The knee is a complex joint made up of different structures - bones, tendons, ligaments, and muscles. They all work together to maintain the knee’s normal function and provide stability to the knee during movement.
Having a well-functioning healthy knee is essential for our mobility and ability to participate in various activities. Understanding the anatomy of the knee enhances your ability to discuss and choose the right treatment procedure for knee problems with your doctor.
Bones of the Knee
The knee is a hinge joint made up of two bones, the thighbone (femur) and shinbone (tibia). There are two round knobs at the end of the femur called femoral condyles that articulate with the flat surface of the tibia called the tibial plateau. The tibial plateau on the inside of the leg is called the medial tibial plateau and on the outside of the leg, the lateral tibial plateau.
The two femoral condyles form a groove on the front (anterior) side of the knee called the patellofemoral groove. A small bone called the patella sits in this groove and forms the kneecap. It acts as a shield and protects the knee joint from direct trauma.
A fourth bone called the fibula is the other bone of the lower leg. This forms a small joint with the tibia. This joint has very little movement and is not considered a part of the main joint of the knee.
Articular Cartilage and Menisci of the Knee
Movement of the bones causes friction between the articulating surfaces. To reduce this friction, all articulating surfaces involved in the movement are covered with a white, shiny, slippery layer called articular cartilage. The articulating surface of the femoral condyles, tibial plateaus and the back of the patella are covered with this cartilage. The cartilage provides a smooth surface that facilitates easy movement.
To further reduce friction between the articulating surfaces of the bones, the knee joint is lined by a synovial membrane that produces a thick clear fluid called synovial fluid. This fluid lubricates and nourishes the cartilage and bones inside the joint capsule.
Within the knee joint, between the femur and tibia, are two C-shaped cartilaginous structures called menisci. Menisci function to provide stability to the knee by spreading the weight of the upper body across the whole surface of the tibial plateau. The menisci help in load-bearing i.e. it prevents the weight from concentrating onto a small area, which could damage the articular cartilage. The menisci also act as a cushion between the femur and tibia by absorbing the shock produced by activities such as walking, running and jumping.
Ligaments of the Knee
Ligaments are tough bands of tissue that connect one bone to another bone. The ligaments of the knee stabilize the knee joint. There are two important groups of ligaments that hold the bones of the knee joint together, collateral and cruciate ligaments.
Collateral ligaments are present on either side of the knee. They prevent the knee from moving too far during side to side motion. The collateral ligament on the inside is called the medial collateral ligament (MCL) and the collateral ligament on the outside is called the lateral collateral ligament (LCL).
Cruciate ligaments, present inside the knee joint, control the back-and-forth motion of the knee. The cruciate ligament in the front of the knee is called anterior cruciate ligament (ACL) and the cruciate ligament in the back of the knee is called posterior cruciate ligament (PCL).
Muscles of the Knee
There are two major muscles in the knee - the quadriceps and the hamstrings, which enable movement of the knee joint. The quadriceps muscles are located in front of the thigh. When the quadriceps muscles contract, the knee straightens. The hamstrings are located at the back of the thigh. When the hamstring muscles contract, the knee bends.
Tendons of the Knee
A tendon is a tissue that attaches a muscle to a bone. The quadriceps muscles of the knee meet just above the patella and attach to it through a tendon called the quadriceps tendon. The patella further attaches to the tibia through a tendon called the patella tendon. The quadriceps muscle, quadriceps tendon, and patellar tendon all work together to straighten the knee. Similarly, the hamstring muscles at the back of the leg are attached to the knee joint with the hamstring tendon.
The patella, also called the kneecap, is a small bone present on the front of your knee joint. The underside of the patella is covered by cartilage that allows smooth gliding of the knee with movement. Overuse or misalignment of the patella can cause wear and tear of the cartilage.
The knee consists of a fluid called synovial fluid, which reduces the friction between the bones of the knee joint while you move your leg. Sometimes this fluid is produced in excess, resulting in its accumulation in the back of your knee. A Baker’s cyst or popliteal cyst is a fluid-filled swelling that develops into a lump behind the knee. This causes stiffness, tightness, and rarely pain behind the knee.
An iliotibial band is a tough group of fibers that runs from the iliac crest of the hip along the outside of the thigh, till the outer side of the shinbone, just below the knee joint. Its function is to coordinate with the thigh muscles and provide stability to the knee joint.
The patella, also called kneecap, is a small flat triangular bone located at the front of the knee joint. It is a sesamoid bone embedded in a tendon that connects the muscles of the thigh to the shinbone (tibia). The function of the patella is to protect the front portion of the knee.
Shin splints are pain and inflammation of the tendons, muscles and bone tissue along the tibia or shinbone (lower leg). It occurs because of vigorous physical activities such as exercise or sports. The condition is also referred to as medial tibial stress syndrome (MTSS).
An unstable knee causes pain, swelling, stiffness and a tendency of the joint to buckle or give way.
When you present with these symptoms, your doctor diagnoses knee instability by performing a thorough physical examination to test the stability of each ligament and may order imaging tests such as X-rays, MRI or CT scans to confirm the diagnosis.
A bursa is a small fluid-filled sac found between soft tissues and bones. It lubricates and acts as a cushion, decreasing the friction between bones when they move. Bursitis refers to the inflammation and swelling of the bursa. Goosefoot bursitis or pes anserine bursitis is the inflammation of the bursa present between the tendons of the hamstring muscle and the tibia (shinbone) on the inner side of the knee.
Knee infection is a serious medical condition that needs immediate treatment. Infection may occur followed by a knee replacement surgery or trauma and is usually caused by bacteria. Infection may spread to the space of the knee joint or deep layers of your knee causing serious complications.
The anterior cruciate ligament (ACL) is one of the major ligaments of the knee. It is located in the middle of the knee and runs from the femur (thighbone) to the tibia (shinbone). The ACL prevents the tibia from sliding out in front of the femur. Together with the posterior cruciate ligament (PCL), it provides rotational stability to the knee.
The knee is one of the most complex and largest joints in the body and is very susceptible to injury. The meniscus is a small, C-shaped piece of cartilage in the knee. Each knee consists of two menisci, medial meniscus on the inner aspect of the knee and the lateral meniscus on the outer aspect of the knee. The medial and lateral menisci act as a cushion between the thighbone (femur) and shinbone (tibia).
The knee is a complex joint that consists of bone, cartilage, ligaments, and tendons that help in your joint’s movements.
The knee is a hinge joint made up of two bones, the thighbone (femur) and shinbone (tibia). Ligaments are tough bands of tissue that connect one bone to another bone. The ligaments of the knee stabilize the knee joint.
The knee is a complex joint of the body that is vital for movement. The four major ligaments of the knee are anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and lateral collateral ligament (LCL). They play an important role in maintaining the stability of the knee. A multiligament injury is a tear in one or more ligaments of the knee, which affects the knee stability.
The joint surface is covered by a smooth articular surface that allows pain-free movement in the joint. Arthritis is a general term covering numerous conditions where the joint surface or cartilage wears out. This surface can wear out for several reasons; often the definite cause is not known. Arthritis often affects the knee joint.
The patella (kneecap) is a protective bone attached to the quadriceps muscles of the thigh by quadriceps tendon. It articulates with the femur bone to form the patellofemoral joint. The patella is protected by a ligament called the medial patellofemoral ligament (MPFL), which prevents the kneecap from gliding out.
The articular or hyaline cartilage is the tissue lining the surface of the two bones in the knee joint. Cartilage helps the bones move smoothly against each other and can withstand the weight of your body during activities such as running and jumping.
The patella is a small piece of bone in front of the knee that slides up and down the groove in the femur bone during bending and stretching movements. The ligaments on the inner and outer sides of the patella hold it in the femoral groove and avoid dislocation of the patella from the groove.
The kneecap or patella forms a part of the knee joint. It is present at the front of the knee, protecting the knee and providing attachment to various muscle groups of the thigh and leg. The undersurface of the kneecap and the lower end of the femur are coated with articular cartilage, which helps in smooth movement of the knee joint. A fracture in the kneecap is rare but common in adult males.
The patella (kneecap) is a small bone that shields your knee joint. It is present in front of your knee, on a groove called the trochlear groove that sits at the junction of the femur (thighbone) and tibia (shinbone). Articular cartilage presents below the patella and end of the femur cushion and helps the bones glide smoothly over each other when the legs move.
The knee joint is formed by the union of two bones, namely the femur (thighbone) and the tibia (lower leg bone). At the junction of these two bones is a cartilage called meniscus, which acts as a shock absorber. There are two menisci – the lateral and medial menisci. The lateral meniscus is the outer meniscus of the knee joint and gives a cushioning effect during weight-bearing activities.
The knee joint is made up of bones, the thighbone, and shinbone (lower leg), which articulate with each other. The upper aspect of the shinbone is made up of the medial (towards the inner side of the knee) and lateral (towards the outer side of the knee) plateaus (flat regions). Between these plateaus, the bone is raised to form the tibial eminence. The tibial eminence consists of the medial and lateral spines.
Angular deformities of the knee are variations in the normal growth pattern during early childhood and are common during childhood. Physiologic angular deformities vary with age
The condition usually becomes more evident when your child is 2 to 3 years old and normally corrects itself by 7 or 8 years. However, if the condition is not corrected, it could be a sign of an underlying problem that requires treatment.
Articular or hyaline cartilage is the tissue lining the surface of the two bones in the knee joint. Cartilage helps the bones move smoothly against each other and can withstand the weight of the body during activities such as running and jumping. Articular cartilage does not have a direct blood supply to it so has little capacity to repair itself.
Bowed leg is a bony deformity resulting in outward curvature of one or both knees of the lower legs. It is commonly seen in toddlers and overweight adolescents.
Children under 2 years of age may present with bowed legs (physiologic), which usually corrects itself by the age of 3 to 4. Bowed legs may be associated with Blount’s disease (an abnormality of growth plates present at the ends of long bones) and rickets (bone disease due to deficiency of vitamin D, calcium and phosphorus).
Osteoarthritis also called degenerative joint disease, is the most common form of arthritis. It occurs most often in older people. This disease affects the tissue covering the ends of bones in a joint (cartilage).In a person with osteoarthritis, the cartilage becomes damaged and worn out causing pain, swelling, stiffness and restricted movement in the affected joint.
Trauma is any injury caused during physical activity, motor vehicle accidents, electric shock, or other activities. Sports trauma or sports injuries refer to injuries caused while playing indoor or outdoor sports and exercising. Sports trauma can result from accidents, inadequate training, improper use of protective devices, or insufficient stretching or warm-up exercises. The most common sports injuries are sprains and strains, fractures, and dislocations.
Tibial tubercle fractures are quite rare occurrences that typically affect physically active adolescents between the age of 14 and 17. It is caused by violent tensile forces exerted over the tibial tuberosity (a bulge in the tibial bone) during activities involving sudden contraction of the knee extensors (springing and jumping).
Of the menisci within the knee, it is the medial that is more easily injured. Differences in the anatomical attachments of the medial meniscus compared to the lateral, mean that the medial meniscus becomes distorted during combined flexion and rotation movements in a manner not experienced on the lateral side.
Robotic-assisted partial knee surgery is an innovative alternative to the conventional surgical procedure to treat degenerative knee diseases such as osteoarthritis. It is performed using robotic-arm technology that allows your surgeon to precisely perform the surgery through small incisions.
The knee joint is a large, complex joint in the body that comprises of three bones, i.e. the lower end of the thighbone or femur, the upper end of the shinbone or tibia, and the kneecap or patella. The patella moves over the joint and allows bending of the knee and straightening of the leg.
Patellofemoral pain syndrome also called runner’s knee refers to pain under and around your kneecap. Patellofemoral pain is associated with a number of medical conditions such as anterior knee pain syndrome, patellofemoral malalignment, and chondromalacia patella.
Osgood-Schlatter disease refers to an overuse injury that occurs in the knee of growing children and adolescents. This is caused by inflammation of the tendon located below the kneecap (patellar tendon). Children and adolescents who participate in sports such as soccer, gymnastics, basketball, and distance running are at a higher risk of this disease.
The knee is made up of the femur (thighbone), tibia (shinbone) and patella (kneecap). The two menisci, soft cartilage between the femur and tibia, serve as a cushion and help absorb shock during motion. Arthritis (inflammation of the joints), injury or other diseases of the joint can damage this protective layer, causing extreme pain and difficulty in performing daily activities.
A total knee replacement surgery involves replacing the damaged surfaces of the articulating bones with artificial implants. Most of these implants wear with use. Thus, the need for revision surgery is high if you are young and active, and if the implant must last your lifetime.
Total knee replacement is the surgical treatment for knee arthritis, where the damaged knee is removed and replaced with an artificial knee implant. Traditionally performed as an inpatient procedure, total knee replacement surgery is now being conducted on an outpatient basis, allowing you to go home on the same day of the surgery.
Total knee replacement is a surgery employed to resurface knee joints damaged by arthritis, degeneration, or injury and replacing the damaged joints with a prosthesis (an artificial knee joint).
The failure of total knee replacement surgery to provide pain relief and improved function despite replacing the damaged joint with a new prosthesis is known as painful or failed total knee replacement.
Total knee replacement is a very successful surgical treatment for knee arthritis. Over the years, minimally invasive knee replacement surgical techniques have been developed to lessen tissue trauma and improve patient outcomes. This minimally invasive approach involves much smaller incisions than the usual 10-12 inch incisions used in the traditional knee replacement and spares the quadriceps muscle and tendon, which control bending of the knee, from being cut to access the knee joint.
Osteoarthritis is a most common form of arthritis which affects the articular cartilage (tissue covering the ends of the bones) of the knee and also other joints such as shoulder, hip, ankle, and foot. The articular cartilage cushions the joint so that there is smooth and pain-free movement between the bones in the joint.
If you are considering knee replacement surgery, there are new developments under study which can help enhance the quality of life. Use of cementless parts that allow new bone to grow into a porous prosthesis and hold the parts in place, creating a biologic fixation
The knee is made up of the femur (thighbone), the tibia (shinbone) and patella (kneecap). The two menisci, the soft cartilage between the femur and tibia, serve as a cushion and helps absorb shock during motion. Arthritis (inflammation of the joints), injury or other diseases of the joint can damage this protective layer of cartilage, causing extreme pain and difficulty in performing daily activities.
Robotic assisted knee replacement surgery is an alternative to the conventional knee replacement procedure. It is performed using robotic-arm technology that allows the surgeon to precisely perform the surgery through a smaller incision as compared to traditional surgery. It is indicated for patients suffering from degenerative knee diseases such as osteoarthritis.
Arthritis is the inflammation of a joint that causes pain, swelling (inflammation) and stiffness.
Osteoarthritis is the most common form of knee arthritis, in which the joint cartilage gradually wears away. It most often affects older people. In a normal joint, articular cartilage allows for smooth movement within the joint, whereas in an arthritic knee the cartilage itself becomes thinner or completely absent.
Unicompartmental knee replacement is a minimally invasive surgery in which only the damaged compartment of the knee is replaced with an implant. It is also called a partial knee replacement. The knee can be divided into three compartments: patellofemoral, the compartment in front of the knee between the knee cap and thigh bone, medial compartment, on the inside portion of the knee, and lateral compartment which is the area on the outside portion of the knee joint.
A unicondylar knee replacement, also known as unicompartmental or partial knee replacement, is a procedure to replace a portion of the damaged knee joint with a prosthetic implant to relieve pain and improve function of the knee joint. Traditionally performed as an inpatient procedure, advances in technology have allowed this procedure to be performed in a minimally invasive manner on an outpatient basis allowing patients to go home the same day of the surgery
A unicondylar knee replacement is a procedure to replace part of the knee joint with a prosthetic implant to relieve pain and improve the function of the joint. Advances in technology have allowed this procedure to be performed in a minimally invasive manner with robotic assistance.
The knee can be divided into three compartments: patellofemoral, the compartment in front of the knee between the kneecap and thighbone, the medial compartment, on the inside portion of the knee, and lateral compartment which is the area on the outside portion of the knee joint.
Partial lateral knee replacement is a surgery to replace only the lateral part of your damaged knee. It is also called unicompartmental knee replacement.
The knee is one of the largest and complex joints in your body. The joint is connected to your thigh bones and bones of the lower leg by various ligaments.
Partial knee replacement is an alternative to total knee replacement in patients with arthritis on only one side of the knee. Partial knee replacement is a surgical procedure which involves resurfacing and replacement of only the diseased surface of the joint instead of the entire joint.
Arthritis (inflammation of the joints), injury, or other diseases of the joint can damage the protective layer of cartilage, causing extreme pain and difficulty in performing daily activities. Osteoarthritis is the most common form of knee arthritis in which the joint cartilage gradually wears away.
A meniscus tear is the commonest knee injury in athletes, especially those involved in contact sports. A sudden bend or twist in your knee can cause the meniscus to tear. This is a traumatic meniscal tear. The elderly are more prone to degenerative meniscal tears as the cartilage wears out and weakens with age.
A torn meniscus causes pain, swelling, stiffness, catching or locking sensation in your knee, making you unable to move your knee through its complete range of motion.
The menisci are two C-shaped cartilages that act as shock absorbers between the thigh and shin bones that articulate at the knee joint. They provide stability and lubrication to the joint as well as nutrition for the articular cartilage. Tears in the meniscus may occur as a result of acute injury or chronic degeneration with age. Symptoms may include pain, swelling, and catching or locking of the joint. Meniscus tears can be surgically treated by meniscectomy.
Meniscectomy is a surgical procedure indicated in individuals with torn meniscus where the conservative treatments are a failure to relieve the pain and other symptoms. Meniscectomy is recommended based on the ability of meniscus to heal, patient’s age, health status, and activity level.
Partial meniscectomy is a surgical procedure to remove the torn portion of the meniscus from the knee joint.
Meniscal tears can occur at any age, but are more common in athletes playing contact sports. These tears are usually caused by twisting motion or over-flexing of the knee joint.
Partial arthroscopic meniscectomy is a procedure to remove the damaged part of a meniscus in the knee joint with the help an arthroscope. The meniscus is a C-shaped disc of cartilage between your thighbone and shinbone. There are 2 menisci in each knee. They act as shock absorbers and provide stability to the joint.
Meniscal transplantation is a surgical procedure to replace the damaged meniscus of the knee with healthy cartilage.
The meniscus is a C-shaped cartilage ring that acts as a cushion between the shinbone and the thighbone. Each of your knees has two menisci - one on the inside (medial aspect) and the other on the outside (lateral aspect)of your knee. Apart from the cushioning effect, the menisci also provide stability to the knee.
The knee is the most complex joint in the body and is formed by the articulation of the thighbone (femur) and shinbone (tibia). A kneecap is present over the front of the joint to provide extra protection. These bones are held together by four strong rope-like structures called ligaments.
The anterior cruciate ligament (ACL) is one of the major stabilizing ligaments in the knee. It is a strong rope-like structure located in the center of the knee, running from the femur to the tibia. When this ligament tears, unfortunately, it does not heal on its own, and often leads to the feeling of instability in the knee.
The anterior cruciate ligament is one of the four major ligaments of the knee that connects the femur (thighbone) to the tibia (shinbone) and helps stabilize the knee joint. The anterior cruciate ligament prevents excessive forward movement of the lower leg bone (tibia) in relation to the thighbone (femur) as well as limits rotational movements of the knee.
The medial patellofemoral ligament is a band of tissue that extends from the femoral medial epicondyle to the superior aspect of the patella. It is a major ligament that stabilizes the patella and helps in preventing patellar subluxation (partial dislocation) or dislocation.
A knee fracture is a broken bone or a crack in or around the joint of the knee. This can involve the tibia (shin bone), the kneecap (patella), or femur (thighbone) where they connect with the knee.
Knee fracture surgery is a surgical procedure performed to correct the cracked or broken bones in or around the knee to restore normal anatomical function, stability, and motion.
Periprosthetic knee fracture fixation is a procedure performed to stabilize a fracture that occurs in the bone present around a knee prosthesis. The fracture may involve the lower part of the thighbone (femur), the kneecap (patella) or the upper part of the shinbone (tibia).
A knee fracture is a break in the continuity of bone within the knee. This can involve the tibia (shinbone), kneecap (patella), or femur (thigh bone).
ORIF refers to open reduction and internal fixation. It is a surgical procedure employed for the treatment of a fracture not amenable to non-surgical conservative treatment.
An osteotomy is a surgical procedure that involves cutting of bone. The distal femur is part of the femur (thighbone) just above the knee joint. Distal femoral osteotomy is performed to correct knee alignment which can lead to excessive loading and degeneration of one side of the knee joint.
Knee osteotomy is a surgical procedure in which the upper shinbone (tibia) or lower thighbone (femur) is cut and realigned. It is usually performed in arthritic conditions affecting only one side of your knee. The aim is to take pressure off the damaged area and shift it to the other side of your knee with healthy cartilage.
High tibial osteotomy is a surgical procedure performed to relieve pressure on the damaged site of an arthritic knee joint. It is usually performed in arthritic conditions affecting only one side of your knee and the aim is to take pressure off the damaged area and shift it to the other side of your knee with healthy cartilage.
Tibial tubercle osteotomy is a surgical procedure that is performed along with other procedures to treat patellar instability, patellofemoral pain, and osteoarthritis. The tibial tubercle transfer technique involves realignment of the tibial tubercle (a bump in the front of the shinbone) such that the kneecap (patella) traverses in the center of the femoral groove.
The knee is a complex joint that consists of bone, cartilage, ligaments, and tendons, which help in joint movements. Knee problems may arise if any of these structures get injured by overuse, trauma or during sports activities. These may impair your mobility as well as your quality of life.
The genicular nerves are nerves surrounding your knee joint that are responsible for the transmission of pain impulses. Knee disorders causing excessive pain can be treated by blocking the genicular nerves from transmitting nerve impulses. The procedure may be performed under the guidance of ultrasound imaging.
Viscosupplementation refers to the injection of a hyaluronan preparation into the joint. Hyaluronan is a natural substance present in the joint fluid that assists in lubrication. It allows the smooth movement of the cartilage-covered articulating surfaces of the joint.
Physical therapy is an exercise program that helps you to improve movement, relieve pain, encourage blood flow for faster healing, and restore your physical function and fitness level. It can be prescribed as an individual treatment program or combined with other treatments. It involves a combination of education, manual therapy, exercises and techniques such as water, heat, cold, electrical stimulation and ultrasound.
The ACL (anterior cruciate ligament) is one of the four major ligaments located within the knee joint. It connects the femur (thighbone) to the tibia (shinbone). It plays a key role in holding the two bones within the knee and keeping the joint stable while your knee moves back and forth.
The knee is a complex joint which consists of bone, cartilage, ligaments, and tendons that make joint movements easy and at the same time it is more susceptible to various kinds of injuries. Knee problems may arise if any of these structures get injured by overuse or suddenly during sports activities.
Arthritis of the knee can cause pain and stiffness, making regular activities such as walking and bending difficult. As arthritis progresses, conservative treatments tend to lose their efficacy and more definitive treatment should be considered. Knee replacement surgery involves replacing worn or damaged joints with implants to reduce pain and improve movement.
Knee replacement is a surgery performed to replace parts of a diseased knee joint with artificial prostheses. The goal of knee replacement is to eliminate pain and return you to your normal activities. You can help in recovery and improve the outcomes of the procedure by following certain precautions and changing the way you carry out your daily activities.
Knee implants are artificial devices that form the essential parts of the knee during a knee replacement surgery. The knee implants vary by size, shape, and material. Implants are made of biocompatible materials that are accepted by the body without producing any rejection response. Implants can be made of metal alloys, ceramic or plastic, and can be joined to the bone.