A guide to preparing for knee replacement surgery. The type of replacement (unicompartmental or total) will be confirmed after review of your X-rays and examination.
ℹ️ This appointment takes place 2-4 weeks before surgery. Blood tests, ECG, MRSA screening, and a full medication review are performed.
Knee replacement is performed under general or spinal anaesthetic. Unicompartmental replacement takes approximately 60 minutes; total knee replacement takes approximately 90-120 minutes.
Routine health checks before anaesthetic.
Blood thinners must be paused. NSAIDs stopped 1 week before surgery.
Nasal and groin swabs. Decolonisation treatment if positive.
Raise toilet seat, install grab rail in shower, arrange ground floor sleeping if possible for the first 2 weeks.
If you have had a knee injection within the last 3 months, inform your surgical team. Recent injection increases infection risk.
ℹ️ You will be given a specific arrival time. Do not eat or drink (other than clear water up to 2 hours before) from midnight the night before. Bring your medication list and any documents sent by the hospital.
You will be admitted to the ward or day surgery unit, change into a gown, and be seen by the nursing, anaesthetic, and surgical teams before theatre.
Your surgeon will confirm the procedure, mark the operative side, and you will sign a consent form before going to theatre.
You will meet the anaesthetist in the anaesthetic room. Once anaesthesia is established, the procedure will begin.
After surgery you will wake in the recovery room where nurses monitor your vital signs until you are stable and comfortable.
Most patients having arthroscopic or day-case procedures go home on the day of surgery. Those having joint replacement typically stay 1–2 nights. Before discharge, the team will check your pain is controlled, give you wound care instructions, and confirm your follow-up appointment.
You will be given oral pain relief before discharge. Take it regularly for the first 48 hours rather than waiting until pain is severe.
A nurse will check the wound before you leave and explain how to keep it clean and dry.
You will receive a letter for your GP and details of your next outpatient appointment - usually at 2 weeks for a wound check.
Arrange for a family member or friend to collect you. You must not drive on the day of surgery if you have had a general anaesthetic or sedation.
⚠️ Important: Urgent signs of infection: increasing warmth, redness, discharge from the wound, fever over 38°C, or sudden severe increase in pain. These require immediate assessment.
Avoid getting the wound wet until it is fully healed - usually 10–14 days. Use a waterproof cover or cling film when showering.
Do not wait until pain is severe before taking medication. Regular simple analgesia (paracetamol, ibuprofen if appropriate) is more effective.
This is usually 2 weeks after surgery. Sutures or clips will be removed if used.
Seek urgent advice if you develop increasing redness, warmth, swelling, discharge from the wound, or a temperature above 38°C - these may indicate infection.
Blood tests, MRSA screen, medication review, home preparation.
60-120 minutes in theatre. Hospital stay 2-4 nights.
Walking with a frame from day 1. Active knee bend exercises begin immediately.
Quadriceps strengthening, knee bend recovery. Stitches out at 10-14 days.
Driving, swimming, cycling. Full recovery takes 6-12 months.
Unicompartmental (partial) knee replacement resurfaces one compartment of the knee and is a smaller operation with faster recovery. Total knee replacement resurfaces all three compartments. The best option for you depends on the pattern of your arthritis on X-ray and MRI.
Modern knee replacements last over 15 years in more than 90% of patients. Unicompartmental replacements have slightly higher revision rates but higher patient satisfaction in appropriate candidates.
Kneeling is possible but can be uncomfortable after knee replacement. Approximately 50-60% of patients can kneel. This should not be a reason to avoid surgery if pain is severe.
The primary aim of knee replacement is significant pain relief and improved function. Unicompartmental replacement has higher satisfaction rates in appropriately selected patients. Total knee replacement achieves significant improvement in over 85% of patients.
Unicompartmental knee replacement: through a smaller incision, only one compartment (usually the medial) is resurfaced with a metal femoral component and a polyethylene tibial component. The ACL must be intact. Total knee replacement: all three compartment surfaces are resurfaced through a midline incision. Both are performed under general or spinal anaesthetic.
If disease involves more than one compartment, total knee replacement is more appropriate than unicompartmental replacement.
If disease is confined to one compartment and the ACL is intact, unicompartmental replacement offers faster recovery and higher satisfaction in appropriate patients.
For younger, active patients with isolated medial compartment disease, realignment osteotomy may delay the need for replacement.
If symptoms are tolerable, continued non-operative management is appropriate.
Deep infection is the most feared complication. Requires removal of the implant, prolonged antibiotics, and staged revision in most cases.
Blood clot in the leg or lungs. Anticoagulation given after surgery.
Insufficient range of motion after knee replacement. Manipulation under anaesthetic may be required at 6-8 weeks.
A significant proportion of patients have persistent pain after technically successful total knee replacement. This risk is lower for unicompartmental replacement in appropriate patients.
Loosening, wear, or fracture may require revision surgery.
Unicompartmental replacements may require conversion to total knee replacement due to disease progression in other compartments or implant failure.
Expected in the early post-operative period. The knee may remain swollen for 3-6 months.
Numbness lateral to the scar is common due to division of small sensory nerves. Usually permanent.
Minor clicking is common and not harmful.
Knee osteoarthritis does not improve spontaneously. Non-operative management can control symptoms for a variable period. The decision to proceed with knee replacement is made when symptoms and functional limitation are severe enough to justify the procedure and its recovery period, and non-operative measures have been fully tried.