Total Hip Arthroplasty (THA) MCQs

A patient complains that their operative leg feels substantially longer following a primary THA. Postoperative anteroposterior pelvic radiographs indicate that the vertical distance from the inter-teardrop line to the lesser trochanter on the operative side is 15 mm greater than on the unoperated side. Global offset is equal bilaterally. Which surgical error most likely caused this leg length discrepancy?

A 68-year-old man presents with recurrent posterior dislocations of his total hip arthroplasty (THA). He underwent a primary THA through a posterior approach 6 months ago. Radiographs demonstrate a well-fixed, uncemented acetabular cup with 40 degrees of inclination and 0 degrees of anteversion. The femoral stem is well-fixed with 15 degrees of anteversion.

To optimally stabilize this hip during revision surgery, the surgeon should aim to:

A 55-year-old woman complains of new-onset, sharp groin pain radiating to the anterior thigh 8 months after an uncomplicated primary total hip arthroplasty. The pain is worst when initiating movement, particularly when lifting her leg to get into a car or climbing stairs. Physical examination reveals severe pain with resisted active straight leg raise. A diagnostic anesthetic injection into the psoas bursa provides complete relief. Which of the following is the most common radiographic finding associated with this condition?

A 65-year-old man presents with his third posterior dislocation of a total hip arthroplasty performed 6 months ago via a posterior approach. Radiographs reveal the acetabular component has 5 degrees of anteversion and 40 degrees of abduction. The femoral stem is well-fixed with 15 degrees of anteversion. What is the most appropriate surgical management?

A 68-year-old woman complains that her operative leg feels "too long" 6 weeks after a right total hip arthroplasty. On physical examination with her pelvis leveled, her right medial malleolus is 2 cm distal to the left medial malleolus. On the standard postoperative AP pelvis radiograph, the vertical distance from the inter-teardrop line to the right lesser trochanter is 35 mm, and the distance to the left lesser trochanter is 35 mm. What is the most likely cause of her perceived leg length discrepancy?

A 62-year-old female presents with recurrent anterior dislocations of her total hip arthroplasty (THA). The original surgery was performed via a posterior approach. Which of the following combinations of component positioning is most classically associated with an anterior dislocation mechanism?

A 72-year-old woman presents with recurrent posterior dislocations following a primary total hip arthroplasty performed via a posterior approach. Radiographic evaluation demonstrates the acetabular component is positioned in 35 degrees of abduction and 5 degrees of retroversion. The femoral stem has 15 degrees of anteversion. What is the most appropriate surgical management?

A 65-year-old woman experiences recurrent anterior dislocations after a primary total hip arthroplasty performed via a posterior approach. Radiographs demonstrate that the acetabular component is placed in 35 degrees of anteversion and 50 degrees of inclination. The femoral stem is placed in 25 degrees of anteversion. What is the most appropriate definitive management?

A 50-year-old active man with a ceramic-on-ceramic total hip arthroplasty reports a high-pitched squeaking noise from his hip during deep flexion activities. He is otherwise asymptomatic. Which of the following factors has been most strongly associated with squeaking in ceramic-on-ceramic THA?

A 65-year-old man presents with recurrent posterior dislocations following a primary total hip arthroplasty (THA) performed via a posterior approach 6 months ago. He has no signs of infection and neurologic exam is intact. Radiographic evaluation and subsequent CT scan demonstrate that the acetabular component is placed in 10 degrees of anteversion and 40 degrees of abduction. The femoral component is noted to be in 10 degrees of retroversion. Which of the following component adjustments during revision surgery would most effectively reduce his risk of future posterior dislocations?

A 65-year-old woman undergoes a primary total hip arthroplasty (THA) via a direct anterior approach. Three weeks postoperatively, she sustains an anterior dislocation of the prosthetic hip while lying in bed and reaching behind her (hip in extension and external rotation). Which of the following acetabular component malpositions most likely contributed to this specific complication?

A 68-year-old male sustained a posterior dislocation of his right THA 6 weeks postoperatively after tying his shoes. Figure 3 shows his radiograph.

Assuming component malposition was the primary etiology, which combination most commonly predisposes to a posterior dislocation?

A 42-year-old female complains of localized anterior groin pain 1 year following an uncemented THA. The pain is worst when actively lifting her leg to get into a car or actively performing a straight leg raise. A diagnostic injection of local anesthetic into the iliopsoas bursa provides complete, temporary relief. Which acetabular component factor is the most likely structural cause of this complication?

A surgeon is performing a primary THA utilizing the direct anterior approach (DAA). To minimize the risk of injury to the lateral femoral cutaneous nerve (LFCN), the superficial internervous plane is developed between the tensor fasciae latae (TFL) and the sartorius. During the approach, understanding the variable anatomy of the LFCN is critical. The main trunk of the LFCN most typically crosses the inguinal ligament at what anatomic location?

During preoperative planning for a primary total hip arthroplasty in a patient with significant coxa vara, the surgeon decides to use a high-offset femoral stem. Compared to a standard-offset stem, what is the primary biomechanical advantage of increasing femoral offset?

A 68-year-old woman presents to the emergency department with an anterior dislocation of her primary total hip arthroplasty (THA). The index procedure was performed 6 weeks ago via a standard posterior approach. Which of the following component malpositions is most likely responsible for this specific direction of dislocation?

A 64-year-old man presents with progressive groin pain and swelling 6 years after a metal-on-polyethylene total hip arthroplasty utilizing a large-diameter cobalt-chromium femoral head on a titanium stem. Serum cobalt levels are markedly elevated (15 ppb) while chromium levels are normal (1.5 ppb). What is the most likely source of the elevated metal ions?

A 55-year-old man reports a new-onset squeaking noise originating from his hip when walking, 4 years after undergoing a primary total hip arthroplasty. Radiographs show a well-fixed uncemented titanium stem and acetabular shell with a ceramic-on-ceramic bearing. Which of the following factors is most strongly associated with the development of squeaking in ceramic-on-ceramic THA?

Postoperatively, a THA patient complains that their operative leg feels "too long." Radiographs confirm the vertical distance from the teardrop to the lesser trochanter is equal bilaterally, but the horizontal distance is increased by 15 mm on the operative side. What is the most likely clinical consequence?

A 60-year-old female presents with persistent lateral hip pain and a positive Trendelenburg sign 6 months after a posterior approach THA. MRI demonstrates a complete avulsion of the conjoined tendon of the abductors. Where does the primary insertion of the gluteus medius strictly lie?