Knee replacement, also known as knee arthroplasty, is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve pain and disability. It is most commonly performed for osteoarthritis, and also for other knee diseases such as rheumatoid arthritis and psoriatic arthritis. In patients with severe deformity from advanced rheumatoid arthritis, trauma, or long-standing osteoarthritis, the surgery may be more complicated and carry higher risk. Osteoporosis does not typically cause knee pain, deformity, or inflammation and is not a reason to perform knee replacement.
The knee joint is among the strongest, largest and most complex joints of the body. When you walk, sit, squat, climb stairs up and down, play, jump and drive or do many other simple movements, you are depending on the knee for support and mobility.
When your knee is healthy, you may take it for granted, not giving a thought about the job it does for you. However, once it starts to become painful, stiff and you are forced to restrict certain activities, you may come to realise how much freedom of movement means for you.
Fortunately, today’s remarkable advances in medical technology and research makes it possible to replace the knee joint with a long-lasting durable and fine-tuned artificial one that eliminates pain, corrects the deformity, strengthens your legs and improve your quality of life. This page provides information for you and your family regarding Total Knee Replacement surgery. The surgical procedure, pre-operative and post-operative care, the risks and benefits of surgery, as well as rehabilitation, are explained.
BONES: Bones also protect the body’s organs. The skull protects the brain and forms the shape of the face. The spinal cord, a pathway for messages between the brain and the body, is protected by the backbone, or spinal column. The ribs form a cage that shelters the heart and lungs, and the pelvis helps protect the bladder, part of the intestines, and in women, the reproductive organs.
Bones are made up of a framework of a protein called collagen, with a mineral called calcium phosphate that makes the framework hard and strong. Bones store calcium and release some into the bloodstream when it’s needed by other parts of the body. The amounts of some vitamins and minerals that you eat, especially vitamin D and calcium, directly affect how much calcium is stored in the bones.
Bones are made up of two types of bone tissues:
- Compact bone is the solid, hard outside part of the bone. It looks like ivory and is extremely strong. Holes and channels run through it, carrying blood vessels and nerves.
- Cancellous bone, which looks like a sponge, is inside compact bone. It is made up of a mesh-like network of tiny pieces of bone called trabeculae. This is where bone marrow is found.
In this soft bone is where most of the body’s blood cells are made. The bone marrow contains stem cells, which produce the body’s red blood cells and platelets, and some types of white blood cells. Red blood cells carry oxygen to the body’s tissues, and platelets help with blood clotting when someone has a cut or wound. White blood cells help the body fight infection.
Bones are fastened to other bones by long, fibrous straps called ligaments. Cartilage, a flexible, rubbery substance in our joints, supports bones and protects them where they rub against each other.
How Do Bones Grow?
The bones of kids and young teens are smaller than those of adults and contain “growing zones” called growth plates. These plates consist of multiplying cartilage cells that grow in length, and then change into hard, mineralized bone. These growth plates are easy to spot on an X-ray. Because girls mature at an earlier age than boys, their growth plates change into hard bone at an earlier age.
Bone-building continues throughout life, as a body constantly renews and reshapes the bones’ living tissue. Bone contains three types of cells:
- osteoblasts, which make new bone and help repair damage
- osteocytes, mature bone cells which help continue new born formation
- osteoclasts, which break down bone and help to sculpt and shape it
JOINTS: A joint or articulation (or articular surface) is the connection made between bones in the body which link the skeletal system into a functional whole. They are constructed to allow for different degrees and types of movement. Some joints, such as the knee, elbow, and shoulder, are self-lubricating, almost frictionless, and are able to withstand compression and maintain heavy loads while still executing smooth and precise movements. Other joints such as sutures between the bones of the skull permit very little movement (only during birth) in order to protect the brain and the sense organs. The connection between a tooth and the jawbone is also called a joint, and is described as a fibrous joint known as a gomphosis. Joints are classified both structurally and functionally.
Joints are where two bones meet. They make the skeleton flexible — without them, movement would be impossible.
Joints allow our bodies to move in many ways. Some joints open and close like a hinge (such as knees and elbows), whereas others allow for more complicated movement — a shoulder or hip joint, for example, allows for backward, forward, sideways, and rotating movement.
Joints are classified by their range of movement:
- Immovable, or fibrous, joints don’t move. The dome of the skull, for example, is made of bony plates, which move slightly during birth and then fuse together as the skull finishes growing. Between the edges of these plates are links, or joints, of fibrous tissue. Fibrous joints also hold the teeth in the jawbone.
- Partially movable, or cartilaginous, joints move a little. They are linked by cartilage, as in the spine. Each of the vertebrae in the spine moves in relation to the one above and below it, and together these movements give the spine its flexibility.
- Freely movable, or synovial, joints move in many directions. The main joints of the body — such as those found at the hip, shoulders, elbows, knees, wrists, and ankles — are freely movable. They are filled with synovial fluid, which acts as a lubricant to help the joints move easily.
Three kinds of freely movable joints play a big part in voluntary movement:
- Hinge joints allow movement in one direction, as seen in the knees and elbows.
- Pivot joints allow a rotating or twisting motion, like that of the head moving from side to side.
- Ball-and-socket joints allow the greatest freedom of movement. The hips and shoulders have this type of joint, in which the round end of a long bone fits into the hollow of another bone.