Procedures › ACL reconstruction

Anaesthesia for ACL reconstruction

This page explains the anaesthetic and pain relief for anterior cruciate ligament (ACL) reconstruction, including the adductor canal block used to keep your knee comfortable after surgery. Your own plan is agreed with you before surgery.

Before surgery

• Fasting: No food for 6 hours before surgery. Clear fluids (water, black tea/coffee without milk, clear apple juice) are allowed until 2 hours before.
• Medications: Most regular medicines should be taken as usual unless advised otherwise. Blood thinners and some diabetes medications may require adjustments.
• Pre-operative consultation: I may contact you before surgery to discuss the anaesthetic plan and answer any questions if you would like this.

See our fasting guidance and medicines before surgery page for more detail.

Anaesthetic plan

For ACL reconstruction, your anaesthetic usually involves a combination approach to keep you comfortable during and after surgery:

• General anaesthetic (GA) - You will be fully asleep and unaware of the procedure.
• Adductor canal block - Local anaesthetic is injected near the nerves in the thigh using ultrasound. This provides pain relief in the front and inside of your knee without significantly weakening the leg muscles.
• Local anaesthetic from the surgeon - Additional numbing medicine is placed into the joint and tissues by your surgeon at the end of surgery.

Medications during surgery

• Strong pain relief (opioids): Medicines such as opioids are given through your drip during the operation and in post anaesthesia unit if needed.
• Dexamethasone (Dex): A steroid given during surgery to reduce inflammation, improve comfort, and limit nausea.
• Intravenous Parecoxib: An anti-inflammatory medicine given during surgery to reduce pain and swelling.
• Antiemetics: Medicines are also given to reduce the chance of nausea or vomiting afterwards.

After surgery

• Regular pain relief: Paracetamol and an anti-inflammatory are started straight after surgery.
• Additional pain medicines:
  • Tapentadol (Palexia) given regularly in sustained release formulations for 2 weeks and as needed for stronger pain.
  • Buprenorphine a longer-acting painkiller if extra support is required.
• Medicines are adjusted to balance comfort with safety and to minimise side effects.

Recovery and pain expectations

• The adductor canal block usually provides pain relief for the first 12-24 hours.
• As it wears off, your tablets will take over to keep you comfortable.
• It is normal to have moderate discomfort in the first 1-2 weeks, especially with physiotherapy and knee bending, but pain generally improves steadily after this.

Side effects

• Temporary leg weakness or numbness while the block is working.
• Drowsiness or nausea from stronger pain medicines - these are monitored and treated if they occur.
• Constipation can occur if opioids are needed - this is preventable with simple measures.

Safety and monitoring

• Your pain relief will be reviewed regularly by the nursing and anaesthetic teams.
• All medicines and techniques used are standard practice and tailored to you.
• Side effects are monitored, and adjustments are made as needed.