Direct answer
Knee replacement surgery resurfaces the worn ends of the thigh bone and shin bone with metal and plastic components. It is done for severe knee arthritis that no longer responds to other treatment, takes about 1 to 2 hours, usually means a hospital stay of a day or less in Canada, and about 82% of implants are still in place at 25 years. The essentials:
- Who it is for: people with knee pain and stiffness that limit walking, stairs or sleep despite physiotherapy, medication and injections. Most are 50 to 80.
- Total or partial: total replacement resurfaces the whole joint; partial replacement treats one compartment through a smaller cut. In Canada about 9 in 10 are total.
- Robotic assistance: ROSA, VELYS and Mako systems help the surgeon plan and execute bone cuts; trials show more accurate alignment and similar function.
- Recovery: walking with an aid the same day; daily activities within 3 to 6 weeks; driving at about 4 to 6 weeks; work at 6 to 12 weeks.
- Wait in Canada: 63% of patients were treated within the 182-day benchmark in 2025, with a national median of about 146 days.
This guide is for people who have been told they may need a knee replacement, and for the family helping them decide. It explains what the operation is, who it helps, the choices you will hear about, what happens on the day, recovery, risks, how long the implant lasts, and the wait in Canada.
The figures below come from public health guides, Canadian health data and published studies. Your surgeon’s plan and your health shift them.
What is knee replacement surgery?
The knee is where the thigh bone (femur) meets the shin bone (tibia), with the kneecap (patella) in front. Smooth cartilage covers the bone ends; arthritis wears it away until bone grinds on bone. A knee replacement, or total knee arthroplasty, removes the damaged cartilage and a thin layer of bone, and caps the surfaces with new parts. The American Academy of Orthopaedic Surgeons (AAOS) notes it “might be more accurately termed a knee ‘resurfacing’” because only the bone surfaces are replaced. The AAOS describes four steps:
- Remove the damaged cartilage and a small amount of bone from the ends of the femur and tibia.
- Fit metal components to the prepared bone, either cemented in place or press-fit so bone grows into them.
- In some cases, resurface the underside of the kneecap with a plastic button.
- Insert a medical-grade plastic spacer between the metal parts so the new surfaces glide.
Pathway’s surgeons use implants including the Persona knee (Zimmer Biomet) and the ATTUNE knee (DePuy Synthes, Johnson & Johnson), described on Pathway’s knee replacement procedure page. Your surgeon chooses the implant and fixation for your anatomy.
Who is knee replacement surgery for?
The AAOS lists the reasons surgeons recommend it: severe pain or stiffness that limits walking, stairs or getting out of a chair; pain at rest, day or night; swelling that does not settle; a bowing deformity; and little lasting benefit from anti-inflammatories, injections or physiotherapy. There are no absolute age or weight limits; most patients are 50 to 80, and the decision rests on pain and disability. In Canada, the Canadian Joint Replacement Registry reports that 99.6% of primary knee replacements in 2024–2025 were for osteoarthritis, that the most common age group was 65 to 74, and that 58% of patients were women.
Knee replacement is the last step, after the others have been tried. The NHS frames it the same way: an option when other treatments or lifestyle changes have not worked and pain affects daily life. Your surgeon reviews your X-rays and your goals before recommending it.
Total or partial knee replacement: what is the difference?
The knee has three compartments: inside (medial), outside (lateral) and under the kneecap (patellofemoral). A total knee replacement resurfaces all of them; a partial, or unicompartmental, replacement resurfaces one. The AAOS says a partial replacement requires arthritis limited to one compartment, pain almost entirely on one side of the knee, intact ligaments and good motion. Inflammatory arthritis, stiffness, ligament damage or pain throughout the knee point toward a total replacement.
| Feature | Total knee replacement | Partial knee replacement |
|---|---|---|
| What is resurfaced | All compartments; kneecap in about a third of Canadian cases. | One compartment, most often the inside of the knee. |
| Who qualifies | Arthritis in more than one compartment, deformity, stiffness or ligament damage. | Arthritis confined to one compartment with intact ligaments. |
| Incision and tissue | Longer cut down the front of the knee. | Smaller cut; healthy bone, cartilage and ligaments preserved. |
| Early recovery | Daily activities in 3–6 weeks; driving at about 4–6 weeks (NHS: at least 6). | Quicker; daily activities by about 6 weeks; driving at 3 weeks (NHS). |
| Longevity | About 82% in place at 25 years (registry data). | About 70% in place at 25 years; a later total replacement is the usual revision. |
| Share in Canada, 2024–2025 | About 90% of primary knee replacements. | About 9%. |
The UK TOPKAT trial randomized 528 patients with arthritis confined to the inside of the knee to partial or total replacement. Knee scores were the same at 5 years, and the 10-year follow-up again found no clinically meaningful difference, with revision in 6% of partial and 4% of total replacements by treatment received. Pathway’s partial knee replacement page and its guide to partial vs total knee replacement cover the decision in more depth.
What does robotic-assisted knee replacement change?
The surgeon operates; the robotic system guides. The surgeon maps your knee, either from a CT scan or from points collected during surgery, plans the size and position of the implant, and the robot then guides or constrains the saw so the bone cuts match the plan. Pathway’s surgeons work with three systems: the ROSA Knee System (Zimmer Biomet) and the VELYS Robotic-Assisted Solution (DePuy Synthes, Johnson & Johnson), described on Pathway’s knee replacement page, and the Mako system (Stryker), which Dr. Justin Chang uses for partial and total knee replacement.
The evidence is consistent. A 2023 systematic review of 12 randomized trials with 2,200 patients found robotic assistance produced fewer alignment outliers, with little or no difference in patient-reported outcomes or range of motion and no difference in revisions or major complications. A 2026 meta-analysis of 24 randomized trials with 3,425 patients again found no difference in function, pain or hospital stay, and an operation about 22 minutes longer on average, partly reflecting surgeons’ learning curves. In Canada, the registry reports that 4.9% of knee replacements in 2024–2025 used robotic assistance, up from 146 cases in 2020–2021 to 4,708. Robotic assistance is a tool for precision; your surgeon’s judgement sets the plan. Pathway’s guide to robotic vs conventional knee replacement goes deeper.
What happens on the day of surgery?
You arrive fasted, usually on the morning of surgery. The anaesthesia team offers a general anaesthetic or a spinal anaesthetic that numbs you from the waist down, often with a nerve block; the AAOS says the choice is made with your input. The NHS describes the operation: a cut down the front of the knee, the kneecap moved aside, the damaged bone ends removed, the new parts fitted, and the wound closed with stitches or clips under a dressing. The AAOS and the NHS both give about 1 to 2 hours for the operation itself.
The AAOS says physiotherapy can start within hours: standing, then walking with a walker or crutches. Blood-clot prevention starts the same day with leg exercises, compression and a blood thinner, and pain control combines several types of medication, with opioids taken only as directed.
How long is the hospital stay?
The Canadian Joint Replacement Registry reports a median acute-care stay of 1 day and a mean of 1.9 days for primary knee replacements in 2024–2025, and that 31.1% of knee replacements for osteoarthritis were done as day surgery. The NHS describes 1 to 4 days. A 2022 meta-analysis of 41 studies found outpatient hip and knee replacement pathways as safe as inpatient stays in selected, generally younger and healthier patients, with 92% of planned same-day patients going home as planned. Your surgeon decides based on your health, your home support and how you are moving.
What does recovery look like?
The AAOS says most people resume normal daily activities within 3 to 6 weeks and drive at about 4 to 6 weeks, once the knee bends enough and reaction time allows. The NHS describes walking aids for about 6 weeks, a follow-up visit at about 6 weeks, a return to work at about 6 to 12 weeks depending on the job, compression stockings for at least 6 weeks, and no kneeling on the new knee until your doctor approves.
- Weeks 0–2: home; walker or crutches; ice, elevation and daily exercises; stitches or clips out at about 10 days.
- Weeks 2–6: physiotherapy for bend, straightening and strength; move to a cane; light daily activities return.
- Weeks 6–12: driving and desk work for most; walking without an aid; physical work later.
- Months 3–12: low-impact sport such as walking, swimming, cycling and golf; stamina and stair confidence keep improving.
The AAOS says to expect an average knee bend of about 115 degrees, and that running, jumping and other high-impact sport should be avoided for life to protect the implant. Pathway’s knee replacement recovery time guide covers each phase in detail.
What are the risks of knee replacement surgery?
The AAOS describes the overall complication rate as low, with serious complications such as joint infection in fewer than 2% of patients. The main risks are:
- Blood clots in the leg veins, which can travel to the lungs. Early walking, compression and blood thinners lower the risk.
- Infection, which can appear within weeks or years later and may need further surgery. In Canada, infection was the reason for 34.1% of knee revisions in 2024–2025.
- Stiffness, sometimes treated with a manipulation under anaesthesia.
- Loosening or wear of the implant over time; aseptic loosening accounted for 15.0% of Canadian knee revisions, and instability for 11.5%.
- Persistent pain (uncommon) and injury to nerves or blood vessels (rare).
The NHS adds that needing another replacement is uncommon. Among Canadian patients surveyed one year after surgery, 87% were satisfied with the result.
Warning signs: when to call your care team
Call 911 for sudden shortness of breath, sudden chest pain, or chest pain that worsens with coughing. These can signal a blood clot in the lungs.
Call your surgeon or care team right away for increasing calf pain, tenderness or redness above or below the knee, or new swelling in the calf, ankle or foot (possible leg clot); and for a fever, chills, increasing redness, tenderness or swelling at the wound, drainage, or knee pain that increases with both activity and rest (possible infection). These signs reflect AAOS and NHS guidance; your care team may give you a different contact plan, so follow theirs.
How long does a knee replacement last?
A 2019 Lancet systematic review pooled national registry data on 299,291 total knee replacements and 7,714 partial replacements and found about 82% of total and 70% of partial replacements still in place at 25 years. The AAOS puts it another way: more than 90% of modern total knee replacements are still functioning well 15 years after surgery. The NHS says a knee replacement can last 25 years. Your surgeon will discuss what your age and activity mean for your implant.
How long is the wait for knee replacement in Canada?
Canada’s national benchmark is 182 days (26 weeks) from the decision to operate to surgery. CIHI’s wait-time data (April to September each year) show the share treated within that benchmark fell from 70% in 2019 to 50% in 2022, then recovered to 61% in 2024 and 63% in 2025. In 2025 the national median wait was about 146 days and the 90th percentile about 361 days, meaning 1 in 10 patients waited almost a year.
| Province (April–September 2025) | Treated within 182 days | Median wait (days) |
|---|---|---|
| Ontario | 82% | 81 |
| Nova Scotia | 69% | 129 |
| British Columbia | 57% | 152 |
| Alberta | 53% | 172 |
| New Brunswick | 49% | 186 |
| Saskatchewan | 43% | 210 |
| Quebec | 42% | 217 |
| Newfoundland and Labrador | 37% | 298 |
| Manitoba | 31% | 286 |
| Prince Edward Island | 12% | 424 |
| Canada | 63% | 146 |
Source: CIHI wait-time data tables, 2008 to 2025. These figures count the wait from the surgeon’s decision to operate; the wait to see a surgeon comes before that. Pathway’s guide to knee replacement wait times in Canada covers the full referral-to-surgery picture province by province.
What are the private options with Pathway?
Pathway’s surgeons perform total and partial knee replacement at Pathway’s partner surgical centres in Toronto and Montreal; patients travel from every province. All are fellowship-trained arthroplasty specialists: Dr. Sebastian Rodriguez-Elizalde (ROSA robotic knee replacement; fellowship at the Hospital for Special Surgery; more than 5,000 combined robotic knee and hip replacements; consults in Toronto and Montreal), Dr. Justin Chang (Mako robotic partial and total knee replacement), Dr. Michael Zywiel (Toronto Western Hospital) and Dr. Thomas Zochowski (fellowship in adult lower-extremity reconstruction, UHN).
The timeline is fixed: a consultation within 1–4 business days, and surgery typically 2–4 weeks after consultation and quote approval. No referral is required. Pathway’s care team handles records, imaging, scheduling, travel and follow-up. Pathway’s guides on how it works and out-of-province surgery in Canada explain the steps.
Quick answers
What is knee replacement surgery?
Knee replacement surgery removes the worn cartilage and a thin layer of bone from the ends of the thigh bone and shin bone and caps them with metal components separated by a medical-grade plastic spacer. It is done for severe arthritis that no longer responds to other treatment.
How long does knee replacement surgery take?
The operation itself usually takes about 1 to 2 hours, according to the AAOS and the NHS. Robotic-assisted operations run somewhat longer on average in randomized trials. Add time for anaesthesia and the recovery room.
How long do you stay in hospital after a knee replacement?
In Canada in 2024 to 2025, the median acute-care stay for a primary knee replacement was 1 day, and 31.1% of knee replacements for osteoarthritis were done as day surgery, according to CIHI. The NHS describes 1 to 4 days. Your surgeon decides based on your health, your home support and how you are moving.
How long does a knee replacement last?
A 2019 Lancet meta-analysis of national registry data found about 82% of total knee replacements and 70% of partial knee replacements were still in place at 25 years. The AAOS says more than 90% of modern total knee replacements are still functioning well at 15 years.
How long is the wait for a knee replacement in Canada?
CIHI data for April to September 2025 show 63% of Canadians received their knee replacement within the 182-day benchmark, with a national median wait of about 146 days and a 90th percentile of about 361 days. The wait varies widely by province.
Questions to ask your surgeon
- Is my arthritis confined to one compartment, and am I a candidate for a partial replacement?
- Which implant do you plan to use, and will it be cemented or press-fit?
- Will you use robotic assistance, and what does it change for my knee?
- Do you expect me to go home the same day or stay overnight?
- What anaesthetic do you recommend, and what is the plan for pain control and blood-clot prevention?
- When do you expect me to drive, return to my job, and return to my sport?
- Who do I call after hours if I notice a warning sign?
References
- American Academy of Orthopaedic Surgeons (OrthoInfo). Total Knee Replacement. Accessed October 21, 2026.
- American Academy of Orthopaedic Surgeons (OrthoInfo). Unicompartmental Knee Replacement. Accessed October 21, 2026.
- NHS. What is a knee replacement?, How it’s done, Recovery and Complications. Last reviewed September 9, 2026. Accessed October 21, 2026.
- Canadian Institute for Health Information. Explore wait times for priority procedures across Canada, with the Wait Times for Priority Procedures in Canada, 2008 to 2025 — Data Tables. Accessed October 21, 2026.
- Canadian Institute for Health Information. Hip and Knee Replacements in Canada: CJRR Annual Report, 2024–2025. Ottawa, ON: CIHI; 2026. Accessed October 21, 2026.
- Evans JT, Walker RW, Evans JP, Blom AW, Sayers A, Whitehouse MR. How long does a knee replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 15 years of follow-up. Lancet. 2019;393(10172):655–663.
- Beard DJ, Davies LJ, Cook JA, et al. Total versus partial knee replacement in patients with medial compartment osteoarthritis (TOPKAT): 5-year outcomes of a randomised controlled trial. Lancet. 2019;394(10200):746–756.
- Beard DJ, Davies LJ, Cook JA, et al. Total versus partial knee replacement (TOPKAT): 10-year follow-up of a multicentre, randomised controlled trial. Lancet Rheumatol. 2026;8(2):e116–e126.
- Ruangsomboon P, Ruangsomboon O, Pornrattanamaneewong C, Narkbunnam R, Chareancholvanich K. Clinical and radiological outcomes of robotic-assisted versus conventional total knee arthroplasty: a systematic review and meta-analysis of randomized controlled trials. Acta Orthop. 2023;94:60–79.
- Abdelaziz O, Zayed ZG, Altukhy AM, et al. Comparative pain relief and functional outcomes following robotic-assisted versus conventional total knee arthroplasty: a GRADE-assessed meta-analysis with meta-regression of randomized controlled trials. J Robot Surg. 2026;20(1):1021.
- Bemelmans YFL, Keulen MHF, Heymans M, et al. Safety and efficacy of outpatient hip and knee arthroplasty: a systematic review with meta-analysis. Arch Orthop Trauma Surg. 2022;142(8):1775–1791.
Health information notice: This article provides general information about knee replacement surgery and cannot replace individual medical advice. Your surgeon and care team decide whether surgery is right for you and set your plan based on your health, your knee, and your goals.