Rehab after a knee replacement: a stage-by-stage guide

Before surgery: why prehab helps

Rehab really starts before the operation. People who go into surgery with stronger thigh muscles, better fitness and a clear understanding of what to expect generally find the early weeks easier. If you have a date, use the waiting time to build quad and hip strength, practise the exercises you will do afterwards, and keep as active as your knee allows.

Practical preparation helps too: arranging help at home, setting up a comfortable chair with arms, moving everyday items to waist height, and planning how you will get to physio appointments.

It is also worth thinking about what a good result looks like for you. Walking the dog without pain, playing golf again or getting down on the floor with grandchildren are all realistic goals for many people, and naming them early helps shape the rehab.

The first two weeks

Most people are up and walking with a frame or crutches within a day of surgery, supported by the hospital physio team. The focus in the first weeks is managing pain and swelling, getting the knee as straight as possible, starting to bend it, and walking safely. Pain relief as prescribed is important, because it lets you do the exercises that matter.

1. Quad sets: tighten the thigh to press the back of the knee down, hold for 5 to 10 seconds, 10 times, several times a day.
2. Straight leg raises once the quad can hold the knee straight, 10 reps.
3. Heel slides lying down, bending the knee as far as comfortable, 10 to 15 reps.
4. Knee straightening: rest the heel on a rolled towel with nothing under the knee for a few minutes, several times a day.
5. Short, frequent walks around the house with your walking aid.

Weeks 2 to 12: building movement and strength

Over the next few weeks, the aim is to steadily increase how far the knee bends, keep it fully straight, and build strength and walking confidence. Many people move from crutches to a stick and then no aid over this period, depending on their progress and the surgeon's advice.

An exercise bike is a great tool once you can bend the knee enough to pedal a full circle, usually starting with the seat high and no resistance. Strength exercises progress from lying and sitting exercises to standing work such as sit to stand, mini squats, step-ups, calf raises and balance exercises. Later, gym exercises such as the leg press can be added.

Swelling, warmth and stiffness are normal and can last several months. Raising the leg above heart level, ice as advised by your team and regular gentle movement help. Sleep is often disturbed in the early weeks; our guide to sleep for recovery has practical tips.

Progress is rarely a straight line. It is common to have a few good days followed by a stiff, sore one, especially after doing more. Keep the exercises going on the harder days, perhaps with fewer reps, rather than stopping altogether.

Getting back to normal life

• Driving: commonly around 6 weeks, once you can safely perform an emergency stop, but always check with your surgeon and insurer.
• Work: desk jobs often from around 6 weeks; physical jobs usually take longer.
• Walking, cycling and swimming (once the wound has fully healed) are excellent long-term activities.
• Gym training: strength training is encouraged and can progress over months with guidance.
• Kneeling: often uncomfortable at first but usually safe; build up gradually on a cushion.
• High-impact sports and running: discuss with your surgeon, as advice varies.

Our guide to strength training over 50 is a good next step once you are through the early rehab stages and want to build long-term strength.

Many people are surprised by how much better their knee feels once the thigh muscles are genuinely strong again. The new joint removes the arthritic surfaces, but the muscles still need rebuilding after years of pain and months of reduced activity.

How long recovery takes

Most people are managing daily activities fairly comfortably within 6 to 12 weeks, but improvement in strength, stiffness and swelling can continue for up to a year. A minority have ongoing stiffness or pain, which is why the early work on straightening and bending matters so much. If progress stalls, speak to your surgical team early, because some stiffness problems are easier to address in the first few months.

The on-site physio at Lycan Strength offers pre and post-operative rehab, with therapeutic exercise and home exercise programmes as part of treatment, and members get 20% off. You can book a physio appointment online. Our page on knee osteoarthritis covers the condition that leads many people to surgery.

When to get urgent help

Follow the specific advice given by your hospital team, and use the contact numbers they provide. In general:

• Call 999 for chest pain, sudden breathlessness or coughing up blood, which can be signs of a blood clot in the lungs.
• Contact your surgical team or NHS 111 urgently for a swollen, warm, painful calf.
• Contact your surgical team urgently if the wound becomes increasingly red, hot or swollen, leaks fluid or pus, or you have a fever or feel unwell.
• Contact your surgical team urgently for a sudden increase in pain, sudden inability to bear weight, or if the knee gives way badly after a fall.
• Contact your surgical team if the knee is not bending past about 90 degrees after several weeks despite doing your exercises.

Questions