Range of Motion (ROM) After Knee Replacement Surgery: The Basics

Throughout your knee replacement recovery, you’ll likely be monitoring, obsessing over, and measuring one thing: range of motion. Chances are your doctor and physical therapist will give you range of motion milestones to hit and chances are it won’t be easy to get there. Gaining back knee flexion (bending), extension (straightening), adduction (movement towards middle of the body), abduction (movement away from middle of the body), rotations (inward and outward) must be worked towards. It not something that happens overnight.

When thinking about range of motion (ROM), that irritating saying, “no pain, no gain” comes to mind. To hit your range of motion goals after knee replacement surgery, you’re going to have to work through some pain and dedicate yourself to improvement. Besides putting in good old fashion work, there are things you can do to accelerate and improve your post-op knee range of motion. Read on as we walk you through the best things you can do after knee replacement surgery to hit your ROM goals.

Range of Motion Basics After Knee Replacement Surgery

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First, we need to start off by saying that everyone is different. Some people are naturally born with more flexion and extension in their knee joints, some people have complications or severe osteoarthritis degradation to overcome, some people may experience knee stiffness, and so forth. In fact, one of the best indicators of your knee range of motion after surgery is your ROM before surgery.

A completely straight, unflexed knee joint will measure 0° of flexion. A fully bent knee will max out at about a full range of motion of 135° degrees of flexion.

As a general rule, a knee flexion of about 125° will allow you to carry out most normal activities. For daily living, a minimum flexion of around 105°-110° is required. Here’s the approximate range of motion flexion required for everyday activities:

  • 65° to walk
  • 70° pick an object off the ground
  • 85° to climb up stairs
  • 95° to stand from a sitting position
  • 105° to tie shoelaces
  • 115° (or greater) to squat or sit cross-legged
  • 125°+ covers most activities. However, squatting or sitting on your heel may always prove challenging.

In a study conducted with 108 total knee arthroplasty patients, the mean postoperative active flexion was 111°. Passive range of motion (when a therapist helps move the knee joint) was reported as 117°. As such the average degree of flexion after a knee replacement is between 111°-117°.

Knee Replacement Range of Motion Timeline: Where You Should Be After Surgery

Not only do people have different ROM potential to begin with, people also heal at different rates. With that in mind, here are the flexion goals our team of medical advisors (US-based orthopaedic surgeons and physical therapists) look for in their total knee replacement patients.

  • Stage 1 (0-2 Weeks)—65-90° flexion. This amount of flexion allows for walking without assistance, standing, and some stair climbing (likely with support). Before you leave the hospital, your doctor will be looking for flexion as close to the 90° as possible.
  • Stage 2 (2 to 6 Weeks)—115° flexion. At this point, you should have made noticeable improvements from your early recovery days. This means moving around normally, bending to the ground, sitting down, and even tying shoelaces!
  • Stage 3 (12 Weeks +)—A goal to hit 115°or greater should be the aim. The timeframe for this varies, but should be consistently work towards. A flexion of 125° is great and 135° is excellent (whether you’ve had a joint replacement or not!).

Throughout each stage, it’s important that you keep working your surgical knee and artificial knee prosthesis. The first 3 months of your recovery are critical for working out your new knee to gain back flexibility, bending, extension, and movement. If you stay idle, inconsistent or not fully committed to gaining back range of motion, your knee may become stiff. If your knee becomes stiff, you risk the need for revision surgery and a joint that will cause lifelong issues.

Exercises to Increase Your ROM

If you worked at a PreHab program before joint replacement surgery, you’ll already be leaps and bounds ahead for achieving optimal range of motion. If you’re reading this before your joint replacement surgery, great! In the weeks leading up to surgery, we strongly encourage you to start a daily PreHab program of exercises and everyday movements that will help build strength and movement in your joint.

If you’re newly into recovery, you will likely be setup with a physical therapist or occupational therapist. Taking advantage of as many sessions as possible is key. However, strictly relying on in-class sessions to optimize your ROM isn’t enough. It’s absolutely, positively imperative that you supplement classes with an at-home guided ReHab program.

A great at-home program will include “early exercises” that will help get you mobile after surgery, “functional exercises” that will help bring back regular movements, “advanced exercises” that aim to build strength and push you further, and later stage “maintenance exercises” after the 12+ week mark where you engage in low-impact exercises to keep fit and keep moving.

The 5 ROM Exercises You Should be Doing Daily

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Pro Tip: People who’ve suffered from chronic pain or range of motion limitations are often scared to fully flex their joint. However, please know that a lot of your recovery is about “emotionally letting go” of expecting pain.

1. Seated Knee Flexion (Knee Bends)

This exercise helps increase knee range of motion and strength in your quadricep to enhance mobility.

  1. Sit on a chair with a rolled towel under your surgical leg.
  2. Keep both feet flat on the ground.
  3. Slide one foot back behind the stationary foot, bending your surgical knee.
  4. Hold for a few seconds, then slide your foot forward.

10 reps, 2x per day

2. Seated Knee Extension

This exercise is one you should do throughout the day to cut down on stiffness. It also helps strengthen the quad muscles at the front of your thigh.

  1. Sit on a chair.
  2. Straighten your surgical leg and bend it back down.

10 reps, 2x per day

3. Short Arc Quads (Lying Kicks)

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This exercise improves the endurance of your quad muscle and allows for greater control over leg movements.

  1. Lie on your back with a rolled towel under your knee
  2. Slowly straighten your surgical knee by lifting your foot up while keeping your knee on the rolled towel

10 reps, 2x per day

4. Heel Slides

This is a range of motion exercise that strengthens thigh and improve movement.

  1. Lie on your back in bed with your legs straight.
  2. Keeping your non-surgical leg flat, bend your surgical knee by sliding your heel toward your buttocks.

10 reps, 2x per day

5. Ankle Pumps

Ankle pumps help to improve circulation and blood flow, both of which promote healing and reduce swelling. Swelling is a major roadblock to regaining full motion.

  1. Lie on your back.
  2. Gently flex your foot up and then point down. You can move just your surgical side or move both ankles at once.

10 reps, 2x per day

For a daily PreHab exercise plan (which can be applicable to at-home ReHab exercises), click here.

Bonus Exercise: Water Therapy

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If you have access to water therapy, this is one the of best ways to work out at a higher intensity, while offloading most of your body weight. Water therapy lets patients work on their range of motion through leg exercises, stretching, and even jogging—all inside a swimming pool.

Most major cities in the US have a water therapy (sometimes called “pool” or “aquatic therapy”) center. Click here to read more about the benefits of water therapy after a joint replacement and to find a water therapy center near you.


With PeerWell’s ReHab program, you can track and measure your ROM at home for the first time ever. You just need the PeerWell ReHab app and your smartphone or tablet. PeerWell is proud to bring this innovative technology to our app users as helpful tool to track progress!

Sign-up for PeerWell ReHab today!

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Hi, I'm Grace. I write all things surgery for the PeerWell blog. You may remember me from such titles as: "Diabetes & Joint Replacement 101" & "Sex After a Joint Replacement".

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