Ligaments of the Knee

Author: Derek Moore

Topic updated on 05/16/13 6:24pm

Introduction

A diarthrodial joint that allows simulataneous rotation and translation

Overview of Knee Ligament Function
Ligament	Primary function	Secondary function
Anterior Cruciate Ligament (ACL)	Resists anterolateral displacement of the tibia on the femur	Resist varus displacement at 0 degrees of flexion
Posterior Cruciate Ligament (PCL)	Resists posterior tibial displacement, especially at 90 degrees of flexion	Resist varus displacement at 0 degrees of flexion
Lateral Collateral Ligament (LCL)	Resists varus displacement at 30 degrees of flexion	Resists posterolateral rotatory displacement with flexion that is less than approximately 50 degrees
Popliteofibular Ligament / Posterior Lateral Corner (PLC)	Resist posterolateral rotation of the tibia on the femur	Resists varus angulation and posterior displacement of the tibia on the femur
Medial Collateral Ligament (MCL)	Resists valgus angulation	Works in concert with ACL to provide restraint to axial rotation

Lateral Structures of Knee
Layer I	Iliotibial tract, biceps femoris
	Common peroneal nerve lies between layer I and II
Layer 2	Patellar retinaculum, patellofemoral ligament
Layer 3	Superficial: LCL, fabellofibular ligament
	Lateral geniculate artery runs between deep and superficial layer
	Deep: Arcuate ligament, coronary ligament, popliteus tendon, popliteofibular ligament, capsule

Medial Structures of Knee
Layer I	Sartorius and fascia (patellar retinaculum)
gracilis, semitendinosis, and saphenous nerve run between layer 1 and 2
Layer 2	Semimembranosus, superficial MCL, posterior oblique ligament
Layer 3	Deep MCL, capsule

ACL

Function
- prevents anterior translation of the tibia relative to the femur
Anatomy
- origin
  - lateral femoral condyle
- insertion
  - broad and irregular
  - anterior and between the intercondylar eminences of the tibia
- structure
  - 33mm x 11mm in size
  - two bundles
    - anteromedial
    - posterolateral
      - PL bundle prevents pivot shifting of the knee
      - prevents internal tibial rotation with knee near extension
Blood supply
- middle geniculate artery
Composition
- 90% Type I collagen
- 10% Type III collagen
Biomechanics
- strength: 2200 N (anterior)

	ACL	PCL
Tight in flexion	AM	AL
Tight in extension	PL	PM

PCL

Function
- prevents posterior translation of the tibia relative to the femur
- PCL and PLC work in concert to resist posterior translation and posterolateral rotatory instability
Anatomy
- origin
  - medial femoral condyle
- insertion
  - tibial sulcus
- structure
  - 38mm x 13mm in size
  - two bundles
    - anterolateral
    - posteromedial
  - variable meniscofemoral ligaments originate from the posterior horn of the lateral meniscus and insert into the substance of the PCL. These include
    - Ligament of Humphrey (anterior to PCL)
    - Ligament of Wrisberg (posterior to PCL)
- blood supply
  - middle geniculate artery
Biomechanics
- strength: 2500 N (posterior)

	ACL	PCL
Tight in flexion	AM	AL
Tight in extension	PL	PM

LCL (Lateral Collateral Ligament)

Function
- to provide support to varus angulation
- works in concert with MCL to provide restraint to axial rotation
- also known as "Fibular Collateral Ligament".
Anatomy
- origin
  - on lateral femoral condyle posterior and superior to insertion of popliteus
- path
  - runs superficial to popliteus
- insertion
  - on the fibula anterior to the popliteofibular ligament on the fibula
  - capsule's most distal extent is just posterior to the fibula
- structure
  - cord-like
Biomechanics
- tight in extension and lax in flexion
- strength: 750 N (valgus)

PLC (Posterior Lateral Corner)

Function
- works synergistically with the PCL to control external rotation and posterior translation
Anatomy
- included structures
  - LCL (295N)
  - popliteus muscle and tendon (680N)
  - popliteofibular ligament (229N)
  - lateral capsule
- variable
  - arcuate ligament
  - iliotibial track
  - fabellofibular ligament

MCL

Function
- to provide restraint to valgus angulation
- works in concert with ACL to provide restraint to axial rotation
Anatomy
- origin
  - MFC to medial tibia extending down several centimeters
- structure
  - two components
    - superficial portion (tibial collateral ligament)
      - lies just deep to gracilis and semitendinosus
      - originates from medial femoral epicondyle and inserts into periosteum of proximal tibia (deep to pes anserinus)
      - the superficial portion of the MCL contributes 57% and 78% of medial stability at 5 degrees and 25 degrees of knee flexion, respectively.
      - the superficial MCL is the primary stabilizer to valgus stress at all angles
    - deep portion (medial capsular ligament)
      - separated from supficial portion by a bursa
      - attaches to medial meniscus (coronary ligament)
      - divided into meniscofemoral and meniscotibial portions
      - posterior fibers of the deep MCL blend with posteromedial capsule and POL
      - the deep MCL and posteromedial capsule act as secondary restraints to valgus stress at full knee extension.
Biomechanics
- strength: 4000 N (varus)

Posteromedial corner

Function
- important for rotatory stability
Anatomy
- lies deep to MCL
- formed by
  - insertion of semimebranosus
  - posterior oblique ligament
  - oblique popliteal ligament
  - posterior capsule

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Qbank (2 Questions)

TAG

(OBQ10.239) Isolated transection of the posterolateral(PL) bundle of the ACL has what effect on anterior tibial translation and rotatory stability of the knee? Topic

Review Topic

1. Increased tibial translation and rotation at 30 degrees of flexion
2. Increased tibial translation and rotation at 90 degrees of flexion
3. Increased tibial translation at 30 degrees of flexion and increased rotation at 90 degrees of flexion
4. Increased tibial translation at 90 degrees and negligible effect on rotatory stability
5. Increased tibial translation at 30 degrees and negligible effect on rotatory stability

PREFERRED RESPONSE ▶

DISCUSSION: Zantop and Herbort et al determined the influence of isolated deficiency of the AM or PL bundle of the ACL on the resulting knee kinematics. They found that transection of the anteromedial bundle leads to increased anterior tibial translation at 90 degrees of knee flexion, whereas transection of the posterolateral bundle shows an increased anterior tibial translation as well as a combined rotatory instability at 30 degrees. This rotatory stability provided by the PL bundle prevents the pivot shift phenomenon found in ACL deficient knees. Zantop and Wellman et al performed a cadaveric study to determine the distances from the tibial and femoral center of the native AM and PL bundle to the articular cartilage and meniscus. They concluded that the center of the femoral PL bundle is shallow and inferior to the AM bundle, and on the tibia the AM bundle lies anterior when compared with the typical single-bundle ACL tunnel. Illustrations A and B highlight the ACL bundle anatomy.

Illustrations: A

REFERENCES:

1. Zantop T, Wellmann M, Fu FH, Petersen W. Tunnel positioning of anteromedial and posterolateral bundles in anatomic anterior cruciate ligament reconstruction:anatomic and radiographic findings. Am J Sports Med. 2008 Jan;36(1):65-72. Epub 2007 Oct 11. PMID:17932407 (Link to Abstract)

2. Zantop T, Herbort M, Raschke MJ, Fu FH, Petersen W. The role of the anteromedial and posterolateral bundles of the anterior cruciate ligament inanterior tibial translation and internal rotation. Am J Sports Med. 2007 Feb;35(2):223-7. Epub 2006 Dec 7. PMID:17158275 (Link to Abstract)

Question Authors:

Joshua Blomberg MD, Patrick McCulloch MD, Ben Taylor MD,

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Groups

ABOS II: Ligament of the Knee

General - Oral Boards Review

7/29/2011

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Evidence & References Show References

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012

Undefined

Wijdicks CA, Griffith CJ, LaPrade RF, Johansen S, Sunderland A, Arendt EA, Engebretsen L. Radiographic identification of the primary medial knee structures. J Bone Joint Surg Am. 2009 Mar 1;91(3):521-9. PMID:19255211 (Link to Abstract)
Wijdicks CA, Griffith CJ, Johansen S, Engebretsen L, LaPrade RF. Injuries to the medial collateral ligament and associated medial structures of the knee. J Bone Joint Surg Am. 2010 May;92(5):1266-80. PMID: 20439679 (Link to Abstract)
Zantop T, Wellmann M, Fu FH, Petersen W. Tunnel positioning of anteromedial and posterolateral bundles in anatomic anterior cruciate ligament reconstruction:anatomic and radiographic findings. Am J Sports Med. 2008 Jan;36(1):65-72. Epub 2007 Oct 11. PMID:17932407 (Link to Abstract)
Zantop T, Herbort M, Raschke MJ, Fu FH, Petersen W. The role of the anteromedial and posterolateral bundles of the anterior cruciate ligament inanterior tibial translation and internal rotation. Am J Sports Med. 2007 Feb;35(2):223-7. Epub 2006 Dec 7. PMID:17158275 (Link to Abstract)

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Ligaments of the Knee

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