What can be palpated by following the superior portion of the ilium from the asis to the psis?

The left and right hip bones (innominate bones, pelvic bones) are two irregularly shaped bones that form part of the pelvic girdle - the bony structure that attaches the axial skeleton to the lower limbs.

The hip bones have three main articulations:

• Sacroiliac joint - articulation with the sacrum.
• Pubic symphysis - articulation between the left and right hip bones.
• Hip joint - articulation with the head of femur.

In this article, we shall look at the anatomy of the hip bones - their composition, bony landmarks, and clinical relevance.

[caption id="attachment_6815" align="aligncenter" width="290"]

Composition of the Hip Bone

The hip bone is comprised of the three parts; the ilium, pubis and ischium. Prior to puberty, the triradiate cartilage separates these parts - and fusion only begins at the age of 15-17.

Together, the ilium, pubis and ischium form a cup-shaped socket known as the acetabulum (literal meaning in Latin is 'vinegar cup'). The head of the femur articulates with the acetabulum to form the hip joint.

We shall now look at the individual parts of the hip bone, and their respective bony landmarks.

[caption id="attachment_6791" align="aligncenter" width="389"]

The Ilium

The ilium is the widest and largest of the three parts of the hip bone, and is located superiorly. The body of the ilium forms the superior part of the acetabulum (acetabular roof). Immediately above the acetabulum, the ilium expands to form the wing (or ala).

The wing of the ilium has two surfaces:

• Inner surface - has a concave shape, which produces the iliac fossa (site of origin of the iliacus muscle).
• External surface (gluteal surface) - has a convex shape and provides attachments to the gluteal muscles.

The superior margin of the wing is thickened, forming the iliac crest. It extends from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS).

On the posterior aspect of the ilium there is an indentation known as the greater sciatic notch.

[caption id="attachment_18193" align="aligncenter" width="1105"]

[start-clinical]

Clinical Relevance: Anterior Superior Iliac Spine

The anterior superior iliac spine (ASIS) is an important anatomical landmark:

• Mid-inguinal point - halfway between the ASIS and the centre of the pubic symphysis. The femoral artery can be palpated here.
• Mid-point of the inguinal ligament - halfway between the ASIS and the pubic tubercle.

In clinical practice, a patient's "true" leg length is measured from the ASIS to the medial malleolus at the ankle joint. This is distinct from "apparent" leg length, which is measured from the umbilicus to the medial malleolus.

True leg length discrepancy is a feature of various hip disorders, as well as being a potential complication of hip joint replacement (arthroplasty).

[end-clinical]

The Pubis

The pubis is the most anterior portion of the hip bone. It consists of a body, superior ramus and inferior ramus (ramus = branch).

• Pubic body - located medially, it articulates with the opposite pubic body at the pubic symphysis. Its superior aspect is marked by a rounded thickening (the pubic crest), which extends laterally as the pubic tubercle.
• Superior pubic ramus - extends laterally from the body to form part of the acetabulum.
• Inferior pubic ramus - projects towards the ischium.

Together, the superior and inferior rami enclose part of the obturator foramen - through which the obturator nerve, artery and vein pass through to reach the lower limb.

[caption id="attachment_18194" align="aligncenter" width="1351"]

[caption id="attachment_111703" align="aligncenter" width="750"]

[start-clinical]

Clinical Relevance - Pubic Rami Fractures

Pubic rami fractures can sometimes be observed on x-rays in elderly patients who are investigated after simple low energy falls from standing height. In this context and provided they are the only injury a patient has sustained, these fractures are usually treated without surgery.

Healing can be expected within 6-8 weeks and patients are encouraged to fully weight bear straightaway.

[end-clinical]

The Ischium

The ischium forms the posteroinferior part of the hip bone. Much like the pubis, it is composed of a body, an inferior ramus and superior ramus.

The inferior ischial ramus combines with the inferior pubic ramus forming the ischiopubic ramus, which encloses part of the obturator foramen. The posterorinferior aspect of the ischium forms the ischial tuberosities and when sitting, it is these tuberosities on which our body weight falls.

Near the junction of the superior ramus and body is a posteromedial projection of bone; the ischial spine.

Two important ligaments attach to the ischium:

• Sacrospinous ligament - runs from the ischial spine to the sacrum, thus creating the greater sciatic foramen through which lower limb neurovasculature (including the sciatic nerve) transcends.

• Sacrotuberous ligament - runs from the sacrum to the ischial tuberosity, forming the lesser sciatic foramen.

Read more about the greater and lesser sciatic foramen here.

[caption id="attachment_18195" align="aligncenter" width="950"]

[start-clinical]

Clinical Relevance: Pelvic Fractures

There are two broad groups of pelvic fractures:

• Low energy injuries:
  • For example, a simple fall from standing height in an osteoporotic patient resulting in pubic rami fracture.
  • These are usually ‘stable’ injuries, not requiring surgery.
• High energy injuries with direct or transmitted trauma:
  • For example, after a high speed road traffic accident. These result in more extensive fractures which may include the acetabulum and sacroiliac joint.
  • These can be ‘unstable’ injuries and may require urgent surgery.
  • Higher energy injuries can be associated with soft tissue and vascular injury. In particular, the bladder and urethra are at high risk of damage. Vascular injury can result in life threatening haemorrhage.

In the context of a high energy major trauma patient, the pelvis can be a major source of bleeding due to fracture. As a result, major trauma patients are assumed to have a pelvic fracture until proven otherwise and a ‘pelvic binder’ is used to stabilise the pelvis and minimise further bleeding. Circumferential pressure is applied by the binder at the level of the greater trochanters – an important anatomical landmark.

[caption id="attachment_10766" align="aligncenter" width="420"]

[end-clinical]

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton  

Manual palpation is commonly used for the assessment of patients with neuromusculoskeletal dysfunction[1]. Many pelvic landmarks are easily palpable on physical exam eg the iliac crest, the anterior superior iliac spine (ASIS), posterior superior iliac spine (PSIS). These landmarks are instrumental in physical examinations by allowing practitioners to quickly and simply identify anatomy for both diagnostic and therapeutic measures.[2]

Iliac Crest[edit | edit source]

You can find the iliac crests by placing the sides of your forefinger/hand in the fleshy part of the waist at the level of the umbilicus, move inferiorly and the first hard lumps you feel on each side are the iliac crests. [3]

This level corresponds to around L3-L4 lumbar vertebrae[2].

Greater Trochanter of the Femur[edit | edit source]

Move inferior from the iliac crests down the most lateral part of the hip. The first hard lump you feel is the greater trochanter of the femur. You can check by rotating the leg[3].

ASIS[edit | edit source]

In supine from the anterior midline of the thighs move superior. The first lump you feel will be the ASIS on each side[3].

• The ASIS is the most anterior portion of the iliac crest and is the attachment point for the sartorius muscle as well as the inguinal ligament which connects to the pubic tubercle.
• The ASIS also becomes helpful in identifying leg length discrepancies, as pelvic rotation often accommodates these differences while standing and walking. Therefore, leg length is measured from the ASIS to the medial malleolus[2].

PSIS[edit | edit source]

The PSIS marks the posterior edge of the iliac crest and manifests in some individuals as dimples on the lower back, colloquially called “dimples of Venus.” [2]

• In prone, easily found by moving superior and medially with the thumbs from the mid part of the fleshy part of the buttocks. Try to feel up and under the PSIS on each side. You are at the level of S2.[3]
• This landmark is useful for identifying the sacroiliac joint, and tenderness over this joint can be a symptom of sacroiliitis, a condition present in some inflammatory spondyloarthropathies[2].

Pubic Symphysis[edit | edit source]

Move inferior from the umbilicus it will be soft and then you will eventually feel the bones of the pubic arch. Often easier to get the client to find it for you.

Other[edit | edit source]

• 
  Sacral spines: The sacral spines can usually be felt easily on the midline.
• Coccyx: The outline of the coccyx can be felt in the cleft of the buttocks[3].

Validity[edit | edit source]

A study to determine the validity of manual palpation (MP) of specific landmarks in the lumbo-pelvic area (using US) found that MP may have acceptable validity when used for applying manual therapy. However, the degree of measurement error found in this study may be unacceptable when assessing for pelvic symmetry.[1]

References[edit | edit source]