• 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.

Arthritis simply means an inflammation of a joint causing pain, swelling, stiffness, instability and often deformity. Severe arthritis interferes with a person’s activities and limits his or her lifestyle.

• Osteoarthritis or Degenerative Joint Disease - the most common type of arthritis. Osteoarthritis is also known as "wear and tear arthritis" since the cartilage simply wears out. When cartilage wears away, bone rubs on bone causing severe pain and disability. The most frequent reason for osteoarthritis is genetic, since the durability of each individual’s cartilage is based on genetics. If your parents have arthritis, you may also get it.
  

• Trauma - can also lead to osteoarthritis. A bad fall or blow to the knee can injure the joint. If the injury does not heal properly, extra force may be placed on the joint, which over time can cause the cartilage to wear away.
  

• Inflammatory Arthritis - swelling and heat (inflammation) of the joint lining causes a release of enzymes which soften and eventually destroy the cartilage. Rheumatoid arthritis, Lupus and psoriatic arthritis are inflammatory in nature.

TOTAL KNEE REPLACEMENT VIDEO:

The animation below visually guides you through the process of a total knee replacement, a surgical procedure in which parts of an arthritic or damaged hip joint are removed and replaced with a metal, plastic or ceramic device called a prosthesis.

When Is Total Knee Replacement Recommended?

Several conditions can cause joint pain and disability and lead patients to consider joint replacement surgery. In many cases, joint pain is caused by damage to the cartilage that lines the ends of the bones (articular cartilage)—either from arthritis, a fracture, or another condition.

If nonsurgical treatments like medications, physical therapy, and activity modifications do not relieve your pain and disability, your doctor may recommend total joint replacement.

Preparing for Surgery

In the weeks before your surgery, your surgical team and primary care doctor will spend time preparing you for your upcoming procedure. For example, your primary care doctor may check your general health, and your surgeon may require several tests — such as blood tests and a cardiogram — to help plan your surgery.

There are also many things you can do to prepare. Talk to your doctor and ask questions. Prepare yourself physically by eating right and exercising. Take steps to manage your first weeks at home by arranging for help and obtaining assistive items, such as a shower bench, handrails, or a long-handled reacher. By planning ahead, you can help ensure a smooth surgery and speedy recovery.

Surgical Procedure

During the surgery, the damaged cartilage and bone is removed from your joint and replaced with prosthetic components made of metal, plastic, or ceramic. The prosthesis mimics the shape and movement of a natural joint. For example, in an arthritic hip, the damaged ball (the upper end of the femur) is replaced with a metal ball attached to a metal stem that is fitted into the femur, and a plastic socket is implanted into the pelvis, replacing the damaged socket.

Long-Term Outcomes

The majority of patients are able to perform daily activities more easily after joint replacement surgery. Most people can expect their joint replacement to last for many years, providing them with an improved quality of life that includes less pain, along with improved motion and strength that would not have been possible otherwise.

For more details on a total knee replacement CLICK HERE

CAOS has two basic components:

1. A special camera designed to see the surgical joint and limb and create a picture or image of the hip or knee

2. Computer programs which integrate these images with surgical information and assist the surgeon during the operation

CAOS can use actual images of the joint (X-Rays/fluoroscopic, ultrasound or CT images) or can create virtual images of the damaged joint. The camera and computer are given information by the surgeon about the normal and abnormal anatomic landmarks of the joint and limb. This information can be transmitted in several ways. Some CAOS systems use special cameras to identify and record the position of photo reflective spheres or infra-red light emitting devices. Some other systems use ultrasonic devises to identify bony landmarks. The surgeon uses the computer generated information and images to accurately and reproducibly reconstruct the damaged joint and limb.

Benefits

Potential benefits of using CAS/Robotics in joint replacement surgery include:

1. Computer organised and directed surgical work flow

2. Potential improved reliability of sizing and positioning of joint implants

3. Documentation of limb/joint anatomy and deformity

4. Data storage for research and outcome analysis

5. Potential improved accuracy of reconstructed limb length

6. Potential improved accuracy of prosthetic component alignment

7. Potential impact on functional outcomes and implant durability

Candidates for Surgery

While these technologies can be used in any patient, it is especially helpful in those patients who have specific bone deformities or have hardware from previous surgeries.

In unicompartmental knee replacement (also called partial knee replacement) only a portion of the knee is resurfaced. This procedure is an alternative to total knee replacement for patients whose disease is limited to just one area of the knee.

Your knee is divided into three areas: medial (inside of your knee), lateral (outside of your knee) and patella (kneecap/front of your knee).

Your orthopaedic surgeon can replace just the damaged area of your knee. This enables you to keep more of your natural bone, tissue and ligaments when compared with a total knee replacement (replacing two or three knee surfaces). A partial knee replacement is less invasive, which may afford you a faster recovery, less time in the hospital (1-2 days for a partial joint replacement compared with 3-4 days for a total joint replacement), and a more active life than with a total knee replacement.

There are a range of treatments for knee osteoarthritis, and your doctor will discuss with you the options that will best relieve your individual osteoarthritis symptoms.

Description

In knee osteoarthritis, the cartilage protecting the bones of the knee slowly wears away. This can occur throughout the knee joint or just in a single area of the knee.

The knee is divided into three major compartments:

• Medial compartment (the inside part of the knee)

• Lateral compartment (the outside part of the knee)

• Patellofemoral compartment (the front of the knee between the kneecap and thighbone)

Advanced osteoarthritis that is limited to a single compartment may be treated with a unicompartmental knee replacement. During this procedure, the damaged compartment is replaced with metal and plastic. The healthy cartilage and bone, as well as all of the ligaments, are preserved.

Advantages and Disadvantages of Partial Knee Replacement

Multiple studies show that most patients who are appropriate candidates for unicompartmental knee replacement have good results with this procedure.

The advantages of partial knee replacement over total knee replacement include:

• Quicker recovery

• Less pain after surgery

• Less blood loss

• Lower risk of infection and blood clots

Also, because the bone, cartilage, and ligaments in the healthy parts of the knee are preserved, many patients report that a unicompartmental knee replacement feels more natural than a total knee replacement. A unicompartmental knee may also bend better.

The disadvantage of partial knee replacement compared with total knee replacement is the potential need for more surgery. For example, a total knee replacement may be necessary in the future if arthritis develops in the parts of the knee that have not been replaced. The need for additional surgery is slightly higher for partial knee replacement than for total knee replacement. 

Candidates for Surgery

If your osteoarthritis has advanced and nonsurgical treatment options are no longer relieving your symptoms, your doctor may recommend knee replacement surgery.

To be a candidate for unicompartmental knee replacement, your arthritis must be limited to one compartment of your knee.

If you have any of the following characteristics, you may not be eligible for the procedure:

• Inflammatory arthritis

• Significant knee stiffness

• Ligament damage

With proper patient selection, modern unicompartmental knee replacements have demonstrated excellent medium- and long-term results in both younger and older patients.

Orthopaedic Evaluation

A thorough evaluation by an orthopaedic surgeon will determine whether you are a good candidate for a partial knee replacement.

For more details on a partial knee replacement VISIT ORTHO INFO.