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What type of joint is the knee joint?
The knee joint is a hinge-type synovial joint that mainly allows for flexion and extension, with a small degree of medial and lateral rotation. It is formed by articulations between the patella, femur, and tibia.
What are the two articulations in the knee joint?
The knee joint consists of two articulations: tibiofemoral and patellofemoral. The joint surfaces are lined with hyaline cartilage and enclosed in a single joint cavity.
What is the tibiofemoral articulation?
The tibiofemoral articulation involves the medial and lateral condyles of the femur articulating with the tibial condyles. It is the weight-bearing component of the knee joint.
What is the patellofemoral articulation?
The patellofemoral articulation involves the anterior aspect of the distal femur articulating with the patella. This allows the quadriceps tendon to be inserted directly over the knee, increasing the muscle’s efficiency.
What is the function of the patella?
The patella serves as a fulcrum to increase the power of the knee extensor and as a stabilizing structure, reducing frictional forces on the femoral condyles.
What are the main bursae found in the knee joint?
The main bursae in the knee are:\n1. Suprapatellar bursa – between the quadriceps femoris and femur.\n2. Prepatellar bursa – between the apex of the patella and skin.\n3. Infrapatellar bursa – with deep and superficial components. The deep lies between the tibia and the patella ligament, and the superficial lies between the patella ligament and skin.\n4. Semimembranosus bursa – located posteriorly, between the semimembranosus muscle and the medial head of the gastrocnemius.
What is the patellar ligament?
The patellar ligament is a continuation of the quadriceps femoris tendon and attaches distally to the tibial tuberosity.
What are the collateral ligaments?
The collateral ligaments are:\n1. Medial collateral ligament – a wide, flat ligament on the medial side of the knee that attaches proximally to the medial epicondyle of the femur and distally to the medial condyle of the tibia.\n2. Lateral collateral ligament – thinner and rounder, it attaches proximally to the lateral epicondyle of the femur and distally to the lateral surface of the fibular head.
What is the function of the collateral ligaments?
The collateral ligaments stabilize the knee joint, preventing excessive medial or lateral movement during its hinge motion.
What are the cruciate ligaments?
The cruciate ligaments are two ligaments that connect the femur and tibia. They cross each other and are named based on their positions:\n1. Anterior cruciate ligament (ACL) – prevents anterior dislocation of the tibia.\n2. Posterior cruciate ligament (PCL) – prevents posterior dislocation of the tibia.
How do the cruciate ligaments prevent knee instability?
The ACL attaches at the anterior intercondylar region of the tibia and ascends to attach to the femur in the intercondylar fossa, preventing anterior tibial dislocation. The PCL attaches at the posterior intercondylar region of the tibia and ascends to attach to the anteromedial femoral condyle, preventing posterior tibial dislocation.
What movements does the knee joint permit?
The knee joint allows the following movements:\n1. Extension – produced by the quadriceps femoris.\n2. Flexion – produced by the hamstrings, gracilis, sartorius, and popliteus.\n3. Lateral rotation – produced by the biceps femoris.\n4. Medial rotation – produced by the semimembranosus, semitendinosus, gracilis, sartorius, and popliteus.\nNote: Lateral and medial rotation only occur when the knee is flexed.
How is the medial collateral ligament (MCL) injury assessed?
MCL injury is assessed by rotating the leg medially. Pain during medial rotation indicates damage to the MCL, and if the MCL is damaged, it is likely that the medial meniscus is also torn due to their attachment.
How is the lateral collateral ligament (LCL) injury assessed?
LCL injury is assessed by rotating the leg laterally. Pain during lateral rotation suggests damage to the LCL.
How can anterior cruciate ligament (ACL) injury occur?
ACL injury can occur due to hyperextension of the knee or a force applied to the back of the knee when the joint is partially flexed. An anterior drawer test can confirm ACL damage by pulling the tibia forward and testing its movement.
