Remember! Our guides are to be used following an assessment with a qualified medical professional. Do not attempt these exercises if you have not been given a formal diagnosis, or given consent to complete these exercises by a Physical Therapist.

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Knee Replacement Physical Therapy Guide

What Is A Knee Replacement?

Arthritis causes the weight bearing surfaces (cartilage) of the knee joint to permanently wear away. The cartilage loses its smoothness that a knee joint requires to perform optimally, and this leads to stiffness and pain. Eventually the joint wears out to such an extent that the bone of the femur (thigh bone) grinds on the bone of the tibia (shin bone). A total knee replacement replaces the worn down surfaces of the knee joint with plastic and metal. The femoral (upper leg) replacement is a smooth metal component, whilst the tibia replacement (lower leg) in in two parts. If necessary the patellar surface (under the knee cap) is replaced with a plastic button, which glides over the metal surface of the femoral replacement, however the patella is often satisfactory, and may not require surgery. To ensure they replace the knee adequately, a 20cm incision is made down the front of the knee and the joint is opened during surgery. The arthritic joint surfaces that have been gradually eroded away are removed and the pain is shaped so that the joint replacement fits firmly on the bone, before being held in place with cement.

Why Do You Need A Knee Replacement?

A knee replacement is usually required as a result of cartilage erosion and break down in the knee joint. The cartilage break down has got to the extent that mobility is reduced and you often experience pain even while resting.

The most common reasons for a knee replacement surgery include:

  • Osteoarthritis
  • rheumatoid arthritis
  • haemophilia
  • gout
  • Previous knee injury

Benefits Of A Knee Replacement

The main benefit of knee replacement surgery is pain relief! Other benefits include improvement of function, allowing patients to walk easier and further. Daily activities should become more comfortable and quality of life improved. Some patients may find an improved range of movement in the knee straight after the surgery although this can not be guaranteed, and is usually achieved following an exercise programme like the one below.

Many patients report that the function and pain relief from their knee replacement continues to improve for up to 18 months following the surgery.

Risks And Complications Of A Knee Replacement

The majority of patients will recover extremely well from their knee replacement surgery without significant problems. As with all operations however, there are some risks that might occur and these include:

  • Infection: Infections may require further hospitalisation and treatment.
  • Deep Vein Thrombosis: All operations on the lower limbs carry a risk of blood clots forming in the deep veins of the leg, follow the advice below to reduce the risk of developing a DVT.
  • Stiffness: Sometimes the knee actually becomes stiff after surgery due to scar tissue forming inside the knee.
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Difficulty Sleeping Following A Knee Replacement

A knee replacement is a major operation. You may find you tire quite easily after the operation and it is important to take rest. When you rest on a chair it is important to keep the leg elevated on a foot stool to reduce any tendency for the leg to swell. Trying to sleep at night is often the biggest difficulty following the surgery. It is advised that you make some modifications to improve your pain at night, this includes sleeping on a firm mattress, sleeping on your back and side, and placing a pillow between your knees. Our favourite knee replacement pillow can be found here!

What Are My Treatment Options?

There are many treatment options available to people who undergo knee replacement surgery! Like all injuries, it requires a mix of rest, exercise and gradual return to normal function.

Rest & Time

Immediately after surgery, you will find yourself less able to complete the activities you normally do such as housework / working. Following the knee replacement surgery you should commence the RICE protocols:

  • Rest. Rest, relax and protect the knee replacement. Stop, change, or take a break from any activity that may be increasing your pain.
  • Ice. Ice packs will help reduce pain and swelling. Apply the ice or cold pack for 10 to 20 minutes, 3 or more times a day. Do no place ice directly on to skin, wrap them in a towel first to avoid ice burn! You can find our favourite ice pack here!
  • Compression. Wrapping the thigh with a compression sleeve will help decrease swelling and improve recovery time. You can find our favourite knee compression sleeve here!
  • Elevation. Elevate your feet to reduce swelling and bruising.

Physical Therapy

Although rest is a vital component of the recovery process following a knee replacement surgery, it doesn’t mean the affected leg has to be completely immobilised for long periods. In fact,  that will make things much worse! The best way to recover following surgery? Exercise! 

Knee Replacement Exercises

1) Knee Extensions

The number 1 exercise that must be completed following a surgery is knee extensions. Following a knee op the knee will be unable to go fully straight due to swelling, pain etc. However as this starts the decrease the patient absolutely has to try and push the knee into extension through exercise.
How to do it:
  • The easiest way to do this is to raise your leg whilst sitting, with only your heel on the leg rest in front of you, this will allow gravity to push the knee in to extension.
  • When exercising though, the easiest way to perform this is in sitting, simply straighten your leg as far as you can go, then try and gently push it further!
  • If the leg isn’t exercised and doesn’t go adequately straight, it will have to be painfully pushed there by a surgeon!

Repeat multiple times throughout the day.

2) Knee Flexions

The number 2 exercise that must be completed following a surgery is knee extensions. Following a knee op the knee will be unable bend very much due to swelling, pain etc. However as this starts the decrease you must absolutely try and push the knee further into flexion through exercise. You need to aim for 90° knee flexion within 6 weeks of surgery. (Your knee joint should be able to reach a right angle)
How to do it:
  • Sitting down on a chair
  • Slowly bend your knee, moving your foot underneath you.
  • You can also pull it back whilst lying down using a resistance band

Repeat multiple times throughout the day.

3) Static Quads

Maintaining strength in the leg and hip is very important for the knee to function properly once the swelling has gone down. It will also allow you to get back to a normal walking pattern quicker. Static quads are the easiest exercise to strengthen the quads.

How to do it:

  • Place a towel under the straight (operated) leg.
  • Tighten your thigh muscles and imagine you are pushing your knee cap down into the towel.
  • Hold for 15 seconds and release.

Repeat multiple times throughout the day!

4) Ankle Pumps

The biggest and most dangerous risk patients face following a total knee replacement is a deep vein thrombosis or DVT. This risk can be managed via a compression stocking, or more importantly, through exercise.

How to do it:

  • In either sitting or standing (harder), point your toes down as if you were going up on your tip toes. Hold for 10 seconds.

Repeat multiples times throughout the day.

5) Chair Drags

This is a fantastic hamstring exercise that can easily be done on an office chair or any chair that has wheels. . Pulling yourself along by bending at your knees creates a great contraction in your hamstrings and will progress your rehabilitation.

How to do it:

  • Sit on a office chair.
  • Pull yourself along digging in your heels as opposed to pushing off the floor.
  • Build up to 10 repetitions traveling 10 metres each time.

6) Mini Squats

A great exercise that will progress your ability to perform daily activities such as standing up from a chair, going up and down stairs etc.

How to do it:

  • Stand up with something stable (like a kitchen counter) in front of you for support.
  • Slowly bend your hips and knees as if you were sitting down. Stop half way, before pushing yourself back upright.

Repeat 10 reps, 3 sets, twice a day.


It is common to feel frustrated on days when you feel your progress is slow however this type of injury typically takes 6 months to recover fully. Normally, you will notice significant improvements in pain, mobility and strength after 6 weeks, by which point you may be able to discard any walking aids you were given. The aim is continue exercising and improving your mobility little by little each day. The knee often remains swollen and warm compared to the other knee, this is normal and can take a long time to settle down and can be as long as 6-12 months for a total knee replacement.