By Reece Jones, Physiotherapist, WiSE Physiotherapy
The short answer: exercise before a knee replacement can ease pain while you wait and may shorten your hospital stay. Exercise in the first few months after surgery improves function and pain compared with little or no physio. For most people with an uncomplicated recovery, a supervised home program works as well as staying in an inpatient rehab ward.
Knee replacement is one of the most common joint operations in Australia. Below, we explain what the evidence says about each stage and what a sensible plan looks like.
Is a knee replacement the only option?
Not always. Exercise therapy and education are the recommended first steps for knee osteoarthritis. A Danish trial of 100 people compared knee replacement plus a 12 week non-surgical program with the non-surgical program alone (Skou et al., 2015). Surgery gave more improvement in pain and function at 12 months, but it also came with more serious adverse events (24 compared with 6). In the non-surgical group, 26% went on to have surgery within the year, which means most did not.
If you have not yet tried a structured exercise program, it is worth a conversation with your GP, surgeon and physio before deciding.
Does exercise before surgery help?
This is often called prehabilitation, or prehab. A 2023 review of 22 randomised trials with 1,601 people found that home-based prehab before knee replacement reduced pain before surgery and shortened hospital stays (De Klerk et al., 2023). It did not clearly improve function after surgery.
In practice, this means prehab is worth doing to feel better while you wait and to go into surgery stronger and more confident, but it is not a guarantee of a faster recovery. A typical prehab plan includes:
- Strengthening for the quadriceps, hamstrings, hips and calves
- Range of motion work to keep the knee bending and straightening
- Practice with walking aids and stairs
- Education on what to expect in hospital and in the first weeks at home
What does rehab look like after a knee replacement?
A review of 18 randomised trials with 1,739 people found that physio exercise after knee replacement improved physical function and pain at three to four months, compared with minimal physio (Artz et al., 2015). The review did not find clear long-term differences, so the early months are where structured rehab matters most.
Rehab usually moves through stages:
- Weeks 0 to 2: reduce swelling, get the knee straight, start bending, walk safely with an aid.
- Weeks 2 to 6: build bend towards 110 degrees or more, strengthen the quadriceps, wean off aids as advised by your surgeon.
- Weeks 6 to 12: progress strength and balance, return to normal walking, stairs and driving when cleared.
- Three months and beyond: return to activities such as cycling, swimming, golf or bushwalking, guided by your surgeon and physio.
Every recovery is different. Your surgeon’s protocol always comes first, and your physio works within it.
Do I need inpatient rehab, or can I recover at home?
A Sydney trial of 165 people after uncomplicated knee replacement compared 10 days of inpatient rehab plus a home program with a monitored home program alone (Buhagiar et al., 2017). At 26 weeks there was no meaningful difference in walking ability, knee scores or quality of life. The authors concluded the results did not support inpatient rehab for this group.
This does not mean rehab does not matter. It means that for many people, a well-structured, physio-guided program at home and in the clinic is a reasonable choice. People with complications, other health conditions or limited support at home may still need inpatient care, so discuss this with your surgeon.
Frequently asked questions
How soon after a knee replacement should I start physio?
Most people start gentle exercises in hospital, often on the day of or the day after surgery. Outpatient physio usually begins within the first one to two weeks after discharge, depending on your surgeon’s advice.
How long does rehab take?
Most of the early gains happen in the first three months. Many people keep improving strength and confidence for up to a year.
How much should my knee bend?
Around 90 degrees helps with sitting and stairs, and 110 degrees or more makes daily activities like getting out of a low chair or riding a bike easier. Your physio will measure it as you go.
Do I need a referral to see a physio?
No. You can book directly. If you have private health insurance with extras, you may be able to claim part of the fee. If you are eligible for a GP chronic condition management plan or a Department of Veterans’ Affairs referral, speak with your GP about it.
Is some pain normal during rehab?
Some discomfort with exercise is expected. Sharp pain, increasing swelling, redness, fever or calf pain are not normal and need prompt medical review.
Book a knee replacement physio assessment
WiSE Physiotherapy sees people before and after knee replacement at our Macquarie Park, Frenchs Forest and Caringbah clinics. We work with your surgeon’s protocol and tailor your program to your goals.
Book online. No referral needed.
This article is general information only and is not a substitute for advice from your own health professional.
References
- Skou ST, Roos EM, Laursen MB, et al. A randomized, controlled trial of total knee replacement. N Engl J Med. 2015;373:1597-1606.
- De Klerk TC, Dounavi DM, Hamilton DF, Clement ND, Kaliarntas KT. Effects of home-based prehabilitation on pre- and postoperative outcomes following total hip and knee arthroplasty: a systematic review and meta-analysis. Bone Jt Open. 2023;4(5):315-328. Abstract
- Artz N, Elvers KT, Lowe CM, et al. Effectiveness of physiotherapy exercise following total knee replacement: systematic review and meta-analysis. BMC Musculoskelet Disord. 2015;16:15. Abstract
- Buhagiar MA, Naylor JM, Harris IA, et al. Effect of inpatient rehabilitation vs a monitored home-based program on mobility in patients with total knee arthroplasty: the HIHO randomized clinical trial. JAMA. 2017;317(10):1037-1046.