Knee pain is quite common and is experienced by many people, ranging from mild discomfort to severe pain that may limit activities. A variety of things can cause knee pain, but most often, it can be the result of a direct injury like trauma or a sports injury which could lead to a sprain or fracture.
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 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.
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. Bursitis refers to the inflammation and swelling of the bursa. Inflammation of the bursa in front of the kneecap (patella) is known as kneecap bursitis or prepatellar bursitis.
The muscles and bones of your hand are connected by thick flexible tissue called tendons. Tendons are covered by a thin soft sheath of tissue known as synovium. Extensor pollicis brevis and abductor pollicis longus are two tendons located on the thumb side of the wrist.
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.
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. The meniscus has no direct blood supply and for that reason, when there is an injury to the meniscus, healing is difficult.
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.
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.
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. Patellofemoral pain is a common complaint among runners, jumpers, and other athletes such as skiers, cyclists, and soccer players; thus the common name, runner’s knee.
Osteomyelitis of the Knee
Posterior Cruciate Ligament (PCL) Injury
Mako Robotic-Arm Assisted Total Knee replacement is a treatment option for adults living with mid to late-stage osteoarthritis (OA) of the knee. Mako provides you with a personalized surgical plan based on your unique anatomy. First, a CT scan of the diseased knee joint is taken. This CT scan is uploaded into the Mako System software, where a 3D model of your knee is created.
Mako Robotic-Arm Assisted partial knee replacement is a treatment option for adults living with early to mid-stage osteoarthritis (OA) that has not yet progressed to all three compartments of the knee.
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.
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.
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.
Platelet-rich Plasma Therapy
Posterior Crucial Ligament (PCL) Reconstruction
Medial Collateral Ligament (MCL) Reconstruction
Lateral Collateral Ligament (LCL) Reconstruction
Loose Body Removal Procedure
Medial Patellofemoral Ligament (MPFL) Reconstruction for Patella Dislocation