Knee replacement

• The operation takes 1–2 hours; you walk with support within the first day.
• In the Finnish registry about 82 % of total knee implants last 25 years.
• Implant infection in the first year is about 1.2 %; Russian authors report about 3 %.
• No driving for at least 6 weeks; the final result takes close to a year.

How the knee is built

The knee is the largest joint in the body. Three bones meet here: the femur, the tibia and the kneecap (patella). The bone ends are covered with smooth, springy cartilage, so they glide almost without friction. Two cartilage pads, the menisci, lie between them and spread the load. The cruciate ligaments hold the bones from inside, the collateral ligaments from the sides. The synovial membrane lines the joint and produces lubricating fluid.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →

Surgeons divide the knee into three compartments:

1. 1medial (inner): between the inner condyles of the femur and tibia; it wears out most often;
2. 2lateral (outer): its mirror image on the outside;
3. 3patellofemoral: between the kneecap and the front of the femur.

1231Medial(inner)2Lateral(outer)3Patellofemoral(kneecap–femur)

3Cross-section

This division shapes the choice of operation. If one compartment is damaged, sometimes only that part is replaced. If all three are damaged, a total implant is needed.

Why the knee wears out

Gonarthrosis is osteoarthritis of the knee. The cartilage thins and the bone beneath it hardens and grows spurs. The joint deforms and hurts. The main causes are age-related wear and old injuries: fractures, torn menisci or ligaments. Rheumatoid arthritis and excess weight also lead to it. A bowed or knock-kneed leg, from birth or later in life, is another cause.[2, 6]2Total Knee Replacement — AAOS OrthoInfo, 20246Клинические рекомендации «Гонартроз» — Минздрав России, 2024To the list of sources →

Typical complaints:

• start-up pain in the first steps after sleep or sitting;
• stiffness that lasts no longer than half an hour;
• grinding, swelling, trouble with stairs;
• the knee bends and straightens less and less;
• in late stages, night pain and a visible deformity of the leg.[6]6Клинические рекомендации «Гонартроз» — Минздрав России, 2024To the list of sources →

In 2019 about 63,750 primary knee replacements were performed in Russia.[1]1Эпидемиология эндопротезирования тазобедренного и коленного суставов и перипротезной инфекции в Российской Федерации — Травматология и ортопедия России, 27(3):84–93, 2021To the list of sources →

Stages of osteoarthritis

The stage of osteoarthritis is judged from an X-ray. Russia uses two scales for this. The Kellgren–Lawrence scale has five grades, from 0 to IV. The Kosinskaya classification has three stages and takes symptoms into account as well as the X-ray.[6]6Клинические рекомендации «Гонартроз» — Минздрав России, 2024To the list of sources →

Skip the diagram

Keep scrolling — the knee changes from grade 0 to IV

Kellgren–Lawrence grade

Grade 0Grade IGrade IIGrade IIIGrade IV

Grade 0Normal

The joint space is even, with no bony outgrowths at the edges. Cartilage itself does not show on an X-ray: its thickness is judged by the width of the joint space.

Kosinskaya: has no stage 0

Circled: the inner compartment, where changes most often begin

Front view of the knee with the joint ends cut through: smooth cartilage, equal joint space on both sides, smooth bone edges.

Grade IDoubtful changes

A tiny bony spur may be starting at the joint edge; the joint space is barely narrowed. Such an X-ray cannot confirm osteoarthritis.

Kosinskaya: ≈ stage I

A possible tiny spur at the bone edge

Knee diagram: a tiny bony spur is starting at the inner edge of the shin bone; the joint space is unchanged.

Grade IIMinimal changes

Single osteophytes — bony outgrowths — are clearly visible at the joint edges. The joint space may be slightly narrowed.

Kosinskaya: ≈ stage I

A definite osteophyte; the space may be slightly narrower

Knee diagram: a definite small osteophyte at the inner joint edge; in this drawing the inner joint space is slightly narrower, although at this grade it may not be narrowed at all.

Grade IIIModerate changes

The joint space is clearly narrower, with several osteophytes. The bone beneath the cartilage becomes denser, and the joint surfaces begin to change shape.

Kosinskaya: ≈ stage II–III

A narrower space, larger bony outgrowths

Knee diagram: the inner compartment is clearly narrower, cartilage is thinner, larger osteophytes at the inner edge and a small new spur at the outer edge.

Grade IVSevere changes

The joint space is sharply narrowed; on the inner side almost no cartilage is left. Osteophytes are large, the bone beneath is dense and the shape of the bone ends has changed.

Kosinskaya: ≈ stage III

In the centre of the inner side cartilage is almost gone — bone nearly touches bone

Knee diagram: only thin strips of cartilage are left on the inner side and in the centre bone almost touches bone; the joint surface is flattened, with large osteophytes inside and small ones outside.

Schematic illustration, not an X-ray

≈ means an approximate match: the scales rely on different signs, and the clinical guideline has no table for converting one into the other. How much a knee hurts does not always match the stage on the X-ray.[6]6Клинические рекомендации «Гонартроз» — Минздрав России, 2024To the list of sources →

Schematic illustration. The Kellgren–Lawrence scale grades an X-ray, where cartilage does not show; the drawing shows cartilage and bone conditionally. The kneecap is not shown; the joint ends are cut through.

Indications for surgery

Russian guidelines on knee osteoarthritis list these conditions together as the indication for replacement:

• the X-ray shows Kosinskaya stage III (Kellgren–Lawrence grade III–IV);
• the pain is persistent;
• the joint limits movement and daily activities;
• treatment without surgery has not helped.[6]6Клинические рекомендации «Гонартроз» — Минздрав России, 2024To the list of sources →

There is no absolute age or weight limit. The decision rests on pain, how the joint works and your general health.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →

Surgery is postponed or ruled out in active infection and severe uncontrolled heart or lung disease. Poor circulation in the leg and some other conditions can also stand in the way. The surgeon, a physician and the anaesthetist assess them.[6]6Клинические рекомендации «Гонартроз» — Минздрав России, 2024To the list of sources →

The navigator is not a doctor: diagnosis and treatment stay with your physician.

Treatment without surgery

The first steps are exercise therapy, weight loss, painkillers, joint injections and braces. They are usually tried for at least several months before surgery is discussed.[6]6Клинические рекомендации «Гонартроз» — Минздрав России, 2024To the list of sources → How each option works is explained in Treatment without surgery on the basics page.

How the operation works: step by step4 short scenes · one click at a time

Total or partial

A partial implant that fails is usually replaced with a total one. Fewer patients die after partial replacement than after total replacement.[15, 20]15Adverse outcomes after total and unicompartmental knee replacement in 101 330 matched patients: a study of data from the National Joint Registry for England and Wales — The Lancet, 201420Patient relevant outcomes of unicompartmental versus total knee replacement: systematic review and meta-analysis — BMJ (PMC6383371), 2019To the list of sources → Results depend heavily on the surgeon’s experience with this operation. Ask how many they do a year.

What you will be given

A knee implant has three or four parts that copy the shape of the joint.

1. Femoral component: a metal cap on the end of the thigh bone. It is curved like the condyles and glides on the liner.
2. Tibial component (tray): a metal plate with a stem on top of the shin bone.
3. Liner: a plate of medical-grade polyethylene between the metal parts. It takes the friction and slowly wears.
4. Patellar component: a polyethylene button on the back of the kneecap. It is not always used.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →

How the parts fit together

Materials and fixation

· 2 min

Material	Where it is used	What is known
Cobalt-chrome alloy	Femoral component, sometimes the tray	Long-standing standard: the polished surface glides well on polyethylene[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →
Titanium alloys	Tray, porous cementless surfaces	Bond well with bone; too soft for a gliding surface[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →
Oxidised zirconium	Femoral component from some manufacturers	Ceramic surface on metal, an option for nickel allergy; no better than cobalt-chrome in the registry[22]22Annual Report — Hip, Knee & Shoulder Arthroplasty (oxidised zirconium vs CoCr femoral components) — Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), 2024To the list of sources →
Polyethylene (UHMWPE)	Liner, kneecap	The classic material; its wear is the main cause of late revisions
Highly cross-linked polyethylene (HXLPE)	Modern liners	Less wear in the lab and in hip registries; knee data are less clear-cut
Vitamin E polyethylene	Newest liners	Vitamin E protects the plastic from oxidation; no proven long-term benefit yet

Cemented fixation attaches the parts to bone with fast-setting bone cement. It is the standard for most patients, especially older ones: the implant is stable at once, and results have been studied for decades. Cementless fixation uses porous metal that bone grows into over time. It is offered more often to younger patients with dense bone. A hybrid option cements one part only.[2, 5]2Total Knee Replacement — AAOS OrthoInfo, 20245Knee replacement — NHS, 2024To the list of sources →

If you have a metal allergy, especially to nickel, tell your surgeon in advance. Reactions to implants are rare, and nickel-free options exist.

Preparation

Preparation starts several weeks before the operation and makes a real difference to recovery.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →

A few more points:

• Smoking. Stop at least a few weeks before: smoking slows wound healing.[5]5Knee replacement — NHS, 2024To the list of sources →
• Blood sugar. With diabetes, bring it to target beforehand: chronic conditions raise the risk of complications.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →
• X-rays. You need standing X-rays of both knees in two views.
• Paid surgery. Ask what the price includes: implant, hospital days, rehabilitation.

Training before surgery is called prehabilitation. It strengthens the thigh muscles and teaches the exercises you will need afterwards. People who have practised with crutches and exercises feel more confident in the first days.[2, 11]2Total Knee Replacement — AAOS OrthoInfo, 202411Total Knee Replacement Exercise Guide — AAOS OrthoInfo, 2024To the list of sources →

The day of surgery

In the morning the anaesthetist examines you. Spinal or general anaesthesia is used.[2, 5]2Total Knee Replacement — AAOS OrthoInfo, 20245Knee replacement — NHS, 2024To the list of sources → An antibiotic is given before the incision. Drugs that reduce blood loss are given during the operation.[6]6Клинические рекомендации «Гонартроз» — Минздрав России, 2024To the list of sources →

You then spend a few hours in the recovery room as the anaesthesia wears off. Then you return to the ward.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →

In hospital

• Day 0. The anaesthesia wears off within hours. Pain is controlled with tablets, injections and sometimes a nerve block or wound catheter. You start ankle pumps straight away to keep the blood moving. In many clinics you stand with a walker the same day.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →
• Days 1–2. Walking the ward and corridor with a walker or crutches, first exercises with a physiotherapist. Dressing changes and a check X-ray. Swelling and bruising are normal.[5]5Knee replacement — NHS, 2024To the list of sources →
• Days 2–5. Stairs, getting up unaided, full straightening and confident bending. Medicines against blood clots follow the doctor’s plan. When the first dose is given depends on the drug, the anaesthetic and bleeding risk. They usually continue for several weeks, with compression stockings.[5, 6, 16]5Knee replacement — NHS, 20246Клинические рекомендации «Гонартроз» — Минздрав России, 202416Apixaban for the prevention of venous thromboembolism after total hip or knee replacement (TA245) — NICE, 2012To the list of sources →
• Discharge. In the UK and US patients go home after 1–3 days, sometimes the same day.[5]5Knee replacement — NHS, 2024To the list of sources → Russian hospitals, especially state ones, usually keep patients 5–10 days. Some then move to a second-stage rehabilitation unit.[23]23Эндопротезирование сустава в России: сроки госпитализации и стоимость — russianhospitals.ru, 2026To the list of sources →

By discharge, aim to walk with support on floors and stairs and reach the toilet alone. You should also know your exercises and pain-relief plan.

How the operation works: four short scenes

Recovery plan

Timings depend on age, weight, muscle strength before surgery and the type of implant.

Exercises by phase

The programme follows the guide of the American Academy of Orthopaedic Surgeons (AAOS). Exercise for 20–30 minutes, ideally 2–3 times a day, and walk as well. Do not push through sharp pain, but mild discomfort while working on bending is unavoidable.[11]11Total Knee Replacement Exercise Guide — AAOS OrthoInfo, 2024To the list of sources →

These are examples to show the idea. Your physiotherapist or rehabilitation doctor will tailor a routine to your implant and condition.

Complications and how often they happen

Every operation carries risk. You must be told about these complications before surgery.

Smoking, diabetes with high blood sugar and obesity raise the risk of complications, including infection.[2, 5]2Total Knee Replacement — AAOS OrthoInfo, 20245Knee replacement — NHS, 2024To the list of sources → You can act on these factors in advance: see Preparation.

What to expect after a year

• Bending. Most people bend the knee to about 115°. That is enough for walking, stairs, getting into a car and rising from a chair. Deep squats and sitting on your heels are usually hard.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →
• Kneeling is possible, though many find it uncomfortable. It does not harm the implant.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →
• Clicking and tapping when you bend are normal: metal and plastic meet differently from cartilage. Most people stop noticing over time.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →
• Skin numbness beside the scar is common and usually permanent. Small skin nerves are cut during the incision.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →
• Airport metal detectors may go off. A certificate is not needed in most countries. Still, carrying your discharge summary is handy.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →
• Pain disappears or drops sharply for most people. Some remain not fully satisfied because of residual pain, stiffness or unmet expectations.[18]18Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? — Clinical Orthopaedics and Related Research, 468(1):57–63, 2010To the list of sources → So talk with your surgeon before the operation about what you expect.

An implant does not give you the knee of a 30-year-old. For most people the operation greatly reduces pain and improves how the joint works. That is enough for an active life and low-impact sport, although some pain may remain.[2]2Total Knee Replacement — AAOS OrthoInfo, 2024To the list of sources →

Knee replacement is part of the state guarantee programme. Most primary operations are now done under the basic compulsory health insurance (OMS) programme. Complex and revision cases are funded by a VMP quota for high-tech medical care.[14]14Травматология и ортопедия по квоте (ВМП): как получить — gosmed.ru, 2025To the list of sources →

You will need a referral on form 057/u and a summary from your outpatient record.[17]17Приказ Минздрава России от 02.09.2025 № 519н: форма направления 057/у и порядок её ведения — Минздрав России, 2025To the list of sources → The route, documents and appeals are on the quota and OMS page.

Under a quota the implant comes from models the clinic has bought. You usually cannot pick a manufacturer. The wait depends on the region and clinic: a few weeks to a year or more.[14]14Травматология и ортопедия по квоте (ВМП): как получить — gosmed.ru, 2025To the list of sources →

The price of paid surgery covers the operation, the implant, hospital days and rehabilitation. Private clinics often charge for these separately. Reference prices are collected on the quota and international patients pages.