Hip and Pelvis Complex

The hip joint is the articulation of the __________ (convex) with the _________ of the __________ (concave).

femoral head, acetabulum, innominate

The hip and pelvic complex has ____ joints in a ring-like pattern.

5

Hip joint stability

inherently stable peripheral joint

What type of joint is the hip?

ball and socket

How many DOF does the hip have?

3 (flexion/extension, abduction/adduction, and external/internal rotation)

The femoral head is shape is ____ of a ________.

2/3, sphere

Fovea capitis femoris definition and location

an attachment for the ligamentum teres, located on femoral head

Femoral neck orientation from shaft

Runs anterior, superior and medial

How many planes is the femoral neck considered in? what is it/are they?

Two planes, frontal plane and transverse plane

In what planes is the femoral neck typically considered and what does each plane show?

frontal: angle of inclination, and transverse: torsion angle

Frontal plane of the femoral neck shows what angle

angle of inclination

Transverse plane of the femoral neck shows what angle

torsion angle

What are 2 key implications of the femoral neck angles?

can have an effect on joint stability, angles change throughout development

What plane is angle of inclination of the femoral neck in?

frontal plane

What plane is the torsion angle of the femoral neck in?

transverse plane

How does the angle of inclination facilitate motion?

Orients the femoral shaft more lateral and provides a greater lever arm for the hip abductor muscles

What is a typical angle of inclination?

120-125 degrees

What is the angle of inclination of coxa valga?

greater than 135 degrees

What is the angle of inclination of coxa vara?

less than 120 degrees

What are coxa valga and coxa vara related too

angle of inclination

What creates the angle for the angle of inclination?

the axis between the femoral neck and the femoral shaft

What is a normal adult torsion angle?

10-20 degrees anterior to neutral

What is an increased torsion angle called? what is the angle? what direction is the toe in? how are ER and IR impacted?

anteversion (significantly anterior), >20, toe-in, elongated ER and shortened IR

What is a decreased torsion angle? what is the angle? what direction is the toe in? how are ER and IR impacted?

retroversion (still anterior but smaller), <10, toe-out, shortened ER and elongated IR

Angle of anteversion

greater than 20 degrees

Angle of retroversion

less than 10 degrees

How is toe positioned in anteversion

toe-in

How is toe positioned in retroversion

toe-out

If a patient has excessive femoral anteversion, how might they compensate to better position their femoral head (stabilize)?

"in-toe"

If a patient has excessive femoral retroversion, how might they compensate to better position their femoral head (stabilize)?

"out-toe"

The angle of inclination is usually around _____ degrees at birth, progressing to normal values (___-___) by adulthood. What is the trend?

150, 120-125, decreasing trend

Why does the angle of inclination decrease during development

weight-bearing and musculature

The torsion angle at birth normally ranges from ______ to _____ degrees and then progresses to normal (___-____) after puberty. What is the trend?

30-60, 10-20, decreasing trend

The diameter of the neck of the femur is approximately ___% of the femoral head.

65%

Cam impingement

proximal femur has an osseous morphology (extra bone) causing reduced clearance between the femur and acetabulum

Pincer impingement

acetabulum has an osseous morphology (extra bone) causing reduced clearance between the femur and acetabulum

Trabecular pattern

Represents specific bone formation patterns (bundles) to accommodate for stress utilizing Wolff’s law

What are the aspects of the trabecular pattern?

arcuate bundle, supporting bundle, trochanteric bundle, accessory bundle, zone of weakness

What is the primary bundle that handles primary tensile strength caused by weight bearing? How does it run?

arcuate bundle - parallel in femoral neck

Which bundle primarily handles compressive loads? How does it run?

supporting bundle - vertical (weight bearing)

Which bundle is a secondary accommodator of compressive loads? How does it run

trochanteric bundle, trochanter to trochanter

Which bundle is at the lateral edge and where tendons attach?

accessory bundle

What is a common site for femoral neck fractures?

zone of weakness inside Ward’s triangle

Why is the zone of weakness susceptible to fractures?

decreased density so it's more susceptible to injury (overuse, trauma, loading)

The innominate bone fuses what three bones?

ilium, ischium, pubis

Innominate is another word for

pelvic bone

The three components of the innominate fuse in the _________ forming a solid mass of bone.

acetabulum

What structures is the pelvic complex made up of?

sacrum, ilium, ischium, pubis, pubic symphysis, acetabulum

What is the site of innominate articulation with the femoral head?

acetabulum

What deepens the acetabulum?

fibrocartilaginous labrum

What is the orientation of the acetabulum?

**lateral, anterior, inferior (LAI)**

Acetabular notch

inferior area of acetabulum that is missing/interrupted “notched out”

Plane of acetabular overhang

frontal plane

What is an implication of the femoral head not being completely covered by the acetabulum?

exposure allows for greater motion into flexion

The degree of overhang of the acetabulum typically ranges between _____ and ____ degrees and is termed the _________.

30, 40, center edge angle

Acetabular overhang

the amount the acetabulum hangs over the femoral head

A larger center edge angle is _____ coverage and a smaller angle is _____ coverage.

more, less

Center edge angle description and normal value

acetabular overhang, 30-40 degrees

Dysplasia

insufficient acetabular overhang (a small center edge angle), shallow acetabulum at increased risk for dislocation and subluxation

Excessive acetabular overhang leads to

impingement

What plane is acetabular version in

transverse plane

Acetabular version, increased and decreased meaning

level of anterior/posterior orientation of the acetabulum, when increased, acetabulum facing more anterior, when decreased, acetabulum facing more posterior

What is the central, deepest portion of the acetabulum?

acetabular fossa

What is and is not in the acetabular fossa?

contains fibroelastic fat pad, lacks articular cartilage

Transverse ligament of acetabulum

Spans the acetabular notch to complete the acetabulum where bone lacks

Hip articular cartilage qualities and interpretation

**avascular and minimal innervation**, means poor healing ability and you won’t even know its injured until later because of the low innervation

Femoral articular cartilage is thickest ____________ and thinnest _________.

superior-posteriorly (weight-bearing), inferior

Where is the acetabular articular cartilage thickest?

superiorly

What is the horseshoe shaped fibrocartilage ring attached to the periphery of the acetabulum?

acetabular labrum

What are the functions of the acetabular labrum?

increase joint stability (by increasing coverage of the femoral head and creating suction), preserve joint integrity (by decreasing consolidation (tissue compression) of articular cartilage and increasing contact stress (spreads it out))

Labrum healing capacity

has minimal healing, has some vasculature between capsule and labrum but doesn’t heal wel

What is the hip joint capsule made of?

dense, relatively inelastic, fibrous capsule

_______ of the femoral neck is intracapsular.

2/3

Types of capsular fibers

superficial longitudinally-oriented fibers, oblique fibers, arcuate fibers, circular deep fibers (zona orbicularis)

Circular deep fibers (zona orbicularis)

**most clinically important joint capsule fiber**, has no bony attachments and forms a collar around the femoral neck for greater capsule strength

Where does most of the strength to resist separation come from in the joint capsule?

zona orbicularis (circular deep fibers)

What are the ligamentous reinforcement of the joint capsule?

iliofemoral ligament (superior and inferior), pubofemoral ligament, ischiofemoral ligament

Which ligament is the **strongest** in the hip?

iliofemoral ligament (Y-Ligament of Bigelow)

Where does the iliofemoral ligament run from?

AIIS, fannning out to the intertrochanteric line as the top 2 lines of Z shape

What is the primary function of the iliofemoral ligament?

limits extension and external rotation

What is the secondary function of the iliofemoral ligament?

inferior band can limit abduction; superior band can limit adduction

Where does the pubofemoral ligament run from?

pubic ramus to the intertrochanteric fossa, bottom of Z shape

What is the primary function of the pubofemoral ligament?

limits abduction

What is the secondary function of the pubofemoral ligament?

limits extension and external rotation

What are the anterior ligaments of the hip?

iliofemoral and pubofemoral ligaments

The anterior ligaments form a _ Pattern

Z

What is the posterior ligament of the hip?

ischiofemoral ligament

Where does the ischiofemoral ligament run from?

inferior ischium posterior surface of acetabulum to the medial surface of the greater trochanter

What is the primary function of the ischiofemoral ligament?

limits internal rotation

What is the secondary function of the ischiofemoral ligament?

limits extension and adduction

Ligamentum teres

ligament attaching to the fovea capitis and acetabular notch

What factors enhance hip joint stability?

**atmospheric pressure (vacuum effect of joint), gravity (in standing position), capsule and ligaments, and acetabular labrum (with capsuloligamentous structures)**

Which factors compromise joint stability?

boney architecture - decreased center edge angle (below 20 degrees, and coxa valga because of decreased center edge angle) and capsuloligamentous compromise (tearing that reduced negative pressure)

What are the primary hip/pelvis muscle regions?

hip (anterior, medial, posterior/lateral), lower abdomen, and pelvic floor

What muscles are in the anterior hip region?

psoas major, psoas minor, iliacus (iliopsoas), tensor fascia latae, sartorius, quadriceps femoris

What is the primary hip flexor?

iliopsoas

Which muscle has a more efficient hip flexion when the knee is flexed? why?

rectus femoris, active insufficiency due to crossing hip and knee joints

What are the medial muscles?

pectineus, adductor brevis, adductor magnus, adductor longus, gracilis, and obturator externus

Which muscle is the most powerful adductor?

adductor magnus

Which medial muscle of the hip is most commonly injured?

adductor longus