What is a total knee replacement?

A total knee replacement (TKR) is a surgical procedure in which the damaged or deteriorated surfaces of the knee are replaced.

You may also see it termed a “resurfacing” or “arthroplasty”.

A TKR is a last resort treatment to assist in improving a persons knee pain, range of movement and quality of life.

There are three main reasons a person may require a TKR:
– osteoporosis (OP)
– osteoarthritis (OA)
– trauma

What other options are there?

Prior to a total knee replacement, conservative management should be trialled.

Too often people have never tried other options to decrease their knee pain and improve their movement before they consider a total knee replacement.

This may include, but is not limited to:
– physiotherapy
– knee arthroscopy
– injections
– pain medication
– weight loss
– increasing exercise

If there is no improvement or symptoms worsen with conservative measures, a total knee replacement would be the next appropriate treatment.

Are there different types of TKRs?

There are three types of prosthesis (the implant) used in total knee replacements. Non – constrained, semi-constrained, and constrained.

Non-constrained prosthesis rely on the ligaments and muscles for stability.
Semi-constrained prosthesis use the combination of the prosthesis in conjunction with the ligaments and muscles for stability
Constrained prosthesis provide the entirety of the stability, for when a persons muscles and ligaments cannot

As well as there being different types of prostheses, there are different manufacturers and different materials that are used.

What happens in the surgery?

The surgery procedure will vary, depending on the type of prosthesis used and surgical techniques. But in general it will involve:

Removing around 8-10mm of the tibia and femur to allow space for the prosthesis to go
Patella surface removed to make space for the prosthesis
Insertion/fixation of the components of the prosthesis, including a spacer between the femoral and tibial components
Alignment and movement Is checked throughout the process

What is prehabilitation or “prehab”?

Prior to surgery, prehab is usually recommended.

This often includes exercises to strengthen and stretch the musculature around the knee, and may include a walking or weight loss program.

Prehab also allows you to learn about the surgery you will be having and also get comfortable with the type of exercises you will perform in you rehabilitation program.

What happens in rehabilitation or “rehab”?

Rehab is recommended by most surgeons these days.

It was common for rehab to happen in hospital with you staying in hospital for several weeks.

Nowadays, rehab usually takes place in your home (with the healthcare team visiting you at home) or with you attending an outpatient clinic several times a week.

Within the first few days, ideally patients should be able to straight leg raise (lift your leg straight), bend to approximately 90 degrees, walk (often with a walking aid), and be able to walk up and down a single step or stairs.

Effective rehab exercise programs look to strengthen the structures around the knee, and ensure adequate muscle length/range of motion. They should also include swelling and pain management education. An effective program may include:

  • Ankle pumps for swelling management/reduce risk of DVTs
  • Static quads
  • Inner range quads
  • Straight leg raises
  • Squats and or sit to stands
  • Calf rasies
  • Hamstring curls
  • Knee flexion and extension stretches
  • Hamstring and calf stretches
  • Ice may be used in conjunction to analgesia
  • Gait reeducation and stair practice may also be appropriate
  • Hydrotherapy may be recommended or available

Programs usually last around 4-12 weeks, based on your needs and progress. A systematic review by Pozzi et al found that for optimal patient outcomes, therapy should include:

Progressive strengthening and functional exercises (either land or water based) tailored to patient needs
Under the supervision of a physiotherapist, ideally in an outpatient clinic or setting

Takeaway points

If it were my knee, I would consider:
– seeing a Physiotherapist prior to considering a TKR – you may avoid surgery and even if you end up having a surgery you will be in a better prepared for surgery
– be diligent with your rehabilitation program – I would commit to a life long exercise program – the benefits go way beyond looking after your “new” knee

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