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The knee is a joint that unites the thigh with the rest of the leg and is a system of moving parts consisting of cartilage, muscles, tendons, and ligaments. The knee is also a hinge that provides our body with the strength to run, squat, jump, and turn. However, the knee is vulnerable to a number of injuries and conditions because of its inability to rotate in every direction. To read more about knee conditions, click here.

At OrthoNorCal Orthopedic Specialists, our orthopedic knee surgeons have extensive education and training in performing specialized knee procedures. Common techniques our knee surgeons perform include total knee replacement, knee revision, total knee arthroplasty, partial knee arthroplasty, meniscal repair, ACL and PCL reconstruction, ligament repair and reconstruction, and cartilage repair and transplantation among many others.

  • Knee Arthritis

    There are many conditions that can result in degeneration of the knee joint. Osteoarthritis is the most common reason that patients need to undergo knee replacement surgery.

  • 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).

  • 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.

  • 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.

  • Knee Injury

    If the pain and swelling are rapid, then immediate diagnosis and appropriate medical treatment are advised. Initial diagnosis includes physical and joint examination followed by an X-ray.

  • 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.

  • Runner's Knee

    Patellofemoral pain syndrome also called runner’s knee refers to pain under and around your kneecap.

  • Unstable Knee

    The knee joint is one of the largest joints in the body. This highly complex joint has several tissues supporting and stabilizing its movement.

  • Patellar Instability

    Any damage to the supporting ligaments may cause the patella to slip out of the groove either partially (subluxation) or completely (dislocation).

  • 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.

  • 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.

  • Kneecap Bursitis

    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.

  • Fractures of the Tibia

    The lower leg is made up of two long bones called the tibia and fibula that extend between the knee and ankle. The tibia or shinbone is the larger of the two bones.

  • Iliotibial Band Syndrome

    Iliotibial band syndrome is an overuse injury resulting from the inflammation of the iliotibial band. It occurs when the iliotibial band and the lower outside portion of the thighbone at the knee joint rub against each other.

  • 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.

  • ACL Tears

    The anterior cruciate ligament (ACL) is the most commonly injured ligament of the knee, and it is most frequently injured during an athletic activity.

  • MCL Tears

    The medial collateral ligament (MCL) is the ligament located on the inner part of the knee joint. It runs from the femur (thighbone) to the top of the tibia (shinbone) and helps in stabilizing the knee.

  • 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.

  • PCL Injuries

    The posterior cruciate ligament (PCL) is located in the center of the knee joint. It connects the front of the femur (thighbone) and crosses to the back of the tibia (shinbone).

  • Ligament Injuries

    The knee is a complex joint that consists of bone, cartilage, ligaments, and tendons that help in your joint’s movements.

  • Patellar Dislocation/Patellofemoral Dislocation

    Patellar dislocation occurs when the patella moves out of the patellofemoral groove, (trochlea) onto the bony head of the femur.

  • Patellar Tendon Rupture

    Patella tendon rupture is the rupture of the tendon that connects the patella (kneecap) to the top portion of the tibia (shinbone).

  • 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.

  • 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

  • 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).

  • 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.

  • 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.

  • 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.

  • Knee Angular Deformities

    Angular deformities of the knee are variations in the normal growth pattern during early childhood and are common during childhood.

  • 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.

  • 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.

  • Posterolateral Instability

    Posterolateral instability, also known as posterolateral rotatory instability (PLRI), is a common pattern of knee instability that results from injuries to the structures that support the outside of 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.

  • Osteonecrosis of the Knee

    Osteonecrosis is a condition in which the death of a section of bone occurs because of lack of blood supply to it. It is one of the most common causes of knee pain in older women.

  • 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.

  • Tibial Plateau Fracture

    A tibial plateau fracture is a crack or break on the top surface of the tibia or shinbone in the knee joint.

  • Tibial Shaft Fracture

    A tibial shaft fracture is a crack or break in the middle section of the tibia bone due to severe trauma.

  • Periprosthetic Knee Fractures

    Knee replacement, also called knee arthroplasty, is a surgical procedure in which the worn-out or damaged surfaces of the knee joint are removed and replaced with artificial implants.

  • 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..

  • Pediatric Tibial Tubercle Fractures

    Tibial tubercle fractures are quite rare occurrences that typically affect physically active adolescents between the age of 14 and 17.

  • Periprosthetic Knee Infection

    A very small percentage of patients (less than 1%) who undergo knee replacement may develop an infection around the knee joint. This infection is called a periprosthetic knee infection.

  • Pseudogout

    Pseudogout is a type of arthritis that is characterized by the development of a painful swelling that occurs suddenly in one or more joints.

  • Tibial Eminence Fractures

    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.

  • Collateral Ligament Injuries

    Ligaments are tough bands of tissue that connect the ends of bones together. The collateral ligaments, located on either side of the knee, limit side to side motion of the knee.

  • Prepatellar Bursitis

    Prepatellar bursitis causes pain and swelling in the area around the front of the kneecap. If the condition has been present for some time, small lumps may be felt underneath the skin over the kneecap.

  • Torn Meniscus

    Injury to the meniscus of the knee is common and can occur in any age group. In younger people, the meniscus is fairly tough and rubbery, and a tear usually occurs as a result of a forceful twisting injury.

  • Articular Cartilage Lesions of the Knee

    Injuries to the articular cartilage in the knee joint are common. These injuries, called lesions, often show up as tears or “pot holes” in the surface of the cartilage.

  • Osteochondritis Dissecans of the Knee

    Osteochondritis dissecans (OCD) is a problem that affects the knee. The disease behaves much differently in children and for this reason is given a separate name, juvenile osteochondritis dissecans (JOCD).

  • Patellofemoral Problems

    The patella, or kneecap, is the moveable bone on the front of the knee. The patella is wrapped inside a tendon connecting the large muscles on the front of the thigh and the quadriceps muscles, to the lower leg bone.

  • Plica Syndrome

    Plica syndrome occurs when an otherwise normal structure in the knee becomes a source of knee pain due to injury or overuse.

  • Popliteal Cyst

    A popliteal cyst, also called a Baker’s cyst, is a soft, often painless cyst on the back of the knee. A cyst is usually nothing more than a bag of fluid.

  • Revision Knee Replacement

    Revision knee replacement surgery involves replacing a part or all your previous knee prosthesis with a new 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.

  • Robotic Assisted Knee Replacement

    Robotic-assisted knee replacement surgery is an alternative to the conventional knee replacement procedure. It is performed using robotic-arm technology that allows your surgeon to precisely perform the surgery.

  • Knee Arthroscopy

    Knee arthroscopy is a common surgical procedure performed using an arthroscope, a viewing instrument, to diagnose or treat a knee problem.

  • ACL Reconstruction

    ACL (anterior cruciate ligament) 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.

  • LCL Reconstruction

    LCL reconstruction is a surgical procedure to repair torn or damaged lateral collateral ligament in the knee using a tissue graft taken from another part of the body, or from a donor.

  • MCL Reconstruction

    MCL reconstruction is a minimally invasive surgical procedure in which a tendon graft is utilized to reconstruct the injured MCL.

  • Meniscus Replacement

    Meniscus replacement is a surgical procedure performed to replace a torn or damaged meniscus in the knee.

  • 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.

  • Patellar Tendon Repair

    Patellar tendon repair is the surgery performed to reattach the torn tendon to the kneecap and to restore normal function in the affected leg.

  • 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.

  • Meniscal Transplantation

    Meniscal transplantation is a surgical procedure to replace the damaged meniscus of the knee with healthy cartilage.

  • Knee Fracture Surgery

    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 Ligament Reconstruction

    Knee ligament reconstruction is a surgical procedure to repair or replace damaged ligaments of the knee joint. The surgery can be performed using minimally invasive techniques.

  • Patellofemoral Realignment

    Patellofemoral realignment is a surgical procedure performed to treat symptomatic patellofemoral instability that does not respond to nonsurgical treatment measures.

  • Meniscal Surgery

    Meniscal surgery is a surgical procedure employed for the treatment of torn or damaged meniscal tissues in the knee. It is mostly performed as a minimally invasive keyhole procedure.

  • Patient Specific Knee Replacement

    Patient Specific Knee Replacement is a newer technology in total knee replacement surgery. It is an advanced procedure using an individualized patient-specific knee implant for replacement of all three components of the knee.

  • Partial Meniscectomy

    Partial meniscectomy is a surgical procedure to remove the torn portion of the meniscus from the knee 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.

  • Revision Knee Ligament Reconstruction

    Revision knee ligament reconstruction is a complex surgical procedure performed to address failures or to correct the undesirable consequences of primary reconstruction surgery on your knee.

  • What is New in Knee Replacement

    If you are considering knee replacement surgery, there are new developments under study which can help enhance the quality of life.

  • Periprosthetic Knee Fracture Fixation

    Periprosthetic knee fracture fixation is a procedure performed to stabilize a fracture that occurs in the bone present around a knee prosthesis.

  • Patellofemoral Knee Replacement

    Patellofemoral knee replacement is a minimally invasive surgical option performed in the patellofemoral compartment only, preserving the knee parts not damaged by arthritis as well as the stabilizing anterior and posterior cruciate ligaments (ACL and PCL).

  • 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.

  • Failed Anterior Cruciate Ligament (ACL) Reconstruction

    The knee joint is stabilized by four strong ligaments. The anterior cruciate ligament (ACL) passes diagonally in the middle of the knee, ensuring that the thigh and shin bone do not slide out of alignment during movement..

  • Partial Knee Resurfacing

    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.

  • 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.

  • 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.

  • Distal Femoral Osteotomy

    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.

  • Physeal Sparing Surgery (Anderson's Technique)

    Surgery may be necessary to reconstruct an irreparable anterior cruciate ligament (torn ACL). In adults, reconstruction of the ACL involves passing a soft tissue graft through tunnels drilled into the shinbone (tibia) and thighbone (femur).

  • Painful or Failed Total Knee Replacement

    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).

  • Outpatient Unicondylar Knee Replacement

    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.

  • LPFL Reconstruction

    LPFL reconstruction or lateral patellofemoral ligament reconstruction is a surgical procedure employed to treat patients with severe patellofemoral instability.

  • PCL Reconstruction

    PCL reconstruction surgery is a procedure to correct torn posterior cruciate ligament (PCL) in the knee using a tissue graft taken from another part of the body, or from a donor.

  • ACL Reconstruction with Patellar Tendon

    Anterior cruciate ligament (ACL) reconstruction with patellar tendon is a surgical procedure that replaces the injured ACL with a patellar tendon.

  • ACL Reconstruction Procedure with Hamstring Tendon

    ACL reconstruction with hamstring tendon is a surgical procedure to replace the torn ACL with part of the hamstring tendon taken from the back of the thigh.

  • 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.

  • Custom Knee Replacement

    Custom Knee Replacement is an advanced surgical procedure in which the damaged knee joint is replaced by a customized implant, specifically designed to match the unique size and shape of each patient’s knee.

  • Knee Cartilage Restoration

    Knee cartilage restoration is a surgical technique to repair damaged articular cartilage in the knee joint by stimulating new growth of cartilage or by transplanting cartilage into areas with defects in order to relieve pain and restore normal function to the knee.

  • 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.

  • 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.

  • Knee Replacement with OrthAlign Technology

    OrthAlign® uses a technology that simplifies and enhances the precision in implant alignment, significantly improving procedure outcomes.

  • Computer Navigation for Total Knee Replacement

    Computer navigation provides your surgeon with real-time 3-D images of your mapped knee and the surgical instruments during surgery.

  • Tricompartmental Knee Replacement

    Tricompartmental knee replacement, also called total knee arthroplasty, is a surgical procedure in which the worn-out or damaged surfaces of the knee joint are removed and replaced with artificial parts.

  • Correction of a Loose Knee Replacement

    Knee replacement is a surgery employed to resurface a knee joint damaged by arthritis, wear and tear, or injury and replacing the damaged joint with a prosthesis (an artificial knee joint) to resolve a painful knee condition and loss of motion.

  • Partial Lateral Knee Replacement

    Partial lateral knee replacement is a surgery to replace only the lateral part of your damaged knee. It is also called unicompartmental knee replacement.

  • Bicompartmental Knee Resurfacing

    Bicompartmental knee resurfacing is a less invasive surgical alternative to total knee replacement surgery, where instead of all the compartments being replaced only 2 of the 3 compartments of the knee damaged by arthritis are replaced with a prosthesis.

  • Bone-Patellar Tendon-Bone (BPTB) Allograft

    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.

  • Physical Therapy for Knee

    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.

  • 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.

  • Joint Replacement Surgery

    Knee replacement surgery is considered when all available, non-operative treatments for knee arthritis have been tried without relieving the patient’s knee pain or improving their mobility.

  • Tibial Osteotomy

    During a tibial osteotomy, the surgeon removes a wedge-shaped portion of the shin bone (tibia) to help compensate for a deformity in the knee joint.

  • Robotic Assisted Partial Knee Surgery

    Robotic-assisted partial knee surgery is an innovative alternative to the conventional surgical procedure to treat degenerative knee diseases such as osteoarthritis.

  • Oxford Mobile Bearing Knee replacement

    The Oxford Unicompartmental Knee Replacement, also called Oxford mobile-bearing knee replacement and Oxford medial unicompartmental knee replacement, is a type of partial knee replacement where the damaged knee joint, usually the medial knee compartment, is replaced with an Oxford mobile bearing knee implant.

  • Knee Implants for Women

    Knee implants are artificial devices that form the essential parts of the knee during knee replacement surgery. The knee implants vary by size, shape, and material.

  • 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.

  • After Knee Replacement

    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.

  • Knee Implants

    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.

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.

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