What can go wrong with knee surgery?

The knee is one of the most complex joints in the body. When it gets damaged, worn or diseased, usually due to osteoarthritis, the knee can be totally or partially replaced under arthroplasty, aka knee replacement surgery.

A common orthopaedic procedure that should aid mobility and rid a patient of persistent pain, one in 20 people who have knee replacement surgery will experience post-surgery complications.

Some patients may suffer from:

  • Blood clots
  • Change in leg length
  • Dislocation
  • Fractures
  • Infection
  • Premature failure, such as loosening of the implant
  • Ligament, artery or nerve injury, sometimes resulting in a ‘foot drop’.
  • Allergic reaction to the bone cement, if used
  • Allergic reaction to metal as implants may contain titanium or a colbalt-based alloy
  • Pain may not be relieved
  • The joint may be left stiff and with restricted movement if excess bone forms around the artificial joint

If complications occur, then the outlook may not be too bad. A minor wound infection should clear up in a short time with antibiotics and blood clots can resolve with medication.

However, for others, knee surgery going wrong can affect their lives very badly, increasing pain and instability. In the worst possible cases, errors with knee surgery can lead to amputation

Who is at higher risk of things going wrong during knee surgery?

Generally, the risk of complications is around 3%. However, if you carry a combination of risk factors, then the complication rates can increase to around 20%.

The following make knee replacement operations riskier:

  • Older age
  • Being overweight (obese)
  • Diabetes
  • Taking immunosuppressant medication
  • Smoking
  • Drug abuse
  • Repeat knee surgery (revision)
  • Any previous knee surgery

Is a knee surgery complication always due to negligence?

Various things can go wrong during the process of selecting and operating on patients. However, not all instances will be due to clinical negligence. In most cases, it will be a delay to diagnosis of pain or infection that wil create a medicolegal issue. There are examples below where knee surgery claims are often made.

You need to ask yourself the following questions if you are considering a claim:

Was I properly advised about the risks of my surgery?

If you have a combination of risk factors (as listed above) then your surgeon should have told you that. You should make a choice about having major surgery with your eyes wide open. If part of the problem is that you are very overweight, or smoking, you should be told about the increased risks. You should be encouraged to make lifestyle changes before your surgery takes place.

Combined risk factors increase likeliness that you will suffer from serious infection problems. If you do get an infection that ends up on your implant, then antibiotics (even given intravenously in hospital) are often not enough. If so, you must have further surgery to take out the implant, called first-stage revision. You then must live without a knee joint for months before further surgery to put in a new joint, called second-stage revision. The second stage surgery cannot go ahead until doctors are absolutely satisfied that all infection has gone. Patients waiting for second stage knee revision will have difficulty getting around and may need to stay off work. They may also need help at home.

Carrying various risk factors also increases the risk of blood clotting issues after surgery. Blood clots can be treated with medication. A serious clot though can mean lifetime complications. It can also mean you need to take medication for life. Blood clots can be life-threatening if they travel to the lungs or brain.

If you are diabetic, then you have a higher risk of suffering from foot drop, caused by nerve damage (known as neuropathy). For some diabetic patients, making changes to how they eat and exercise before surgery can reduce their risk. Improved medical management (drug therapy) can ensure that the condition is under better control before surgery.

Were preoperative checks carried out properly?

If you have a pre-existing condition, then it may be that other doctors need to see you to confirm it is safe for surgery to go ahead.

For example:

  • If you have a heart condition, you may need to see a cardiologist.
  • For an arthritic type condition, you may be taking steroids. If so, your steroid use may need to be reduced before surgery to a safe level.
  • Patient taking medication such as warfarin may need to be assessed at a haematology clinic. This is to ensure blood levels are safe. Otherwise, you can carry increased risks of bleeding during or after your surgery takes place. If you do have increased bleeding risks, it’s very important that the haematology clinic lets the surgeons know. Nurses and doctors monitoring you during and after surgery can then take extra care to look out for bleeding issues.

Was my surgeon negligent?

We set out below some examples where surgeons find themselves facing knee surgery claims. This list does not cover everything. Please do speak to us if you think something else has happened during surgery and you need advice.

Being awake during surgery

If you find that you are in pain during your surgery, when you should be asleep, that is generally negligent. However, it won’t be your surgeon that is responsible. There is another doctor who puts you to sleep for the surgery, an anaesthetist. The anaesthetist stays with you during the surgery. They are meant to give you enough anaesthetic, as well as a paralysing agent, to make sure that you stay asleep, and do not move. Unfortunately, we have had to investigate various cases where patients have not had enough medication to keep them asleep. This means they are unable to move or speak but experience terrible pain during surgery.

If you suspect that you have been awake during surgery, we have a dedicated page addressing waking up under anesthesia and outlining the subsequent steps to initiate a claim.

Wrong size implant

Sometimes surgeons will not choose the best size implant for you. In some circumstances, this can be negligent. There has recently been a UK trial where a claimant succeeded as the wrong size hip implant was selected. The claimant had previously had their other hip replaced. The surgeon, when placing a new implant on the other side, used a slightly bigger size implant. The judge accepted the claimant’s medical expert’s opinion that this was the wrong decision. The same size implant should have been used on both sides.

This case was about hip implants, but the same principle applies to knee implants. An oversized knee implant will irritate the surrounding soft tissue, causing pain and increasing pressure on the patella. It will need revising, but this often doesn't solve the issue as revision surgery often requires the use of a larger implant.

Wrong sided implant

In hip surgery, hip components are typically bilateral. Therefore, the side that is being operated on doesn’t need to be identified. However, in knee replacements, implants are in labelled boxes “right” or “left”. It has been reported in medical literature that there are significant risks posed to patients by surgeons using implants on the wrong side. Insertion of the wrong medical implant into the correct surgical site is a serious reportable event. Hospitals have protocols in place for confirming the side that is being operated on before starting a procedure. Even so, mistakes happen.

You would think that it would be immediately obvious if the wrong side implant is being used. Unfortunately, the difference between the different size implants can be quite subtle. Therefore, it may not be immediately obvious to the surgeon when they insert an incorrect implant.

Some patients have both knees replaced at the same time. There have been cases reported in which they have ended up with the wrong implant in both knees, as a result. These so-called 'never events' could also be that the replacement joints were placed the wrong way up.

Broken bones during surgery

Fractures can happen during surgery in any part of the femur, tibia and patella.

There is a stem attached to an artificial tibial plate used in knee replacement. The stem has to be inserted into a hole made in the top of the tibia. A break can occur to the tibia if the surgeon does not exercise reasonable care and skill. If so, that is negligent. If the surgeon excessively ‘resects’ the anterior femur during surgery, then that can also lead to fracture.

Fractures can, of course, also be unavoidable. The facts of each case and the patient’s particular vulnerability to bones breaking have to be considered. Many cases involve older patients who suffer from poor bone quality.

Incorrectly placed implant

There are several parts (or components) to a knee replacement. All of these have to be aligned together correctly to ensure the implant sits correctly. Otherwise, a knee replacement will not be a total success. If it is misaligned, it can irritate nearby structures and fail prematurely. The knee will function poorly after surgery with ongoing pain and stiffness. Often repeat surgery is necessary.

In a recent UK trial, a Claimant had suffered a condition called iliopsos tendonitis. The judge found that a surgeon should have checked that the implant was deep enough into the socket. This is a simple check that only involves the surgeon running their finger around it.

The surgeon gave evidence that he had never received training to do this. His medical expert stated that there would be other surgeons, just like the defendant, who had also never been trained to do this. On that basis, the defendant argued that the surgeon was not negligent. The judge was having none of this! Judgement was that it was not logical to fail to do a simple check–all surgeons should be doing it.

Dislocation can occur if the implant is not placed well. A dislocated knee implant will lead to more surgery being needed. It can also end up with nerve injury.

Damaged nerves

Nerve damage is something that all surgeons should tell you is a risk of surgery. However, surgeons must be extremely careful with nerves when operating. Knee surgery claims for foot drop do tend to be pursued. This condition is extremely distressing to live with.

Injury to nerves is rare but is a devastating complication. There are higher risks if you are having a previous knee replacement repeated (a revision) or if you’ve had any knee surgery previously. It’s very important that surgeons properly assess your anatomy before surgery. Surgeons must take precautions to ensure they do not injure nerves. There are very important nerves close to the knee. Above the knee, the sciatic nerve divides into two major nerves (the common peroneal nerve and tibial nerve).

This type of injury can occur due to compression. Poor positioning on the surgical table can be a cause of compression. Improper placement of surgical instruments (‘retractors’) can also cause nerve compression. Surgeons can cause stretching type injuries when manipulating the joint. If too much traction is applied, then this can lead to damage.

Peroneal nerve injury, causing foot drop, is well known as a possible complication of knee surgery. At times, surgeons may try to correct valgus deformities during surgery. If so, this is known to result in traction to the nerve.

It is important that a surgeon checks pre-operatively for any type of nerve damage already suffered by a patient (called neuropathy). Patients who have any neuropathy before surgery are at higher risk from nerve injury.

Direct trauma can be caused by surgical instruments, such as the scalpel, electrical instruments and screws. Tourniquets are used to place pressure to prevent bleeding during knee replacement. If used for more than 2 hours, tourniquets significantly increase the risk to nerves. The risk increases to 7.7% for combined peroneal and tibial nerve palsies.

Post-surgical infection

Infection after knee replacement is also a risk, more so if a hinged replacement is used. It can be difficult to say whether a post-knee surgery infection will be due to negligence as it's hard to trace back the source of infection. However, if there is a delay to diagnosing the infection, this can lead to adverse outcomes such as the need for amputation. 

If a wound is leaking despite being properly dressed by a district nurse, then a GP should prescribe an antibiotic called flucloxacillin. If a deep infection develops, this should be diagnosed within three months to salvage the knee and eradicate the infection. Any longer than this and the aforementioned two-stage revision surgery will be necessary. 

Examples of awards in past knee surgery claims

£1.3M in compensation

For a 66-year-old man who had to have revision surgery after knee replacement. He then suffered an infection in the joint, which kept coming back. Ultimately, he had to have an above-knee amputation and became dependant on a wheelchair.

£620,000 in compensation

For a lady who, aged 61, had the wrong type of knee replacement surgery. In addition, he also did not do the surgery competently. Post-operative checks were insufficient. There was a failure to perform a post-operative x-ray. In addition, the claimant was discharged even though she was still in a lot of pain.  She eventually had to have four more surgeries. She was in chronic pain and was reliant on opiate pain-killing medication. Walking sticks and a wheel-chair were needed for mobilising.

What should happen if a patient thinks there are errors with their knee replacement surgery?

Around 20% of patients who undergo knee replacement surgery are dissatisfied with their experience. The majority put this down to residual pain and incapacity, becoming co-dependable on relatives or suffering anxiety and depression.

If a patients knee replacement becomes painful shortly thereafter, it should be assessed via an algorithm that checks for instability, infection, malalignment, or referred pain from the hip. The pre-operative x-rays should also be looked at to see if the joint spaces were well preserved. If they were, then a patient shouldn't have had the operation and alternative treatments should have been provided instead.

In the UK, there is a National Joint Registry that patients who have had joint replacement surgery can voluntarily join. It can help identify any future problems that may arise and also provides a patient feedback survey.


Please Note: At Medical Solicitors, we specialise in knee surgery claims involving healthcare providers in England and Wales and will be happy to extend a helping hand if your case is located in either of these regions. Unfortunately, we do not manage knee surgery claims outside of England and Wales.

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Matthew Brown

Director and Senior Chartered Legal Executive

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