THA Techniques

Question 1

What are the four quadrants of the acetabulum in relation to screw placement in THA?

Answer 1

Line drawn from ASIS through center of acetabulum, second line perpendicular to the first
Postero-superior: target zone
Postero-inferior: caution zone
Antero-superior: death zone
Antero-inferior: danger zone

Question 2

What structures are at risk in the various zones of screw placement for acetabular cups?

Answer 2

Postero-superior: sciatic nerve if hip center elevated
Postero-inferior: if screw >20mm the sciatic n., inferior gluteal vessels/nerve, internal pudendal vessels
Antero-superior: external iliac vessels
Antero-inferior: obturator n/a/v

Question 3

What factor can lead to bone-on-bone impingement in THA?

Answer 3

Decreased femoral offset

Question 4

When placing acetabular screws to supplement cementless acetabular fixation in total hip arthroplasty, placing screws in which zone poses the highest risk to damaging the external iliac vasculature?

Answer 4

Antero-superior