Chapter 7 Pelvis/Femur

What are the four major parts to the proximal femur?

1. Head

2. Neck

3. Greater trochanter

4. Lesser trochanter

What ridge connects the trochanters posteriorly?

Intertrochanteric crest

Head of femur

• Articulates with acetabulum

• Contains the fovea capitis, where ligament capitis femoris is attached

Neck of femur

• Connects head to shaft

• Located in region of intertrochanteric area

Greater trochanter

• Large bony prominence

• Located superiorly and laterally to shaft

• Important topographic landmark

Lesser trochanter

• Small, blunt, conical projection

• Located posteriorly and medially

• Found at junction of neck and shaft

What is the average angle of the neck-shaft femur, and what does it depend on?

Around 125 degrees (±15°)

• Depends on width of pelvis and height of person

• Shorter person → Smaller angle

• Taller person → Larger angle

What is the average angle of the femoral shaft?

10 degrees from vertical

• Short person w/ wide pelvis → greater angle

• Tall person w/ narrow pelvis → smaller angle (about 5 degrees)

What is the angle of anteversion of the femur head and neck?

15-20 degrees anterior

How do we get a true AP proximal femur?

Femur must be medially rotated to get femoral neck parallel to IR

Meaning of the word “pelvis”

Basin

Main function of the pelvis

Supports the trunk

Pelvis forms connection between what structures?

Spine and lower extremities

Bones of the pelvis

2 hip bones (ossa coxae), sacrum, coccyx

Hip bone divisions

Ilium, Ischium, Pubis

When do hip bones fuse and where?

Fuse into one bone at adulthood at the acetabulum

Largest hip bone

Ilium

Ilium is composed of what?

The ala (wing) and body (closer to acetabulum)

ASIS stands for?

Anterior Superior Iliac Spine

PSIS stands for?

Posterior Superior Iliac Spine

Location of the ischium

Inferior and posterior to the acetabulum

Upper portion of ischium contributes to what?

Acetabulum

Projection ending inferiorly from ischium that supports body weight when sitting

Ischial tuberosity

Projection anterior to the ischial tuberosity

Ischial spine

Notch above ischial spine

Greater sciatic notch

Pubic rami extend in what direction?

Anteriorly and medially

Joint formed by pubic rami

Pubic symphysis (amphiarthrodial)

Largest foramen in the body

Obturator foramen

Plane that divides pelvis into two parts

Pelvic brim

Area above pelvic brim

False (greater) pelvis

What rests on the false pelvis?

Abdominal organs and fetus

Area below pelvis brim

True (lesser) pelvis

Importance of true pelvis

Forms the birth canal

Female pelvis & pelvic inlet eneral shape

Pelvis = Flared ala, shallow and wide

Pelvis Inlet = Round and larger

Pubic arch angle male vs female

Male < 90 degrees

Female > 90 degrees

Male pelvis & pelvic inlet general shape

Pelvis = Less flared, narrower and deeper

Pelvic Inlet = Heart-shaped and narrow

In anatomic position, the femoral neck is

Partially rotated inward

Internal rotation for AP proximal femur

• 15-20 degrees medial rotation places femoral neck parallel to IR

• Toes in, heels out

• Lesser trochanters not/barely visible

External rotation for AP proximal femur

• Toes outward, heels together

• Femoral neck foreshortened

• Lesser trochanters visible internally

Typical kVp for pelvis

70-85 kVp

CR for AP Hip

Femoral head and neck

Frog leg lateral centers where?

Femoral head

When is cross table hip used?

Suspected hip fracture