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.
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. This surface can wear out for several reasons; often the definite cause is not known.
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.
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. Elderly people are more prone to degenerative meniscal tears as the cartilage wears out and weakens with age.
Ligament Injuries
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. 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
A multiligament injury is a tear in one or more ligaments of the knee, which affects the knee stability. Multiligament instability occurs because of a direct blow to the knee, fall from a height or motor vehicle trauma. Multiple ligament knee injuries are common in athletes involved in contact sports such as soccer, football, and basketball.
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.
Patellar Dislocation/Patellofemoral Dislocation
Patellar dislocation occurs when the patella moves out of the patellofemoral groove, (trochlea) onto the bony head of the femur. If the kneecap partially comes out of the groove, it is called subluxation; if the kneecap completely comes out, it is called dislocation (luxation).
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.
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).
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.
Runner's Knee
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.
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).
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. A fracture in the kneecap is rare but common in adult males. The most common cause of fracture is a direct blow to the kneecap such as a fall or a motor vehicle accident. The patella can also be fractured indirectly, due to a sudden contraction of the thigh muscles.
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. It especially occurs in women.
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.
Unstable Knee
An unstable knee can be caused by the sudden twisting of the knee, tears of the meniscus, ligament or capsule, osteoarthritis of the knee (wear and tear of the cushioning cartilage tissue between the bones) and sports injuries. When these tissues get injured, the patella or kneecap can move out of its groove in the knee joint and lead to instability.
MCL Tears
The medial collateral ligament (MCL) is the ligament located on the inner part of the knee joint. An MCL tear can be associated with pain, swelling, and locking or catching sensation in the knee during movement. You may also feel as though your knee may buckle or give way suddenly.
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.
PCL Injuries
Posterior cruciate ligament (PCL), one of the four major ligaments of the knee, is situated at the back of the knee. PCL injuries are very rare and more difficult to detect than other knee ligament injuries. Cartilage injuries, bone bruises, and ligament injuries often occur in combination with PCL injuries.
Pediatric ACL Tears
The anterior cruciate ligament (ACL) is a ligament that provides stability, reduces stress and prevents the knee from rotating or slipping out of position while jumping, running and landing. This ligament can tear during sports activities and exercise, as a result of a non-contact twisting injury, and is becoming a common injury in children.
Chondral or Articular Cartilage Defects
The articular or hyaline cartilage is the tissue lining the surface of the two bones in the knee joint. The damage of the articular cartilage can affect you regardless of your age. It can be damaged by trauma such as accidents, mechanical injury such as a fall or from degenerative joint disease (osteoarthritis) occurring in older people.
Lateral Patellar Compression Syndrome
Lateral patellar compression syndrome refers to pain under and around your kneecap. It is a common complaint among runners, jumpers and other athletes such as skiers, cyclists, and soccer players.
Osteochondritis Dissecans of the Knee
Osteochondritis dissecans is a joint condition in which a piece of cartilage, along with a thin layer of the bone separates from the end of the bone because of inadequate blood supply. The separated fragments are sometimes called “joint mice”.
Recurrent Patella Dislocation
Patellar dislocation occurs when the kneecap slides out of the trochlea. When dislocation of the patella occurs on more than one occasion, it is referred to as recurrent patellar dislocation. The risk of further dislocation increases to almost 70% to 80% after two episodes of dislocation.
Quadriceps Tendon Rupture
The quadriceps can rupture after a fall, direct blow to the leg and when you land on your leg awkwardly from a jump. Quadriceps tendon rupture most commonly occurs in middle-aged people who participate in sports that involve jumping and running.
Lateral Meniscus Syndrome
Lateral meniscus syndrome is characterized by an injury caused by the tearing of the cartilage tissue or a rare case of a congenital abnormality called a discoid meniscus, which results in knee pain.
Articular Cartilage Injury
Articular or hyaline cartilage is the tissue lining the surface of the two bones in the knee joint. The damage in articular cartilage can affect people of all ages. It can be damaged by trauma such as accidents, mechanical injury such as a fall, or from degenerative joint disease (osteoarthritis) occurring in older people.
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. Depending on the severity, you may have one or more loose bodies in your knee 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. Anterior cruciate ligament (ACL) injury is one of the common injuries of the knee. ACL injuries are more common in women than men due to anatomical differences.
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. Medial meniscal injuries are usually considered as either traumatic or degenerative.
Adolescent Knee Problems
Osgood-Schlatter disease refers to a condition in older children and teenagers caused by excessive stress to the patellar tendon (located below the kneecap). Participants in sports such as soccer, gymnastics, basketball, and distance running are at higher risk for this disease.
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. Anterior knee pain refers to various conditions, which include runner's knee or patellar tendinitis, and chondromalacia of the patella.
Tibial Eminence Spine Avulsion Fracture
Tibial eminence spine avulsion fracture is the avulsion (tearing away) of the tibial eminence.
Knee Arthroscopy
Knee arthroscopy is a common surgical procedure performed using an arthroscope, a viewing instrument, to diagnose or treat a knee problem. It is a relatively safe procedure and you will usually be discharged from the hospital on the same day of surgery.
ACL Reconstruction
The anterior cruciate ligament (ACL) is one of the major stabilizing ligaments in the knee. When this ligament tears, unfortunately, it does not heal on its own, and often leads to the feeling of instability in the knee. 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
PCL Reconstruction
The posterior cruciate ligament (PCL), one of four major ligaments of the knee, is situated at the back of the knee. PCL injuries are usually characterized by knee pain and swelling immediately after the injury. There may also be instability in the knee joint, and knee stiffness that causes limping and difficulty in walking. Generally, surgery is considered for a dislocated knee and multiple ligament injuries, including the PCL. Surgery involves reconstruction of the torn ligament using a tissue graft taken from another part of the body, or from a donor.
Outpatient Total Knee Replacement
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
Total knee replacement, also called total knee arthroplasty, is a surgical procedure in which the worn out or damaged surfaces of the knee joint is removed and replaced with an artificial prosthesis.
Minimally Invasive Knee Joint 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.
Meniscal Transplantation
Meniscal transplantation is a surgical procedure to replace the damaged meniscus of the knee with healthy cartilage.
Meniscal Surgery
The treatment of a meniscal tear depends on the type, size, and location of the tear, as well as your age and activity level. If the tear is small, with damage limited to the outer edge of the meniscus, non-surgical treatment may be sufficient. However, if the symptoms do not resolve with non-surgical treatment, surgical treatment may be recommended.
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.
Medial Patellofemoral Ligament Reconstruction
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. Medial patellofemoral ligament reconstruction is a surgical procedure indicated for severe patellar instability.
Patellar Tendon Repair
Patella tendon rupture is the rupture of the tendon that connects the patella (kneecap) to the top portion of the tibia (shinbone). Patellar tendon rupture can be treated by non-surgical and surgical methods.
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. The damaged ligament is replaced by the graft and fixed to the femur and tibia using metallic screws.
Cartilage Replacement
Articular or hyaline cartilage is the tissue that covers bone surface of the knee which helps in smooth interaction between the two bones in the knee joint. It has less capacity to repair by itself because there is no direct blood supply to cartilage. Cartilage replacement is a surgical procedure performed to replace the worn-out cartilage with new 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. Quadriceps tendon rupture most commonly occurs in middle-aged people who participate in sports which involve jumping and running.
LCL Reconstruction
LCL reconstruction involves the replacement of the torn ligament with a healthy tissue or graft. The tissue or graft can be taken either from a tissue bank (called allograft) or from your own body (called autograft).
MCL Reconstruction
Medial collateral ligament reconstruction is indicated for chronic MCL instability despite appropriate non-surgical treatment. Medial collateral ligament reconstruction is contraindicated for degenerative changes in the medial or lateral compartment, active infection, ligament instability, or presence of chronic diseases that can hamper surgical management or compliance to postoperative rehabilitation instructions.
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. It can alleviate knee pain, help you regain function and may even delay or prevent arthritis.
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 Anterior Cruciate Ligament (ACL) Reconstruction
Anterior cruciate ligament reconstruction failure may be due to the following problems which include technical, biological, traumatic and arthrofibrosis.
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. Three months following meniscal repair if pain and disability persist, a failed meniscal repair may be suspected and can be confirmed by performing a repeat arthroscopy.
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.
Mosaicplasty
Mosaicplasty is a surgical technique to repair the defect by transplanting healthy bone and cartilage from non-weight bearing areas of the knee. It is indicated to treat small cartilage defects of less than 2 cm in young active adults less than 45 years of age.
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
Meniscectomy involves the total or partial removal of the damaged or torn meniscus. It is indicated for horizontal and flap tears, and moderate to large tears at the outer edge of the meniscus.
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.
ORIF of the Knee Fracture
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.
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. ACL reconstruction with BPTP autograft is a surgical procedure that replaces the injured ACL with an autograft containing patellar tendon and bony attachments.
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. ACL reconstruction with BPTP allograft is a surgical procedure that replaces the injured ACL with an allograft containing patellar tendon and bony attachments.
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 BPTP allograft is a surgical procedure that replaces the injured ACL with an allograft containing patellar tendon and bony attachments.
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.
Partial Meniscectomy
Partial meniscectomy is a surgical procedure to remove the torn portion of the meniscus from the knee joint.
Physeal Sparing Reconstruction of the Anterior Cruciate Ligament
Physeal sparing reconstruction of the anterior cruciate ligament is a surgery to replace a torn anterior cruciate ligament or ACL, a major ligament of the knee, while minimizing damage to the growth plate (physis) present near the end of the bone.
Partial Arthroscopic Meniscectomy
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.
Non-operative Treatments for ACL Injuries
Coming soon
Non-Surgical Knee Treatments
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.
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.
Pre-op and Post-op Knee Guidelines
Planning for your knee surgery prepares you for the operation and helps to ensure a smooth surgery and easier recovery. Here are certain pre-operative and post-operative guidelines which will help you prepare for knee surgery.
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.
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.
