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Acetabular Labrum

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  • General
    • Fibrocartilagenous structure which outlines the acetebular rim
    • Covers 170° of femoral head
    • Functions: shock absorption, joint lubrication, pressure distribution, stability
    • Horse-shoe shaped
    • Continuous with the transverse acetabular ligament
    • Articular side composed of fibrocartilage, capsular side composed of dense connective tissue
  • Structure
    • Usually triangular in cross-section anteriorly
    • More bulbous with square dimensions and a rounded distal edge posteriorly.
    • Lecouvet et al: labrum was triangular in cross section in 66% of 200 asymptomatic volunteers[1]
    • Other studies, rounded, flattened, and irregular variants have been identified, particularly in older age groups[2]
  • The labrum has three surfaces and an apex[3]
    • Articular surface is located internally,
    • External surface is in contact with the joint capsule
    • Basal surface attaches to the transverse acetabular ligament as well as the bone and hyaline cartilage of the rim of the acetabulum
    • The apex of the labrum is a free edge that embraces the head of the femur and forms a seal that enhances lubrication of the joint with synovial fluid.
    • Thus the labrum deepens the cupshaped acetabulum to provide extra coverage for the femoral head
  • The dimensions of the labrum are not uniform.
    • Seldes et al reported that the widest portion is located anteriorly and the thickest superiorly
    • Lecouvet et al found an absence of the labrum in 14% of asymptomatic volunteers



  • General
    • Acts to increase stability at the hip joint by deepening the acetabulum and resisting lateral and vertical translation of the femoral head.[4]
    • Although the labrum deepens the acetabulum by 21%, this stabilizing effect is thought to be less important than the similar function provided by the glenoid labrum because the osseous acetabulum is considerably deeper than the glenoid fossa.
    • Provides a seal for the joint, enhancing fluid lubrication, maintaining synovial fluid pressure, and preventing direct contact of the joint surfaces.
    • This allows some of the load is borne by fluid pressure and applied forces are distributed more evenly across the articular surfaces.
  • Preventing Osteoarthritis
    • The role of the labrum in preventing early osteoarthritis is controversial.
    • A labrum-free hip model showed that contact stress increased by 92%[5]
    • whereas a biomechanical study measuring contact and pressure distribution in cadaveric joints before and after labral removal showed no significant changes

Vascular Supply

  • Capsule and synovium at acetabular margin


Clinical Significance

See Also


  1. Lecouvet FE, Vande Berg BC, Malghem J, et al. MR imaging of the acetabular labrum: variations in 200 asymptomatic hips. AJR Am J Roentgenol 1996;167(4):1025–1028
  2. Abe I, Harada Y, Oinuma K, et al. Acetabular labrum: abnormal findings atMR imaging in asymptomatic hips. Radiology 2000;216 (2):576–581
  3. Thomas, James D., et al. "Imaging of the acetabular labrum." Seminars in musculoskeletal radiology. Vol. 17. No. 03. Thieme Medical Publishers, 2013.
  4. Bharam S. Labral tears, extra-articular injuries, and hip arthroscopy in the athlete. Clin Sports Med 2006;25(2):279–292, ix
  5. Ferguson SJ, Bryant JT, Ganz R, Ito K. The influence of the acetabular labrum on hip joint cartilage consolidation: a poroelastic finite element model. J Biomech 2000;33(8):953–960
Created by:
John Kiel on 14 September 2020 13:13:26
Last edited:
14 September 2020 15:20:50