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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 203 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 4041

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old woman presents to the emergency department after a mechanical fall. She had a THA 10 years ago. Radiographs reveal a periprosthetic femur fracture around the stem. The fracture is at the level of the stem tip, the stem is loose, and there is poor proximal bone stock. According to the Vancouver classification, what is the most appropriate management?

. Open reduction and internal fixation with a lateral locking plate
. Revision to a long-stem cemented component
. Revision to a fluted, tapered, distally fixing cementless stem
. Strut allografting alone
. Cortical windowing and cementation of the fracture

Correct Answer & Explanation

. Revision to a fluted, tapered, distally fixing cementless stem

Explanation

This describes a Vancouver B3 fracture (loose stem, poor proximal bone stock). The most reliable treatment is bypassing the deficient proximal bone and achieving fixation distally using a fluted, tapered cementless stem.

Question 4042

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old man with a metal-on-metal THA placed 8 years ago presents with worsening groin pain. Inflammatory markers are normal. Serum cobalt and chromium levels are significantly elevated. MARS MRI shows a large cystic mass communicating with the joint. What is the most appropriate next step in management?

. Ultrasound-guided aspiration of the cyst
. Surgical debridement and retention of all components
. Revision of the acetabular and femoral components to a metal-on-polyethylene bearing
. Observation and repeat MRI in 6 months
. Oral course of heavy metal chelating agents

Correct Answer & Explanation

. Revision of the acetabular and femoral components to a metal-on-polyethylene bearing

Explanation

The patient has an adverse local tissue reaction (ALVAL/pseudotumor) secondary to metal-on-metal wear. Definitive treatment requires revision of the bearing surface to a non-metal-on-metal articulation.

Question 4043

Topic: Total Hip Arthroplasty (THA)

A 50-year-old man presents with persistent anterior groin pain 1 year after an uncomplicated THA. The pain is reproducible with active straight leg raise and resisted hip flexion. Radiographs demonstrate a well-fixed cup with 5 degrees of retroversion and prominent anterior overhang. A diagnostic injection of local anesthetic into the psoas sheath provides complete temporary relief. If conservative management fails, what is the best surgical intervention?

. Arthroscopic iliopsoas tenotomy
. Femoral nerve decompression
. Revision of the acetabular component to increase anteversion
. Revision of the femoral component to increase offset
. Prescription of a hip brace to limit flexion

Correct Answer & Explanation

. Revision of the acetabular component to increase anteversion

Explanation

The patient has iliopsoas impingement secondary to a malpositioned (retroverted) and prominent acetabular cup. While tenotomy can be tried, the definitive treatment for symptomatic significant component malposition is cup revision.

Question 4044

Topic: 3. Adult Reconstruction (Hip & Knee)
A 30-year-old woman with systemic lupus erythematosus on chronic corticosteroids presents with severe left hip pain. Radiographs reveal a crescent sign and early flattening of the femoral head. An MRI confirms osteonecrosis with 3 mm of depression. What is the most appropriate definitive management?
. Core decompression with autologous bone marrow aspirate
. Vascularized free fibular graft
. Total hip arthroplasty
. Non-weight bearing with crutches for 12 weeks
. Rotational proximal femoral osteotomy

Correct Answer & Explanation

. Total hip arthroplasty

Explanation

Once structural collapse of the femoral head has occurred (Ficat stage III, >2mm depression), joint-preserving procedures like core decompression are highly likely to fail. THA is the most reliable treatment in this setting.

Question 4045

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old man develops recurrent posterior dislocations of his THA. He has a well-fixed cementless cup positioned in 45 degrees of inclination and 20 degrees of anteversion, and a well-fixed cementless stem. His abductor musculature is severely degenerated on MRI. Which of the following is the most appropriate surgical strategy to restore stability?

. Revision to a constrained acetabular liner
. Revision of the acetabular shell to decrease anteversion
. Advancement of the greater trochanter
. Application of a hip abduction orthosis indefinitely
. Revision to a larger femoral head without changing the liner

Correct Answer & Explanation

. Revision to a constrained acetabular liner

Explanation

In the setting of recurrent instability with well-positioned components and severe abductor deficiency, a constrained acetabular liner or a dual mobility construct is the most appropriate surgical option to prevent further dislocations.

Question 4046

Topic: Total Hip Arthroplasty (THA)

Which of the following intervals is utilized during the direct lateral (Hardinge) approach to the hip?

. Between the sartorius and tensor fasciae latae
. Between the gluteus medius and gluteus minimus
. Splitting the gluteus medius and vastus lateralis
. Between the tensor fasciae latae and gluteus medius
. Between the piriformis and superior gemellus

Correct Answer & Explanation

. Splitting the gluteus medius and vastus lateralis

Explanation

The direct lateral (Hardinge) approach splits the anterior third of the gluteus medius and the vastus lateralis. This approach places the superior gluteal nerve at risk if the split extends more than 5 cm proximal to the greater trochanter.

Question 4047

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old man undergoes a standard primary THA using a non-cemented femoral stem. Six months postoperatively, he complains of reproducible mid-thigh pain that occurs only with weight-bearing and resolves with rest. Radiographs show a well-positioned stem with reactive cortical hypertrophy at the stem tip and no radiolucent lines. What is the most likely diagnosis?

. Periprosthetic joint infection
. Aseptic loosening of the femoral stem
. End-of-stem thigh pain (modulus mismatch)
. Undiagnosed intraoperative periprosthetic fracture
. Iliopsoas tendinitis

Correct Answer & Explanation

. End-of-stem thigh pain (modulus mismatch)

Explanation

End-of-stem thigh pain typically occurs with cementless, stiff, extensively porous-coated stems due to a modulus of elasticity mismatch between the rigid metal stem and the flexible femoral diaphysis.

Question 4048

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old man presents with an acute periprosthetic joint infection of his THA. His index surgery was 3 weeks ago. He is medically stable. Aspiration yields purulent fluid with a WBC count of 85,000 cells/uL. What is the most appropriate management?

. Intravenous antibiotics for 6 weeks followed by lifetime suppression
. Single-stage revision arthroplasty
. Two-stage revision arthroplasty
. Debridement, antibiotics, and implant retention (DAIR) with modular exchange
. Resection arthroplasty (Girdlestone procedure)

Correct Answer & Explanation

. Debridement, antibiotics, and implant retention (DAIR) with modular exchange

Explanation

Acute postoperative periprosthetic joint infections (occurring within 4 weeks of the index procedure) with well-fixed components are best managed with aggressive open debridement, modular exchange (DAIR), and IV antibiotics.

Question 4049

Topic: Total Hip Arthroplasty (THA)

A 62-year-old man presents with left hip pain 5 years after a conventional metal-on-polyethylene THA. Radiographs show well-fixed components. Serum cobalt level is markedly elevated, but chromium is normal. MRI shows a large periprosthetic fluid collection. What is the most likely source of the elevated metal ions?

. Wear of the polyethylene liner
. Corrosion at the modular head-neck junction (trunnionosis)
. Galvanic corrosion between the cup and the screw
. Impingement of the stem neck on the acetabular rim
. Systemic absorption of dietary heavy metals

Correct Answer & Explanation

. Corrosion at the modular head-neck junction (trunnionosis)

Explanation

Elevated cobalt levels out of proportion to chromium in a patient with a metal-on-polyethylene bearing strongly suggests mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction.

Question 4050

Topic: Total Hip Arthroplasty (THA)

In the setting of primary THA, which of the following best describes the principle advantage of a dual-mobility construct compared to a standard unconstrained bearing?

. Decreased volumetric wear of polyethylene
. Elimination of trunnionosis risk
. Increased effective head size increasing the jump distance
. Easier extraction during future revision surgery
. Better preservation of femoral offset

Correct Answer & Explanation

. Increased effective head size increasing the jump distance

Explanation

Dual-mobility cups utilize a small femoral head captive within a larger mobile polyethylene liner. This creates a larger effective head size, increasing the jump distance and significantly reducing the risk of dislocation.

Question 4051

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient who received a metal-on-polyethylene THA 15 years ago demonstrates eccentric wear of the polyethylene liner and massive expansile osteolytic lesions in the proximal femur. The stem remains well-fixed. What is the primary biological mediator initiating this osteolytic process?

. Release of endotoxins from subclinical infection
. Macrophage phagocytosis of submicron polyethylene particles
. Direct toxicity of metal ions on osteoblasts
. Type IV hypersensitivity reaction to nickel
. Mechanical stress shielding

Correct Answer & Explanation

. Macrophage phagocytosis of submicron polyethylene particles

Explanation

Aseptic loosening and osteolysis in conventional polyethylene bearings are driven by macrophage phagocytosis of submicron polyethylene wear particles. This triggers an inflammatory cascade resulting in bone resorption.

Question 4052

Topic: Total Hip Arthroplasty (THA)

A 45-year-old active man complains of a painless squeaking sound from his ceramic-on-ceramic total hip arthroplasty (THA) placed 2 years ago. Radiographs show a well-fixed cup with 60 degrees of abduction and 25 degrees of anteversion. What is the most likely cause of this acoustic phenomenon?

. Malposition leading to edge loading
. Ceramic liner fracture
. Trunnionosis at the head-neck junction
. Impingement of the femoral neck on the acetabular rim
. Normal articulation of the ceramic surfaces

Correct Answer & Explanation

. Malposition leading to edge loading

Explanation

Squeaking in ceramic-on-ceramic hips is highly correlated with component malposition, particularly excessive cup abduction or anteversion leading to edge loading. If painless and without signs of wear or fracture, reassurance and observation are typically recommended.

Question 4053

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old man presents with groin pain 6 years after a metal-on-polyethylene THA utilizing a 36-mm cobalt-chrome head on a titanium alloy stem. MRI shows a solid cystic mass with thick walls. Serum cobalt levels are markedly elevated compared to chromium. What is the most likely diagnosis?

. Mechanically assisted crevice corrosion (MACC)
. Polyethylene wear osteolysis
. Periprosthetic joint infection
. Metallosis from head-liner articulation
. Adverse local tissue reaction from a metal-on-metal bearing

Correct Answer & Explanation

. Mechanically assisted crevice corrosion (MACC)

Explanation

MACC, or trunnionosis, occurs at the modular head-neck junction, often seen with large cobalt-chrome heads on titanium stems. It classically presents with a higher ratio of serum cobalt to chromium and can cause an adverse local tissue reaction (pseudotumor).

Question 4054

Topic: Total Hip Arthroplasty (THA)

A 72-year-old woman with Parkinson's disease presents with her third posterior dislocation of a primary THA within 6 months. Her abductor mechanism is grossly intact. Radiographs show acceptable component positioning. What is the most appropriate surgical intervention?

. Revision to a dual mobility construct
. Revision of the acetabular shell to decrease version
. Placement of a constrained acetabular liner
. Distal advancement of the greater trochanter
. Revision to a larger diameter femoral head alone

Correct Answer & Explanation

. Revision to a dual mobility construct

Explanation

Dual mobility constructs provide excellent stability and are the preferred option for recurrent instability in patients with an intact abductor mechanism, particularly in high-risk neuromuscular patients. Constrained liners have a higher failure rate and are generally reserved for deficient abductors.

Question 4055

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old man is evaluated for a painful THA 3 years postoperatively. He has been taking oral antibiotics for a presumed urinary tract infection. Serum ESR and CRP are equivocal. Joint aspiration yields a WBC count of 2,500 cells/microL with 70% PMNs. Which of the following synovial fluid biomarkers is most specific for diagnosing a periprosthetic joint infection in this setting?

. Alpha-defensin
. Interleukin-6
. Leukocyte esterase
. C-reactive protein
. Calprotectin

Correct Answer & Explanation

. Alpha-defensin

Explanation

Alpha-defensin is an antimicrobial peptide released by neutrophils that is a highly specific biomarker for periprosthetic joint infection. Its accuracy remains robust and is minimally affected by concurrent systemic antibiotic administration.

Question 4056

Topic: Total Hip Arthroplasty (THA)

During preoperative planning for a revision THA, radiographs demonstrate an acetabular defect with superior migration of the hip center greater than 3 cm, severe ischial lysis, and destruction of the teardrop. According to the Paprosky classification, what type of defect is present, and what is the optimal reconstructive option?

. Type 2B; hemispherical cup with multiple screws
. Type 2C; jumbo hemispherical cup
. Type 3A; hemispherical cup with structural allograft
. Type 3B; cup-cage construct or custom triflange
. Type 4; saddle prosthesis

Correct Answer & Explanation

. Type 3B; cup-cage construct or custom triflange

Explanation

Paprosky 3B defects involve severe bone loss with destruction of the teardrop, Kohler's line, and ischium, often with pelvic discontinuity. Management typically requires custom triflange implants, cup-cage constructs, or massive structural allografts to achieve stability.

Question 4057

Topic: 3. Adult Reconstruction (Hip & Knee)
A 50-year-old man who underwent a metal-on-metal THA 8 years ago presents for a routine follow-up. He is completely asymptomatic and highly active. Radiographs show well-fixed components. Serum cobalt levels are 8.5 ppb (normal <1 ppb). What is the most appropriate next step in management?
. Immediate revision total hip arthroplasty
. Repeat serum metal ions in 1 year without imaging
. Metal artifact reduction sequence (MARS) MRI of the hip
. Aspiration of the hip joint for cell count
. Diagnostic ultrasound to evaluate abductor tendons

Correct Answer & Explanation

. Metal artifact reduction sequence (MARS) MRI of the hip

Explanation

For patients with metal-on-metal THA and significantly elevated metal ion levels (>7 ppb), current guidelines recommend advanced cross-sectional imaging, ideally a MARS MRI. This evaluates for asymptomatic adverse local tissue reactions (ALTR) or pseudotumors.

Question 4058

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old man on chronic corticosteroids presents with acute bilateral hip pain. MRI demonstrates diffuse bone marrow edema in the right proximal femur with a subchondral band-like lesion, and no collapse. What is the most appropriate initial management for the right hip?

. Total hip arthroplasty
. Core decompression
. Observation and protected weight bearing
. Non-vascularized fibular strut grafting
. Free vascularized fibular graft

Correct Answer & Explanation

. Core decompression

Explanation

For symptomatic, pre-collapse osteonecrosis of the femoral head (Ficat Stage I or II), core decompression is the standard initial joint-preserving surgical treatment. It reduces intraosseous pressure and aims to prevent progression to subchondral collapse.

Question 4059

Topic: 3. Adult Reconstruction (Hip & Knee)

A 22-year-old woman presents with activity-related anterior hip pain. Radiographs reveal a lateral center-edge angle of 15 degrees, an intact Shenton's line, and a congruent joint space without advanced osteoarthritis. The triradiate cartilages are closed. What is the most appropriate surgical intervention?

. Salter innominate osteotomy
. Periacetabular osteotomy (PAO)
. Total hip arthroplasty
. Hip arthroscopy with labral repair
. Femoral varus derotational osteotomy

Correct Answer & Explanation

. Periacetabular osteotomy (PAO)

Explanation

Periacetabular osteotomy (PAO) is the gold standard treatment for symptomatic acetabular dysplasia in young adults with closed triradiate cartilages. It allows significant multidirectional reorientation of the acetabulum while preserving the posterior column.

Question 4060

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old woman complains of chronic lateral hip pain and a new Trendelenburg lurch. She has failed physical therapy and corticosteroid injections for presumed greater trochanteric pain syndrome. MRI confirms a full-thickness retraction of the gluteus medius tendon without fatty infiltration. What is the most appropriate next step in management?

. Total hip arthroplasty
. Open or endoscopic abductor tendon repair
. Ilio-tibial band lengthening
. Core decompression of the greater trochanter
. Proximal femoral osteotomy

Correct Answer & Explanation

. Open or endoscopic abductor tendon repair

Explanation

A full-thickness gluteus medius tear (often termed "rotator cuff tear of the hip") without severe fatty degeneration that fails conservative management is a strong indication for surgical repair. This effectively restores abductor mechanics and resolves the Trendelenburg gait.

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