Knee Replacement Surgery Day
Knee replacement surgery day usually begins several hours before the operation. Admission, identity and side confirmation, fasting and medicine checks, consent, anaesthetic assessment, infection-prevention measures and theatre preparation all occur before the first incision. Repetition of safety questions is intentional and should reassure rather than alarm the patient.
The exact sequence varies by hospital, medical condition, anaesthesia, robotic platform and whether the procedure is partial, total, bilateral or revision replacement. A patient may spend more time in admission, preparation and recovery than in the operation itself. Unexpected delays can occur because emergency cases and clinical safety take priority.
Patients who have not completed preparation should first read Preparing for Knee Replacement Surgery.
Quick Answer: What Happens on Knee Replacement Surgery Day?
The hospital confirms identity, operation, side, consent, fasting, medicines, allergies and current health. The surgeon and anaesthetist review the plan. Anaesthesia and preventive medicines are given, the team completes formal safety checks, the surgeon performs the selected replacement, and the patient is monitored in recovery before ward transfer and early mobilisation when medically safe.
Arrival and Admission
Identification, admission and insurance documents are checked
The planned operation and correct knee are reconfirmed
Fasting time and the last doses of medicines are documented
Allergies, blood thinners, diabetes medicines and previous anaesthetic problems are reviewed
Blood pressure, pulse, oxygen level, temperature and glucose may be checked
Any new fever, cough, urinary symptom, wound, rash or health change must be reported
Consent and Operative-Side Marking
Consent is a continuing discussion rather than a signature alone. Before sedation, the patient should have an opportunity to confirm the diagnosis, planned procedure, alternatives, expected benefits, important risks, implant considerations, anaesthesia, recovery and possibility that the operative plan may need to change for safety.
The surgeon normally marks the operative limb. Name, procedure and side are checked repeatedly by the ward, anaesthesia and theatre teams. Patients should speak up immediately if any detail appears incorrect.
Meeting the Anaesthetist
The anaesthetist reviews medical conditions, airway, heart and lung status, sleep apnoea, previous anaesthesia, nausea, pain medicines, allergies, fasting and relevant tests. The proposed anaesthetic and pain plan is explained. The final choice depends on safety, patient preference and the operative pathway.
Option A: Spinal or regional anaesthesia
A spinal injection temporarily numbs the lower body. Sedation may make the patient relaxed, drowsy or asleep-like without requiring a full general anaesthetic. Suitability depends on anticoagulants, spinal anatomy, infection, neurological factors and anaesthetic assessment.
Option B: General anaesthesia
General anaesthesia produces unconsciousness and requires continuous airway, breathing and circulation management. It may be combined with local infiltration or a peripheral nerve block for pain control. Neither option is automatically best for every patient.
Nerve Blocks and Multimodal Pain Control
Pain control may combine paracetamol, anti-inflammatory medicine when suitable, local anaesthetic infiltration, nerve block, steroids or other adjuncts and limited opioid medicine. The objective is not to promise a painless operation; it is to provide enough comfort for breathing, sleep, movement and rehabilitation while minimising nausea, sedation and motor weakness.
The patient should disclose chronic opioid use, pain sensitivity, medication intolerance and previous severe nausea because these can change the plan.
Before Entering the Operating Theatre
An intravenous line is inserted for fluids and medicines
Preventive antibiotics are timed according to protocol
Tranexamic acid may be used to reduce blood loss when appropriate
The operative leg and skin condition are checked again
Dentures, contact lenses, jewellery and personal devices are handled according to hospital policy
Theatre Safety Checks
The team performs a formal pause before surgery to verify the patient, operation, side, antibiotics, allergies, imaging, equipment, implants and important medical risks. NICE recommends two implant “stop moments”—one before implantation and another before wound closure—to confirm component identity and compatibility.
Monitoring equipment is attached, the patient is positioned with pressure areas protected, and the leg is cleaned and draped using sterile technique. A tourniquet may or may not be used depending on the surgeon, anaesthesia, procedure and patient factors.
What Happens During Total Knee Replacement?
The surgeon exposes and inspects the knee
Controlled bone and cartilage preparation is performed
Implant size, position, rotation and alignment are planned and checked
Trial components assess movement, stability and ligament balance
Final components are fixed with cement or cementless fixation as planned
Patellar tracking and final range are reassessed
The wound is closed and covered with a sterile dressing
What Happens During Partial Knee Replacement?
Partial replacement resurfaces one compartment while retaining suitable structures elsewhere. The surgeon verifies that the arthritis pattern, ligaments and remaining compartments support the preoperative plan. If unexpected widespread disease or instability is found, conversion to the agreed alternative may be considered when this was discussed during consent.
Read Total vs Partial Knee Replacement.
What Happens During Robotic-Assisted Knee Replacement?
Depending on the platform, the surgeon uses a preoperative CT model or maps anatomical landmarks during surgery. Temporary trackers allow the system to recognise the bones. Registration accuracy is checked before the plan is used. The surgeon reviews implant size, resection levels, alignment and estimated ligament gaps and then controls the guided instruments or robotic arm.
The system does not decide the diagnosis, implant or surgical approach and does not operate independently. If registration is unreliable or equipment fails, the team may troubleshoot or safely continue using conventional instruments. Read Robotic vs Conventional Knee Replacement.
The Mini-Subvastus Approach on Surgery Day
The mini-subvastus approach describes how the surgeon accesses the joint. The operative plane passes beneath the vastus medialis while respecting the quadriceps mechanism when clinically suitable. It is separate from robotic planning and does not mean the robot makes the incision.
Dr. Mayur Rabhadiya combines robotic planning with a minimally invasive mini-subvastus approach in suitable patients. Exposure must remain safe; deformity, stiffness, body habitus, previous surgery and anatomy can require modification or extension. Incision length alone is not a measure of surgical quality.
How Long Does the Operation Take?
A primary knee replacement commonly takes approximately one to two hours of operative time, but total theatre time is longer because anaesthesia, positioning, preparation and transfer are included. Partial replacement may be shorter, while severe deformity, bilateral or revision surgery may take longer. Speed is not a quality measure; safe and accurate completion is more important.
Blood Loss, Transfusion and Drains
Modern blood-conservation pathways may include preoperative anaemia treatment, tranexamic acid, careful technique and postoperative monitoring. Blood transfusion is not routine for every patient and depends on symptoms, haemoglobin, ongoing loss and medical condition. A wound drain or urinary catheter is not required for every uncomplicated primary replacement; use depends on the pathway and individual need.
What Happens in the Recovery Room?
Breathing, oxygen, heart rate and blood pressure are monitored
Pain, nausea, sedation and temperature are assessed
The dressing, circulation, sensation and movement are checked
Blood tests or X-rays may be obtained according to the hospital pathway
Fluids and medicines are adjusted before ward transfer
Temporary numbness or weakness can occur after spinal anaesthesia or nerve block and is monitored until safe movement returns. Patients should not attempt to stand without staff assistance.
Eating, Drinking and Passing Urine
Fluids and food are restarted when the patient is awake, stable and not excessively nauseated, following anaesthesia and hospital instructions. Urine output is monitored. Difficulty passing urine can occur after spinal anaesthesia, medicines or surgery and may require temporary bladder assessment or catheterisation.
When Does Walking Begin?
NICE recommends rehabilitation on the day of surgery when possible and no later than 24 hours after primary joint replacement. Walking begins when blood pressure, sensation, muscle control, pain and medical status are safe. A physiotherapist or trained team member teaches bed transfers, standing and walker or crutch use.
Early walking does not mean independent walking without support. Timing varies, and delaying mobilisation for dizziness, motor weakness, bleeding or another safety concern is appropriate. Read Walking After Knee Replacement.
Blood-Clot Prevention Begins Early
Prevention may include early mobilisation, ankle exercises, compression devices and anticoagulant medicine selected according to bleeding and clotting risk. The exact medicine and duration vary. New calf swelling, chest pain, breathlessness or collapse requires urgent assessment.
When Can Surgery Be Delayed or Cancelled on the Day?
Fasting instructions were not followed
A blood thinner or other medicine was taken contrary to the safety plan
New infection, fever, chest symptoms, skin wound or unstable medical problem is found
Essential implant, equipment, imaging or blood support is unavailable
A safety check identifies a mismatch or unresolved consent issue
Emergency cases or operational problems make safe surgery impossible that day
Cancellation is disappointing but can be the correct medical decision. The team should explain the reason and next steps where possible.
Questions Patients Commonly Ask
Will I be admitted on the same day?
Many elective patients are admitted on the day of surgery, but hospital and medical requirements vary.
Why is the same question asked repeatedly?
Repeated identity, side, allergy and procedure checks are deliberate safety barriers.
Can I change my mind on surgery day?
Consent can be withdrawn before the operation. Discuss concerns before sedation so the decision remains informed.
Will I be awake during spinal anaesthesia?
You may be awake or receive sedation. The anaesthetist tailors the level of sedation to safety and preference.
Which is safer—spinal or general anaesthesia?
Neither is universally safer for every person. The anaesthetist considers medical history, medicines, anatomy and procedure.
Will the operation be painless?
Anaesthesia prevents operative pain, but postoperative discomfort is expected and managed through a multimodal plan.
Does the robot perform the operation?
No. The surgeon registers, plans, controls and performs the procedure. The robotic system assists selected steps.
Does the robot decide the surgical approach?
No. The mini-subvastus or another exposure is selected and performed by the surgeon.
Can a planned partial replacement become total?
It may be necessary if unexpected widespread arthritis or instability is found, provided this possibility was discussed during consent.
Will I need a blood transfusion?
Most patients do not automatically require one. The decision depends on blood loss, haemoglobin, symptoms and medical health.
Will I have a urinary catheter or wound drain?
Not routinely in every uncomplicated case. They are used when the surgical, anaesthetic or recovery situation requires them.
How soon will I see my family?
After recovery-room monitoring and ward transfer, subject to hospital visiting and clinical policies.
When can I eat after surgery?
Food and fluids restart when you are awake, stable and not significantly nauseated, according to the anaesthesia plan.
Will I walk on the same day?
Many patients do when medically safe, but dizziness, numbness, weakness, bleeding or other concerns may appropriately delay walking.
How long will I stay in hospital?
Discharge depends on medical stability, pain control, walking, wound status, home support and the hospital pathway rather than one fixed number of days.
What happens after the first night?
Monitoring, medicines, wound checks, walking, exercises and discharge planning continue. Read Hospital Stay After Knee Replacement.
Clinical References and Further Reading
NICE NG157: Anaesthesia, infection prevention, implant checks and postoperative rehabilitation
NHS: How a Knee Replacement Is Done
AAOS OrthoInfo: Total Knee Replacement
About Dr. Mayur Rabhadiya
Dr. Mayur Rabhadiya is an Orthopedic and Joint Replacement Surgeon in Mumbai. His focused knee practice includes total and partial replacement and minimally invasive mini-subvastus robotic knee replacement when clinically indicated. Robotic assistance supports planning and execution; Dr. Rabhadiya performs the operation and decides the approach, alignment, implant and soft-tissue strategy. His qualifications are MBBS, D’Ortho, DNB (Orthopedics), MNAMS (Orthopedics) and FIJR (Robotic & Navigation).
Last medically reviewed: 24 July 2026. Medical reviewer: Dr. Mayur Rabhadiya.
Book a Knee Replacement Consultation in Mumbai
Patients seeking clarity about surgery-day planning, anaesthesia, robotic assistance, the mini-subvastus approach or total versus partial replacement can consult Dr. Mayur Rabhadiya in Ghatkopar East or Ghatkopar West, Mumbai. Call or WhatsApp +91 84249 03913 or +91 96113 30063, or use the orthopedic appointment page.
Medical Disclaimer
This guide provides general education and does not replace the treating surgeon, anaesthetist or hospital protocol. Admission, anaesthesia, medicines, operative steps, mobility and discharge vary by diagnosis, health, procedure and clinical events on the day.