Knee Replacement Consent
The knee is a ‘hinge-type’ of joint, and is a very important joint as it allows a great deal of movement but is also weight-bearing. As a result of this, it is often prone to ‘wearing away’. This is a simplified reason as to why arthritis occurs. Arthritis can be a very painful disorder, causing you to slow down your walking or even stop you from sleeping.
During a knee replacement the severely damaged surfaces of the knee are replaced with artificial parts, which are secured to the bone to function like the natural joint.
The aim of the surgery is to reduce the pain in your knee, allow you to move more easily, and improve your quality of life.
If however you decide not to have surgery, there are alternative ways to reduce the pain, which you may have already tried. These include:
- Weight-loss
- Stopping strenuous exercises or work
- Physiotherapy and gentle exercises
- Medicines, such as anti-inflammatory drugs (e.g. ibuprofen, steriods)
- Using a stick or a crutch
- Arthroscopy (key-hole surgery)
- Using a knee brace
- Cartilage transplant
- Knee fusion (arthrodesis)
What happens during the surgery?
During the surgery you will either be asleep (with a general anaesthetic) or remain awake, but be completely numb from the hips down (spinal anaesthetic). If you have a spinal anaesthetic, you will not be able to see the surgery, but may be able to hear what is going on.
Before the surgery a tight inflatable band (tourniquet) will be placed across the top of the thigh to limit the bleeding. Your skin will be cleaned with antiseptic fluid, and clean towels (drapes) will be wrapped around the knee.
In order to remove the arthritic bone, we make a cut in the skin, fat and muscles which lie in the way of the knee bones.
Parts of the thigh bone (femur), shin bone (tibia) and knee-cap (patella) are cut away, and the new replacement knee surfaces are secured in their place, with a plastic layer between the metal surfaces.
When the Surgeon is satisfied with the position, the wound is closed with stitches in layers and the skin is under stitched with a dissolvable stitch. Dressings are then applied.
Are there any risks or possible complications?
As with all procedures, there are some risks and complications that may result following the surgery, some are more common than others. Here we discuss these individually.
COMMON (2-5%)
Blood clots
DVT (deep vein thrombosis) is a blood clot in a vein. The risks of developing a DVT are greater after any surgery (and especially bone surgery). DVT can pass in the blood stream and be deposited in the lungs (a pulmonary embolism – see below). To limit the risk of DVTs from forming we will give you stockings to wear on your legs, and give you an injection (or tablet) to thin the blood. Starting to walk and moving early is one of the best ways to prevent blood clots from forming.
Bleeding
A blood transfusion or iron tablets may occasionally be required. Rarely, the bleeding may form a blood collection or large bruise within the knee, which may become painful and require an operation to remove it.
Pain
The knee will be sore after the operation. Pain will improve with time. Rarely, pain will be a chronic problem and may be due to any of the other complications listed below, or, for no obvious reason. Rarely, some replaced knees can remain painful.
Knee stiffness
This may occur after the operation, especially if the knee is stiff before the surgery. If this continues for some time, the Surgeon may decide to try and increase the movement under general anaesthetic.
Numb patch of skin next to the scar
Implant wear and loosening
With modern operating techniques and new implants, knee replacements last many years. In some cases, they fail earlier. The reason is often unknown. The plastic layer is the most commonly worn away part
LESS COMMON (1-2%)
Infection
You will be given antibiotics at the time of the operation and the procedure will also be performed in sterile conditions (theatre). The wound site may become red, hot and painful. There may also be a discharge of fluid or pus. This is usually treated with antibiotics and an operation to washout the joint may be necessary. In rare cases, the implant may be removed and replaced at a later date. The infection can sometimes lead to sepsis (blood infection) and strong antibiotics are required.
RARE (<1%)
Pulmonary embolism:
This happens when a blood clot has spread to the lungs and can affect your breathing. This is a very serious condition and can be fatal.
Altered leg length:
The leg that has been operated upon may appear shorter or longer than the other.
Poor scars:
The wound may become red, thickened and painful (keloid scar) especially in Afro-Caribbeans.
Nerve injury:
Efforts are made to prevent this, however damage to the small nerves of the knee is a risk. This may cause temporary or permanent altered sensation or movement around the knee and the lower leg. Changed sensation to the outer half of the knee may be normal.
Bone injury:
Bone may be broken when the new implant is inserted. This may require fixing immediately or at a later operation.
Vessel injury:
Blood vessels at the back of the knee may rarely be damaged. This may require further surgery by the Vascular surgeons.
Death:
This very rare complication may occur after any major surgery and from any of the above.
If you believe you have any of the above complications when you are home, contact your GP or go to your local Emergency Department.
Anaesthesia for Knee Replacement Surgery
Two types of Anaesthetic techniques are commonly used.
- Spinal Anaesthesia (Or Epidural Anaesthesia OR Combined Spinal &
Epidural Anaesthesia) with OR without Sedation
OR
- General Anaesthesia (GA).
Knee Replacement surgery can be done under Spinal Anaesthetic, where an injection is placed in your back, which makes you numb waist downwards. It is currently the preferred choice for Knee Arthroplasty, as immediate recovery is considered better compared to General Anaesthesia.
Spinal Anaesthesia
Advantages of Spinal Anaesthesia:
- Least effect on Lungs and breathing
- Excellent pain relief during and for few hours after the operation
- Less need for stronger painkillers like Morphine
- Less sickness (nausea & vomiting) compared to General Anaesthetic
- Ability to eat and drink soon after the operation
- Spinal Anaesthetic might decrease the chances of developing blood clots (deep vein thrombosis)
Technique:
Your Anaesthetist will insert an intravenous cannula (IV Cannula) generally at the back of your hand and connects you to routine monitors (ECG, Blood Pressure and Pulse Oximetry). You will then be asked to sit at the edge of the bed. Spinal Anaesthetic technique is a completely sterile procedure and your back is sprayed with an anti-septic spray. A small dose of Local Anaesthetic is injected to the skin (at the lower part of your back) to make it numb and then the needle is passed through the space in your back to the correct depth.
Once the anaesthetic drug is injected, it takes about 5-7 minutes for spinal anaesthetic to take effect. At this point you will not be able to feel touch sensation or be able to move your legs. You will also lose sensation of lower part of your abdomen. (Sometimes up to lower part of your ribcage). Spinal effect can last up to 3-4 hours.
You will then be transferred into the operating theatre where you will be securely positioned on your back. You will be re-connected to the monitor and oxygen mask. At this point your Anaesthetist will administer sedative drug to keep you calm and comfortable throughout the operation.
Sedation:
Sedation is routinely offered to all patients who have Spinal/ Epidural anaesthesia. Sedative drugs are given through intravenous cannula, which makes you calm, comfortable and (may be) slightly sleepy. Sedatives will NOT result in complete sleep. You will be able to hear the noises arising from the operating theatre including the conversations. You can also talk to your Anaesthetist or Surgeon during the procedure (and vice versa).
Complications of Spinal/Epidural Anaesthesia
Spinal/Epidural Anaesthesia is generally considered safe. The significant side effects are as follows
- Nerve damage:
There is 1 in 12,000 chance of temporary nerve damage in the spine that can cause numbness or weakness in your legs, which can last from 6 weeks to 6 months. Permanent nerve damage is very rare
- Drop in Blood Pressure
(BP) can make you feel ‘dizzy’. Your Anaesthetist will monitor it continuously and manage any drop in BP
- Shivering
occasional, quite often not related to body temperature
- Itching
uncommon and can be treated
- Headache
up to 1 in 300 due to spinal fluid leak. You should report to Anaesthetist if headache is persistent or worsening.
- Backache for a few days
You may not notice backache, as you will be taking painkillers. Spinal Anaesthetic is not known to cause long-term backache.
- Urinary retention
can happen in up to 10 percent of patients and may require urinary catheterisation.
- Infection of spine causing meningitis
extremely rare
- Bleeding into spine causing spinal haematoma
extremely rare
- Complete paralysis (Paraplegia) or death
extremely rare (1:50,000- 1:140,000).
- Failure of the Spinal Anaesthetic
If the spinal anaesthetic doesn’t work, you will be offered general anaesthetic
General Anaesthesia (GA)
General Anaesthesia (or simply called GA) involves administration of anaesthetic drugs through intravenous cannula (IV cannula or drip). Your Anaesthetist will insert an IV cannula first. You will be connected to routine monitors (ECG, Blood Pressure (BP) and Pulse Oximetry). The Anaesthetist will then inject the anaesthetic drugs directly into your vein through the IV cannula. As soon as the drugs are injected, you will fall asleep. After that you will NOT know, see, hear or feel any sensation until the procedure is over. The Anaesthetist will also insert an airway device into your throat (Laryngeal Mask) or into your windpipe (Tracheal tube) when you are asleep. At the end of the operation, the Anaesthetist will switch off/reverse the anaesthetic drugs and you will begin to wake up. You may still feel sleepy as you recover in the Recovery Room. A recovery nurse will monitor you until you are completely awake, comfortable and fit to go back to the Ward. Your Anaesthetist will also prescribe combination of painkillers, anti-emetics, laxative and IV fluids. You will be able to eat and drink as soon as possible provided your recovery is straightforward.
Modern anaesthetic drugs are much safer, short acting and have fewer side effects. However, you can still have complications from general anaesthetic.
Complications/side effects of General Anaesthesia (GA)
- Pain
on injection of anaesthetic drugs into your vein- common
- Nausea and Vomiting–
common but manageable with routine anti-emetics
- Damage to teeth/crowns/caps/dentures/lips/tongue–
uncommon, but can happen when the airway device is inserted or removed.
- Fluctuations in Blood Pressure (BP) and Heart Rate (HR)
Your Anaesthetist will monitor you continuously and manage any fluctuations in BP or HR.
- Drowsiness
is common until anaesthetic drugs wear off completely. Painkillers like Morphine can also make you drowsy and tired.
- Shivering
occasional, either due to exposure to cold in operation theatre or sometime not related to your body temperature.
- Itching
is a common side effect of analgesics like Morphine. It can also be caused by an allergy to anything you have been in contact with, including drugs, sterilising fluids, stitch material, latex and dressings. It can be treated with drugs
- Breathing difficulties
some people wake up after GA with slow or slightly difficult breathing. If this happens to you, you will be cared for in the Recovery Room until your breathing is better.
- Sore throat
can happen due to airway intervention. It can last a few days and usually responds to simple pain killers
- Damage to Eyes
It is possible that surgical drapes or other equipment can rub the cornea (clear surface of the eye) and cause a graze. Anaesthetists take care to prevent this. Serious and permanent loss of vision can happen, but it is very rare.
- Nerve damage (paralysis or numbness)
has a number of causes during local, regional or GA. Temporary nerve damage can happen due to pressure points, but full recovery often follows. Permanent nerve damage is uncommon
- Bladder Problems
Difficulty passing urine, or leaking urine, can happen after most kinds of moderate or major surgery. If this happens, the team looking after you will consider whether you need a urinary catheter
- Confusion or Memory Loss
This is common among older people who have had a GA. It may also be due to an illness developing such as chest or urine infection. There are other causes, which the team looking after you will take care of. It usually recovers but this can take some days, weeks or months.
- Postoperative Delirium
can happen especially in elderly patient population
- Postoperative Cognitive Dysfunction
has been reported after GA. However, it generally affects elderly patients
- Serious allergy to drugs
difficult to predict
- Equipment failure
difficult to predict
- Chest infection
is more likely to happen after major surgery on the chest or abdomen, after emergency surgery and after surgery in people who smoke. Occasionally severe chest infections develop which may need treatment in the intensive-care unit. These infections can be life threatening.
- Awareness under General Anaesthesia (GA)
Extremely rare, about 1 in 20,000 Anaesthetics.
- Death due to General Anaesthesia
is extremely rare in healthy patients undergoing non-emergency surgery (about 1 in 100,000 general anaesthetics)
If you are having any complications of General Anaesthesia, please report it to your ward Doctor who will contact Anaesthetic Team if necessary.
Death due to General Anaesthesia is extremely rare in healthy patients undergoing non-emergency surgery (about 1 in 100,000 general anaesthetics)
If you are having any complications of General Anaesthesia, please report it to your ward Doctor who will contact Anaesthetic Team if necessary.
General Information
- Your Anaesthetist (Consultant) will see you on the day of the operation. This is your opportunity to discuss any issues related to your Anaesthesia & ask any questions you may have regarding your anaesthetic.
- Irrespective of the anaesthesia technique, the Surgeon will generally inject local anaesthetic drug around your joint and wound at the end of the operation. This will help you with pain relief.
- You may need more blood tests, X-rays or scans whilst in the hospital if necessary
For more information about your anaesthetic please go to https://www.rcoa.ac.uk/patientinfo/anaesthesia-information-leaflets
FAQ
What happens before my surgery date?
Once listed for surgery, you will be given a date to attend the pre-operative assessment clinic. The pre-operative assessment clinic gives the team an opportunity to make sure you are fit enough for the anaesthetic and the surgery.
They will want to review your medications so please bring these with you. If you are taking any blood thinning medications (such as aspirin, clopidogrel, or warfarin), these will need to be stopped a few days before your surgery, and you will be given special instructions regarding these.
In the clinic your blood pressure will be checked, you will have blood tests, have swabs to look for MRSA, and we may need to listen to your chest and do a tracing of your heart (ECG).
What should I bring into Hospital ?
Please bring with you:
- All tablets, medicines or inhalers that you have been prescribed (including those stopped prior to surgery) with the exception of Temazepam and Pethidine. Please ensure that all medication is in the original packaging, labelled with your name. Please do not mix tablets or bring them in your own tablet dispenser tray or dosette box from your local pharmacy
- Personal items – including night clothes, dressing gown and slippers, bedjacket or shawl.
- Comfortable day clothes
- Your spectacles (labelled with your name)
- Denture pot (as you will be asked to remove any false teeth)
- Toiletry items (toothbrush, toothpaste, flannel, soap, shampoo, shaving equipment, comb or hairbrush etc).
- Mobile phone – please use with consideration for other patients and keep on silent.
You might also want to bring:
- Tissues and baby wipes
- Proof of entitlement to free travel costs if appropriate
- Items of religious importance to you
- Your hearing aid
- Sanitary products such as tampons
- Mobility aids such as a walking stick or frame
- Some money to purchase newspapers or to use the telephone
- Books, magazines, knitting
- Writing paper and pen
- Non perishable snacks, squash
Please do not bring:
- Jewellery or valuables
- Large bags or suitcases, as bed space is limited
- Electrical items such as hairdryers, electric razors
- Food that needs reheating (we cannot reheat food for infection control reasons)
What do I do on the day of my surgery?
All patients need to fast for 6 hours (for solid food) before any anaesthesia or sedation is administered. You may drink clear liquids like Water, Black Coffee or Black Tea up to two hours before the operation. Please do not chew gum or eat sweets. Milk, fizzy drinks (including Red Bull and Lucozade), fruit juice or milky tea/coffee are not allowed.
Please follow the advice of the Hospital Pharmacist (or Anaesthetist or Pre-op Assessment nurse) regarding taking or stopping your routine medication before the operation. Please bring all your medicines with you to the hospital
If you are using any devices (eg. CPAP machine), please bring it with you. You may need it whilst in the hospital
If you are having spinal anaesthetic, we may allow you to listen to your own music. You may wish to bring your own iPod (or similar device) and ear piece You will be expected to attend the ward shown on your letter at the specific time indicated.
Prior to surgery a nurse will take you to your bed where health checks and a nursing assessment will be completed. You will be given a gown, underwear and stockings to change into, however you will remain in your own clothes until the theatre team are ready to start your operation. This may be some hours after your arrival.
You will meet the Orthopaedic team undertaking the surgery. They will ask several questions about the symptoms and examine your knee, and then draw an arrow on the side of the surgery (using a thick black marker). They will then consent you for the surgery, and answer any questions that you may have. The team may also ask you to partake in research that may be running alongside the surgery (they will give you further information about their research separately). Once all the checks have been done, and it is your turn for surgery, you will be escorted to the operating theatre.
What happens immediately after the surgery?
The surgery can take between one to two hours. Immediately after the surgery you will rest in the recovery unit until you are more awake, before being taken to the inpatient ward.
It is normal to be sore around the knee, and the team will ensure you have enough pain medications available. This may involve tablets, injections given by the nursing team, or injections that you control (PCA). A PCA will give you a small volume of pain medications after you have pressed a button – keeping you in control.
You will have a white waterproof dressing on the wound and a bulky dressing around the knee, which will stay in place until the next day before the team looks at the wound on the ward. When the bulky dressing is removed, you will be given a stocking to wear on the operated leg. You may also have a ‘drip’ attached to your hand (or arm), which is giving you fluids to help hydration.
It is not unusual to have some difficulty to pass urine on the night of surgery so occasionally we may need to insert a tube into your bladder (catheter) to empty your bladder or monitor your urine. Once the team is satisfied with your urine production, the catheter will be removed.
What do I do when I am on the ward?
You will normally stay on the same ward for the duration of your stay.
During this time, you will be seen daily by the ward doctor or member of the Orthopaedic team to make sure you are recovering well, and blood tests and X-rays will be undertaken. They may examine your leg and review the wound to ensure there are no complications.
Medication that you were previously on will be restarted, and you will be given an injection or pill to reduce the risk of blood clots from forming in your leg or lungs (see risks above).
Part of the recovery from the surgery is regaining your mobility, and the Physiotherapists will see you regularly on the ward. They will encourage you to sit out of bed on the first day after your surgery (if the pain is well under control, and there are no complications).
Over the next few days they will aim to progress your mobility, as they help you mobilise with a frame or crutches, and give you an exercise program (further information regarding individual exercises is available from the Physiotherapy team).
When will I leave hospital?
The expected length of stay for a total knee replacement surgery is 2-3 days. When the doctors, therapists, and the nurses are happy with your progress you will be able to go home.
When you are discharged from hospital a pack will be made with all your medications. This will include the new painkillers and medication to thin your blood. These blood thinners should be continued for 14 days from your surgery, and your stockings must also be worn for this amount of time.
What should I expect when I am home?
When you are discharged from hospital a follow-up appointment will be made for you with the Orthopaedic team at 6 to 8 weeks
Your wound will be closed with dissolvable stitches but you will be required to visit the nurse at your GP practice to check the wound and change the dressing if required (the nursing staff on the ward will give specific instructions before you leave hospital).
The ward physiotherapist will send a referral for follow on physiotherapy and you should expect to start ohysiotherapy between 2 – 3 weeks.
It can take between 6 to 12 months to recover fully from the surgery. The pain associated with your old knee may be gone, but it takes a while for your muscles to heal, and for your body to adjust to your new knee. It is therefore important that you give yourself time to recover, and avoid pushing yourself too soon after the surgery.
What else should I know?
Leg swelling
As a result of the surgery we expect there to be some swelling and brusing around your knee and your lower leg. To help with this we recommend you elevate your leg regularly and use ice (wrapped in a towel) at least thre to four times a day. If it becomes too painful and very red, you must seek medical attention. It can takes approximately 6 to 12 months for the swelling to go.
Sleeping
We suggest not sleeping on the operated side until the wound has healed, which may take 6 weeks.
Bathing
It is best to shower or sponge bath until your wound has healed, and when you feel able to get in and out of a bath safely.
Driving
Your insurance company should be informed about your operation. Some companies will not insure drivers for a number of weeks after knee surgery, so it’s important to check your policy.
Before driving, you need to be fully recovered from your surgical procedure, free from the distracting effect of pain or of any pain relief medication, and be able to safely control your car, and perform an emergency stop.
Work
Time off from work depends on the physical demands expected of you, especially if it involves heavy lifting, standing for long periods of time, or lots of walking. Everyone recovers differently but in most cases if you have a light job or are office-based you may return quite early. If your job involves heavy duties, you may need to be off work for several weeks with a phased return.
