Knee
Knee Anatomy
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.
Chondromalacia Patella
Chondromalacia patella is a common condition characterized by softening, weakening and damage of the cartilage. The condition is most often seen in young athletes and older adults who have arthritis of the knee.
Knee Injury
Pain, swelling, and stiffness are the common symptoms of any damage or injury to the knee. If care is not taken during the initial phases of injury, it may lead to joint damage, which may end up destroying your knee.
Knee Sprain
Knee sprain is a common injury that occurs from overstretching of the ligaments that support the knee joint. A knee sprain occurs when the knee ligaments are twisted or turned beyond its normal range, causing the ligaments to tear.
MCL Sprains
MCL sprains occur due to a sudden impact from the outside of your knee, most commonly while playing sports such as rugby and football. Rarely, the MCL can get injured when the knee gets twisted or following a quick change in direction.
Meniscal Injuries
Meniscal tears are among the commonest injuries to the knee joint. It can occur at any age but are more common in athletes involved in contact sports.
Meniscal Tears
A meniscal tear is a common knee injury in athletes, especially those involved in contact sports. A sudden bend or twist in your knee causes the meniscus to tear.
Ligament Injuries
Knee problems may arise if any of these structures get injured by overuse or suddenly during sports activities. Pain, swelling, and stiffness are the common symptoms of any damage or injury to the knee.
Multiligament Instability
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).
Knee Arthritis
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.
PCL Injuries
Posterior cruciate ligament (PCL), one of the four major ligaments of the knee, is situated at the back of the knee. It connects the thighbone (femur) to the shinbone (tibia). The PCL limits the backward motion of the shinbone.
Chondral or Articular Cartilage Defects
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.
Patellar Instability
Any damage to the supporting ligaments may cause the patella to slip out of the groove either partially (subluxation) or completely (dislocation). This misalignment can damage the underlying soft structures such as muscles and ligaments that hold the kneecap in place.
Patellofemoral Instability
Patellofemoral instability means that the patella (kneecap) moves out of its normal pattern of alignment. This malalignment can damage the underlying soft structures such as muscles and ligaments that hold the knee in place.
Recurrent Patella Dislocation
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).
Patellar Tendon Rupture
The patellar tendon works together with the quadriceps muscle and the quadriceps tendon to allow your knee to straighten out. Patella tendon rupture is the rupture of the tendon that connects the patella (kneecap) to the top portion of the tibia (shinbone).
Knee Angular Deformities
Angular deformities of the knee are variations in the normal growth pattern during early childhood and are common during childhood.
Articular Cartilage Injury
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.
Loose Bodies in the Knee
Loose bodies are fragments of detached cartilage or bone inside the knee joint. These fragments may be free floating (unstable) or may be trapped (stable) within the joint.
Knee Sports Injuries
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.
Women and ACL Injuries
The anterior cruciate ligament is one of the four major ligaments of the knee that connects the femur (thigh bone) to the tibia (shin bone) and helps stabilize the knee joint.
Multiligament Knee Injuries
Injury to more than one knee ligament is called a multiligament knee injury and may occur during sports or other physical activities.
Knee Pain
Knee pain is a common condition affecting individuals of various age groups. It not only affects movement but also impacts your quality of life. An injury or disease of the knee joint or any structure surrounding the knee can result in knee pain.
Anterior Knee Pain
Anterior knee pain is characterized by chronic pain over the front and center of the knee joint. It is common in athletes, active adolescents (especially girls) and overweight individuals.
Jumper's Knee
Jumper’s knee, also known as patellar tendinitis, is inflammation of the patellar tendon that connects your kneecap (patella) to your shinbone. This tendon helps in the extension of the lower leg.
Kneecap Bursitis
A bursa is a small fluid-filled sac found between soft tissues and bones. It lubricates and acts as a cushion to decrease friction between bones when they move.
Baker's Cyst
A bursa is a small fluid-filled sac found between soft tissues and bones. It lubricates and acts as a cushion to decrease friction between bones when they move.
Osteochondritis Dissecans of the Knee
Two femoral condyles make up the rounded end of the femur (thighbone). Each knee has two femoral condyles, the medial femoral condyle on the inside of the knee and the lateral femoral condyle on the outside of the knee.
Shin Splints
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).
Goosefoot Bursitis of the Knee
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
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.
Fractures of the Patella
The patella or kneecap is a small bone present in the front of your knee where the thigh bone meets the shinbone. It provides protection to your knee and attachment to muscles in the front of the thigh. An injury to the knee can result in a break or fracture of the patella.
Patella Fracture
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.
Patellar Tendinitis
Patellar tendinitis, also known as "jumper's knee", is an inflammation of the patellar tendon that connects your kneecap (patella) to your shinbone. This tendon helps in extension of the lower leg
Lateral Meniscus Syndrome
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
Osteochondral Defect of the Knee
An osteochondral defect, also commonly known as osteochondritis dissecans, of the knee refers to a damage or injury to the smooth articular cartilage surrounding the knee joint and the bone underneath the cartilage. The degree of damage may range from a rupture of the cartilage to a slight crack of the bone to a piece of the bone breaking off within the joint.
Bowed Legs
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.
Knee Fracture
A fracture is a condition in which there is a break in the continuity of the bone. In younger individuals, these fractures are caused by high energy injuries, as from a motor vehicle accident. In older people, the most common cause is a weak and fragile bone.
Knee Osteoarthritis
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.
Medial Meniscus Syndrome
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.
Runner's Knee
The patella, also called the kneecap, is a small flat triangular bone located at the front of the knee joint. The kneecap or patella is a sesamoid bone that is embedded in a tendon that connects the muscles of the thigh to the shinbone (tibia). The function of the patella is to protect the knee joint from the front.
Osgood-Schlatter Disease
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.
Combined Hyaluronic Therapy for the Knee
Combined hyaluronic therapy is the process of injecting hyaluronic acid (HA) along with platelet-rich plasma (PRP) into your knee to treat osteoarthritis.
Matrix Induced Autologous Chondrocyte Implantation (MACI)
Matrix-Induced autologous chondrocyte implantation is an innovative, FDA-approved cartilage restoration procedure that uses your own cells to repair cartilage defects in your knee.
Arthroscopic Debridement
Arthroscopic debridement or a clean-up is a surgical procedure performed using an arthroscope. In this procedure, the cartilage or the bone that is damaged is removed using surgical instruments and the edges of the articular cartilage that are rough will be smoothened.
Failed Meniscus Repair
Meniscal repair may be performed either by open surgery under direct vision or minimally invasively using an arthroscope, which is a thin tube fitted with a camera that can be inserted into the knee through a very small incision to locate and repair the damaged meniscus.
Meniscal Transplantation
Meniscal transplantation is a surgical procedure to replace the damaged meniscus of the knee with healthy cartilage.
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.
Mosaicplasty
Weight-bearing joints, such as the knee, may develop defects in the articular cartilage (spongy tissue that lines and cushions joints during movement) due to stress, trauma or degenerative disease
Posterolateral Corner Reconstruction
Posterolateral corner injury is damage or injury to the structures of the posterolateral corner. The structures of the posterolateral corner include the lateral collateral ligament, the popliteus tendon, and the popliteo-fibular ligament.
Prior Meniscectomy
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.
Quadriceps Tendon Repair
Quadriceps tendon is a thick tissue located at the top of the kneecap. The quadriceps tendon works together with the quadriceps muscles to allow us to straighten our leg.
Tibial Eminence Fracture
The tibia or shin bone is a major bone of the leg which connects the knee to the ankle. A fracture or break in the upper part of the tibia is known as a proximal tibial fracture and commonly occurs just below the knee joint.
Chondroplasty
Chondroplasty is a surgical procedure to repair and reshape damaged cartilage in a joint. The procedure involves smoothing degenerative cartilage and trimming any unstable flaps of cartilage.
Bone-Patellar Tendon-Bone (BPTB) Autograft
An autograft refers to using organ or tissue (bone, cartilage, tendon or skin) from the same person to transplant elsewhere on their body.
Bone-Patellar Tendon-Bone (BPTB) Allograft
An allograft is an organ or tissue such as bone, cartilage, tendon or skin, taken from one person (donor) and surgically placed in another person to repair damaged tissue.
Hamstring Autograft
An autograft refers to using organ or tissue (bone, cartilage, tendon or skin) from the same person to transplant elsewhere on their body.ACL reconstruction with hamstring autograft method is a surgical procedure to replace the torn ACL with part of the hamstring tendon taken from your leg.
Knee Arthroscopy
Knee arthroscopy is a common surgical procedure performed using an arthroscope, a viewing instrument, to diagnose or treat a knee problem.
Knee Osteotomy
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.
High Tibial Osteotomy
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
Tibial tubercle osteotomy is a surgical procedure that is performed along with other procedures to treat patellar instability, patellofemoral pain, and osteoarthritis.
Medial Patellofemoral Ligament Reconstruction
Medial patellofemoral ligament reconstruction is a surgical procedure indicated for severe patellar instability.
Distal Realignment Procedures
Distal realignment procedures, also known as tibial tubercle transfer (TTT) procedures, are performed to reposition the kneecap after subluxation or dislocation by realigning the tendon under the kneecap to the underlying tibial tubercle.
Arthroscopic Reconstruction of the Knee for Ligament Injuries
The surgical repair of the completely torn ligament involves reconstruction of the torn ligament using a tissue graft taken from another part of the body or from a donor.
PCL Reconstruction
PCL injuries are very rare and are more difficult to detect than other knee ligament injuries. Cartilage injuries, bone bruises, and ligament injuries often occur in combination with PCL injuries.
LCL Reconstruction
The lateral collateral ligament (LCL) is a thin set of tissues present on the outer side of the knee, connecting the thighbone (femur) to the fibula (bone of the lower leg).
ACL Reconstruction
ACL reconstruction is a commonly performed surgical procedure. With recent advances in arthroscopic surgery, it can now be performed with minimal incision and low complication rates.
ACL Reconstruction of Patellar Tendon
Anterior cruciate ligament (ACL) reconstruction patellar tendon is a surgical procedure that replaces the injured ACL with a patellar tendon.
ACL Reconstruction Procedure of Hamstring Tendon
Anterior cruciate ligament reconstruction hamstring method is a surgical procedure to replace the torn ACL with part of the hamstring tendon taken from your leg.
MCL Reconstruction
Medial collateral ligament reconstruction is indicated for chronic MCL instability despite appropriate non-surgical treatment.
Cartilage Replacement
Cartilage replacement is a surgical procedure performed to replace the worn-out cartilage with new cartilage.
Autologous Chondrocyte Implantation
Autologous chondrocyte implantation (ACI) is a procedure to treat the articular cartilage defects of the knee. This procedure is effective for treating small areas of cartilage damage that causes pain and swelling and restricts range of motion.
Meniscal Surgery
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.
Intraarticluar Knee Injection
Knee pain and stiffness can be disabling and difficult to treat. It can limit an individual’s lifestyle and negatively impact body image and emotional well-being.
ORIF of the Knee Fracture
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).
Viscosupplementation
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 for Knee
Physical Therapy for Knee 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.
Multiligament Reconstruction of the Knee
Multiligament knee reconstruction is a surgical procedure to repair or replace two or more damaged ligaments of the knee joint. The surgery can be performed using minimally invasive techniques.
Patellofemoral Knee Replacement
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.
TLS Short Graft ACL Reconstruction
The TLS short graft ACL reconstruction is an advanced surgical technique performed to repair a torn ACL ligament in the knee. It involves the use of a tape locking screw (TLS) system that enhances the strength and mobility of the reconstructed ACL tendon, allowing the return to sports or an active lifestyle.
Physical Examination of the Knee
A complete physical examination of the knee is performed when you present to your doctor with a knee complaint. Both of your knees are examined and the results of the injured knee are compared to those of the healthy knee.
Am I a Candidate for Knee Surgery?
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.
