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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 79 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 1561

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old active male is undergoing a primary total hip arthroplasty. The surgeon is deciding on the optimal bearing surface. Compared to other bearing combinations, which of the following is the most distinct clinical profile of a ceramic-on-ceramic articulation?

. Lowest volumetric wear rate, high resistance to third-body wear, but increased risk of squeaking and catastrophic component fracture.
. Highest resistance to catastrophic fracture, self-polishing properties, but highest risk of trunnionosis.
. Eliminates the risk of squeaking, high resistance to third-body wear, but associated with elevated serum cobalt levels.
. Excellent toughness and elasticity, lowest risk of squeaking, but susceptible to accelerated wear from third-body debris.
. Optimal boundary lubrication, lowest risk of bearing fracture, but requires a larger minimum head size.

Correct Answer & Explanation

. Lowest volumetric wear rate, high resistance to third-body wear, but increased risk of squeaking and catastrophic component fracture.

Explanation

Ceramic-on-ceramic bearings have the lowest volumetric wear and are highly resistant to scratching. However, they carry a unique risk of squeaking (audible noise) and a rare but devastating risk of catastrophic bearing fracture.

Question 1562

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary posterior-stabilized total knee arthroplasty, the surgeon performs the initial bone cuts and inserts spacer blocks. The knee is perfectly balanced and stable in full extension, but it is extremely tight and unable to flex past 80 degrees in flexion. Which of the following technical adjustments is the most appropriate next step to balance the knee?

. Resect additional distal femur.
. Upsize the femoral component.
. Release the posterior cruciate ligament.
. Downsize the femoral component and use the same thickness polyethylene insert.
. Decrease the posterior slope of the tibial cut.

Correct Answer & Explanation

. Resect additional distal femur.

Explanation

A knee that is tight in flexion but balanced in extension requires an increase in the flexion gap only. Downsizing the femoral component (resecting more posterior condylar bone) or increasing the posterior tibial slope will selectively increase the flexion gap.

Question 1563

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old female with end-stage ankle osteoarthritis is being evaluated for a total ankle arthroplasty (TAA). Which of the following preoperative findings represents an absolute contraindication to performing a TAA?

. Body Mass Index of 32 kg/m2.
. Avascular necrosis involving 60% of the talar body.
. Concomitant subtalar joint arthritis.
. Previous open reduction and internal fixation of a bimalleolar fracture.
. A 10-degree coronal plane varus deformity of the tibiotalar joint.

Correct Answer & Explanation

. Body Mass Index of 32 kg/m2.

Explanation

Avascular necrosis involving more than 50% of the talar body is an absolute contraindication to TAA due to the high risk of component subsidence and failure. Other absolute contraindications include active infection, severe Charcot neuroarthropathy, and absent lower extremity sensation.

Question 1564

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male undergoes a right total hip arthroplasty. Six months postoperatively, he has experienced three episodes of posterior dislocation while rising from a low chair. Radiographs and CT imaging demonstrate the acetabular cup is positioned in 20 degrees of anteversion and 40 degrees of inclination. The femoral stem is fixed in 10 degrees of retroversion. What is the most appropriate surgical management?

. Revision of the acetabular cup to increase anteversion to 45 degrees.
. Prescription of a hip abduction brace for 3 months.
. Revision of the femoral stem to achieve 10 to 15 degrees of anteversion.
. Conversion to a dual mobility bearing with retention of the current stem.
. Advancement of the greater trochanter to increase abductor tension.

Correct Answer & Explanation

. Revision of the acetabular cup to increase anteversion to 45 degrees.

Explanation

The patient has recurrent posterior instability due to a malpositioned (retroverted) femoral stem, while the cup is in acceptable position. The definitive treatment for a well-fixed, retroverted stem causing recurrent instability is revision of the femoral component to restore normal anteversion.

Question 1565

Topic: 3. Adult Reconstruction (Hip & Knee)

A 71-year-old male presents with a 4-day history of acute, severe right knee pain and swelling. He underwent an uncomplicated primary total knee arthroplasty 3 years ago. He recently had a dental extraction 2 weeks prior without prophylactic antibiotics. Joint aspiration yields a synovial fluid WBC count of 85,000 cells/uL with 92% neutrophils. Radiographs show well-fixed components. What is the most appropriate surgical intervention?

. Arthroscopic joint lavage and 6 weeks of intravenous antibiotics.
. One-stage revision total knee arthroplasty.
. Two-stage revision total knee arthroplasty with an antibiotic spacer.
. Open debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange.
. Suppressive oral antibiotic therapy indefinitely without surgical intervention.

Correct Answer & Explanation

. Arthroscopic joint lavage and 6 weeks of intravenous antibiotics.

Explanation

This is an acute hematogenous periprosthetic joint infection (symptoms < 3 weeks in a previously well-functioning, chronically implanted joint). The standard of care is an open debridement, antibiotics, and implant retention (DAIR) with exchange of the modular polyethylene insert.

Question 1566

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon is performing a primary total knee arthroplasty (TKA). During trialing, the extension gap is excessively tight, preventing full extension, but the flexion gap is perfectly balanced. Which of the following is the most appropriate next step to correct this kinematic mismatch?

. Upsize the femoral component
. Downsize the femoral component
. Resect more distal femur
. Resect more posterior femur
. Resect more proximal tibia

Correct Answer & Explanation

. Upsize the femoral component

Explanation

A tight extension gap with a balanced flexion gap indicates that the distal femoral resection is insufficient. Resecting more distal femur will open the extension gap without affecting the flexion gap.

Question 1567

Topic: Total Hip Arthroplasty (THA)

A 45-year-old active female undergoes THA with a ceramic-on-ceramic bearing. At 2 years postoperatively, she complains of a loud, reproducible squeaking noise from her hip during normal gait. Which of the following is the most established biomechanical cause for this phenomenon?

. Acetabular component malposition leading to edge loading
. Isolated excessive femoral offset
. Decreased femoral anteversion alone
. Subsidence of an undersized femoral stem
. Use of a 36-mm instead of a 32-mm ceramic head

Correct Answer & Explanation

. Acetabular component malposition leading to edge loading

Explanation

Squeaking in ceramic-on-ceramic THA is heavily associated with edge loading, typically caused by acetabular component malposition (e.g., steep inclination or excessive anteversion/retroversion). This leads to stripe wear and disruption of fluid-film lubrication.

Question 1568

Topic: Total Hip Arthroplasty (THA)

A 55-year-old female presents with anterior groin pain 1 year after an uncemented THA. The pain is exacerbated by active hip flexion. Radiographs demonstrate that the acetabular component is placed with 10 degrees of anteversion and overhangs the anterior acetabular rim by 12 mm. Image-guided injection of the psoas bursa temporarily resolves her pain. What is the most appropriate definitive management?

. Iliopsoas tenotomy at the lesser trochanter
. Revision of the acetabular component
. Revision of the femoral component to increase lateral offset
. Hip arthroscopy and labral debridement
. Endoscopic gluteus medius repair

Correct Answer & Explanation

. Iliopsoas tenotomy at the lesser trochanter

Explanation

While iliopsoas tenotomy is an option for functional impingement, an anterior component overhang greater than 8 mm is a structural cause of psoas impingement. Revision of the malpositioned acetabular cup is required for definitive resolution.

Question 1569

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male presents with a painful, audible "clunk" in his knee when extending from 45 degrees of flexion, 1 year after a posterior-stabilized (PS) TKA. Radiographs show well-fixed components. Which of the following is the primary pathophysiologic cause of this condition?

. Undersized femoral component causing flexion instability
. Fibrous nodule formation at the superior pole of the patella catching in the intercondylar box
. Patellar tendon shortening (patella baja)
. Oversized tibial tray causing medial impingement
. Aseptic loosening of the patellar button

Correct Answer & Explanation

. Undersized femoral component causing flexion instability

Explanation

Patellar clunk syndrome occurs primarily in posterior-stabilized TKA when a fibrous nodule forms at the superior pole of the patella. As the knee extends, this nodule catches in the femoral intercondylar box and abruptly snaps out, causing a painful clunk.

Question 1570

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male with a metal-on-polyethylene THA presents with a large anterior thigh mass and significantly elevated serum cobalt levels, while chromium levels remain normal. Radiographs demonstrate well-fixed components with a modular femoral head. Aspiration reveals sterile, opaque fluid. What is the most likely etiology?

. Polyethylene wear osteolysis
. Unrecognized metal-on-metal bearing placement
. Trunnionosis (taper corrosion)
. Head-neck dissociation
. Adverse local tissue reaction due to acetabular titanium debris

Correct Answer & Explanation

. Polyethylene wear osteolysis

Explanation

Trunnionosis (mechanochemical corrosion at the head-neck modular taper) characteristically presents with an elevated cobalt-to-chromium ratio. It can cause a severe adverse local tissue reaction (ALTR) or pseudotumor, even in metal-on-polyethylene bearings.

Question 1571

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female is 8 weeks post-operative from an uncomplicated primary TKA. Her current range of motion is 10 degrees to 75 degrees despite aggressive, compliant physical therapy. She is medically stable and radiographs show well-aligned components. What is the most appropriate next step in management?

. Continued physical therapy for 4 additional weeks
. Manipulation under anesthesia (MUA)
. Arthroscopic lysis of adhesions
. Open arthrolysis and polyethylene exchange
. Revision total knee arthroplasty

Correct Answer & Explanation

. Continued physical therapy for 4 additional weeks

Explanation

Manipulation under anesthesia (MUA) is highly effective for TKA stiffness when performed between 6 and 12 weeks post-operatively. Delaying MUA beyond 12 weeks significantly decreases its success rate due to mature fibrous scar formation.

Question 1572

Topic: Total Knee Arthroplasty (TKA)

A patient complains of anterior knee pain and a sensation of patellar subluxation 1 year after a primary TKA. A computed tomography (CT) scan evaluates component rotation and demonstrates excessive internal rotation of the tibial component. What is the expected biomechanical consequence of a severely internally rotated tibial component on patellar tracking?

. Medialization of the tibial tubercle leading to lateral patellar tracking
. Lateralization of the tibial tubercle leading to medial patellar tracking
. Proximal patella alta
. Distal patella baja
. No significant effect on the Q-angle or patellar tracking

Correct Answer & Explanation

. Medialization of the tibial tubercle leading to lateral patellar tracking

Explanation

Internal rotation of the tibial component effectively medializes the tibial tubercle relative to the trochlear groove. This increases the dynamic Q-angle, resulting in increased lateral vector forces and subsequent lateral patellar tracking or subluxation.

Question 1573

Topic: 3. Adult Reconstruction (Hip & Knee)
An otherwise healthy 57-year-old woman has limited range of motion and moderate effusion after undergoing total knee arthroplasty 6 months ago. One of two cultures of joint aspirate reveals methicillin-resistant Staphylococcus epidermidis. Management should now consist of:
. repeat aspiration to rule out culture contamination.
. IV administration of kanamycin for 6 weeks, followed by suppressive oral antibiotics.
. removal of the implant and 6 weeks of antibiotics, followed by reimplantation.
. removal of the implant, followed by knee fusion.
. open irrigation of the implant and intraoperative cultures, followed by 6 weeks of antibiotics.

Correct Answer & Explanation

. removal of the implant and 6 weeks of antibiotics, followed by reimplantation.

Explanation

DISCUSSION: The rapidly increasing prevalence of infection from Staphylococcus epidermidis has made this the most frequently cultured organism. In most patients, the infection occurred intraoperatively, thereby resulting in a chronic infection if not detected within the first 6 weeks after surgery. Irrigation of the joint may be successful during this time in 60% of patients, but the most successful treatment is extirpation for 6 weeks, followed by delayed reimplantation. This approach may result in a salvage rate of as high as 90% in some patients. REFERENCES: Drancourt M, Stein A, Argenson JN, et al: Oral rifampin plus ofloxacin for treatment of staphylococcus-infected orthopedic implants. Antimicrob Agents Chemother 1993;37:1214-1218. Duncan CP, Beauchamp C: A temporary antibiotic-loaded joint replacement system for the management of complex infections involving the hip. Orthop Clin North Am 1993;24:751-759. Oyen WJ, Claessens RA, van Horn JR, et al: Scintiographic detection of bone and joint infections with indium-111-labeled nonspecifonal human immunoglobulin G. J Nucl Med 1990;31:403-412.

Question 1574

Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 3 shows the AP radiograph of a patient with diabetes mellitus who has knee pain. A semiconstrained knee prosthesis was used in this patient to prevent which of the following complications?
. Infection
. Instability
. Stiffness
. Bone loss
. Malalignment

Correct Answer & Explanation

. Instability

Explanation

DISCUSSION: The radiographic appearance of the joint is highly suspicious for neuropathic joint (Charcot’s joint). Evidence of bone loss on both the tibial and the femoral sides may necessitate the use of metal and/or bone augments. Patients with a neuropathic joint often have excellent range of motion, and postoperative stiffness is not a problem. The main problem with these patients is instability that occurs secondary to ligamentous laxity. Use of a semiconstrained prosthesis prevents the latter complication. REFERENCES: Parvizi J, Marrs J, Morrey BF: Total knee arthroplasty for neuropathic (Charcot) joints. Clin Orthop 2003;416:145-150. Kim YH, Kim JS, Oh SW: Total knee arthroplasty in neuropathic arthropathy. J Bone Joint Surg Br 2002;84:216-219.

Question 1575

Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following statements most accurately describes the risk of ileus following total joint arthroplasty?
. Older age decreases risk.
. Male gender decreases risk.
. The risk is roughly 1% in total joint arthroplasty patients.
. The risk more commonly occurs in total knee arthroplasty (TKA) patients than in total hip arthroplasty (THA) patients.
. A history of abdominal surgery has no effect on risk.

Correct Answer & Explanation

. The risk is roughly 1% in total joint arthroplasty patients.

Explanation

DISCUSSION: The risk of postoperative ileus is noted to be higher in patients undergoing THA than patients undergoing TKA. Older age, male gender, and a history of abdominal surgery have been identified as risk factors. REFERENCE: Parvizi J, Han SB, Tarity TD, et al: Postoperative ileus after total joint arthroplasty. J Arthroplasty 2008;23:360-365.

Question 1576

Topic: 3. Adult Reconstruction (Hip & Knee)

A 54-year-old woman undergoes an interposition arthroplasty that fails and requires conversion to a total elbow arthroplasty. She has progressive elbow pain and radiographic loosening. Erythrocyte sedimentation rate and C-reactive protein are normal. Joint aspiration is positive for Staphylococcus epidermidis. What surgical treatment would best optimize function and decrease risk of recurrence?

. Resection arthroplasty
. Single-stage revision total elbow arthroplasty
. Two-stage revision elbow arthroplasty
. Aggressive arthroscopic debridement and retention of components

Correct Answer & Explanation

. Resection arthroplasty

Explanation

The most reliable surgical option in this case for eradicating a deep infection following a total elbow arthroplasty is a two-stage revision. One study, however, reported that staged reimplantation of an infected total elbow replacement could be successful in the setting of organisms other than S epidermidis. Arthroscopic debridement is not a viable option with poorly fixed or loose components. A single-stage revision, while considered an option in hip and knee arthroplasty, has not been definitively proven to be an option for revision total elbow arthroplasty. Single-stage revision has shown moderate success in the setting of Staphylococcus aureus infections, although with only short-term follow-up. A resection arthroplasty would likely be successful in managing the deep infection but would not optimize the functional result. Resection arthroplastyis best reserved for low-demand or infirm patients.

Question 1577

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 C. Full-thickness skin graft D. Local rotational flap

Correct Answer & Explanation

. Continued dressing changes

Explanation

DISCUSSION: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 1578

Topic: 3. Adult Reconstruction (Hip & Knee)
Venous thromboembolism is a common complication following total hip and total knee arthroplasty; therefore, prophylaxis is deemed efficacious. Several studies on low-molecular-weight heparin (LMWH) have shown which of the following findings?
. LMWH is associated with bleeding complications of less than 1% and may be administered immediately after surgery.
. LMWH is superior to adjusted-dose warfarin.
. LMWH acts on several sites of the coagulation cascade, with its principal action inhibition of factor 10a.
. LMWH and unfractionated heparin are equally likely to cause thrombocytopenia.
. LMWH may be used in conjunction with regional anesthesia and is not contraindicated in patients with indwelling epidural catheters.

Correct Answer & Explanation

. LMWH acts on several sites of the coagulation cascade, with its principal action inhibition of factor 10a.

Explanation

DISCUSSION: Prophylactic LMWH is associated with a risk of bleeding complications, especially if administered too soon after surgery. The risk of major bleeding is 0.3% for control, 0.4% for aspirin, 1.3% for warfarin, 1.8% for LMWH, and 2.6% for unfractionated heparin. Colwell and associates conducted a prospective, randomized trial on over 1,500 total hip arthroplasty patients. Overall, the risk of clinically apparent venous thromboembolism was 3.6% for LMWH and 3.7% for warfarin. LMWH acts in several sites of the coagulation cascade, with its principal action being inhibition of factor 10a. Thrombocytopenia is less common with LMWH than with unfractionated heparin. The use of LMWH is a relative contraindication with indwelling epidural anesthesia. REFERENCES: Colwell CW Jr, Collis DK, Paulson R, et al: Comparison of enoxaparin and warfarin for the prevention of venous thromboembolic disease after total hip arthroplasty: Evaluation during hospitalization and three months after discharge. J Bone Joint Surg Am 1999;81:932-940. Salvati EA, Pelligrini VD Jr, Sharrock NE, et al: Recent advances in venous thromboembolic prophylaxis during and after total hip replacement. J Bone Joint Surg Am 2000;82:252-270.

Question 1579

Topic: 3. Adult Reconstruction (Hip & Knee)
A 73-year-old man presents to your clinic many years after undergoing total shoulder arthroplasty with pain and the radiographic findings demonstrated in Figure 56. The most likely cause of this patient’s pain is
. stress shielding.
. humeral osteolysis.
. glenoid loosening.
. progressive glenoid arthritis.

Correct Answer & Explanation

. glenoid loosening.

Explanation

DISCUSSION: The radiograph shows proximal humeral migration and loosening of the glenoid component. Proximal migration of the humeral head may represent rotator cuff dysfunction and can lead to progressive failure of the glenoid component. Stress shielding will not cause lysis or loosening of the glenoid component. Humeral osteolysis is an uncommon finding and is not shown. Progressive glenoid arthrosis is not possible with a resurfaced glenoid. RECOMMENDED READINGS: Hill JM, Norris TR. Long-term results of total shoulder arthroplasty following bone-grafting of the glenoid. J Bone Joint Surg Am. 2001 Jun;83-A(6):877-83. PubMed PMID: 11407796. Fox TJ, Cil A, Sperling JW, Sanchez-Sotelo J, Schleck CD, Cofield RH. Survival of the glenoid component in shoulder arthroplasty. J Shoulder Elbow Surg. 2009 Nov-Dec;18(6):859-63. doi: 10.1016/j.jse.2008.11.020. Epub 2009 Mar 17. PubMed PMID: 19297199.

Question 1580

Topic: 3. Adult Reconstruction (Hip & Knee)
At the level of tibial bone resection in total knee arthroplasty, where does the common peroneal nerve lie?
. Deep to the arcuate ligament
. Closer to bone in larger legs
. On the muscle belly of the popliteus
. On the bony posterolateral corner of the tibia
. Superficial to the lateral head of the gastrocnemius

Correct Answer & Explanation

. Superficial to the lateral head of the gastrocnemius

Explanation

DISCUSSION: At the level of tibial bone resection in total knee arthroplasty, the common peroneal nerve lies superficial to the lateral head of the gastrocnemius and is therefore protected by this structure. In an MRI study of 60 knees, the mean distance from the bony posterolateral corner of the tibia to the nerve was 1.49 cm, with no distance less than 0.9 cm. The distance from the bone to nerve was greater in larger legs. REFERENCES: Clarke HD, Schwartz JB, Math KR, et al: Anatomic risk of peroneal nerve injury with the “pie crust” technique for valgus release in total knee arthroplasty. J Arthroplasty 2004;19:40-44. Anderson JE: Grant’s Atlas of Anatomy, ed 7. Baltimore, MD, Lippincott Williams & Wilkins, 1978, pp 4-52, 4-53.

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