Ligaments of knee joint

LIGAMENTS OF KNEE JOINT

• The ligaments surrounding the knee joint offer stability by limiting movements and, together with the menisci and several bursae, protect the articular capsule.

INTRACAPSULAR LIGAMENT:

• The knee is stabilized by a pair of cruciate ligaments. 

1. The anterior cruciate ligament (ACL) 

• One of the most important ligament of the knee joint.
• The ACL is critically important because it prevents the tibia from being pushed too far anterior relative to the femur. 
• Begins from anterior part of intercondylar area of tibia just behind the anterior horn of medial meniscus.
• Provide proprioceptive function of knee joint.
• ACL is intrasynovial i.e it lies inside the synovium.
• ACL is taut during extension.
• Middle genicular artery is a branch of popliteal artery and supplies the cruciate ligaments & the synovial membrane of knee joint piercing the oblique popliteal ligament of knee.

2. The posterior cruciate ligament (PCL)   

• Originates from Posterior part of intercondylar area of tibia.
• It stretches from medial condyle of femur to the posterior intercondylar area. 
• Injury to this ligament is uncommon but can occur as a direct result of forced trauma to the ligament. 
• This ligament prevents posterior displacement of the tibia relative to the femur.
• It is taut in flexion.
• PCL is extrasynovial but intracapsular i.e lies b/w synovium & capsule of the knee joint.

Blood supply of anterior & posterior ligaments is from:

1. Middle genicular artery (major supply)
2. Inferior genicular artery (medial & lateral)

• Nerve supply of cruciate ligaments (ACL & PCL) is from posterior articular branch of tibial nerve.

3. The transverse ligament 

• It stretches from the lateral meniscus to the medial meniscus. 
• It passes in front of the menisci. 
• It is divided into several strips in 10% of cases.
• The two menisci are attached to each other anteriorly by the ligament.

4.  The posterior and anterior meniscofemoral ligaments 

• Stretch from the posterior horn of the lateral meniscus to the medial femoral condyle. 
• They pass posteriorly behind the posterior cruciate ligament. 
• The posterior meniscofemoral ligament is more commonly present (30%); both ligaments are present less often.

5. Coronary Ligament

• Part of capsule that connects the peripheral part of menisci with corresponding tibial condyles.

EXTRACAPSULAR LIGAMENTS:

1. Ligamentum patella (patellar tendon)

• It connects the patella to the tuberosity of the tibia. 
• occasionally called the patellar tendon because there is no definite separation between the quadriceps tendon (which surrounds the patella) and the area connecting the patella to the tibia.
• This very strong ligament helps give the patella its mechanical leverage and also functions as a cap for the condyles of the femur. 

2. Tibial collateral (medial collateral) ligament

• It stretches from the medial epicondyle of the femur to the medial tibial condyle.
• It is composed of three groups of fibers, one stretching between the two bones, and two fused with the medial meniscus. 
• The MCL is partly covered by the pes anserinus and the tendon of the semimembranosus passes under it.
• MCL injury is most common ligament injury to the knee.
• Phylogenetically this ligament injury is the most common ligament injury to the knee.

3. Fibular (lateral) collateral ligament

• It stretches from the lateral epicondyle of the femur to the head of fibula. 
• It is separate from both the joint capsule and the lateral meniscus.
• It protects the lateral side from an inside bending force (a varus force). 
• The anterolateral ligament (ALL) is situated in front of the LCL.
• In comparison to deep part of tibial collateral ligament it is not attached to capsule & lateral meniscus.

4. Oblique popliteal ligament

• An expansion from the tendon of semimembranous attachment to intercondylar line of femur.
• Closely related to popliteal artery & is pierced by middle genicular vessels & nerve & the terminal part of the posterior division of the obturator nerve.

5. Arcuate popliteal ligament 

• It is a posterior expansion from the short lateral ligament.
• Extends from the head of the fibula to the posterior border of the tibial intercondylar area.