What Is the Knee Joint?

The knee joint is composed of the lower end of the femur, the upper end of the tibia, and the sacrum. It is the largest and most complex joint of the human body and belongs to the tackle joint.

Western Medicine Name: Knee joint
Chinese Medicine Name: Knee joint
English name: knee, knee joint, articulatio genus
Other name: Block joint
Affiliated Department: Surgery-Orthopedics

Disease site: Knee joint
The main symptoms: Pain, difficulty in flexion and extension
Main cause: Long-term physical work, obese people
Multiple groups: Long-term manual workers, obese
Contagious: Non-contagious
Whether to enter health insurance: Yes

Knee joint anatomy

The patella is in contact with the metatarsal surface of the femur. The medial and lateral condyles of the femur are opposite the medial and lateral condyles of the tibia.

Knee joint (3 photos)

Knee joint two major ligaments

The joint capsule of the knee joint is thin and loose, attached to the periphery of each articular surface, and surrounded by ligaments to strengthen the stability of the joint. Major ligaments:

1 Knee joint 1, patellar ligament

It is the central fibrous cord of the quadriceps tendon, which stops from the sacrum to the tibial tuberosity. The zygomatic ligament is flat and strong. Its superficial fibers pass over the sacrum to the quadriceps tendon.

2 Knee joint 2, fibula collateral ligament

It is a string-like tough fiber cord that starts from the outer epicondyle of the femur and extends down to the fibula head. The surface of the ligament is mostly covered by the biceps femoris tendon and is not directly connected to the lateral meniscus.

3 Knee joint 3, tibial collateral ligament

It is broad and flat and is located behind the medial knee. It starts from the internal condyle of the femur and attaches downward to the medial condyle of the tibia and adjacent bones, and is closely combined with the joint capsule and the medial meniscus. The tibial collateral ligament and fibular collateral ligament are tense when they stretch their knees, relax when they flex their knees, and are most relaxed when they flex their knees. Therefore, in the semi-flexed knee position, the knee joint is allowed to make a few internal and external rotation movements.

4 Knee joint 4, oblique ligament

Extending from the semi-membrane tendon, it starts from the medial condyle of the tibia, obliquely outwards and upwards, and stops at the epicondyle of the femur. Part of the fibers are fused with the joint capsule, which can prevent the knee joint from overextending.

5 Knee joint 5, knee cruciate ligament

It is located behind the center of the knee joint and is very strong. It is lined by the synovium and can be divided into anterior and posterior:

The anterior cruciate ligament, which rises from the medial side of the iliac crest, which rises from the intercondylar tibia, and the anterior angle of the lateral meniscus, is obliquely rearward, upward, and lateral, and the fibers are fan-shaped attached to the medial side of the lateral femoral condyle.

Posterior cruciate ligament. Shorter and stronger than the anterior cruciate ligament, and more vertical. It starts from the back of the tibial intercondylar bulge, obliquely forward, upper, and medial, and is attached to the outer side of the medial condyle of the femur.

The knee cruciate ligament firmly connects the femur and tibia, preventing the tibia from moving forward and backward along the femur. The anterior cruciate ligament is most tense when it stretches the knee and prevents the tibia from moving forward. The posterior cruciate ligament is most tense during knee flexion and prevents the tibia from moving backwards.

Knee joint three, other auxiliary structures

The synovial layer of the knee joint is the widest and most complex of the whole body joints. It is attached to the perimeter of the articular surface of the bones of the joint, covering all the structures in the joint except the articular cartilage and meniscus. The synovium is above the upper edge of the sacrum, and it protrudes upward to form a sacral sac which is about 5 cm deep between the quadriceps tendon and the lower part of the femoral body. On both sides of the midline below the sacrum, part of the synovial layer protrudes into the joint cavity, forming a pair of wing-shaped alar folds. The contains fatty tissue and fills the space in the joint cavity. There are also synovial sacs that are not in communication with the joint cavity, such as the deep subcondylar sac located between the sacral ligament and the upper end of the tibia.

Knee joint 4, related diseases and treatment

Knee osteoarthritis is the most common musculoskeletal disease and the leading cause of disability in the elderly. 85% of total knee replacements are due to knee osteoarthritis. One of the common problems in total knee arthroplasty is the treatment of bone defects. The position of bone defects can occur in the tibia, femur and sacrum. It is more common in the tibial plateau defects. The incidence of distal femoral bone defects is lower than that of tibial bone defects. Distal bone defects can increase the flexion and extension gap of the knee joint, especially the flexion gap. The main causes of bone defects in the first total knee replacement include wear of the tibial plateau, osteonecrosis, dysplasia of the iliac crest, trauma, and inflammatory reactions. The main causes of defects in total knee arthroplasty include arthritis, angulation deformity, and ischemia. Necrosis, stress shielding, history of high tibial osteotomy or total knee replacement surgery and improper removal of prosthesis, or seen in infected joint replacement, the first stage of debridement. Bone defects can also occur during total knee arthroplasty, especially in total knee arthroplasty and revision. The reasons include excessive osteotomy, infection, and improper removal of the prosthesis during the revision. The surgeon needs to deal with the bone defect reasonably, accurately place the prosthesis and establish a solid bone-prosthesis contact interface to provide sufficient support for the prosthesis and obtain satisfactory surgical results.

Knee joint five, analgesic treatment

Radiofrequency thermocoagulation of sensory nerves of the knee joint is an analgesic of radiofrequency thermocoagulation of the articular branches of the saphenous and femoral nerves. This method does not affect the patient's motor function, and has minimal trauma and small impact on the patient's general condition, which is very promising. Method of treating severe OA. Prior radiofrequency thermocoagulation of the sensory nerves of the knee joints often used X-ray positioning. Because the sensory nerves of the knee joints are very small and the movements are large, it is difficult to locate them with the help of bone marks. The development of ultrasound technology and intensive research on the anatomy of the sensory nerves of the knee joint allow us to use ultrasound guidance for accurate saphenous and femoral nerve branch radiofrequency thermocoagulation.