Fasting Instructions

No food or milk-containing fluids for 6 hours before your operation.

Please continue to drink clear fluids culminating up to 300ml two hours before surgery (water, clear fruit juice, black tea/ weak coffee).



Take all your usual medications.

If diabetic and taking insulin, take half your usual dose the night before and no insulin or diabetic tablets on the morning of your operation. If you are taking a “Gliflozin” diabetic tablet (Invokana, Forxiga, Xigduo or Jardiance), this should be ceased three days pre-operatively.

Discuss your use of blood thinners with Mr Buelow and Dr Brien Hennessy especially if you have cardiac stents or heart valve replacements. Aspirin can be continued. Paracetamol, Anti-Inflammatories and Pregabalin will usually be offered to all patients as a ‘pre-med’ (unless you have had prior problems with these medications).


Anaesthetic Plan

The typical anaesthetic sequence is listed below. This may be altered to suit your requirements. Firstly, all patients will be asleep for the operation with a full general anaesthetic, unless otherwise indicated/requested. In addition to this, we will use three types of local anaesthetic, the first two will be done before you go to sleep.

  1. A spinal injection
  2. A local anaesthetic catheter in your leg 
  3. A local anaesthetic in your knee joint, placed by the surgeon


Spinal Anaesthetic

This is a simple single injection in the lower back designed to keep your legs numb during the operation and for several hours afterwards. It is not an “epidural”. It is done in the sitting position or lying on your side. The main benefits of a spinal anaesthetic are total pain relief for several hours after the operation and a marked reduction in the amount of morphine-based pain medications used during this period. This often means fewer side effects relating to morphine medications such as nausea, drowsiness and itch. The effect of the injection is to put both legs to sleep so that you will not be able to feel or move them at all for a few hours. This is a very safe technique and complications are uncommon.  Serious complications are rare. The spinal anaesthetic is recommended but optional. It does not contribute to low back pain and is considered quite safe however if you do not wish to have this injection please discuss this with me. If you have had previous spinal fusion surgery it will be technically difficult and may not be offered.


Local Anaesthetic Catheter

This is a small catheter the size of a fishing line, which will be placed through your thigh muscle to lie next to a nerve supplying sensation to your knee using ultrasound guidance. The catheter will be connected to a portable pump, which will trickle local anaesthetic into your leg for 3 nights after your surgery. The effect is to reduce pain from your knee. Muscle strength may be affected by this infusion but should be sufficient to allow you to walk. You may feel a numb sensation around the knee and down the inside of your leg as far as the ankle while the infusion is running. The catheter will provide continuous pain relief in the background but you will need additional pain relief tablets. Please note that the pain catheter will not block pain from the back of the knee or the thigh muscles, which can be sore in the first 24 hours due to the application of a tourniquet during surgery. There will be additional analgesics ordered on an “if needed” basis. Simply speak with your nurse to access these if pain becomes problematic.


Direct Local Anaesthetic Injection

When you are asleep, the surgeon will inject local anaesthetic directly into your knee joint. This is very effective at reducing pain immediately after surgery.


After Your Operation

If you have had a spinal anaesthetic injection, you will wake up with numb legs and be unable to move them for at least 2-3 hours. As the spinal anaesthetic wears off you may notice some pain in your knee. For most people, it wears off gradually and they will be comfortable at rest. Occasionally the pain may come on quickly and can be severe. We understand this and will give you a slow release pain tablet, Tapentadol SR, as the spinal anaesthetic wears off.

If you do start to feel pain call the nurse for a pain tablet, usually an immediate release strong pain reliever such as Tapentadol IR.

There is a range of medications used to help with pain management: Paracetamol, Anti-Inflammatories, Pregabalin and Tapentadol. Taking a small dose of a combination of analgesics usually results in much better pain relief with fewer side effects than taking a lot of one analgesic. It is important that you get to understand the analgesic medications and how they make you feel as you will be taking some home to manage your pain following discharge from the hospital.

Most patients are relatively comfortable at rest but will experience moderate or occasionally more severe pain when bending the knee or walking. The most common pain score while walking is 4 out of 10 but the range is wide with some patients almost completely pain-free and others with moderate to severe pain. Approximately 1 in 20 will experience a lot more pain and consume more pain tablets than other patients. We have ward rounds daily by a pain team supervised by a pain specialist who can help make you more comfortable if needed.

For more information visit 


After Hospital Discharge

It is important that your pain is well managed and under control following discharge from the hospital. The aim is to reduce your pain to a level that allows you to walk and perform activities of daily living soon after discharge without too much discomfort. Generally when you are resting, your knee should feel relatively comfortable, however, you may experience an increase in pain with activities such as physiotherapy. Bending the knee is likely to be the most painful. Night pain and sleep disturbance may persist for several months but will steadily improve. Most patients will benefit from taking a balanced selection of pain medications including strong opioids during the first 2  weeks. Some patients will experience an increase in pain following discharge and will struggle to complete their physiotherapy.

If the pain becomes severe

  • Reduce your activity, rest and elevate the leg and apply ice packs.
  • Modify your exercises including physiotherapy that may be exacerbating the pain.
  • Take extra pain relief when needed to allow you to maintain your comfort and mobility

It is important that you understand what medications to use when you leave the hospital.


The First 2 weeks

  1. Paracetamol (Panadol, Panadol Osteo) daily on a regular basis,
  2. Anti-Inflammatories (Mobic, Celebrex, Nurofen etc.) daily on a regular basis for 5 days and “as needed” after that,
  3. Pregabalin twice a day or just at night. Should you experience side effects such as excessive drowsiness, you can reduce your dose or take only at night. If you do not tolerate this medication cease taking it,
  4. Tapentadol SR(Slow release) twice daily until your mobility is not significantly affected by pain. The initial dose is usually 50mg twice daily. This may be increased for some patients up to a maximum of 200mg twice daily.
  5. Tapentadol IR (Immediate release) 50mg as needed up to four times daily. This does not last long but may be useful for rapid onset pain relief before or after exercise. Alternatives such as Buprenorphine, Hydromorphone or Oxycodone may be prescribed as indicated.


 After 2 weeks

  1. Continue PARACETAMOL (Panadol or Panadol Osteo) on a regular basis until you no longer need any other pain medication
  2. Stop taking regular ANTI-INFLAMMATORIES if you are coping well. If you feel that you need to continue taking these please discuss with your doctor.
  3. Stop taking Pregabalin if your pain control is adequate and you no longer need Tapentadol. If pain at night is an issue it may be useful to continue taking Pregabalin at night until this improves.
  4. Reduce or stop using theTapentadol once your pain is under control.

If you are still having difficulties with pain management after two weeks please consult your surgeon or GP for further advice and assessment.