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Total Hip Arthroplasty (THA) MCQs

Practice Set 24 of 36

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

Question 461

Topic: Total Hip Arthroplasty (THA)

A patient presents with a severe limp, lateral hip pain, and a positive Trendelenburg sign 6 months after a primary THA performed via a direct lateral (Hardinge) approach. An MRI with metal artifact reduction sequence (MARS) confirms a massive, full-thickness avulsion of the gluteus medius and minimus tendons. What is the most appropriate management?

. Physical therapy focusing on core strengthening
. Abductor tendon repair, potentially with allograft augmentation
. Revision to a constrained acetabular liner
. Botulinum toxin injection to the iliopsoas
. Trochanteric osteotomy and distal advancement

Correct Answer & Explanation

. Abductor tendon repair, potentially with allograft augmentation

Explanation

A recognized complication of the direct lateral approach is failure of the abductor repair. A massive, symptomatic full-thickness tear resulting in a severe Trendelenburg gait requires surgical repair of the abductor mechanism, often utilizing allograft or synthetic augmentation if tissue quality is poor.

Question 462

Topic: Total Hip Arthroplasty (THA)

A 55-year-old man presents with intractable groin pain when actively flexing the hip, specifically when rising from a seated position, 18 months after a THA. A diagnostic injection of local anesthetic into the iliopsoas bursa completely relieves his pain. Radiographs reveal 12 mm of anterior overhang of the acetabular component.

What is the most definitive surgical management?

. Open iliopsoas tenotomy at the lesser trochanter
. Revision of the acetabular component
. Revision of the femoral component
. Application of a constrained liner
. Arthroscopic labral debridement

Correct Answer & Explanation

. Revision of the acetabular component

Explanation

The patient has iliopsoas impingement secondary to significant anterior cup overhang. While iliopsoas tenotomy is an option for mild overhang, severe anterior prominence (>8-10 mm) definitively requires revision of the acetabular component to eliminate the structural impingement.

Question 463

Topic: Total Hip Arthroplasty (THA)

Mechanically assisted crevice corrosion (trunnionosis) at the head-neck junction in total hip arthroplasty is most strongly associated with which of the following component characteristics?

. Small femoral head diameter
. Large femoral head diameter
. Ceramic femoral head
. Short femoral neck offset
. Cemented femoral stem

Correct Answer & Explanation

. Large femoral head diameter

Explanation

Trunnionosis is driven by increased fretting and corrosion at the modular head-neck junction. Large diameter femoral heads increase the lever arm and torsional forces on the trunnion, significantly increasing this risk.

Question 464

Topic: Total Hip Arthroplasty (THA)
Radiographs of a 70-year-old female reveal severe superior migration of the acetabular component with discontinuity of the pelvic ring (>60% host bone loss). Which of the following is the most reliable reconstruction option for this Paprosky Type IIIB defect?
. Jumbo uncemented hemispherical cup
. Standard cup with multiple screws and allograft
. Cup-cage construct or custom triflange
. Impaction bone grafting alone
. Bipolar hemiarthroplasty

Correct Answer & Explanation

. Cup-cage construct or custom triflange

Explanation

Paprosky IIIB defects with pelvic discontinuity require bypassing the defect to achieve stable fixation in the ilium and ischium. A cup-cage construct or a custom triflange component provides the necessary mechanical stability.

Question 465

Topic: Total Hip Arthroplasty (THA)

A patient develops anterior groin pain reproducible with active straight-leg raise and rising from a seated position immediately following a primary THA. Cross-sectional imaging reveals significant anterior overhang of the acetabular component. If conservative management fails, what is the best initial surgical intervention?

. Adductor tenotomy
. Revision of the femoral stem
. Gluteus medius repair
. Iliopsoas fractional lengthening or tenotomy
. Sciatic nerve neurolysis

Correct Answer & Explanation

. Iliopsoas fractional lengthening or tenotomy

Explanation

Anterior overhang of the acetabular cup can cause iliopsoas impingement, presenting as pain with active hip flexion. If conservative measures fail, an iliopsoas tenotomy or fractional lengthening is the preferred initial surgical treatment before attempting cup revision.

Question 466

Topic: Total Hip Arthroplasty (THA)

A ceramic-on-ceramic total hip arthroplasty is associated with a distinct risk of 'squeaking'. Which of the following technical factors is most strongly associated with the development of this complication?

. Excessively large femoral head diameter
. Use of an un-cemented femoral stem
. High body mass index of the patient
. Acetabular component malposition causing edge loading
. Profound leg length discrepancy

Correct Answer & Explanation

. Acetabular component malposition causing edge loading

Explanation

Squeaking in ceramic-on-ceramic bearings is strongly correlated with edge loading. This abnormal wear pattern is typically caused by malpositioning of the acetabular component, such as excessive inclination or anteversion.

Question 467

Topic: Total Hip Arthroplasty (THA)

A 45-year-old active man underwent a total hip arthroplasty with a ceramic-on-ceramic bearing 3 years ago. He now complains of a squeaking noise during walking. Radiographs show a well-fixed stem and an acetabular component abducted to 60 degrees. What is the most likely cause of this phenomenon?

. Stripe wear from edge loading
. Impingement of the psoas tendon
. Third-body wear from retained cement
. Fatigue failure of the ceramic head
. Trunnionosis at the head-neck junction

Correct Answer & Explanation

. Stripe wear from edge loading

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading caused by component malposition, particularly a steeply placed acetabular cup. Edge loading disrupts the fluid film lubrication, leading to stripe wear and the characteristic squeaking sound.

Question 468

Topic: Total Hip Arthroplasty (THA)
During an acetabular revision for a failed total hip arthroplasty, the surgeon encounters severe superior migration of the hip center (>3 cm) and destruction of the teardrop, with less than 50% of the host bone available for cup contact. The Kohler line remains intact. Which of the following Paprosky defect classifications does this represent?
. Paprosky IIA
. Paprosky IIB
. Paprosky IIIA
. Paprosky IIIB
. Paprosky IV

Correct Answer & Explanation

. Paprosky IIIA

Explanation

A Paprosky IIIA defect is characterized by severe bone loss (>3 cm superior migration), destruction of the teardrop, and <50% host bone contact, but with an intact Kohler line indicating no severe medial migration. Paprosky IIIB defects, by contrast, feature severe medial migration crossing Kohler's line or pelvic discontinuity.

Question 469

Topic: Total Hip Arthroplasty (THA)

During templating for a total hip arthroplasty, increasing the femoral head neck length (e.g., using a +4 mm head instead of a +0 mm head) without changing the stem size or position will have what effect on hip biomechanics?

. Increases femoral offset and increases leg length equally
. Increases femoral offset more than leg length
. Increases leg length without affecting femoral offset
. Decreases the abductor moment arm
. Increases leg length and femoral offset, dependent on the neck-shaft angle

Correct Answer & Explanation

. Increases leg length and femoral offset, dependent on the neck-shaft angle

Explanation

Increasing the head neck length increases both the vertical height (leg length) and the horizontal distance (femoral offset). The exact proportion depends on the neck-shaft angle of the selected femoral stem.

Question 470

Topic: Total Hip Arthroplasty (THA)

A 60-year-old male with a history of bilateral total hip arthroplasties presents with new-onset squeaking from his left hip during ambulation. He has a ceramic-on-ceramic bearing on the left. Radiographs reveal a well-fixed cup with an abduction angle of 65 degrees. What is the most likely cause of the squeaking?

. Alumina ceramic phase transformation
. Edge loading due to component malposition
. Trunnionosis at the head-neck junction
. Impingement of the greater trochanter
. Infection

Correct Answer & Explanation

. Edge loading due to component malposition

Explanation

Squeaking in ceramic-on-ceramic THA is highly correlated with edge loading, which typically occurs due to acetabular cup malposition (e.g., steep inclination angle >50 degrees or excessive anteversion), leading to microseparation and stripe wear.

Question 471

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 472

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 473

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 474

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 475

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 476

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 477

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 478

Topic: Total Hip Arthroplasty (THA)

A 60-year-old woman is 6 weeks post-primary THA. She complains her operative leg feels 1 cm longer. Clinical examination and standing radiographs confirm a 1 cm lengthening on the operative side. Her hip is completely stable. What is the most appropriate initial management?

. Immediate revision THA to shorten the neck length
. Prescription of a 1 cm shoe lift for the contralateral leg
. Reassurance and observation for up to 6 months
. Botulinum toxin injection to the abductors
. Closed manipulation under anesthesia

Correct Answer & Explanation

. Reassurance and observation for up to 6 months

Explanation

Perceived leg length discrepancy is very common in the early postoperative period after THA, often due to pelvic obliquity and resolving muscle contractures. Reassurance and observation for 3-6 months is appropriate, as most patients accommodate over time.

Question 479

Topic: Total Hip Arthroplasty (THA)

Increasing femoral offset during total hip arthroplasty, without altering leg length, results in which of the following biomechanical changes?

. Decreased abductor muscle tension
. Increased joint reaction force
. Decreased bending moment on the femoral stem
. Increased abductor moment arm
. Decreased range of motion

Correct Answer & Explanation

. Increased joint reaction force

Explanation

Increasing femoral offset increases the abductor moment arm, which decreases the required abductor muscle force and subsequently decreases the overall joint reaction force. However, it does increase the bending moment on the femoral stem.

Question 480

Topic: Total Hip Arthroplasty (THA)



A 55-year-old woman presents with hip pain and a palpable groin mass 6 years after a metal-on-metal hip resurfacing. Histologic examination of the periarticular tissue is most likely to reveal which of the following predominant features?

. Diffuse polymorphonuclear cell infiltrate
. Acellular fibrous capsule with abundant polyethylene debris
. Perivascular lymphocytic infiltrate with tissue necrosis
. Multinucleated giant cells with birefringent particles
. Caseating granulomas with epithelioid macrophages

Correct Answer & Explanation

. Perivascular lymphocytic infiltrate with tissue necrosis

Explanation

Adverse local tissue reactions to metal debris (ALVAL) are characterized by a delayed type IV hypersensitivity response. Histology shows a predominant perivascular lymphocytic infiltrate, massive tissue necrosis, and macrophages containing metal particles.

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