L3 Knee

The knee joint is comprised of two articulations: the patellofemoral joint and the tibiofemoral joint. The tibiofemoral joint is further divided into the medial and lateral compartments.

The superior tibiofibular articulation is not considered part of the knee joint complex.

Proximal ends of the femur are involved in knee articulation. These include the medial & lateral condyles, the medial & lateral epicondyles, the adductor tubercle, and the patellar articular surface.

The intercondylar notch separates the medial and lateral condyles of the femur. The adductor tubercle is a bony protrusion on the medial epicondyle.

The posterior surface of the patella articulates with the anterior surface of the femur, specifically the trochlea.

The proximal tibia has several key features involved in knee articulation: the medial and lateral condyles, the tibial plateau, the intercondylar eminences, and the tibial tuberosity.

The knee joint capsule is reinforced by the medial and lateral retinacula.

The suprapatellar pouch is a proximal extension of the synovial cavity, located superior to the patellar ligament.

The synovial membrane lines the inside of the fibrous capsule of the knee joint. It is not found over articular cartilage.

The posterior knee joint capsule is reinforced by the oblique popliteal ligament, which is formed by part of the semimembranosus tendon, and the arcuate popliteal ligament, which arches over the popliteus muscle.

The iliotibial tract attaches to the distal femur, patella, and lateral tibial tubercle. It blends with the knee joint capsule at the lateral retinaculum.

Gerdy's tubercle is another name for the lateral tibial tubercle.

Normal knee joints contain between 0.5 and 4.0 cc of synovial fluid.

The cruciate ligaments and the menisci attach to the intercondylar region of the tibia. The menisci are C-shaped cartilage pads that act as shock absorbers and provide stability to the knee joint.

The medial meniscus is oval, larger, and narrower than the lateral meniscus, which is round, smaller, and wider.

The menisci bear a portion of the body's weight during knee articulation. If a meniscus is removed, the weight is distributed over a smaller area of articular cartilage, increasing the risk of premature cartilage degradation.

Only the outer edge of the menisci has blood supply. The inner section lacks blood supply, which makes it difficult for tears on the inside portion to heal.

The infrapatellar fat pad is a cushion located between the patellar ligament and the anterior surface of the tibia.

The collateral ligaments and cruciate ligaments are key components of the knee joint. The medial collateral ligament connects the medial epicondyle of the femur to the medial tibia, while the lateral collateral ligament connects the lateral epicondyle of the femur to the head of the fibula.

The medial collateral ligament also attaches to the medial meniscus. A tear in the medial collateral ligament might damage the adjacent medial meniscus.

The lateral collateral ligament does not attach to the lateral meniscus.

The valgus stress test examines the integrity of the medial collateral ligament, while the varus stress test assesses the lateral collateral ligament.

The outer aspect of the medial meniscus is connected to the inner surface of the medial collateral ligament.

The anterior cruciate ligament (ACL) connects the anterior intercondylar area of the tibia to the lateral condyle of the femur. It prevents hyperextension of the knee and limits posterior movement of the femur.

The posterior cruciate ligament (PCL) connects the posterior intercondylar area of the tibia to the medial condyle of the femur. It limits anterior movement of the femur and prevents knee hyperflexion.

The ACL is a crucial factor in knee stability, playing a major role in preventing excessive forward or backward movement of the femur on the tibia.

An ACL tear can be identified using the anterior drawer test and the sag sign. An ACL tear can cause instability in the knee.

A PCL tear can be identified using the posterior drawer test. A PCL tear can lead to instability of the knee joint and difficulty with activities requiring bending or twisting.

Prepatellar bursitis is a condition in which the prepatellar bursa, a fluid-filled sac located in front of the patella, becomes inflamed.

When the knee is flexed beyond 90 degrees, the patellofemoral joint experiences higher forces. This occurs because the patella has greater contact area with the femur.

The tibia can rotate medially and laterally on the femur when the knee is flexed to 90 degrees and not weight-bearing.

The Q angle is the angle formed between a vertical line drawn through the patella and a line parallel to the shaft of the femur. It is measured using the anterior superior iliac spine (ASIS) as the proximal landmark.

A high Q angle may contribute to lateral dislocation of the patella.

Genu valgum is a condition characterized by an inward angulation of the lower legs at the knees, or 'knock-knees'. Genu varum is the opposite condition, characterized by an outward angulation of the lower legs at the knees, or 'bowlegs'.

Degenerative arthritis of the knee, also known as knee osteoarthritis (OA), is a condition that causes pain, swelling, and stiffness in the knee joint.

Total knee arthroplasty (TKA) is a surgical procedure that involves replacing the damaged joint surfaces of the knee with artificial components. It is a common treatment for severe knee osteoarthritis.

The popliteal fossa, also known as the 'knee pit', is a diamond-shaped depression located behind the knee joint. It is bordered by the muscles surrounding the knee.

The small saphenous vein drains into the popliteal vein, but sometimes travels superiorly into the posterior thigh to connect with perforating veins.

The popliteal fossa is bounded by the semitendinosus, semimembranosus, and biceps femoris muscles superiorly, the medial and lateral heads of the gastrocnemius muscles inferiorly, and the distal femur as its floor.

The popliteal fossa contains various structures, including branches of the sciatic nerve, the popliteal vein, the popliteal artery, popliteal lymph nodes, and fat.

The sciatic nerve branches into the tibial nerve and common fibular nerve within the popliteal fossa. The tibial nerve runs down the midline, while the common fibular nerve runs laterally along the biceps femoris tendon.

The femoral artery is anterior to the femoral vein in the adductor canal and becomes more superficial as it passes through the adductor hiatus. This relationship changes in the popliteal fossa where the popliteal artery becomes deep to the vein, and the tibial nerve is located more superficially.

The genicular anastomosis supplies the knee joint and surrounding structures. It is formed by a network of arteries that originates from multiple sources.

A popliteal (Baker's) cyst is a fluid-filled sac that forms behind the knee joint. It occurs when synovial fluid leaks into the joint capsule. Deep vein thrombosis (DVT) is a blood clot that forms in the popliteal vein, a common site for DVTs in the lower limbs.

This vein usually drains into the popliteal vein, but sometimes travels up into the posterior thigh to drain into perforating veins.

The distal femur is the lower end of the thigh bone. Bony landmarks include the medial and lateral condyles, the epicondyles, the adductor tubercle, and the patellar articular surface.

The posterior surface of the patella articulates with the anterior surface of the femur. The specific area of contact on the femur is the trochlea.

The proximal tibia (top of the shinbone) has several features involved in knee articulation, including the medial and lateral condyles, the tibial plateau, the intercondylar eminences, and the tibial tuberosity.

The medial and lateral retinacula are dense connective tissue bands that help reinforce the fibrous capsule of the knee joint.

The synovial membrane lines the inside of the knee joint capsule, excluding the articular cartilage. It secretes synovial fluid.

The posterior capsule of the knee joint is reinforced by two ligaments: the oblique popliteal ligament and the arcuate popliteal ligament.

The iliotibial tract is a strong band of connective tissue that runs down the side of the thigh. It attaches to the distal femur, patella, and lateral tibial tubercle.

Normally, there is about 0.5 to 4.0 cubic centimeters of synovial fluid in the knee joint. This fluid helps to lubricate the joint.

Within the intercondylar region of the tibia, the cruciate ligaments and the menisci attach. The menisci are C-shaped cartilage pads that act as shock absorbers.

The medial meniscus is oval shaped, larger, and narrower than the lateral meniscus, which is round, smaller, and wider.

The menisci are C-shaped cartilage pads that act as shock absorbers and provide stability to the knee joint. They bear a portion of the body's weight during knee articulation. Removing a meniscus results in a smaller weight-bearing surface, increasing the risk of premature cartilage degeneration.

The medial collateral ligament connects the medial epicondyle of the femur to the medial tibia, and also to the medial meniscus. A tear in this ligament can damage the adjacent medial meniscus.

The lateral collateral ligament does not attach to the lateral meniscus. It connects the lateral epicondyle of the femur to the head of the fibula.

The valgus stress test examines the integrity of the medial collateral ligament, while the varus stress test assesses the lateral collateral ligament.

The anterior cruciate ligament (ACL) connects the anterior intercondylar area of the tibia to the lateral condyle of the femur. It prevents hyperextension of the knee and limits posterior movement of the femur.

The posterior cruciate ligament (PCL) connects the posterior intercondylar area of the tibia to the medial condyle of the femur. It limits anterior movement of the femur and prevents knee hyperflexion.

The popliteal fossa contains various structures, including branches of the sciatic nerve, the popliteal vein, the popliteal artery, popliteal lymph nodes, and fat.

The genicular anastomosis supplies the knee joint and surrounding structures. It is formed by a network of arteries that originates from multiple sources.

The proximal end of the tibia features several landmarks for knee articulation: medial and lateral condyles, tibial plateau, intercondylar eminences, and tibial tuberosity.

The medial and lateral retinacula are bands of connective tissue that help reinforce the fibrous capsule of the knee joint.

The synovial membrane lines the inner surface of the knee joint capsule, except for the articular cartilage. It is responsible for producing synovial fluid.

The cruciate ligaments and menisci attach to the intercondylar region of the tibia. The menisci are C-shaped cartilage pads that act as shock absorbers and provide stability to the knee joint.

The medial collateral ligament connects the medial epicondyle of the femur to the medial tibia and also to the medial meniscus. It prevents excessive outward movement of the knee joint.