopoulos EC, Parvizi J, Lai CH, et al: Total knee arthroplasty following distal femoral fractures. Knee 2002;9:267-274. Lonner JH, Siliski JM, Lotke PA: Simultaneous femoral osteotomy and total knee arthroplasty for treatment of osteoarthritis associated with severe extra-articular deformity. J Bone Joint Surg Am 2000;82:342-348.
Question 1648
Topic: Total Hip Arthroplasty (THA)
Figure 1 shows the radiograph obtained from a 60-year-old man recently diagnosed with osteoarthritis, 8 years after receiving a left metal-on-metal total hip arthroplasty (THA). The acetabular component has a modular cobalt alloy acetabular liner. The patient states that he did very well postoperatively, but for the last 6 months has noted worsening pain and swelling in his left hip. Serum metal ion testing reveals a chromium level of 4 ng/mL, compared with a normal level of less than 3 ng/mL, and a cobalt level of 8 ng/mL, compared with a normal level less than 7 ng/mL. An MRI with metal artefact reduction sequence (MARS) was performed and is shown in Figure 2. What is the most appropriate management at this time?
Correct Answer & Explanation
. Conversion of the THA to a ceramic femoral head with an inner titanium sleeve and polyethylene bearing
Explanation
DISCUSSION: Metal-on-metal THA was initially introduced in the 1990s, with the proposed advantages of decreased wear and improved stability. However, catastrophic adverse local tissue reactions associated with their use have raised numerous concerns. In a patient with clinical symptoms, elevated metal ion levels, and a large fluid collection seen on MRI, the most appropriate treatment would be removal of the metal-on-metal bearing. Given the presence of an adverse reaction involving cobalt and chromium, a revision ceramic head may be most appropriate to avoid the potential of trunnion-associated corrosion.
Question 1649
Topic: 3. Adult Reconstruction (Hip & Knee)
A 54-year-old man undergoes revision surgery for loosening and osteolysis of a cementless acetabular component. The membrane obtained from behind the component at the time of surgery is analyzed for particulate debris particle size. Which particle size is most likely responsible for the membrane formation?
Correct Answer & Explanation
. 1 to 1 micron
Explanation
In performing a posterior stabilized total knee arthroplasty (TKA), which component malpositioning is associated with the wear damage shown in this tibial component retrieval (Figure 1)?A. Excessive femoral component flexionB. Excessive anterior slope of the proximal tibiaC. Excessive tibial component varusD. Excessive valgus resection of the distal femur
Question 1650
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 89a is the radiograph of a 24-year-old man who was involved in a motor vehicle accident. A closed reduction is performed and a post-reduction CT scan is shown in Figure 89b. What is the next most appropriate step in management?
Correct Answer & Explanation
. Total hip arthroplasty
Explanation
The radiograph and CT scan show a posterior hip dislocation with an associated posterior wall acetabular fracture. The next step in management is assessment of hip instability. As suggested by Tornetta, assessment of hip instability with dynamic stress views is helpful to determine which posterior wall fractures are unstable and therefore require open reduction and internal fixation. Although protected weight bearing may be correct if the hip is stable, stability needs to be determined first. The CT scan reveals a small fragment in the cotyloid fossa. However, in this location, the presence of a loose body alone does not require surgical treatment. Hip instability needs to be assessed before determining if this fracture should be treated with open reduction and internal fixation. Total hip arthroplasty is not appropriate for a 24-year-old patient with a small posterior wall acetabular fracture.
Question 1651
Topic: 3. Adult Reconstruction (Hip & Knee)
A 71-year-old woman with coronary artery disease underwent an uncomplicated right total hip arthroplasty for osteoarthritis 12 years ago. Her hip has functioned well until approximately 18 months ago when she noted the spontaneous onset of groin, buttock, and proximal thigh pain that is present at rest and made worse with activity. A radiograph is shown in Figure 15. What is the recommended management at this point?
Correct Answer & Explanation
. Protected weight bearing with urgent revision hip arthroplasty when the patient is medically cleared
Explanation
DISCUSSION: The radiograph shows significant osteolysis with loosening of the femoral component. The patient is symptomatic and surgery is indicated because of the extent of osteolysis and the loose femoral component. Reassurance and follow-up if symptoms worsen places the patient at risk for further bone loss and periprosthetic fracture. Emergent surgery is not required because the symptoms have been present for more than a year; however, urgent revision hip arthroplasty is recommended when the patient is medically cleared.
Question 1652
Topic: Total Knee Arthroplasty (TKA)
A 72-year-old female sustains a supracondylar distal femur fracture directly above a well-fixed total knee arthroplasty (TKA). The TKA is a posterior stabilized (PS) design. Which specific feature of the TKA component is the primary contraindication to utilizing a retrograde intramedullary nail for fracture fixation?
Correct Answer & Explanation
. Cruciate retaining polyethylene insert
Explanation
A posterior stabilized (PS) TKA relies on a cam-and-post mechanism that requires an intercondylar 'box' on the femoral component. Some older or specific PS designs have a 'closed box' (a solid roof in the intercondylar notch), which physically prevents the passage of a retrograde intramedullary nail. An 'open box' PS design or a CR design typically allows nail passage.
Question 1653
Topic: 3. Adult Reconstruction (Hip & Knee)
A 65-year-old male presents with acute onset of severe knee pain, swelling, and fever 3 weeks after an uncomplicated total knee arthroplasty (TKA). Aspiration confirms acute periprosthetic joint infection. Radiographs show well-fixed components. What is the most appropriate initial surgical management?
Correct Answer & Explanation
. Open debridement, antibiotic therapy, and implant retention (DAIR) with modular exchange
Explanation
For acute postoperative periprosthetic joint infections (typically within 4 weeks of index surgery) with well-fixed implants and intact soft tissues, DAIR with polyethylene liner exchange is the treatment of choice. It offers a chance to eradicate infection while avoiding the morbidity of a full revision.
Question 1654
Topic: 3. Adult Reconstruction (Hip & Knee)
During primary total knee arthroplasty, the trial components are in place. The extensor space is tight, but the flexion space is normal. What is the best gap balancing solution?
Correct Answer & Explanation
. Resect additional distal femoral bone.
Explanation
DISCUSSION: The first rule of total knee arthroplasty is to restore the joint line to its original location. This will ensure optimal patellofemoral biomechanics and will facilitate ligament balancing. Changes on the tibial side affect both the flexion and extension gaps equally. Changes in femoral component sizing or position affect the flexion gap only. Tibial changes affect both the flexion and extension gaps. To convert a tight extension gap to a normal flexion gap, more distal femur needs to be resected. REFERENCES: Vince KG: Revision knee arthroplasty technique. Instr Course Lect 1993;42:325-339. Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 513-536.
Question 1655
Topic: 3. Adult Reconstruction (Hip & Knee)
One advantage of using onlay strut allograft in femoral revision surgery is that it can
Correct Answer & Explanation
. provide some structural support to host bone.
Explanation
DISCUSSION: Onlay grafts can provide more structural support than morcellized grafts. They are more easily incorporated into the host femur than bulk segmental total femur allografts; however, the incorporation is never complete. The use of onlay grafts is principally directed at addressing segmental defects of the femur; their use can be applied with either cementless or cement fixation of the femoral stem. REFERENCES: Emerson RH Jr, Malinin TI, Cuellar AD, Head WC, Peters PC: Cortical strut allografts in the reconstruction of the femur in revision total hip arthroplasty: A basic science and clinical study. Clin Orthop 1992;285:35-44. Pak JH, Paprosky WG, Jablonsky WS, Lawrence JM: Femoral strut allografts in cementless revision total hip arthroplasty. Clin Orthop 1993;295:172-178. Head WC, Emerson RH Jr, Malinin TI: Structural bone grafting for femoral reconstruction. Clin Orthop 1999;369:223-229.
Question 1656
Topic: 3. Adult Reconstruction (Hip & Knee)
Elbow distraction interposition arthroplasty may be most appropriate treatment for which of the following patient profiles? Review Topic
Correct Answer & Explanation
. year-old woman with destructive juvenile rheumatoid arthritis
Explanation
Elbow interposition arthroplasty is reserved for younger, active patients who may otherwise be candidates for prosthetic replacement. Osteoarthritis, posttraumatic arthritis, and rheumatoid arthritis patients may all be candidates for interposition arthroplasty if bone stock is preserved and the elbow maintains inherent stability. Primary osteoarthritis may also be treated with ulnohumeral arthroplasty (ie, Outerbridge) or arthroscopic debridement with release. Patients with destructive juvenile rheumatoid arthritis and distal humerus osteonecrosis would better benefit from prosthetic replacement because of bone loss issues.
Question 1657
Topic: Total Knee Arthroplasty (TKA)
A 58-year-old patient suddenly develops cardiac arrest while undergoing a routine total knee arthoplasty. He is resuscitated with 20% lipid emulsion. What was the most likely causative agent for cardiac arrest?
Correct Answer & Explanation
. Epinephrine
Explanation
This patients cardiac arrest was likely caused by an intravascular bolus of Bupivacaine.Bupivacaine is a long acting local anesthetic. It acts on intracellular voltage-gated sodium channels to block sodium influx into nerve cells, which prevents depolarization. If administered systemically, bupivacaine can cause serious complications to the cardiovascular system. Side effects include hypotension, arrhythmia, bradycardia, heart block, and cardiac arrest. Treatment should involve urgent administration of intravascular lipid emulsion alongside standard ACLS protocols.Rosenblatt et al. describe the successful use of a 20% lipid emulsion to resuscitate a patient after a presumed bupivacaine-related cardiac arrest. Resuscitation involved a lipid emulsion bolus of 1 mL/kg given immediately, which was followed by a continuous infusion until the patient stabilized.Corman et al. evaluated the use of lipid emulsion for reversal of local anesthetic-induced toxicity. They suggest that lipid emulsion may reverse local anesthetic toxicity by extracting lipophilic local anesthetics from aqueous plasma or tissues or by counteracting local anesthetic inhibition of myocardial fatty acid oxygenation.Illustration A shows an ECG of a patient with clinical deterioration after systemic administration of bupivicaine. The ECG shows complete heart block with multifocal ventricular beats. The patient progressed to asystole.Inncorrect Answers:
Question 1658
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure below shows the radiograph obtained from a 73-year-old woman who returns status post total hip arthroplasty 14 years earlier. She denies pain and has no discomfort on examination. She then undergoes revision total hip arthroplasty with head and liner exchange and bone grafting. After a physical therapy session two days after surgical intervention, she develops inability to dorsiflex the foot while she is sitting in a chair. The initial treatment should consist of
Correct Answer & Explanation
. transferring back to bed with the head of the bed level and the surgical knee flexed.
Explanation
Gamma irradiation produces free radicals. Although these free radicals can form cross-links with other polyethylene chains, the free radicals can also form a bond with oxygen, resulting in early oxidation. Gamma irradiation in air produces the highest risk for oxidized polyethylene, resulting in the highest risk for wear, delamination, and subsequent osteolysis. This patient demonstrates severe periarticular osteolysis. When she is asymptomatic, this suggests the acetabular and femoral components remain well fixed to the bone. Consequently, she can be treated by removing the wear generator (polyethylene exchange), along with bone grafting of the osteolytic defect. Considering the extensive amount of osteolysis, indefinite observation would not be appropriate. A foot drop develops 2 days after surgery. As a result, it can be assumed that the nerve was not injured directly during the surgical procedure. Although MRI or CT may be indicated to identify an evolving hematoma, the immediate concern is to minimize pressure on the sciatic nerve. Tension on the nerve can be reduced by flexing the surgical knee and positioning the bed flat.
Question 1659
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 44 shows the radiograph of a 65-year-old man who underwent a revision arthroplasty to remove a loose, cemented femoral stem. When planning the postoperative restrictions, the surgeon should be aware that
Correct Answer & Explanation
. the approach used reduces the torque-to-failure (fracture) of the construct to less than 50% of the intact femur.
Explanation
The transfemoral approach, also known as the extended trochanteric osteotomy, is an important technique to master for revision hip surgery. When performed correctly, it allows excellent exposure of the femoral canal and aids in exposure of the acetabulum. As demonstrated in the study cited, however, it markedly reduces the torque that the composite can withstand without failure. This type of basic science study is important to guide postoperative rehabilitation.
Question 1660
Topic: 3. Adult Reconstruction (Hip & Knee)
A 45-year-old man has a draining sinus and recurrent infection of his right total knee arthroplasty. He has had two prior revision surgeries after the primary procedure and three other surgeries before his initial replacement, including a proximal tibial osteotomy and subsequent hardware removal. On clinical examination, he has a draining sinus in the mid portion of his surgical scar and a range of motion of 5° to 85°. AP and lateral radiographs of the right knee are shown in figures below. During surgery, the femoral component is found to be grossly loose, but the tibial component is well fixed. What is the most appropriate extensile approach that would provide adequate exposure and aid in tibial component extraction?
Correct Answer & Explanation
. Extended tibial tubercle osteotomy
Explanation
Extended tibial tubercle osteotomy is an extensile approach to revision total knee arthroplasty that affords excellent exposure and can facilitate removal of tibial sleeves and cones. This patient has had multiple surgeries, including a proximal tibial osteotomy, as well as poor range of motion, patella baja, and a well-fixed metaphyseal sleeve component. Classically, an extended tibial tubercle osteotomy provides outstanding exposure for component removal in the setting of prior high tibial osteotomy and patella baja.
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