Skip to main content

Welcome to the Circle Health Group website. We've changed our name from BMI Healthcare.

Knee arthroplasty

Knee arthroplasty is also known as knee replacement. We look at what a knee arthroplasty involves and the recovery time.

Clinician holding knee joint model
Knee arthroplasty, also known as knee replacement, is a procedure to replace the weight-bearing surfaces of the knee joint. Often, this is to relieve pain and disability. The procedure is commonly performed for other knee diseases such as rheumatoid arthritis and psoriatic arthritis.

A knee arthroplasty is the medical term used to describe knee replacement surgery. The main aim of a knee arthroplasty procedure is to reduce pain and improve walking ability in the long term.

In the majority of cases, knee arthroplasty surgery will need to be considered due to severe pain related to age related changes to the knee known as osteoarthritis.

In a far smaller number of patients, a knee arthroplasty will be considered to relieve pain associated with inflammatory joint disease, the most common form being rheumatoid arthritis.

Rarely, significant knee injury, such as severe fractures, may require a knee arthroplasty.

  • Knee pain that prevents you from walking normally
  • Swelling or stiffness
  • Difficulty when bending knees while walking
  • Cracking sounds when you are walking or bending the knees

Prior to undergoing a knee surgery, you will be invited to a pre-operative clinic. The aim of the clinic is to give you the chance to ask any specific questions you have about the surgery with your specialist orthopaedic knee consultant and anaesthetist. Our specialist anaesthetist will also take a more detailed medical history and conduct some tests on your heart and lungs.

There are different types of general anaesthetics, so your anaesthetist will discuss the different options with you. In rare cases, the risks of undergoing a general anaesthetic may be too great due to existing medical conditions affecting the heart, lung or vascular system. In these circumstances, your anaesthetist may offer an alternative to a general anaesthetic known as a spinal anaesthetic, which numbs your legs during the operation.

Your specialist knee orthopaedic surgeon will discuss the different types of knee arthroplasty with you. These include partial (unicompartmental) knee arthroplasty and knee replacement arthroplasty. They may also request up to date X-rays and in some cases more specialist imaging such as CT scans. Sometimes these images can be useful in planning surgery.

Under normal circumstances you will be admitted to hospital on the morning of your surgery.

A knee arthroplasty procedure involves several stages. Before the surgery, your surgical team will position appropriate equipment to monitor vital signs. These will include a blood pressure cuff to monitor blood pressure, ECG leads to monitor the electrical activity of the heart and a monitor to measure oxygen levels.

An incision will be made in a central, vertical line across the front of the knee. Once the knee cap (patella) is exposed it is then placed to the side of the knee so the surgeon is able to gain access to the knee itself.

Using accurate cutting tools your surgeon will then initially remove the bottom part of the thigh bone (femur) and re-shape the end of the bone ready to implant the first part of prosthesis. The total knee arthroplasty implants will have been tailored specifically for your knee. Once the femoral component is fitted, sometimes with the use of bone cement, the surgeon will then remove the damaged tibial (lower leg bone) joint surface and fit the tibial component.

Once in place, a strong insert is placed between the two components to reduce the impact of weight bearing and moving the knee during its lifespan. Your knee cap will be returned to the groove provided by the femoral prosthesis. Prior to stitching, your surgeon will ensure the knee is moving through an appropriate range of moving in a smooth fashion.

The procedure will normally take between one to two hours. The procedure is slightly shorter for a partial knee arthroplasty surgery.

You will require a short stay in hospital after a knee arthroplasty, which is normally lasts from three to seven days. Depending on your location and your preference you may stay as an inpatient for longer to commence more advanced rehabilitation supervised by your physiotherapy team. Prior to your discharge from hospital your surgeon may request an up-to-date x-ray to ensure that the placement of the knee prosthesis is correct and there are no early signs of infection.

During your inpatient stay, your vital signs will be monitored by our specialist doctors and nurses. Your pain levels will be monitored and appropriate analgesia will be offered. To reduce the pain and swelling in your knee we will encourage the use of regular icing by way of a device known as a cryocuff. This provides an easy to use, shaped bag of iced water to surround the knee joint and soft tissues.

A continual passive motion (CPM) machine will also be offered. This provides a supportive brace to place the operated knee while moving the joint gently through an appropriate range of motion. The device can be useful to prevent too much post-operative stiffness and allow a more rapid transition to movements such as sitting to standing and climbing stairs when appropriate strength has been achieved.

Your rehabilitation from total knee replacement surgery will be conducted under the supervision of expert physiotherapists at all time. Initial total knee arthroplasty rehab aims to reduce knee pain and stiffness and restore full extension (straightening) and at least 90 degrees of flexion (bend) of the knee. Under normal circumstances your physiotherapist will aim for your knee to have full extension and at least 90 degrees flexion six weeks after the operation.

To achieve this, you will be shown physical therapy exercises to extend and flex your knee as your pain allows. These exercises will normally be done in lying so you are able to perform them in bed to prevent excessive stiffness developing when resting.

Strengthening exercises should also be commenced immediately after a knee arthroplasty. The exact type of exercise will be determined by your pain levels and how much activity you are able to get in your quadriceps muscles (thigh muscles).

Depending on the strength of your knee and your pain levels your physiotherapist will decide whether to issue a walking frame or two elbow crutches. You will be advised as to how best to transfer from lying to sitting over the edge of the bed and then how best to transfer safely in to standing.

Our physiotherapists will teach you on how to safely use the particular walking aid you have been provided with. On your first few attempts at walking, you will be supervised at all times. Patients are reviewed by their specialist orthopaedic surgeon at 10 to 14 days after their operation. At this appointment the surgeon may request a further x-ray and will conduct a physical examination of the knee.

Patients will also see a member of the hospital’s orthopaedic nursing staff, who will examine the wound and extract the staples.

During your rehabilitation, you will be progressed from using a walking frame to crutches. Once you feel safe with crutches your physiotherapist will advise you to begin walking with one crutch only. When you are able to walk with a more equal stride pattern your physiotherapist will assess your walking pattern (gait) and may suggest a walking stick.

Your knee consultant will review your progress at six months following surgery. Many individuals are able to progress to walking with no walking aid six months after a knee arthroplasty.

General complications can occur in a small number of patients with any type of invasive surgery. These can include:

  • Reaction to undergoing a general anaesthetic can be highly variable among individuals.
  • Drowsiness is common and some individuals may experience some nausea and vomiting following surgery.
  • A blood clot (deep vein thrombosis - DVT) can occur after surgery due to the reduced time spent being active which normally helps to pump the blood around the legs. Your specialist will often recommend blood thinning (anticoagulant) medication to help prevent this. Our physiotherapists will also encourage bed and chair exercises to help keep the blood moving in the lower legs. 

In rare cases if a blood clot develops it can travel to the lungs, which is known as a pulmonary embolism (PE), or travel to the brain, which can be life threatening or cause permanent neurological damage.

The medications used as part of the general anaesthetic reduce the sensation of the nerves and muscles around the bladder, which can lead to urinary retention. In a small number of cases individuals may need catheterisation for a short period after their surgery until they are able to pass urine properly.

Due to general activity being reduced following surgery as well as the effects of some general anaesthesia and pain controlling medication individuals will tend to breath in a shallower pattern. For this reason, patients are encouraged to complete regular breathing exercises to circulate the air in the lungs and prevent chest infections following a knee arthroplasty.

There are also some specific risks associated with a knee arthroplasty operation. These will be discussed in detail with you by your surgeon prior to your operation and can include:

  • Patients may suffer with permanent numbness in the side of the knee next to the site of the incision. More significant nerve damage affecting the strength of the muscles or lower down the leg is, however, extremely rare.
  • Some patients may also notice a difference in the length of their legs. This may seem more prominent in patients who had significant bowing (in or out) of their knees prior to the surgery.
  • The risk of infection is increased with knee arthoplasty surgery compared with keyhole surgery procedures. However, infection rates are still extremely low. Your specialist will also prescribe antibiotic treatment to help reduce the risk of infection. They will also prescribe pain medication.
  • In very rare cases the knee replacement implant itself can fracture the bone which it is inserted in to. This normally occurs during the operation itself.

The cost of this treatment varies between locations. It also depends on other important factors, such as:

  • Which Circle Health hospital you receive treatment in;
  • The reason why you are getting this treatment, and
  • Your individual healthcare needs.

The cost includes all your hospital visits, such as initial consultation, the surgery and recovery afterwards when you are an inpatient. We provide high-quality care throughout, and we reflect that within our costs.

We also understand that your treatment needs to be tailored to your needs, both physical and emotional. This no one-size-fits-all approach means that the cost of knee replacement surgery often varies from person to person.

Specialists offering Knee arthroplasty

View all specialists

Mr Neil Hunt

Consultant Specialist Knee Surgeon


The Huddersfield Hospital

View profile Book online

Mr Ben Brooke

Consultant Orthopaedic Surgeon

MBChB, MRCS, FRCS (Tr & Orth)

The Huddersfield Hospital

View profile Book online

Mr Graham Walsh

Consultant Orthopaedic Knee & Sports Injuries Surgeon

MBBS BSc.(Hons) MRCS FRCSEd(Tr &Orth)

The Huddersfield Hospital

View profile Book online

Mr Jeya Palan

Orthopaedic Consultant Surgeon

BSc (Hons), MB BS, PhD, FRCS (Tr & Orth)

The Huddersfield Hospital

View profile Book online

Mr Guy McWilliams

Consultant Orthopaedic Surgeon

BSc, MB BS, FRCS, FRCS (Tr and Orth

The Huddersfield Hospital

View profile Enquire

Find a specialist