Total Hip Arthroplasty (THA) MCQs

During revision surgery of a modular total hip arthroplasty, the surgeon notes black particulate debris and severe tissue staining around the modular head-neck junction. The implant system consists of a titanium-alloy femoral stem and a cobalt-chromium alloy femoral head. Which combination of corrosive mechanisms is primarily responsible for this specific presentation (trunnionosis)?

During a direct lateral approach to the hip (Hardinge), proximal splitting of the gluteus medius must be limited to avoid denervation of the muscle. What is the generally accepted safe limit for proximal dissection from the tip of the greater trochanter?

During a posterior (Kocher-Langenbeck) approach to the hip, which structure provides the primary protection to the medial femoral circumflex artery (MFCA) during the capsulotomy?

Which specific branch of the medial circumflex femoral artery (MCFA) provides the primary blood supply to the weight-bearing dome of the femoral head in an adult, making it critical to protect during posterior approaches to the hip?

During a posterior approach to the hip (Kocher-Langenbeck), the short external rotators are divided. The deep branch of the medial femoral circumflex artery (MFCA) provides the main blood supply to the femoral head. It is at greatest risk of iatrogenic injury if which of the following structures is released too close to its femoral insertion?

During a posterior approach to the humerus for plate fixation of a midshaft fracture, the radial nerve is identified within the spiral groove. Which muscle head must be sharply split to expose the bone directly beneath the nerve in this region?

During a posterior approach to the hip, an artery is at risk of iatrogenic injury if the quadratus femoris is divided too far proximally. This artery typically courses between the quadratus femoris and which of the following structures?

A posterior approach (Kocher-Langenbeck) is utilized for an open reduction and internal fixation of a transverse acetabular fracture. The surgeon takes care to protect the primary blood supply to the femoral head. The primary vessel supplying the adult femoral head courses between which two muscles prior to piercing the posterior hip capsule?

During a standard Kocher-Langenbeck (posterior) approach to the hip for an associated posterior wall acetabular fracture, the surgeon performs a tenotomy of the short external rotators. To protect the main blood supply to the femoral head, which of the following muscles should ideally remain intact because its tendon directly overlies and protects the deep branch of the medial femoral circumflex artery (MFCA)?

A 65-year-old man experiences recurrent posterior dislocations after a primary THA. Radiographs (

) show the acetabular component in 30 degrees of inclination and 5 degrees of retroversion. The femoral stem is neutrally versioned. Which surgical intervention is most likely to resolve the instability?

A 45-year-old active male underwent a cementless THA with a ceramic-on-ceramic bearing. Three years postoperatively, he complains of a new, audible squeaking sound from his hip during deep flexion. Radiographs demonstrate well-fixed components with the acetabular cup placed at 60 degrees of inclination and 30 degrees of anteversion.

What is the most likely cause of the squeaking?

A 55-year-old active man presents with an audible squeaking sound originating from his hip that occurs when bending or walking.

He underwent a primary total hip arthroplasty (THA) 4 years ago utilizing a ceramic-on-ceramic bearing. Which of the following factors is most strongly associated with the development of this complication?

A 71-year-old woman presents to the emergency department with severe hip pain and inability to bear weight after bending over to pick up an object from the floor.

She underwent a primary THA via a posterior approach 6 weeks ago. Which specific combination of hip movements most commonly precipitates this specific complication?

Following a primary THA performed via a direct lateral (Hardinge) approach, a patient presents with a persistent Trendelenburg gait at 6 months postoperatively.

Which nerve and corresponding muscle group are most at risk of injury with excessive superior splitting of the muscle in this approach?

A polished, double-tapered, collarless cemented femoral stem is chosen for an 80-year-old patient undergoing THA.

On which biomechanical principle does this specific stem design rely to achieve and maintain stability?

Proper orientation of the acetabular component is critical to minimize the risk of dislocation after THA.

According to the historically established "Lewinnek safe zone", what are the optimal target angles for acetabular inclination (abduction) and anteversion?

A 45-year-old woman underwent a ceramic-on-ceramic THA 3 years ago. She now complains of a high-pitched squeaking noise during gait, without significant pain. Radiographs are unremarkable. Which of the following conditions is most strongly associated with this phenomenon?

In modern total hip arthroplasty, the use of large-diameter femoral heads has increased to reduce the risk of dislocation. However, which of the following is a recognized trade-off when using a large-diameter cobalt-chromium head on a standard titanium femoral stem trunnion?

During a direct anterior approach for THA, the surgeon uses fluoroscopy to assess leg length and offset. Which of the following anatomical landmarks provides the most reliable horizontal reference on an AP pelvis radiograph for evaluating leg length discrepancy intraoperatively?

A 55-year-old woman presents with an apathetic abductor lurch (Trendelenburg gait) 6 months after a primary THA performed via a direct lateral (Hardinge) approach. Physical exam shows profound weakness in hip abduction. Which neurologic structure was most likely injured during the proximal extension of the split in the gluteus medius?