It's a good idea to make sure your general health is as good as it can be before your operation, for example if you have other health problems such as diabetes or high blood pressure. It’s also advisable to have a dental check-up and get any problems dealt with well before your knee operation. There’s a possible risk of infection if bacteria from dental problems get into the bloodstream.
Your orthopaedic surgeon will probably suggest exercises to strengthen the muscles at the front of your thigh (quadriceps), which often become weak with arthritis. The stronger these muscles are before surgery, the quicker your recovery is likely to be. Exercises that involve raising your foot against gravity are best.
You'll probably be invited to a pre-admission clinic a few weeks before surgery. You’ll be examined to make sure you’re generally well enough for the anaesthetic and the operation. This may include the following tests:
- blood tests to check for anaemia and to make sure your kidneys are working properly
- an MRSA swab to check that you’re not carrying resistant bacteria
- a urine sample to rule out infection
- an electrocardiograph (ECG) tracing to make sure your heart is healthy.
You should also discuss with your surgeon, anaesthetist or nurse whether you should stop taking any of your medications or make any changes to the dosage or timings before you have your surgery. Different units may have different views.
You’ll have the opportunity to ask questions about your operation and discuss anything you’re concerned about. Start planning for your return home and recovery arrangements.
You may also meet a physiotherapist or occupational therapist, who’ll talk about the exercises you’ll need to do after your surgery, your arrangements for going home, and special equipment to help you manage at home. If you’re not invited to see an occupational therapist and you’re worried about coping at home after the operation, you should ask about home help and aids when you go for your pre-admission clinic.
Going into hospital
You’ll probably be admitted to hospital on the day of surgery. You’ll be asked to sign a consent form if you haven't already completed one, which gives the surgeon permission to carry out the treatment. It's important to ask any questions you may still have at this stage. Your knee will then be marked for the operation.
You'll be asked if you're willing for details of your operation to be entered into the National Joint Registry (NJR) database. The NJR collects data on hip and knee replacements in order to monitor the performance of joint implants. It is only by measuring the outcomes of all knee replacements that we can learn what works best and for which patients.
If you're taking drugs that affect blood clotting, such as warfarin and clopidogrel, you should follow instructions to prevent too much bleeding during and after surgery.
Just before your operation you’ll be walked or taken in a chair or bed to the operating theatre. You'll probably be given a sedative medication (a pre-med) while waiting in the admission ward. You’ll then be given an anaesthetic. Most knee replacements are now done under either a spinal or an epidural anaesthetic. These numb the body from the waist down, but you'll remain awake throughout the operation. If you have a general anaesthetic instead, you may also be given a nerve block – this will block pain in your leg for up to 36 hours after surgery but will also weaken the leg temporarily. Many surgeons instead inject a type of local anaesthetic into the tissues around the knee during the operation to numb the pain but still allow the muscles to work so you can get up sooner after the operation.
The operation itself may take from as little as 45 minutes to over two hours, depending on how complex the surgery is.