*2.1.1.1 Column concept of the acetabulum*

The acetabulum is an incomplete hemispherical socket with an inverted horse shoe-shaped articular surface surrounding the nonarticular cotyloid fossa. Two columns of bone which form an inverted 'Y', form and support the cotyloid fossa anteriorly and posteriorly [6–8] (**Figure 1**).

The anterior half of the iliac crest, the iliac spines, the anterior half of the acetabulum and the pubis form the anterior column.

The ischium, the ischial spine, the posterior half of the acetabulum and the dense bone forming the sciatic notch form the posterior column.

The shorter posterior column meets with the anterior column at the top of the sciatic notch. The column concept is very vital not only for classification of acetabular fractures but also in deciding the operative approach and hence the management. The weight-bearing portion of the articular surface is known as the dome or roof that supports the femoral head. The goal of both operative and nonoperative treatment is the anatomic restoration of roof or dome with concentric reduction of femoral head [8–10] (**Figure 2**).

**5**

*Surgical Anatomy of Acetabulum and Biomechanics DOI: http://dx.doi.org/10.5772/intechopen.92330*

fractures of acetabulum [10] (**Figure 3**).

*Quadrilateral surface and iliopectineal eminence.*

*2.1.2 Iliac wing and innominate bone*

• Posterior (gluteus maximus)

• Anterior (gluteus minimus)

• Middle (gluteus medius)

three zones [1–5]:

**Figure 3.**

**Figure 2.**

*Anterior column and posterior column.*

The flat plate of bone forming the lateral border of true pelvic cavity is known as quadrilateral surface. It lies adjacent to the medial wall of the acetabulum. The iliopectineal eminence is the prominence in the anterior column that lies directly over the femoral head. Both these structures limit the fixation of anterior column

The external iliac fossa is marked with two semi-circular lines dividing it into

Looking from above iliac wing appears S shaped. It begins anteriorly with a slight medial oblique orientation. Posteriorly it forms posterior iliac spine which is sagittally oriented. The iliac wing contains hematopoietic and osteogenic

**Figure 1.** *Column concept of the acetabulum by Letournel and Judet.*

*Surgical Anatomy of Acetabulum and Biomechanics DOI: http://dx.doi.org/10.5772/intechopen.92330*

*Essentials in Hip and Ankle*

**2.1 Osseous anatomy**

*2.1.1 Acetabulum*

[8–10] (**Figure 2**).

connected to one another via the symphysis.

mitted from lower limb to innominate bone [4–6].

*2.1.1.1 Column concept of the acetabulum*

anteriorly and posteriorly [6–8] (**Figure 1**).

*Column concept of the acetabulum by Letournel and Judet.*

acetabulum and the pubis form the anterior column.

dense bone forming the sciatic notch form the posterior column.

fractures. This chapter focuses on various aspects of acetabular anatomy, which are very vital in acetabular fracture fixation and also in other pelvic surgeries [1–5].

The pelvis is the bony structure that transmits the weight of the upper axial skeleton to both the lower extremities via hip joint [1–5]. It comprises of the sacrum and three bones on each side that coalesce during adolescence to form the innominate bone of the adult pelvis. The iliosacral joint connects the sacrum to ilium. The ilium becomes the pubis anteriorly and the ischium inferiorly. Two pubic bones are

The three bones, the ilium, ischium and pubis, join each other centrally to form the acetabular cavity. The blood supply to the femoral head traverses through the cotyloid fossa and ligamentum teres in childhood. The horse shoe-shaped cartilaginous portion of acetabulum is the main region through which the weight is trans-

The acetabulum is an incomplete hemispherical socket with an inverted horse shoe-shaped articular surface surrounding the nonarticular cotyloid fossa. Two columns of bone which form an inverted 'Y', form and support the cotyloid fossa

The anterior half of the iliac crest, the iliac spines, the anterior half of the

The ischium, the ischial spine, the posterior half of the acetabulum and the

The shorter posterior column meets with the anterior column at the top of the sciatic notch. The column concept is very vital not only for classification of acetabular fractures but also in deciding the operative approach and hence the management. The weight-bearing portion of the articular surface is known as the dome or roof that supports the femoral head. The goal of both operative and nonoperative treatment is the anatomic restoration of roof or dome with concentric reduction of femoral head

**4**

**Figure 1.**

**Figure 2.** *Anterior column and posterior column.*

**Figure 3.** *Quadrilateral surface and iliopectineal eminence.*

The flat plate of bone forming the lateral border of true pelvic cavity is known as quadrilateral surface. It lies adjacent to the medial wall of the acetabulum. The iliopectineal eminence is the prominence in the anterior column that lies directly over the femoral head. Both these structures limit the fixation of anterior column fractures of acetabulum [10] (**Figure 3**).

## *2.1.2 Iliac wing and innominate bone*

The external iliac fossa is marked with two semi-circular lines dividing it into three zones [1–5]:


Looking from above iliac wing appears S shaped. It begins anteriorly with a slight medial oblique orientation. Posteriorly it forms posterior iliac spine which is sagittally oriented. The iliac wing contains hematopoietic and osteogenic

#### *Essentials in Hip and Ankle*

marrow elements and is the primary source of autogenous bone graft. Various structures are attached on different sides of iliac crest. The lower extremity hip motors are attached on the outer side. Along the inner portions, the iliacus and obturator internus and the pelvic floor musculatures are attached. The abdominal (anteriorly) and paraspinal (posteriorly) muscles are attached on the top [11, 12].

There is a strong buttress of bone extending from the iliosacral joint toward the acetabulum known as the sciatic buttress. The lumbosacral plexus as well as the gluteal vasculature lies in the vicinity. These vessels are the main source of bleeding and they can also be injured during surgical approach. The posterior superior iliac spine is adjacent to the sacroiliac joint and outer ilium.

The neurovascular structures exit the pelvis along with the piriformis muscle through sciatic notch. Sacrospinous ligament, the gemellus superior and the levator ani are inserted on the ischial spine. On the inferior side of ischial spine is the lesser sciatic notch, which contains the obturator internus tendon. The pudendal vessels and nerves pass through this area first exiting the pelvis via grater sciatic notch and then re-entering the pelvis via lesser sciatic notch.

The anterior-most border of the iliac bone begins with the anterosuperior iliac spine (ASIS), which gives origin to:


The antero-inferior iliac spine (AIIS) lies just below the ASIS where the *direct head of the rectus femoris* is inserted. The *iliopsoas muscle* passes just medial to AIIS under which lies the iliopectineal eminence. Indirect head of the rectus femoris is attached inferior to AIIS.

The boundaries of obturator foramen is formed by the pubis superiorly, the ischium inferiorly, and the anterior horn of the acetabulum posteriorly. Medially, the ischial and pubic rami join to form the symphyseal pubic junction. At its superolateral border, the obturator duct is present, which is occupied by obturator vessels and nerve. Obturator membrane covers the foramen circumferentially, which is a thick fascial structure. The integrity of the inguinal ligament and obturator membrane prevents the separation of rami fractures during reduction and fixation of symphyseal plate.

#### **2.2 Ligament anatomy: the joints**

The iliosacral joint is a fibrocartilaginous joint that acts as a dual wedge in axial and antero-posterior directions [12–15]. It acts as a keystone during the transmission of force to the lower limbs. The joint is supported anteriorly and posteriorly by strong ligaments. The posterior sacroiliac ligament consists of


**7**

**Figure 4.**

*The sacrotuberous and sacrotuberous ligaments.*

*Surgical Anatomy of Acetabulum and Biomechanics DOI: http://dx.doi.org/10.5772/intechopen.92330*

pelvis via lesser sciatic foramen [13–15].

junction into the external and internal iliac arteries.

(**Figure 4**).

foramens:

nerve.

**2.3 Vascular anatomy**

cavernous artery [16, 17].

form the femoral artery.

The sacrotuberous ligament connects sacrum to the ischial tuberosity

The sacrospinous ligament connects the border of sacrum and coccyx and sciatic spine deep to sacrotuberous ligament. This ligament divides the ischial area into two

i.The Greater Sciatic Foramen: contains the piriformis muscle, superior glutei nerves, sciatic nerve, ischial vessels, and internal pudendal vessels and

ii.The Lesser Sciatic Foramen: contains the obturator internus muscle and internal pudendal vessels. These structures exit the pelvis via greater sciatic foramen and after crossing over the sacrospinous ligament re-enters the

The aorta bifurcates in the lower peritoneal region into the common iliac arteries. The common iliac artery is begins at around L4 and divides at around the L5–S1

*The internal iliac artery* also known as hypogastric artery, branches to form the superior and inferior gluteal vessels, the obturator, the pudendal, and the coccygeal, the sacral and vesicular vessels. The internal pudendal artery exits the pelvis underneath the piriformis and re-enters the pelvis through the lesser sciatic notch and terminates as the dorsal artery of the penis and clitoris and

*The external iliac artery* just proximal to the inguinal ligament branches to

The femoral artery has three rami: urethral inferior, epigastric and iliac circumflex. The epigastric travels deep and then anastomoses with obturator vessels. The corona

*Surgical Anatomy of Acetabulum and Biomechanics DOI: http://dx.doi.org/10.5772/intechopen.92330*

The sacrotuberous ligament connects sacrum to the ischial tuberosity (**Figure 4**).

The sacrospinous ligament connects the border of sacrum and coccyx and sciatic spine deep to sacrotuberous ligament. This ligament divides the ischial area into two foramens:


## **2.3 Vascular anatomy**

*Essentials in Hip and Ankle*

the top [11, 12].

marrow elements and is the primary source of autogenous bone graft. Various structures are attached on different sides of iliac crest. The lower extremity hip motors are attached on the outer side. Along the inner portions, the iliacus and obturator internus and the pelvic floor musculatures are attached. The abdominal (anteriorly) and paraspinal (posteriorly) muscles are attached on

There is a strong buttress of bone extending from the iliosacral joint toward the acetabulum known as the sciatic buttress. The lumbosacral plexus as well as the gluteal vasculature lies in the vicinity. These vessels are the main source of bleeding and they can also be injured during surgical approach. The posterior superior iliac

The neurovascular structures exit the pelvis along with the piriformis muscle through sciatic notch. Sacrospinous ligament, the gemellus superior and the levator ani are inserted on the ischial spine. On the inferior side of ischial spine is the lesser sciatic notch, which contains the obturator internus tendon. The pudendal vessels and nerves pass through this area first exiting the pelvis via grater sciatic notch and

The anterior-most border of the iliac bone begins with the anterosuperior iliac

The antero-inferior iliac spine (AIIS) lies just below the ASIS where the *direct head of the rectus femoris* is inserted. The *iliopsoas muscle* passes just medial to AIIS under which lies the iliopectineal eminence. Indirect head of the rectus femoris is

The boundaries of obturator foramen is formed by the pubis superiorly, the ischium inferiorly, and the anterior horn of the acetabulum posteriorly. Medially, the ischial and pubic rami join to form the symphyseal pubic junction. At its superolateral border, the obturator duct is present, which is occupied by obturator vessels and nerve. Obturator membrane covers the foramen circumferentially, which is a thick fascial structure. The integrity of the inguinal ligament and obturator membrane prevents the separation of rami fractures during reduction and fixation of

The iliosacral joint is a fibrocartilaginous joint that acts as a dual wedge in axial and antero-posterior directions [12–15]. It acts as a keystone during the transmission of force to the lower limbs. The joint is supported anteriorly and posteriorly by

• The superficial part going from the posterior iliac crest and posterior iliac spines to the posterior tubercles of the sacrum made up of several fascicles.

• The deep portion or interosseous ligament, which is the strongest ligament in

strong ligaments. The posterior sacroiliac ligament consists of

spine is adjacent to the sacroiliac joint and outer ilium.

then re-entering the pelvis via lesser sciatic notch.

spine (ASIS), which gives origin to:

• Fascia Lata

• Sartorius

• Inguinal ligament

attached inferior to AIIS.

symphyseal plate.

**2.2 Ligament anatomy: the joints**

the human body.

**6**

The aorta bifurcates in the lower peritoneal region into the common iliac arteries. The common iliac artery is begins at around L4 and divides at around the L5–S1 junction into the external and internal iliac arteries.

*The internal iliac artery* also known as hypogastric artery, branches to form the superior and inferior gluteal vessels, the obturator, the pudendal, and the coccygeal, the sacral and vesicular vessels. The internal pudendal artery exits the pelvis underneath the piriformis and re-enters the pelvis through the lesser sciatic notch and terminates as the dorsal artery of the penis and clitoris and cavernous artery [16, 17].

*The external iliac artery* just proximal to the inguinal ligament branches to form the femoral artery.

The femoral artery has three rami: urethral inferior, epigastric and iliac circumflex. The epigastric travels deep and then anastomoses with obturator vessels. The corona

**Figure 4.** *The sacrotuberous and sacrotuberous ligaments.*

mortis is the anomalous connection between epigastric and obturator vessels. It can cause fatal bleeding if not identified and ligated during surgery [17, 18] (**Figure 5**).
