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Partial Knee Replacement

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The knee is the largest joint in the body, and one of the most easily injured. It is made up of four main things: bones, cartilage, ligaments, and tendons.

Due to the complex anatomy of the knee, knee pain can have many causes. However, these can be divided into knee pain resulting from injuries and knee pain resulting from degenerative changes.

Common causes of knee pain are:

  • Ligament injuries
  • Cartilage tears
  • Arthritis
  • Rheumatoid arthritis
  • Post-traumatic arthritis
  • Osteoarthritis

Osteoarthritis (degenerative joint disease) may cause knee pain that is worse in the morning and improves during the day. It often develops at the site of a previous injury.

A partial knee replacement is an alternative to total knee replacement for those who suffer with osteoarthritis of the knee. This surgery can be done when the damage is confined to a particular compartment of the knee.

In the past, partial knee replacements were reserved for older patients who were involved in a few activities. Your range of motion may be limited.

In knee osteoarthritis, the cartilage protecting the bones of the knee slowly wears away. This can occur throughout the knee joint or just in a single area of the knee.

Partial Knee Replacement


The knee is divided into three major compartments:

  • Medial compartment (the inside part of the knee)
  • Lateral compartment (the outside part)
  • Patellofemoral compartment (the front of the knee between the kneecap and thighbone)

How common is knee osteoarthritis?

Up to 30% of the population is believed to have knee Osteoarthritis. After age 50, more women are affected.

What are the advantages of partial knee replacement over total knee replacement?

Compared to total knee replacement, partial knee replacement better preserves range of motion and knee function because it preserves healthy tissue and bone in the knee. For these reasons, patients tend to be more satisfied with partial knee replacement compared with total knee replacement. They are still candidates for total knee replacement should they ever need it in the future.

There is also less blood loss during surgery, and knee motion recovers faster with partial knee replacement.
Multiple studies show that a majority of patients who are appropriate candidates for the procedure have good results with unicompartmental knee replacement.

The advantages of partial knee replacement over total knee replacement include:

  • Quicker recovery

  • Less pain after surgery

  • Less blood loss

Also, because the bone, cartilage, and ligaments in the healthy parts of the knee are kept, many patients report that a unicompartmental knee replacement feels more natural than a total knee replacement. A unicompartmental knee may also bend better.

Are there disadvantages to partial knee replacement?

The disadvantages of partial knee replacement compared with total knee replacement include:

  • Slightly less predictable pain relief

  • Potential need for more surgeryFor example, a total knee replacement may be necessary in the future if arthritis develops in the parts of the knee that have not been replaced.

If your osteoarthritis has advanced and nonsurgical treatment options are no longer relieving your symptoms, your doctor may recommend knee replacement surgery.

In order to be a candidate for unicompartmental knee replacement, your arthritis must be limited to one compartment of your knee.

In addition, if you have any of the following characteristics, you may not be eligible for the procedure:

  • Inflammatory arthritis

  • Significant knee stiffness

  • Ligament damage

With proper patient selection, modern unicompartmental knee replacements have demonstrated excellent medium- and long-term results in both younger and older patients.

Orthopaedic Evaluation

A thorough evaluation with an orthopaedic surgeon will determine whether you are a good candidate for a partial knee replacement.

Medical History

Your doctor will ask you several questions about your general health, your knee pain, and your ability to function.

Location of pain – He or she will be specifically concerned with the location of your pain. If your pain is located almost entirely on either the inside portion or outside portion of your knee, then you may be a candidate for a partial knee replacement.

If you have pain throughout your entire knee or pain in the front of your knee (under your kneecap) you may be better qualified for a total knee replacement.

What will a physical examination involve?

Your doctor will closely examine your knee. He or she will try to determine the location of your pain.

Your doctor will also test your knee for range of motion and ligament quality. If your knee is too stiff, or if the ligaments in your knee feel weak or torn, then your doctor will probably not recommend unicompartmental knee replacement (although you still may be a great candidate for total knee replacement).

Imaging Tests

X-rays – These images help to determine the extent of damage and deformity in your knee. Your doctor will order several x-rays of your knee to see the pattern of arthritis.

Magnetic resonance imaging (MRI) scans – Some surgeons may also order an MRI scan to better evaluate the cartilage.

Partial Knee Replacement


Surgical Procedure

A partial knee replacement operation typically lasts between 1 and 2 hours.

What does an inspection of the joint involve?

Your surgeon will make an incision at the front of your knee. He or she will then explore the three compartments of your knee to verify that the cartilage damage is, in fact, limited to one compartment and that your ligaments are intact.

If your surgeon feels that your knee is unsuitable for a partial knee replacement, he or she may instead perform a total knee replacement. This contingency plan will have been discussed with you before your operation to make sure that you agree with this strategy.

What is the procedure for a partial knee replacement?

There are three basic steps in the procedure:

  • Prepare the bone.Your surgeon will use special saws to remove the cartilage from the damaged compartment of your knee.

  • Position the metal implants.The removed cartilage and bone is replaced with metal coverings that recreate the surface of the joint. These metal parts are typically held to the bone with cement.

  • Insert a spacer.A plastic insert is placed between the two metal components to create a smooth gliding surface.

  • Recovery room.After the surgery you will be taken to the recovery room, where you will be closely monitored by nurses as you recover from the anesthesia. You will then be taken to your hospital room.

What surgical complications may arise?

As with any surgical procedure, there are risks involved with partial knee replacement. Your surgeon will discuss each of the risks with you and will take specific measures to help avoid potential complications.

Although rare, the most common risks include:

  • Blood clots – Blood clots in the leg veins are a common complication of knee replacement surgery. Blood clots can form in the deep veins of the legs or pelvis after surgery. Blood thinners such as warfarin (Coumadin), low-molecular-weight heparin, and aspirin can help prevent this problem. Newer blood thinners, such as apixaban (Eliquis) and rivaroxaban (Xarelto), may also be prescribed by your doctor, depending upon your needs.

  • After surgery an infection may occur in the skin over the wound or deep in the wound – An infection may happen while you are in the hospital or after you go home. You will be given antibiotics before the start of your surgery and these will be continued for about 24 hours afterward to prevent infection.

  • Injury to nerves or vessels – Although it rarely happens, nerves or blood vessels may be injured or stretched during the procedure.

  • Continued pain

  • Risks of anesthesia

  • Need for additional surgery

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What happens during the recovery period?

  • Hospital discharge – Partial knee replacement patients usually experience less postoperative pain, less swelling, and have easier rehabilitation than patients undergoing total knee replacement. In most cases, patients go home 1 to 3 days after the operation. Some patients go home the day of the surgery.

  • Pain management.

After surgery, you will feel some pain, but your surgeon and nurses will make every effort to help you feel as comfortable as possible.

Many types of medicines are available to help control pain, including opioids, non-steroidal anti-inflammatory drugs (NSAIDs), and local anesthetics. Treating pain with medication can help you feel more comfortable, which will help your body heal and recover from surgery faster.

  • You will begin putting weight on your knee immediately after surgery – You may need a walker, cane, or crutches for the first several days or weeks until you become comfortable enough to walk without assistance.

  • Rehabilitation exercise – A physical therapist will give you exercises to help maintain your range of motion and restore your strength.

  • Doctor visits – You will continue to see your orthopaedic surgeon for follow-up visits in his or her clinic at regular intervals.

You will most likely resume all of your regular activities of daily living by six weeks after surgery.

What other factors must I consider?

You may want to consider a knee replacement if your knee pain persists despite your taking anti-inflammatory drugs and maintaining a healthy weight. Your doctor will ask you to identify the area of pain in your knee, then check your range of motion and the knee’s stability.

An X-ray of the knee will determine your eligibility for partial knee replacement. However, your surgeon may not know for certain if you are a good candidate until the surgery has begun. You must have an intact anterior cruciate ligament, a sufficient range of knee motion, damage to only one compartment, and a stable knee. The angulation of the deformity is also considered.

In the past, a partial knee replacement was considered only in patients older than 60 years who were sedentary but younger, more active patients are increasingly being considered.

Partial Knee Replacement



Knee replacement is a common operation to treat severe knee osteoarthritis that has not been resolved by other treatments. More than 300,000 knee replacements were carried out in the UK between 2015 and 2017.

At present, fewer than 9% of knee replacements are partial. However, a recent study of registry data from England suggested that partial knee replacement could be more cost-effective than total knee replacement.

Analysis by Oxford University found partial replacements, which are safer and easier to recover from, should be performed on nearly half of those who having full-joint surgery.

Nearly 100,000 knee replacements were carried out in 2016, but fewer than one in 10 patients had a partial replacement, a procedure where only the affected part of the knee joint is replaced.

The procedure is less invasive, allows for a faster recovery, carries less post-operative risks and provides better function.

It is also a cheaper intervention for the NHS, in both the short and long term, they said.

The study saw them analyse data from the National Joint Registry (NJR), where they found that partial replacements are better for patients who have only part of their knee affected by arthritis and could therefore have either a partial or a total replacement.

According to the NJR, of the 98,147 knee replacements undertaken in 2016, only 9 per cent were partial, also known as unicompartmental replacements (UKR).

The research, published in BMJ Open, compared people who had a partial knee replacement with those who had a total knee replacement, but could have had a partial replacement.

They found the use of partial replacement varies greatly between different surgeons.

Other Studies


A funded trial of 528 people with osteoarthritis affecting only one compartment of the knee, those who had partial knee replacement saw at least as much improvement as those who had a total joint replacement. Their care also cost about £900 less over five years, making partial knee replacement more cost-effective.

Partial knee replacement did not lead to a greater need for further surgery, a surprise finding which contrasted with previous evidence. However, the need for further surgery is uncommon and the study may not have been large enough to capture data on this.

Longer-term follow up of the trial is underway. However, the current results suggest that partial knee replacement could be offered more often to eligible patients as a first-line option, assuming that surgeons experienced with the technique are available.


(Total Or Partial Knee Arthroplasty Trial) was a randomised controlled trial carried out at 27 sites across the UK, involving 68 surgeons and 528 patients.

The sites recruited people who were being considered for knee replacement, who had osteoarthritis of the medial compartment of the knee. This meant they would be suitable for either partial or total knee replacement. People were randomly assigned to one or other operation.

Amongst the 528 people randomised, 44 people had a knee replacement using the technique they had not been assigned to. This was either because of patient choice or surgeon decision once surgery was underway. For example, partial knee replacement was not possible if the arthritis was more widespread than expected.

Participants were followed up for five years and checked annually.

The results should be relevant to UK hospitals, assuming they have surgeons with sufficient expertise in partial knee replacement.

What did it find?

  • Both groups of patients had much-improved knee pain and function, assessed by the 48-point Oxford Knee Score. After five years, people who had total knee replacement had an 18 point improvement and people who had partial knee replacement had a 19 point improvement. A 5-point difference is considered clinically significant, so the two procedures were similar for this outcome.

  • The study’s cost-effectiveness analysis found that partial knee replacement was more effective in terms of quality of life, resulting in 0.24 additional quality-adjusted life-years (QALYs) over five years. It was also less expensive, with care costing £910 less over the five years of follow-up.

  • Average hospital stay was longer for those who underwent total knee replacement (4.3 days) than those who had partial knee replacement (3.2 days).

  • The proportion of people who had a re-operation was similar in both groups. Re-operation rates were 6% among the partial knee replacement group and 8% among the total knee replacement. In both groups, 4% of people needed a revision of their knee replacement.

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How do I make a claim?

If you feel that your diagnosis has been delayed or that your treatment has been inappropriate then you may be entitled to bring about a claim.

The team at Oakwood Solicitors Ltd will be able to give you free advice on the prospects of your case and whether you would be eligible to make a claim.

Who can bring about a claim?

The victim of the negligence can bring about a claim in their own right however it is often sadly the case that the victim is either unable to bring about a claim or has sadly passed.   In such circumstances a claim can be brought about on their behalf either by an appropriate person or litigation friend if the victim is still with us or by the executor of the estate of surviving dependant if the victim has passed.

Our specialist team will be able to discuss whether you have a right to bring about a claim so if you or a loved one has been affected do not hesitate to contact us.

How long do I have to claim?

Claims of this nature are subject to a three year limitation period.  This means that claims have to be commenced within the Courts in three years of rather the date the negligent act occurred or the date you became aware that negligence had occurred.

In cases involving deceased victims this limitation period commences from the date of death and in cases involving minors, the limitation period starts when they reach their 18th Birthday.

The law surrounding limitation periods is complex, our specialist team will be able to advise further.

How long will my case take to run?

Given the complexities involved in pursuing Clinical Negligence claims, they can often take 18-24 months to conclude and longer if Court proceedings have to be issued.   Our investigations start by obtaining all relevant records and protocols before approaching independent medical experts for their opinion.  We will provide you with regular updates on the progress of your case to ensure that you are kept up to speed.

How much is my claim worth?

It is often difficult to value clinical negligence claims at their outset given the complexities involved however we will pursue two forms of compensation for you:

General damages – An award of money for the pain and suffering you have endured as a result of the negligence.

Special damages – An award for all your out of pocket expenses such as travel expenses, medication costs, loss of earnings, treatment costs both past and future. This list is not exhaustive and is very case-specific.



How is my case funded?

The majority of Clinical Negligence cases are funded by a Conditional Fee Agreement, more commonly known as a “no win no fee” agreement.   This means that there will be nothing to pay upfront and nothing to pay if the claim has been lost.

If you are successful in your claim a deduction of 25% of damages will be taken to cover the success fee and the shortfall in legal fees.

It may also be the case that an After The Event (ATE) insurance policy will be obtained to cover the costs of expensive medical reports and investigations.   If an ATE insurance policy has to be obtained the cost of the same will be discussed with you at the appropriate point.

The cost of the ATE insurance policy is again taken from your damages and only payable if you are successful with your claim.

Why use Oakwood Solicitors Ltd to make your Clinical Negligence case?

We have a dedicated team of solicitors and paralegals who have many years’ experience between them in running cases of this nature. They are highly trained to deal with all aspects of clinical negligence.

We want to ensure at Oakwood Solicitors that clients are not overwhelmed by legal jargon, medical terms that they don’t understand and to allow the claims procedure to be as transparent as possible.


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