Bone: Hip Bone, Femur, and Patella: Parts

Pelvis:the pelvis is tilted 50 degree anteriorly.

* **Ilium**
	+ Thin ala & 2 large columns
	+ Concave internal iliac fossa
	+ Convex external auricular surface (gluteal fossa)
	+ Arcuate line marks inferior aspect iliac fossa
	+ Superior iliac crest with overhanging external lip extends from ASIS to posterior superior iliac spine
		- Tubercle of iliac crest at anterosuperior margin
	+ Anterior protuberances: Anterior superior iliac spine, anterior inferior iliac spine
		- Shallow notch between
	+ Posterior protuberances: Posterior superior iliac spine, posterior inferior iliac spine
	+ Forms 2/5 acetabulum
	+ Clinical note: Use superior aspect iliac crest on physical examination or radiographs to identify the L4/5 level
* **Ischium**
	+ V-shaped bone with body & ramus
	+ Apex is ischial tuberosity
	+ Ischial spine: Oriented posteromedially
		- Greater sciatic notch
		- Lesser sciatic notch below
	+ Ramus joins inferior pubic ramus forming ischiopubic ramus
	+ Body forms 2/5 acetabulum
	+ Clinical note: In seated position ischial tuberosities bear all body weight
* **Pubis**
	+ Body & 2 rami
	+ Bodies meet midline at symphysis pubis
	+ Inferior ramus part of ischiopubic ramus
	+ Pubic crest along anterior superior border of symphysis & pubic bodies
	+ Pubic tubercle: Lateral aspect pubic crest
		- Attachment inguinal ligament
	+ Pecten: Lateral ridge along superior ramus from pubic tubercle to arcuate line
	+ The pectineal line and arcuate line forms the iliopectineal eminence at the junction of the ilium.
	+ Body is 1/5 acetabulum
	+ Clinical note: Iliopubic eminence is common site of insufficiency fracture
	+ Clinical note: Iliopectineal thickening is often first site of Paget disease

    Femur

* Femoral head is 2/3 sphere
	+ Central cartilage void at fovea capitis
* Neck connects shaft, head
	+ Narrower near head, wider near trochanters
	+ Allows shaft to clear acetabulum & pelvis during motion
	+ Subcapital region: Head-neck junction
	+ Basicervical region: Base of neck
* Shaft: Circular cross section with thick ridge posteriorly (linea aspera)
* Femoral neck/shaft angle is around 125 degree.
	+ Smaller in women secondary to wider pelvis
	+ Anterior angulation neck relative to shaft

* Greater trochanter: Lateral facing extension from superior femur
* Lesser trochanter: Conical projection arising posterior medial proximal diaphysis
* Intertrochanteric line: Anterior ridge connecting trochanters
	+ Winds under lesser trochanter & continues posteriorly as spiral line
* Intertrochanteric ridge/crest: connects trochanters posteriorly
* Linea aspera: Ridge along posterior femoral diaphysis
	+ Divides proximally into medial & lateral lips
	+ Medial lip blends with spiral line
	+ Lateral lip blends with gluteal tuberosity
	+ Distally divides into supracondylar lines
* Piriformis (trochanteric) fossa: Deepening posteriorly between greater trochanter & femoral neck
	+ Insertion site of hip external rotators

* The distal shaft expands to becomes the medial and lateral condyles.

**Normal variant**

* Allen’s fossa – small cervical depression by NOF on the medial aspect.
* Hypotrochanteric fossa
* 3rd trochanter – found at the superior border of gluteal crest
* Exostosis of trochanteric fossa

Patella

Triangular sesamoid bone, in quadriceps femoris tendon/patella ligament. Posterior groove divides larger lateral articular surface from smaller medial articular surface. It forms part of the knee joint.

**Osteology**

* The patella is triangular in shape with a superior base and inferior apex.
* The posterior surface is smooth, composed of articular cartilage, and is divided into medial and lateral facets.
* The anterior surface is rough, for attachment of tendons and ligaments.

The ossification centres of the patella appear between 3 and 6 years. They fuse at puberty, with higher levels of activity.

**Articulations**

The medial and lateral facets of the patella articulate with the medial and lateral condyles of the femur, respectively, to form the patellofemoral component of the knee joint.

**Ligaments**

* quadriceps tendon (superiorly)
* the patella ligament or tendon (which attaches to the tibial tubercle, inferiorly), although few quadriceps tendon fibres are continuous of the anterior surface.

* The medial and lateral patellar retinaculum, which are condensations of fascia rather than true ligaments, attach the patella margins to surrounding fascia.
	+ The medial patellar retinaculum attaches to the vastus medialis/sartorius fascia and is often disrupted in lateral patellar dislocation.
	+ The lateral patellar retinaculum is attached to the fascia of vastus lateralis and iliotibial band.

The quadriceps muscle pulls the patella obliquely and laterally in relation to the femur. There are factors that prevent such displacement: larger lateral condyle of femur, tension in the medial retinacular fibers and direction of insertion of fibers of the vastus medialis muscle.

**Blood supply**

Arterial blood enters via the anterior surface of the patella and an anastomotic patella ring is formed supplied by the paired superior and inferior geniculate arteries as well as the anterior tibial recurrent artery.

**Variant anatomy**

* bipartite patella
* multipartite patella
* absent patella
* variation in shape (see: Wiberg classification)
* dorsal defect of the patella (may occasionally be symptomatic)
* vastus notch
* Vastus fossa