Knee Stiffness After ACL Surgery

Knee Stiffness After ACL Surgery

Although ACL surgery is done to replace a torn knee ligament and alleviate pain, you may experience stiffness after your surgery. This stiffness is often due to scar tissue formation; without physical therapy, it can lead to reduced mobility and function. This blog discusses the causes of knee stiffness after ACL surgery and how Barkman & Smith's physical therapy can help.

What Are The Causes Of Knee Stiffness After ACL Surgery?

After an ACL surgery, you may experience knee stiffness due to the formation of scar tissue, the surgery itself, or inflammation and swelling around the knee joint.

Scar Tissue Formation

The formation of scar tissue is a natural part of the healing process. After an ACL surgery, scar tissue forms within and around the knee joint. Unfortunately, the accumulation of this tissue limits the range of motion.

Inflammation And Swelling

An ACL surgery is invasive, involving the manipulation of the knee joint. Surgical manipulation may result in inflammation and swelling around the surgical site, contributing to knee stiffness. Although inflammation and swelling are part of the healing process, when prolonged, they can hinder normal function and reduce mobility.


Although surgery is necessary to replace a torn ACL, the procedure can contribute to post-operative knee stiffness. The replacement graft for a torn ACL can usually be taken from other tissues in your body or from a donor. However, the choice of graft material and the fixation method can cause stiffness post-procedure.

Pre-Existing Conditions

Previous surgeries, underlying joint conditions, and other knee injuries can increase the likelihood of experiencing knee stiffness after ACL surgery. Besides causing stiffness, these pre-existing conditions can also slow the healing process.

Delayed Physical Therapy

Barkman & Smith physical therapists develop individualized programs to help you heal properly and regain function after surgery. Unfortunately, some people experience knee stiffness years after ACL surgery due to delayed treatment. Late physical therapy delays restoring function and range of motion to your knee joint, resulting in stiffness. A physical therapy treatment plan usually includes stretches, strengthening, and mobilization exercises.

What Are The Symptoms Of Knee Stiffness After ACL Surgery?

It is essential to recognize the symptoms of knee stiffness post-ACL surgery for proper treatment. The stiffness may hinder your return to normal activities, including sports, without prompt treatment. It can also lead to secondary injuries or disability.

The symptoms of knee stiffness post-ACL surgery include;

Limited Range Of Motion

A primary symptom of knee stiffness is a limited range of motion. For example, you may experience difficulty extending your knee fully or flexing your knee joint. In addition, if you cannot bend the knee to its normal degree post-surgery, your knee may be stiff.

Swelling And Inflammation

If your knee joint appears visibly swollen and tender to the touch, especially around the surgical site, your knee may be stiff. Swelling and inflammation contribute to stiffness and overall discomfort.

Difficulty With Weight-Bearing Activities

You may find it challenging to carry out weight-bearing activities such as walking, climbing stairs, or standing for long periods. In addition, you may experience pain or discomfort when you put your weight on the affected knee, affecting your posture and gait.

How To Treat Knee Stiffness After ACL Surgery

Treating knee stiffness after ACL surgery is necessary to restore range of motion, speed recovery, and prevent a disability. There are several ways to manage and reduce knee stiffness, including;


Resting your leg is essential for reducing knee stiffness. Nevertheless, it is best to avoid prolonged periods of inactivity. You can take short walks or perform gentle range of motion exercises to reduce stiffness and maintain joint mobility.

Ice Therapy

Ice constricts the blood vessels to reduce swelling. You can manage knee stiffness by applying ice packs to the affected knee. When using ice, avoid direct contact with the skin. Instead, wrap it in a cloth and place it on the affected knee for 15 to 20 minutes several times daily.

Compress And Elevate

You can reduce knee stiffness and support your knee joint by using compression badges or knee sleeves. In addition, you can wrap your knee in an elastic bandage and elevate it when sitting or lying down to prevent fluid buildup and reduce swelling.


Your doctor may prescribe non-steroidal anti-inflammatory drugs (NSAIDs) to reduce inflammation and pain associated with knee stiffness. However, you must consult your doctor before using these drugs and follow the recommended dose and duration.

Physical Therapy

Physical therapy can help reduce stiffness and swelling and restore function to your knee after ACL surgery. Your physical therapist in Fort Worth, TX & Bedford, TX, will use techniques that improve your range of motion, strengthen your muscles, and reduces pain. A comprehensive rehabilitation program is usually tailored to your needs to reduce knee stiffness and boost your recovery.

Physical Therapy Exercises For Knee Stiffness After ACL Surgery

Your physical therapist will examine the severity of your knee stiffness post-ACL surgery before developing an appropriate treatment plan. Physical therapy exercises for knee stiffness include a range of motion, stretching, and strengthening exercises. You may also undergo proprioception and balance training.

Range Of Motion Exercises

Range of motion (ROM) exercises promote flexibility and break up scar tissue in the knee. The exercises also improve joint function, allowing you to move your knee joint in different directions. ROM exercises for knee stiffness include heel slides and knee extensions.

How to do heel slides

  • Lie on your back and extend your legs.
  • Slowly bend your knee and slide your heel towards your buttocks. Use your hands for assistance if needed.
  • Slide your heel back to starting position.
  • Repeat the exercise.
  • Gradually increase your range of motion as tolerated.

How to do knee extensions

  • Lie on your back or sit on a chair with your legs extended.
  • Lift your foot off the ground and extend your leg by slowly straightening your knee.
  • Hold for a few seconds.
  • Lower your foot back down.
  • Repeat the exercise.
  • Gradually increase your range of motion as tolerated.

Stretching Exercises

Stretching exercises improve flexibility and reduce muscle stiffness. These exercises target muscles, including the quadriceps, hamstrings, and calves, contributing to knee stiffness post-ACL surgery. Stretching exercises that can help with knee stiffness include side leg raise, hamstring stretch, and quadriceps stretch.

How to do hamstring stretch

  • Sit on the edge of a chair and extend one leg in front of you.
  • Keep your back straight and slowly reach forward to touch your toes. You should feel a stretch at the back of your thigh.
  • Hold the stretch for 20-30 seconds and release.
  • Repeat the exercise on the other leg.
  • Perform the stretch multiple times a day.

How to do quadriceps stretch

  • Stand near a wall or hold a sturdy object.
  • Bend your knee and grab your ankle with your hand.
  • Gently pull your heel towards your buttocks. You should feel a stretch in front of your thigh.
  • Hold the stretch for 20-30 seconds and release.
  • Repeat the exercise on the other leg.
  • Perform the stretch multiple times a day.

Strengthening Exercises

Strengthening exercises reduce stiffness and improve knee stability by targeting the calf muscles, hamstrings, and quadriceps. Leg raises, heel raises, and hamstring curls are common exercises for alleviating knee stiffness post-ACL surgery.

How to do heel raises

  • Stand near a wall or hold a sturdy object for support.
  • Slowly raise your toes, lifting your heels off the ground.
  • Hold the raised position for a few seconds.
  • Slowly lower your heels back down.
  • Repeat the exercise.

How to do hamstring curls

  • Stand behind a chair or hold a sturdy object for support.
  • Bend one knee and lift your heel towards your buttocks while contracting your hamstring muscles.
  • Hold the contraction for a few seconds.
  • Slowly lower your foot back down.
  • Repeat severally on each leg.

Proprioception And Balance Training

Proprioception and balance exercises improve your body's awareness and control of the knee joint's position. Consequently, there is improved stability and minimal risk of re-injury. Proprioception and balance exercises after ACL surgery include standing on one leg, lateral hops, and performing balance board exercises.

How to do lateral hops

  • Stand on one leg.
  • Hop laterally from side to side.
  • Land softly and maintain your balance after each hop.
  • Start with small hops.
  • Gradually increase the distance as your stability improves.
  • Repeat severally on each leg.

How to do balance board exercises

  • Use a balance board.
  • Stand on the board with your feet shoulder-width apart.
  • Maintain your balance while keeping the board level.
  • You can add squats as you improve your balance.

What Is The Recovery Timeline Post-ACL Surgery?

Recovery after ACL surgery varies for individuals. The extent of surgery, overall health, and adherence to rehabilitation will determine how long your knee stiffness post-ACL surgery will last. Physical therapy after ACL surgery is expected to last from a few weeks to a few months. Communicating and following your physical therapist's instructions is essential for the best results.

Week 1 – 2

During the first two weeks following your ACL surgery, your knee will be swollen and stiff. Your physical therapist will recommend painkillers, rest, and ice therapy to reduce swelling and relieve pain.

Week 2 – 6

After the swelling and pain have reduced, your physical therapist will carry out passive exercises with you to improve your range of motion and stretch your knee. These exercises will improve your balance, strengthen your leg muscles, and allow you to begin to walk properly. You should be able to walk without crutches within three weeks of physical therapy.

Week 6 – 24

You should be able to return to regular activity during this period. It is best to carry out an active range of motion exercises. For example, you can swim and cycle. However, avoid sports that require jumping and twisting.

After six months

You can return to playing sports after six months. However, checking with your physical therapist to know if you can fully return to sports is best.  


Knee stiffness needs prompt treatment to restore function and prevent disability. You can get physical therapy in Bedford, TX, after your ACL surgery to avoid stiffness knee and ensure you heal properly after your procedure. Physical therapists at Barkman & Smith Physical Therapy will examine your symptoms and create a treatment plan suited to your needs to achieve the best results for your post-ACL surgery recovery.