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Anterior Cruciate Ligament

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Description

Ligamentous anatomy of the knee[1]
1 Femur 2 Quadriceps femoris muscle 3 Suprapatellar bursa and articular cavity 4 Patella 5 Articular cartilage of femur 6 Infrapatellar fat pad 7 Patellar ligament 8 Tibia 9 Tibial nerve 10 Adductor magnus muscle 11 Popliteal vein 12 Semitendinosus muscle 13 Semimembranosus muscle 14 Popliteal artery 15 Gastrocnemius muscle 16 Anterior cruciate ligament 17 Posterior cruciate ligament 18 Popliteus muscle 19 Soleus muscle 20 Lateral epicondyle of femur 21 Fibular collateral ligament 22 Head of fibula 23 Fibula 24 Articular cavity of knee joint 25 Lateral meniscus of knee joint 26 Lateral condyle of tibia 27 Tibiofibular joint[1]
Normal ACL seen in the sagittal plane[2]

Anatomic Description

  • Tibial insertion
    • Anteromedial aspect of the intercondylar region of the Tibial Plateau
    • Anterior tibia, between intercondylar eminences
  • Femoral insertion
    • Posteromedially to attach to the lateral Femoral Condyle
    • Lateral intercondylar ridge demarcates the anterior border of the ACL
    • Bifurcate ridge separates the anteromedial and posterolateral bundle attachment
  • Anteromedial (AM) bundle
    • Nearly isometric, with a tendency toward slightly more tension during flexion than in extension
    • Considered the center of ACL rotation[3]
    • Provide both rotational, translational (sagittal plane) stability
  • Posterolateral (PL) bundle
    • Lax in flexion, becomes taught during the end range of extension (from 15° of flexion to 0°)
    • Provides primarily more rotational stability.

Histology

  • Composed of connective tissue, collagenous fibers
  • Type I collagen (90%), Type II collagen (10%)

Variant Anatomy

  • Single bundle: 25%[4]
  • Third Intermediate Bundle
  • Anomalous insertion of the medial meniscus

Actions

  • Aids in stabilization of the knee joint
  • Prevents excess forward translation of the tibia relative to the femur during flexion and extension
  • Rotational stability to the knee with varus or valgus stress
  • 2200 N strength (anterior)

Radiographic Appearance

  • MRI
    • Heterogenous appearance
    • Anteromedial/ posterolateral bundles are defined by surrounding high intensity structures
  • ACL Blumensaat line
    • Drawing a line parallel to the roof of the intercondylar notch of the femur (Blumensaat line)
    • One parallel to the distal portion of the anterior cruciate ligament
    • Angle is calculated at the intersection of these two lines
    • Normally ≤ 15°, abnormal > 15° suggests an ACL tear

Vascular Supply

  • Middle Geniculate Artery

Innervation

Clinical Significance

See Also

References

  1. ↑ 1.0 1.1 Rohen, Johannes Wilhelm, Chihiro Yokochi, and Elke Lütjen-Drecoll. Color atlas of anatomy: a photographic study of the human body. Schattauer Verlag, 2006.
  2. ↑ Case courtesy of Andrew Dixon, Radiopaedia.org, rID: 22993
  3. ↑ Sonnery-Cottet B, Chambat P. Arthroscopic identification of the anterior cruciate ligament posterolateral bundle: The figure-of-four position. Arthroscopy. 2007;23:1128.e1–3.
  4. ↑ Hassebrock J, Gulbrandsen M, Asprey W, Makovicka J, Chhabra A. Knee Ligament Anatomy and Biomechanics. Sports Med Arthrosc. 2020;28(3):80-6. doi:10.1097/jsa.0000000000000279
Created by:
John Kiel on 19 November 2020 07:05:53
Authors:
Last edited:
4 September 2024 18:22:08
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