Medically Reviewed by Dr. K on 15 April 2021
Table of Contents :
- Function and Design
- Knee Injuries
- Ligament Injury of the Knee
- Meniscus Tears of the Knee
- Tendinitis of the Knee
- Fractures of the Knee
- Disease of the Knee
- Knee Pain At A Glance
Knee Injuries and Osteoarthritis
Function and Design
The knee is made up of three separate parts. The main knee joint is formed by the femur (thigh bone) and the tibia (large shin bone). There are two compartments in this joint: an inner (medial) and an outer (lateral). The patellofemoral joint is formed when the patella (kneecap) meets the femur to form a third joint.
A joint capsule surrounds the knee joint, with ligaments securing the inside and outside of the joint (collateral ligaments) as well as crossing inside it (cruciate ligaments). The knee joint is held together by these ligaments, which give it stability and strength.
The meniscus is a thickened cartilage pad that connects the femur and tibia, forming a joint. The meniscus provides a smooth surface on which the joint can pass. Bursae are fluid-filled sacs that surround the knee joint and act as gliding surfaces for the tendons, reducing friction. The patellar tendon is a long tendon that wraps around the knee cap and connects to the front of the tibia bone. The region behind the knee is densely packed with blood vessels (referred to as the popliteal space). The knee is moved by the broad muscles of the thigh. The quadriceps muscles tug on the patellar tendon in the front of the thigh to stretch or straighten the knee joint. The hamstring muscles in the back of the thigh bend or flex the knee. Under the direction of specific thigh muscles, the knee rotates slightly as well.
The knee is necessary for normal walking because it allows leg movement. The natural range of motion for the knee is 135 degrees of flexion and 0 degrees of extension. The bursae, or fluid-filled sacs, act as gliding surfaces for the tendons, reducing friction forces as they travel. A weight-bearing joint is the knee. Each meniscus helps to distribute joint fluid for lubrication and uniformly fills the surface during weight-bearing.
Any of the ligaments, bursae, or tendons that form the knee joint may be injured. Ligaments, cartilage, menisci (plural for meniscus), and the bones that make up the joint may all be affected by injury. The complexities of the knee joint's construction, as well as the fact that it is an active weight-bearing joint, lead to it being one of the most frequently injured joints.
- Ligament Injury of the Knee
Trauma may injure the ligaments on the inside (medial collateral ligament), outside (lateral collateral ligament), or within the knee (cruciate ligaments). Injuries to these areas cause acute pain, but they can be difficult to pinpoint. A collateral ligament damage is usually felt on the inside or outside of the knee. A collateral ligament damage is often accompanied by local tenderness in the ligament's affected area. The pain of a torn cruciate ligament is felt deep inside the leg. The initial shock is often accompanied by a “popping" feeling. At rest, a ligament injury to the knee is normally painful, swollen, and warm. Bending the leg, putting weight on the knee, or walking generally makes the pain worse. The severity of the injury can range from moderate stretching or tearing of ligament fibres (as in a low-grade sprain) to serious (complete tear of the ligament fibers). In a single traumatic incident, patients may sustain injuries to different body parts.
Ice packs and immobilisation, as well as rest and elevation, are used to treat ligament injuries at first. It's usually best to avoid putting any weight on the injured joint at first, and crutches may be needed for walking. Splints or braces are used to immobilise the joint and reduce discomfort and facilitate healing in some patients. To repair serious injuries, arthroscopic or open surgery may be needed.
Suturing, grafting, and synthetic graft repair are all options for ligament repair surgery. Open knee surgery or arthroscopic surgery may be used to perform these procedures (described in the section below). The extent of ligament injury and the patient's activity expectations influence the decision to perform different forms of surgery. Many arthroscopic repairs are now possible. Certain serious injuries, on the other hand, would necessitate an open surgical repair. With today's surgical methods, cruciate ligament reconstruction is becoming more successful.
- Meniscus Tears of the Knee
The shearing forces of rotation that are applied to the knee during sharp, rapid motions can tear the meniscus. This is particularly common in sports that require fast body movements. Aging and degeneration of the underlying cartilage cause a higher occurrence. In certain cases, a single meniscus may have multiple tears. With some activities or movements of the knee, a patient with a meniscal tear can experience a rapid onset of a popping sensation. Swelling and warmth in the knee are also associated with it. It's sometimes led to a locking or unsteady feeling in the knee joint. During an examination of the knee, the doctor may conduct such manoeuvres that could provide more information about the presence of a meniscal tear.
Although routine X-rays do not show a meniscal tear, they can be used to rule out other knee problems. An arthroscopy, arthrography, or an MRI may all be used to diagnose a meniscus tear. Arthroscopy is a surgical procedure that involves inserting a small diameter video camera through small incisions on the sides of the knee to examine and fix internal knee joint problems. During arthroscopy, tiny tools may be used to patch the broken meniscus.
Arthrography is a radiology procedure in which a solvent is applied directly into the knee joint, allowing the internal structures to be seen on X-ray. Another technique is an MRI scan, which uses magnetic fields and a device to create two- or three-dimensional representations of the body's internal structures. It does not require the use of X-rays and can provide detailed information about the internal structures of the knee when a surgical operation is being considered. An MRI scanner will also detect meniscal tears. In the diagnosis of meniscal tears of the knee, MRI scans have increasingly replaced arthrography. Arthroscopy is typically used to repair meniscal tears.
- Tendinitis of the Knee
Tendinitis of the knee may occur in the front of the knee, below the kneecap, at the patellar tendon (patellar tendinitis), or at the back of the knee, at the popliteal tendon (popliteal tendinitis) (popliteal tendinitis). Tendinitis is an inflammation of the tendon that is often caused by activities that strain the tendon, such as jumping. As a result, patellar tendinitis is also known as “jumper's knee." The occurrence of discomfort and tenderness localised to the tendon is used to diagnose tendinitis. Ice packs, immobilisation with a knee brace when required, rest, and anti-inflammatory drugs are used to treat it. Exercise programmes will gradually rehabilitate the tissues in and around the affected tendon. Cortisone injections, which are often used to treat tendinitis elsewhere, are usually avoided in patellar tendinitis due to the possibility of tendon rupture. Surgery may be needed in serious cases. A tendon rupture may happen below or above the kneecap. If this happens, there could be bleeding in the knee joint as well as excruciating discomfort for every knee movement. The ruptured tendon is often repaired surgically.
- Fractures of the Knee
Bone breakage (fracture) of any of the three bones of the knee can occur as a result of serious knee trauma, such as motor vehicle accidents and impact traumas. Bone fractures in the knee joint may be severe, necessitating surgery as well as immobilisation with casts or other supports.
Diseases of the Knee
Diseases or disorders affecting the knee joint, the soft tissues and bones surrounding the knee, or the nerves that provide sensation to the knee region might cause pain in the knee. Rheumatic diseases, immune diseases that affect different tissues of the body, including the joints, usually affect the knee joint.
Arthritis is caused by joint pain and swelling. Knee joint pain and swelling may be caused by noninflammatory forms of arthritis, such as osteoarthritis, which is a degeneration of the knee cartilage, or inflammatory types of arthritis, such as rheumatoid arthritis (such as rheumatoid arthritis or gout). The nature of the particular form of arthritis determines how the arthritis is treated.
Infections of the bone or joint may be a severe cause of knee pain and have symptoms such as fever, excessive heat, warmth of the joint, body chills, and can be associated with puncture wounds in the area around the knee.
Tumors of the joint are very uncommon. They have the potential to cause discomfort in the local area.
Pellegrini-Stieda syndrome occurs when the collateral ligament on the inside of the knee joint becomes calcified. The knee may become inflamed as a result of this disease, and can be handled conservatively with ice packs, immobilisation, and rest. A local injection of corticosteroids is sometimes needed.
The softening of the cartilage under the kneecap is referred to as chondromalacia (patella). It's a frequent cause of deep knee pain and stiffness in younger women, and it's linked to pain and stiffness from long periods of sitting as well as scaling stairs or hills. Although anti-inflammatory drugs, ice packs, and rest can help, strengthening exercises for the front of the thigh muscles are the best way to get long-term relief.
The medial side of the knee (anserine bursitis) and the front of the kneecap (patellar bursitis, or “housemaid's knee") are the most popular sites for bursitis. Bursitis is usually treated with ice packs, immobilisation, and anti-inflammatory medications like ibuprofen (Advil, Motrin) or aspirin. It can also include local injections of corticosteroids (cortisone medication) and also exercise therapy to strengthen the front thigh musculature.
Knee Pain At A Glance
- There are three compartments in the knee joint.
- Injury, degeneration, inflammation, infection, and bone tumours are also possible causes of knee pain.
- The joint is stabilised by ligaments inside the knee (cruciate ligaments) and on the inner and outer sides of the knee (collateral ligaments).
- Suturing, grafting, and synthetic graft repair are all options for surgical ligament repair.
- Meniscus tears are not visible on routine X-rays, but they can be used to rule out other bone and tissue problems.
- Rheumatic diseases, which affect various tissues of the body, including the joints, frequently affect the knee joint.
Referenced on 9.4.2021
- Arthritis Foundation: “Juvenile Rheumatoid Arthritis."
- American College of Rheumatology: “Juvenile Idiopathic Arthritis."
- Arthritis Foundation: “Juvenile Rheumatoid Arthritis: Treatment Options."
- The Johns Hopkins Arthritis Center: “Rheumatoid Arthritis Treatment."