Knee replacement changes damaged joint surfaces using artificial parts. It is also called knee arthroplasty. Total and partial replacement describe how much of the joint is being treated. The NHS describes the operation in the setting of pain affecting daily life when alternatives have not worked. The pattern of damage, the rest of the joint, and the person's health are part of the discussion. NHS knee-replacement overview; NHS reasons for replacement; OrthoInfo partial-replacement assessment.
The knee surfaces and osteoarthritis
The knee brings together the lower end of the thighbone, the upper end of the shinbone, and the kneecap. Smooth articular cartilage covers the meeting surfaces. Menisci, tough cartilage structures between the thighbone and shinbone, help cushion and stabilize the joint. The joint's thin lining produces lubricating fluid. These structures contribute different parts of normal knee movement. OrthoInfo knee anatomy.
In knee osteoarthritis, the smooth cartilage becomes rough and wears away. The space between the bones narrows, and bone can rub against bone or form spurs. Symptoms can include pain, swelling, stiffness, catching, or a feeling of weakness. The osteoarthritis guide explains the condition in more detail. Arthritis after injury and inflammatory arthritis are other categories discussed by OrthoInfo. OrthoInfo arthritis of the knee.
Why replacement is discussed and what assessment covers
The NHS says knee replacement may be discussed when pain has a substantial effect on life and alternatives have not worked. It identifies osteoarthritis as the common reason and also describes other arthritis and damage after injury. This is a clinical discussion about symptoms and function, rather than a decision determined by the presence of arthritis alone. NHS reasons for knee replacement.
OrthoInfo describes assessment through medical history, examination, and imaging. The examination considers movement, stability, strength, and leg alignment. Imaging helps show the pattern of damage. The discussion includes other care categories, possible benefits, and risks. A published article on knee replacement also notes that the threshold for surgery is not well defined and is influenced by several factors, including patient and surgeon preferences. OrthoInfo orthopedic evaluation; Knee-replacement article.
Total replacement: changing the bearing surfaces
OrthoInfo explains that total knee replacement is a replacement of surfaces. The surgeon removes damaged cartilage and a small amount of underlying bone from the thighbone and shinbone. Metal components cover the prepared bone ends, with a plastic spacer between them to provide a gliding surface. The back of the kneecap may also receive a plastic component, depending on the case. OrthoInfo total-replacement description.
The NHS describes reaching the joint through the front of the knee, moving the kneecap aside, preparing the damaged bone ends, fitting components, and closing the wound. Regional anesthesia blocks sensation below the waist, while general anesthesia places the person asleep. The choice of operation is described in relation to damage, age, and general health. These are descriptions of hospital care, rather than steps a patient carries out. NHS knee-operation description.
MedlinePlus uses prosthesis to mean the artificial joint. Its explanation describes components made mainly from metal and strong plastic and attachment using bone cement or screws. OrthoInfo also describes press-fit attachment. The component material, its attachment, and which surfaces are treated are distinct questions within the full operation plan. MedlinePlus knee-replacement components; OrthoInfo implant placement.
Partial replacement: a limited pattern of disease
The knee can be described in compartments: the inside area, the outside area, and the area between the kneecap and thighbone. Partial knee replacement, also called unicompartmental replacement, changes the damaged area while preserving healthy cartilage, bone, and ligaments elsewhere. The anatomical pattern matters because the procedure is described for disease limited to a compartment, rather than damage spread throughout the joint. OrthoInfo compartments and partial replacement.
OrthoInfo says assessment for partial replacement includes the location of pain, range of movement, ligament quality, and imaging. Inflammatory arthritis, substantial stiffness, or ligament damage may affect eligibility. These are factors for professional assessment, rather than criteria that can be checked from symptoms alone. The word partial identifies what is treated; it does not establish that the procedure is appropriate for every person with localized pain. OrthoInfo partial-replacement evaluation.
The same source discusses the possibility of further surgery if arthritis later develops in areas left untreated. It also describes checking the compartments during the operation and discussing a possible change to total replacement beforehand. Understanding what is intended to remain and what might change is therefore part of the explanation of partial replacement, alongside the amount of tissue being replaced. OrthoInfo limitations and operative planning.
Osteotomy changes alignment instead of surfaces
An osteotomy involves cutting and realigning bone. Around the knee, MedlinePlus describes changing the shinbone or thighbone to shift weight away from a damaged area. Its explanation says the area receiving that shifted load needs to have little or no arthritis. This makes osteotomy a different operation from attaching replacement surfaces, with a different anatomical purpose. MedlinePlus knee-osteotomy explanation.
MedlinePlus lists risks including stiffness, injury to a nerve or blood vessel, infection, blood clots, fixation problems, and failure of the bone to join. Those risks belong to the alignment operation and should not be assumed to be identical to the risks of replacement. The treatment overview places these surgical categories alongside the non-surgical care described by agencies. MedlinePlus osteotomy risks.
Possible complications and changes after surgery
The NHS lists blood clots, wound infection, and damage to nearby nerves, blood vessels, or ligaments among knee-replacement complications. It also describes ongoing pain or stiffness, difficulty bending, and instability. Infection can extend into the joint and may require further surgery. These are possibilities to discuss in the context of the proposed procedure and health history, rather than a prediction about a reader's recovery. NHS knee-replacement complications.
For someone who has recently had a knee replacement, the NHS lists symptoms that need urgent medical advice: throbbing or cramping pain in the leg, a high temperature or feeling hot, cold or shivery, oozing or pus from the wound, and redness, tenderness, swelling or pain that is not getting better or is getting worse. It notes that these could be signs of an infection or a blood clot in its knee-replacement complications information.
Rehabilitation is part of the operation plan
The NHS describes recovery-room care and pain management, followed by help from nurses and physiotherapists with walking. Discharge depends in part on being able to get around safely and the absence of signs of complications. Therapists discuss daily activities and a home exercise program. The recovery and rehabilitation guide explains these care categories without giving a personal activity schedule. NHS knee-replacement recovery information.
Follow-up is used to check recovery, and MedlinePlus also describes later checks of the artificial joint's position and condition. It notes that a replacement may eventually loosen or wear and require another operation. The implant and registry guide explains how implants are followed more broadly. The planned procedure, rehabilitation, and longer-term review are related topics for the care-team conversation. NHS follow-up information; MedlinePlus later assessment.