Having an anaesthetic:
What to expect before, during, and after your knee surgery
Having an anaesthetic for knee surgery can feel daunting if you haven't experienced it before. Our comprehensive anaesthetic guide explains exactly what happens at each stage – from your pre-operative assessment and consent process through to recovery – so you feel fully informed and confident. Whether you're undergoing keyhole knee surgery, ACL reconstruction, knee arthritis treatment, or total knee replacement, we walk you through everything you need to know to prepare for your procedure safely and with peace of mind.
Dr Alexander Jones
(MBBS BSc MMedSci FRCA PgCert)
Alex is a Consultant Anaesthetist who holds a full time NHS position at University Hospitals Bristol and Weston NHS Trust, and practices privately at both the Spire and Nuffield Hospitals in Bristol. He qualified in 2011 and completed his specialist training in the Peninsula and Severn Deaneries, before completing two specialist fellowships in Adelaide, Australia; - one in Regional Anaesthesia and another as a “flying doctor” in Pre-Hospital & Retrieval Medicine.
Alex has developed expertise in regional anaesthesia and an interest in short-stay arthroplasty surgery. He is a Fellow of the Royal College of Anaesthetists (FRCA) and holds a Postgraduate Certificate in Regional Anaesthesia from the University of East Anglia, alongside a Master's in Medical Education from Karolinska Institutet, Stockholm.
Based in the Chew Valley with his wife and cocker spaniel Fergus, Alex balances hospital life with country walks, cycling the Mendips, and supporting Bristol Rugby (through thick and thin).
Dr John Hickman
(MBChB FRCA PGCMEd)
John is a Consultant Anaesthetist who holds a full time NHS position at University Hospitals Bristol and Weston NHS Trust, and practices privately at both the Spire and Nuffield Hospitals in Bristol. He qualified in 2011 from the University of Bristol and completed his specialist training in the London and Severn Deaneries. He completed a year fellowship in Perth, Australia; specialising in Regional Anaesthesia, Acute Pain Medicine and Orthopaedic Anaesthesia.
John has a passion for regional anaesthesia and acute pain medicine with an expanding interest in day case arthroplasty. He is a leader in the field of sustainable healthcare and is working hard to minimise the impact healthcare has on the environment. He is a Fellow of the Royal College of Anaesthetists (FRCA) and holds a Postgraduate Certificate in Medical Education from the University of Dundee.
He is based outside Bristol with his wife and two young boys, when time allows he loves getting in the water, being a keen surfer and wing foiler.
This happens in the weeks building up to surgery. This process ensures that we identify any medical issues or required changes to medications early, helping to plan the safest anaesthetic for your surgery. In the pre-op clinic, a specialist nurse will:
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Review your full medical history (e.g. heart/lung conditions, diabetes), current medications, (please bring a list), and check if you have any allergies
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Arrange for necessary investigations (e.g. blood tests, heart tracing/ECG, MRSA swabs)
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Discuss previous anaesthetic experiences
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Seek advice from a consultant anaesthetist if there are any issues
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A consultant anaesthetist will review your notes and ensure you are optimised for surgery
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Anaesthesia is the name given to the process that causes a loss of feeling or awareness, and it is given to remove pain around surgery. This can be provided in a number of different ways. The anaesthetic is tailored to your surgery, any relevant medical conditions and the your individual preferences. The types of anaesthetic commonly used for knee surgery are:
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General anaesthesia
This is ‘going to sleep’, and being fully ‘unconscious’. This is achieved by using anaesthetic medications that are either a gas delivered via a mask, or liquids delivered into the vein. via a cannula (small plastic tube) Usually intravenous anaesthetic is used, which has been shown to reduce nausea and vomiting. -
Spinal anaesthesia
This is numbing the nerves to the legs via an injection into back. It is often referred to by patients as an epidural (though technically not correct, it is very similar). Spinal anaesthetic is often combined with sedation to make you sleepy, but if you prefer you can be wide awake throughout. There may be circumstances where a ‘spinal’ is not appropriate or feasible e.g. previous back surgery. In such cases, the operation can be performed under a general anaesthetic and nerve blocks -
Peripheral nerve blocks
This involves injecting anaesthetic around the nerves above the knee to block their feeling. This is performed under ultrasound image guidance, to ensure that it is only blocks the intended nerve (commonly saphenous or sometimes femoral) -
Local anaesthsia
This is performed by the surgeon, and involves injecting anaesthetic into the skin and soft tissues around the the surgical area to block the small nerves in that area. It is performed during the surgery, so that you wake up comfortable.
The table below is a guide as to the types of anaesthesia we often provide for different knee operations:
Type of Surgery
Anaesthetic Plan
Arthroscopy +/- meniscus or cartilage Surgery
General anaesthesia
+ Local anaesthesia around the keyhole surgical sites
ACL reconstruction
General anaesthesia
+ Ultrasound nerve block to nerves supplying the front of the knee
+ Local anaesthesia around the surgical site
MPFL reconstruction
General anaesthesia
+ Ultrasound nerve block to nerves supplying the front of the knee
+ Local anaesthesia around the surgical site
Tibial tubercle osteotomy (TTO)
General anaesthesia
+ Ultrasound nerve block to nerves supplying the front of the knee
+ Local anaesthesia around the surgical site
Distal femoral osteotomy (DFO)
General anaesthesia
+ Ultrasound nerve block to nerves supplying the front of the knee
+ Local anaesthesia around the surgical site
Knee replacement surgery
Spinal anaesthesia (often in combination with sedation) or general anaesthesia
+ Ultrasound nerve block to nerves supplying the front of the knee
+ Local anaesthesia around the surgical site
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On the day of surgery, both your surgeon and anaesthetist will visit you on the ward to:
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Check your health history and test results
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Explain the risks and benefits of anaesthetic techniques in a way that is relevant to you
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Discuss the potential anaesthetic options for your surgery, and agree with you on the best individualised anaesthetic plan
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Discuss pain control after surgery, whether you can have some water to drink if you are not first on the list, and whether you need to take some pain-relieving tablets prior to your operation, (known as premedication)
This is your opportunity to ask questions and talk about:
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Any fears or concerns you may have about the anaesthetic or pain relief plan
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Previous experiences with anaesthesia (often people have concerns about nausea)
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You preferences for sedation
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The anaesthetic room is an unfamiliar place for most people, and so we will endeavour to explain every step of the process to you on the day to put you at ease. Below is an outline of what to expect.
1. Final safety checks
Before any of the anaesthetic starts, we perform some safety checks. We will:
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Confirm with you your name, date of birth and hospital number
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Ask you to confirm what surgery you are having, and on which side
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Check that the correct surgical site is marked
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Ask again about any allergies
2. Getting prepared
A small plastic tube, called a cannula, is placed in your arm using a small needle. This allows medications and anaesthetic to be administered. Monitoring devices are attached (heart monitor, blood pressure cuff, oxygen sensor).
3. Going to sleep and/or getting numb for the operation
For general anaesthesia:
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Prior to giving general anaesthesia, you will breathe oxygen through a clear mask for 2-3 minutes. This is painless and helps keep you safe.
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You will receive anaesthetic medicine through your cannula, and gently drift off to sleep in seconds. We tend to use a modern intravenous anaesthetic which is shown to reduce nausea and vomiting.
For spinal anaesthesia:
- A local anaesthetic injection into the back takes place after numbing the skin. Once the numbing injection has occurred, we often usually combine the spinal anaesthesia with sedation or general anaesthesia depending on your preference.
For both:
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We routinely give strong pain-relieving medications, anti-inflammatory and several anti-sickness medications during the surgery.
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The environment is often cool when you arrive in the anaesthetic room, (as this helps to prevent surgical site infections), but we provide you with a warming blanket during the operation.
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We will protect your eyes from damage, (as you cannot blink for yourself under general anaesthesia). We aim to wake you up warm and comfortable in the recovery area but also have further medications in recovery if needed.
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Immediately after your surgery, you will be cared for in the recovery area. You may feel drowsy at first, which is normal. Nurses will monitor you closely, and pain will be carefully attended to.
When ready, you will then return to the ward. This is usually after about an hour. Prior to going home you will receive instructions about:
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Pain medications - We advise taking painkillers regularly for the first 48 hours at least (don't wait for severe pain to develop)
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Mobilising early (as per the physiotherapists instructions). This helps reduce pain and reduces the risk of post-op complications such as blood clots or pneumonia. In between periods of mobilisation, elevating the limb and using a cool compress or ice pack over the knee can be helpful for pain relief and to reduce stiffness.
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Taking laxatives to avoid constipation
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Whether you need to take any medications to prevent the formation of blood clots (DVTs). This is usually reserved for patients having a joint replacement procedure.
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Follow-up appointments
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Anaesthesia is increasingly safe, especially with modern drugs, techniques and highly trained teams. Having an anaesthetic and an operation is still not without risks, however. The below table presents the risks of anaesthesia related to an operation. If you are concerned about any of the risks, please discuss these in the pre-op clinic or with your anaesthetist. Most side effects are mild and temporary. Serious complications are rare, and your anaesthetist will take steps to minimise these risks. More detailed information on risks can be found here: https://www.rcoa.ac.uk/patients/patient-information-resources/anaesthesia-risk
Type of anaesthetic
Risk frequency
Common (>1%)
Less common (0.1 - 1%)
Rare (<0.1%)
General Anaesthetic (GA)
- Nausea / vomitting
- Sore throat / hoarse voice
- Damage to teeth
- Shivering
- Mild allergic reaction (rash)
- Scratch to surface of the eye
- Period of confusion or memory loss
- Chest infection
- Severe allergic reaction (anaphylaxis 1:10,000)
- Nerve injury due to positioning
- Cardiac arrest (1:10,000)
- Genetic based adverse reaction (1:100,000)
- Awareness under anaesthesia (1:136,000)
- Death (1:100,000 - 1:200,000)
Spinal Anaesthtic
- Failure and conversion to GA
- Low blood pressure
- Headache (PDPH, 1–3%)
- Backache
- Nausea/vomiting- Difficulty passing urine after surgery
- Localised infection at injection site
- Spinal canal blood clot or abscess damaging nerves to the legs (1:200,000)
Ultrasound peripheral nerve blocks
- Reduced effect or duration of block (failure)
- Bruising/pain at site- Vascular puncture (haematoma)
- Nerve injury:
-Temporary 1:4000
-Permanent 1:25,000
- Local Anaesthetic Systemic Toxicity (LAST)
- Infection or abscessWill I feel any pain during surgery?
No - you will either be completely unconscious or comfortably numb
What if I'm very nervous?
Tell us! We can provide reassurance as to what’s making you anxious and plan a good anaesthetic experience tailored to you.
How long until I feel normal after anaesthesia?
Most people feel much better within 24 hours
Can I eat before surgery?
You will be given specific fasting instructions from the pre-op assessment clinic nurses. (Usually nothing to eat for 6 hours before arriving in the hospital but you can have sips of water at least until you arrive in the hospital)
Patient information: Royal College of Anaesthetists: https://www.rcoa.ac.uk/patients
Preparing for surgery: Royal College of Anaesthetists: https://www.rcoa.ac.uk/patients/patient-information-resources/preparing-for-surgery
Royal College of Anaesthetists Video and Leaflet Resources: https://www.rcoa.ac.uk/patients/patient-information-resources/patient-information-leaflets-video-resources