How Long Does a Total Knee Replacement Take? Realistic Surgery Timeline and Factors

You want a straight answer before you book time off, arrange a ride, or reassure your family: how many hours does a total knee replacement take? The short version: the operation itself usually takes around an hour to an hour and a half, but your total time at the hospital will be much longer. What actually matters to you is the day’s timeline - from arrival and anesthesia to recovery and the first walk - and the handful of factors that can stretch or shrink it.

TL;DR: How long does a total knee replacement take?

Here’s the reality you can plan around, based on UK and international orthopedic norms in 2025 and what most patients experience in modern surgical centres:

• knee replacement surgery duration (skin-to-skin): typically 60-90 minutes. Fast, straightforward cases can finish in 45-60 minutes; complex knees can run 90-120 minutes.
• Operating room time (wheels-in to wheels-out): 2-3 hours. This includes anesthesia, positioning, prep, the operation, and dressings.
• Recovery room (PACU): 1-2 hours. You’ll wake up, get pain relief, check blood pressure, and wiggle toes. Many people are up with a physiotherapist the same day.
• Door-to-door at hospital: 6-10 hours if you’re a day-case; 24-36 hours if you stay overnight. London NHS and private centres increasingly run safe day-case protocols.
• When it takes longer: revision knees (2-4+ hours skin-to-skin), severe deformity or stiffness, BMI over 40, major scar tissue, bone grafts, or bilateral knees (both knees in one sitting can be 3-4 hours skin-to-skin).

What the big bodies say: the American Academy of Orthopaedic Surgeons typically quotes 1-2 hours for the operation; the UK’s NHS patient info notes around one to two hours for surgery and emphasises that full theatre time is longer. UK joint registries and audit reports show most primary total knee replacements cluster around the 60-90 minute mark for the surgical portion.

Step-by-step: Your surgery day timeline (with realistic times)

Use this door-to-door walk-through to plan your day and set expectations for family waiting at home.

1. Arrival and check-in (60-90 minutes)
   Paperwork, changing into a gown, ID checks, site marking, and a last chat with your surgeon and anesthetist. If you’re diabetic or have complex meds, this part can run longer as the team fine-tunes your plan.

2. Anesthesia (15-40 minutes)
   Most UK centres use a spinal anesthetic with sedation. The spinal itself often takes 5-10 minutes; add monitoring, IV lines, antibiotics, blood-thinner timing, and oxygen. If you have general anesthesia, the setup and airway can take similar time. Regional nerve blocks (for pain control) add about 10 minutes but pay off later.

3. Positioning and sterile prep (10-20 minutes)
   Your leg is cleaned and draped, a tourniquet may be applied, instruments and implants are checked. Robotic or navigation systems add set-up steps, especially early in a team’s learning curve.

4. The operation: skin-to-skin (60-90 minutes typical)
   Incision to dressing. Straightforward knees often come in around an hour. Complex anatomy, deformity, or dense scar tissue asks for more time. Cemented implants are common in the UK and go quickly once cuts are made; cementless may add a few minutes for press-fitting and trial checks.

5. Closing and dressings (10-15 minutes)
   Final checks, closure, waterproof dressing, and sometimes a knee X-ray in theatre or in recovery.

6. Recovery room (PACU) (60-120 minutes)
   Waking up, pain relief fine-tuning, drink of water, sandwich if you’re day-case, and the first assessment from physio. If spinal anesthesia was used, you’ll feel the legs come back over 1-3 hours. Oxygen and monitors stay on until you’re steady.

7. Ward time and first walk (1-4 hours day-case; overnight if admitted)
   Most patients stand and take a few steps with a physio the day of surgery. You’ll practice getting in/out of bed, using stairs if needed, and managing pain meds. If you clear the safety checks and feel well, discharge the same day is now common in many UK centres. If not, one night is normal.

Rule of thumb for family pick-up: if your list time says 9:00 am, expect “ready to go” no earlier than 3:00-5:00 pm for day-case. Always add a buffer for delays and list shuffles.

What changes the clock: factors, scenarios, and trade‑offs

Not all knees are equal. Here’s what makes your time longer or shorter - and what it means for pain, safety, and going home.

• Primary vs. revision surgery
  Primary (first-time) knees are the benchmark: 60-90 minutes skin-to-skin. Revision knees can take 2-4+ hours depending on removing old implants, bone loss, and specialist stems or augments. More time often means more fluid, careful cement removal, and extra X-rays. Expect an overnight stay, sometimes two.

• Bilateral (both knees same day)
  Additive times. Two straight-forward knees often run 2.5-3.5 hours skin-to-skin combined, plus extra anesthesia and recovery time. Some centres prefer staged (one knee, then the other weeks later) for safety if you have significant heart or lung disease.

• Robotic or computer‑navigated assistance
  Early in a team’s learning curve, setup and mapping can add 10-25 minutes. Once slick, the total time often matches manual surgery. The goal is alignment and soft-tissue balance, not speed. If your surgeon uses robotics regularly, it shouldn’t noticeably prolong your day.

• Spinal vs. general anesthesia
  Spinal with light sedation often shortens the groggy period afterward and can reduce nausea. The on-table time is similar. With general anesthesia, waking can add 10-20 minutes in PACU for some patients. The Royal College of Anaesthetists supports either approach; choice hinges on your health, preference, and anesthetist’s view.

• Body size, stiffness, and deformity
  BMI over 40, previous fractures around the knee, or a very tight, stiff joint can add 15-45 minutes. More careful exposure and soft-tissue releases are the usual reasons.

• Bleeding and anticoagulants
  Operating teams plan for blood thinners. Tranexamic acid and modern protocols keep blood loss low. If your anticoagulant plan is complex, anesthesia prep may be longer and drain or hemostasis checks more meticulous.

• Implant choice and cement
  Cemented implants are standard in the UK and fast to seat once surfaces are ready. Uncemented or hybrid options are also common and don’t dramatically change time in experienced hands.

• List position and hospital workflow
  If you’re second or third on the list, add 30-90 minutes of potential drift. Turnover between cases, equipment issues, or unplanned complexity in the case before you are normal reasons.

For context and credibility: AAOS patient guidance still quotes roughly one to two hours for the surgical portion in 2025. NHS trusts across England report median “theatre time” for primary total knee replacement that lands around the two-hour mark including anesthesia and setup, with fast-track pathways pushing same-day discharge for suitable patients. The National Joint Registry (NJR) data and UK GIRFT audits show shorter lengths of stay in recent years, thanks to standardized anesthesia, tranexamic acid, and rehab bundles.

Cheat-sheets, examples, and quick answers (FAQ + checklists)

Here’s the practical stuff you’ll actually use when planning your day, calming nerves, and getting home safely.

Example timelines

• Simple primary knee, first on the list (day-case)
  07:00 arrive → 08:30 anesthesia → 08:45 skin-to-skin → 09:45 closure → 10:00 PACU → 11:30 ward → 13:30 walk with physio → 15:00 discharge. Total hospital time: ~8 hours.

• Primary knee, second on the list (overnight)
  10:00 into theatre → 12:30 out → 14:00 ward → 16:00 first walk → next morning discharge by 10:00. Total in-hospital time: ~24 hours.

• Revision knee with bone work
  08:30 into theatre → 12:00 out → PACU until ~14:00 → ward → usually 1-2 nights inpatient. Family should expect 5+ hours from theatre call to PACU exit.

• Bilateral knees, same day
  08:30 into theatre → 12:00 out → PACU until ~14:00 → ward → often 1-2 nights. Some centres will only offer this to leaner, fitter patients.

Quick heuristics (rules of thumb)

• Skin-to-skin: think 1-1.5 hours for a first-time knee.
• Operating room total: double the surgical time and add 15-30 minutes.
• PACU: budget 1-2 hours; longer if nausea-prone or after general anesthesia.
• List drift: if you’re not first, add 30-90 minutes of “unknowns.”
• Family pickup: plan a 2-hour window, not a single time. Bring a book and phone charger.

Patient checklist (time-proof your day)

• Confirm: arrival time, list order, and expected discharge (day-case vs overnight) 24-48 hours before surgery.
• Medications: clarify blood thinners, diabetes meds, and blood pressure pills with your pre-op team. Write it down.
• Fasting: stick to the exact fasting instructions. Clear fluids are often allowed up to two hours pre-op, but follow your hospital’s rules.
• Pack light: slip-on shoes, loose shorts, phone charger, simple toiletries, and your CPAP if you use one.
• Home setup: clear trip hazards, prep a chair with arms, freeze a few meals, and place frequently used items at waist height.
• Ride home: arrange a responsible adult to collect you; rideshare drivers are not a safe plan post-anesthesia.

Partner/family checklist (so you’re not guessing all day)

• Ask for the theatre call time when they’re taken down; add 2-3 hours to estimate “out of theatre.”
• Expect radio silence: phones are off in theatre/PACU. The ward will update once they’re back.
• Pick-up window: plan a 2-hour window. Parking and pharmacy can add 30-60 minutes.
• Prepare home: remove rugs, set up ice packs, and stage pillows for leg elevation.

FAQ

• Does spinal anesthesia make the day shorter?
  Often, yes, in the recovery phase. Spinals can mean less nausea and a faster first walk. Theatre time is similar either way.

• Is robotic knee replacement slower?
  Early on, it can add 10-25 minutes. Experienced teams usually match manual times. The purpose is precision, not speed.

• Why do some people finish in under an hour?
  Favourable anatomy, slim soft tissues, and a very experienced team. It’s not a race; safe, accurate cuts and balance matter most.

• How long is the tourniquet on?
  Often 45-70 minutes for primary knees. Some surgeons skip a tourniquet altogether, using careful hemostasis and tranexamic acid.

• When will I walk?
  Usually the day of surgery. A physiotherapist will get you standing and stepping with a frame or crutches, often within hours.

• How long will I be in hospital?
  Day-case is increasingly common for suitable patients. Many others stay one night. Revisions or bilateral knees often mean 1-2 nights.

• Does a longer surgery mean a worse outcome?
  Not by itself. Complexity can mean more time; what matters is good alignment, stable ligaments, and infection prevention. Audit data focus on outcomes, not speed.

• Are delays normal?
  Yes. Lists can overrun, previous cases can be complex, or a bed might free up late. It’s frustrating, but safety comes first.

Safety notes and sources (without the jargon)

• NHS patient pathways still quote roughly one to two hours for the operation, longer in theatre with anesthesia and prep.
• AAOS public guidance echoes that 1-2 hour range for the surgical portion.
• UK NJR and GIRFT reports show continued improvements in length of stay and standardised practices (spinal anesthesia, tranexamic acid), which help same-day protocols.
• Royal College of Anaesthetists guidance supports both spinal and general anesthesia for knee replacement; choice is individual.

Pro tips from the ward

• If you’re second on the list, assume a 60-90 minute drift in start time. Bring headphones.
• If you get carsick, tell anesthesia - they’ll pre-treat and that can save you an extra hour in PACU.
• Ask for your pain plan in plain English before theatre. Knowing the schedule for tablets and breakthrough meds keeps you on track to go home.
• Don’t chase zero pain. Aim for “tolerable and mobile.” Over-sedation slows discharge.
• Drink water when allowed. Hydration helps blood pressure and reduces nausea, speeding discharge checks.

When timelines change: troubleshooting different scenarios

• Your surgery starts late
  Ask the ward for a revised estimate. Update your ride. Eat and drink only if the team allows (they’ll protect fasting times). Bring a snack for your supporter; they’ll need it more than you.

• You wake up and feel very drowsy
  Normal after general anesthesia or heavy sedation. Don’t rush discharge tasks. Once you’re steady and pain is controlled, everything else follows.

• Nausea slows you down
  Say it early. Anti-sickness meds work fast and can cut an hour of misery in PACU and on the ward.

• Blood pressure is low/high
  Common after fluids, spinal anesthetic, or nerves. The team will adjust. Don’t worry if this adds time - safe discharge beats speed.

• Bed isn’t ready
  Occasionally PACU or ward bed flow causes a hold. It won’t affect your knee; it just stretches the clock. Use the time to review exercises with physio when they pass by.

Bottom line you can plan around

• Expect 2-3 hours in the operating room from wheels-in to wheels-out.
• Add 1-2 hours in recovery before the ward.
• Your total hospital day is typically 6-10 hours as a day-case, or about 24 hours with an overnight stay.
• Surgery itself is usually around an hour, give or take, unless it’s a revision or bilateral.

Speed isn’t the point; precision is. If your surgeon is calm and unhurried, that’s what you want. Plan your day with buffers, sort your ride home, and focus on the first walk - that’s the milestone that actually moves the needle.