The hip joint connects the pelvis to the lower weight-bearing extremities. It is a ball and socket joint where the round head of the femur articulates with the socket (acetabulum) of the pelvis. It is an inherently stable joint as the femoral head rests deeply within the acetabulum. The acetabulum faces approximately 15 degrees forward (anteversion) and 45 degrees outwards (abduction)
When dividing it into 4 quadrants the rear and upper quadrant (postero-superior) contains the gluteal nerve and vessels and also the sciatic nerve. Despite these structures being present it is considered the safest place for screw placement. The second safest place is the rear and lower (postero-inferior) quadrant. It contains the gluteal nerves and pudendal vessels. The front and lower (antero-inferior) quadrant contains the obturator vessels and is unsafe for screws. Similar the front and upper (antero-superior) quadrant contains the iliac artery and veins and is also considered unsafe.