Orthopaedics
Spinal anaesthesia for hip and knee joint replacement surgery
Patient Information Leaflets
Introduction
This leaflet is for people who are having hip and knee joint replacement surgery. It gives information about the spinal anaesthesia used during the operation, including how the anaesthetic is given and the advantages and risks of it.
For many operations, patients receive a general anaesthetic and remain anaesthetised (asleep) during the operation. Operations below the waistline such as hip and knee surgery are suitable for a spinal anaesthetic (a ‘spinal’) which has benefits for you. Spinal anaesthesia is a safe technique and it allows for a quick and comfortable recovery.
A spinal involves a local anaesthetic drug being injected through a needle into the small of your back to numb the nerves from the waist down to the toes for two to three hours. You will feel no pain during the operation. You can normally choose to remain fully conscious (awake) or have some drugs which make you feel sleepy and relaxed (sedation).
What are the benefits of a spinal anaesthetic?
What happens before my surgery?
Before your surgery an anaesthetist will see you and will review your medical and anaesthetic history. They will discuss the anaesthetic with you and answer any questions you may have. If the anaesthetist decides a spinal anaesthetic is not appropriate for you, or you are not happy with this type of anaesthetic, they will discuss general anaesthesia with you.
How is the spinal performed?
The spinal is performed in the anaesthetic room by the anaesthetist. You will meet an anaesthetic assistant who will stay with you during your time in the theatre. A needle will be used to insert a thin plastic tube (a cannula) into a vein in your hand or arm.
The staff looking after you will help you get into the correct position for the spinal. You will be asked to wear paper pants and a gown provided by the hospital. The gown will cover you at all times to maintain your dignity.
You will either sit on the side of the bed with your feet on a low stool or lie on your side, curled up with your knees tucked up towards your chest. In either case, the staff will support and reassure you during the injection.
The anaesthetist will explain what is happening throughout the process so that you are aware of what is taking place ‘behind your back’.
The anaesthetist will spray your back with antiseptic solution which can feel cold. They will then find a suitable point in the middle of your lower back and will inject a small amount of local anaesthetic into your skin to numb it.
A fine spinal needle is placed into your back. Sometimes, you may feel a tingling or electric shock down one leg. You should let the anaesthetist know if this happens but it is important that you keep still while the spinal is being put in.
When the needle is in the right position, local anaesthetic and a pain relieving drug will be injected in and the needle is then removed. Usually, a spinal should cause you no unpleasant feelings and should take only a few minutes to set up.
When the injection is finished, you will lie on your side for a few minutes and then lie flat. The spinal is usually effective within five to 10 minutes. Initially, you get a warm, tingling sensation in your bottom and legs. Your skin gradually feels numb to touch and your leg muscles get weaker and feel heavy.
When the injection is fully working, you will be unable to move your legs or feel any pain below the waist. The anaesthetist will check the spinal and make sure you are ready for the operation. Your blood pressure will be taken regularly.
What happens during the operation?
During the operation, you will be given oxygen to breathe through a lightweight, clear plastic mask to improve oxygen levels in your blood. If you choose to have sedation with the spinal, a sedation pump will be started.
A screen is placed across your upper chest so that you see nothing when surgery starts. You will be aware of the ‘hustle and bustle’ of the operating theatre when you come in. However, once surgery starts, noise levels drop and if you are sedated, you may fall asleep.
What happens after the operation?
When the operation is over, you will be taken to the recovery area where you will be monitored by nurses.
It can take up to four hours for feeling to return to your legs. As sensation returns, you may experience some tingling in the skin as the spinal wears off. At this point, you may become aware of some pain from the operation site. You should ask for more pain relief before the pain becomes too bad.
You can normally drink fluids within an hour of the operation and may also be able to eat a light meal.
What are the advantages of having a spinal?
- As blood pressure is lowered when you have a spinal, blood loss is less during surgery and there is therefore less need for blood transfusions.
- Less risk of blood clots forming in the legs.
- Less risk of chest infections after surgery.
- Less effect on the heart and lungs.
- Excellent pain relief immediately after surgery.
- Less need for strong pain relieving drugs.
- Less sickness and vomiting.
- Earlier return to drinking and eating after surgery.
- Less confusion after the operation, particularly in older patients.
What are the side effects and complications of a spinal?
Common side effects
- Headache – one in 100 people may develop a headache after the spinal wears off.
- Low blood pressure – as the spinal takes effect, it can lower your blood pressure and make you feel sick. This can be controlled with the fluids given by the drip, and by giving you drugs to raise your blood pressure.
- Itching which can be treated with antihistamines.
- Difficulty passing water – however, your bladder function will return to normal after the spinal wears off.
Rare complications
Nerve damage is a rare complication of spinal anaesthesia. Temporary loss of sensation, pins and needles and sometimes muscle weakness may last for a few days or even weeks. However, almost all people experiencing this make a full recovery in time. It occurs in about one in 1,000 cases. Permanent nerve damage is very rare and occurs in about one in 10,000 cases.
Can I find out more?
You can find out more on the website:
If you have any questions, or if there is anything you do not understand, please contact the Russells Hall Hospital switchboard number on 01384 456111 and ask for the relevant department who issued this leaflet.
If you have any feedback on this patient information leaflet please email dgft.patient.information@nhs.net.
This leaflet can be made available in large print, audio version and in other languages, please call 0800 073 0510.
Originator: Dr Catherine Brennan, Consultant Anaesthetist. Date reviewed: October 2025. Next review due: October 2028. Version: 4. DGH ref: DGH/PIL/0354.