Topics

Topic

design image
Posterior rim of acetabulum

The posterior rim of the acetabulum is the posterior bony margin of the acetabular socket of the hip joint. It forms a critical part of the weight-bearing and stabilizing architecture of the hip, contributing to containment of the femoral head and maintaining congruency of the hip joint.

It is an important anatomical landmark in orthopedic anatomy, trauma evaluation, hip preservation surgery, and cross-sectional imaging of the pelvis.

Synonyms

  • Posterior acetabular rim

  • Posterior acetabular margin

Location

  • Situated at the posterior aspect of the acetabulum

  • Forms the posterior boundary of the acetabular socket

  • Part of the innominate bone formed by the ischium and ilium

  • Posterior to the acetabular fossa and lunate surface

  • Faces posterolaterally toward the femoral head

Anatomical components

  • Osseous margin:

    • Thick cortical bone forming the posterior edge of the acetabulum

  • Articular surface relation:

    • Adjacent to the posterior segment of the lunate surface

  • Fibrocartilaginous attachment:

    • Anchors the posterior acetabular labrum

  • Associated structures:

    • Posterior joint capsule

    • Ischiofemoral ligament

Relations

Anteriorly:

  • Acetabular cavity and lunate surface

  • Femoral head (in articulation)

Posteriorly:

  • Gluteus maximus muscle

  • Posterior hip capsule

Medially:

  • Pelvic cavity

  • Ischial body

Laterally:

  • Femoral head and neck

Inferiorly:

  • Ischium and inferior acetabular region

Superiorly:

  • Posterior acetabular roof

X-ray appearance

Plain radiographs (AP pelvis and Judet views):

  • Posterior rim: Seen as a smooth curvilinear bony contour outlining the posterior acetabulum

  • Posterior wall line: Best appreciated on oblique (Judet) views

  • Continuity: Appears as a dense cortical arc forming the posterior socket boundary

CT appearance

Non-contrast CT:

  • Posterior rim: Well-defined dense cortical margin

  • Contour: Smooth and continuous along the posterior acetabular edge

  • Trabecular bone: Normal cancellous architecture beneath the cortex

  • Relationship: Clearly defines the posterior acetabular wall and its thickness

MRI appearance

T1-weighted images:

  • Cortical bone: Low signal intensity

  • Adjacent marrow: High signal within the acetabular bone

  • Labral attachment: Seen as a low-signal structure at the rim

T2-weighted images:

  • Cortical margin: Low signal

  • Joint fluid: High signal outlining the acetabular rim

  • Labrum: Low-signal triangular structure adjacent to the rim

STIR:

  • Bone marrow: Fat-suppressed signal allowing clear delineation of rim contours

  • Capsule and soft tissues: Well visualized against suppressed marrow

Proton density fat-saturated (PD FS):

  • Bone marrow: Suppressed fat signal

  • Joint fluid: Bright signal

  • Labrum and capsule: Low-signal structures sharply outlined

CT VRT 3D image

Posterior rim of acetabulum 3d

CT image

Posterior rim of acetabulum ct axial

MRI image

Posterior rim of acetabulum mri anatomy labelled image-img-00000-00000