Benefits of Early Rehab Following ACL Surgery

Rehabilitation following ACL surgery is a long process that can be both physically and mentally taxing. Some patients may want to rest for a week or two prior to initiating physical therapy. However, there are several benefits to early rehab. We like to see patients 2-3 days after surgery to jumpstart the following:

1. Decrease pain and swelling
2. Restore full knee extension
3. Regain volitional quad control
4. Maintain patellar mobility
5. Begin knee flexion mobility
6. Normalize gait pattern

Decrease Pain and Swelling

Excess swelling around the knee joint can contribute to impaired quad function, limit ability to bend and straighten the knee, and contribute to increased pain levels.

Techniques used in the clinic to decrease pain and swelling include gentle soft tissue massage, passive range of motion, electrical stimulation, and ice.

Restore Full Knee Extension

Restoring full knee extension (straightening of the knee) is the #1 priority following ACL surgery, however it is difficult to achieve without managing pain and swelling. Our goal is to increase knee extension equal to the other side which is usually between 5 and 10 degrees of hyperextension. 

Following surgery, the knee defaults to a slightly bent position when the joint is swollen and painful. If full extension is not achieved and maintained, the knee can develop scar tissue and arthrofibrosis.

Full knee extension is important for normal walking and optimal quad contraction for strengthening. Limping around with a bent knee can further contribute to pain and swelling delaying the entire rehab process. Prolonged loss of motion is associated with increased risk of osteoarthritis.

Techniques used in the clinic to achieve full knee extension include soft tissue massage, patellar mobilizations, hamstring stretch, calf stretch, and electrical stimulation to the quad with the heel propped.

We advise patients to never relax or sleep with a pillow under their knee. Instead, we suggest keeping the heel propped on a pillow or chair. This will promote knee extension in a straight position and prevent the knee from becoming stiff in a bent position.

Regain Volitional Quad Control

After ACL surgery, it is extremely difficult to contract your quad due to a process called arthrogenic inhibition which is caused by disruption of nerve endings during surgery, pain, swelling, and inflammation. This leads to significant quad weakness and atrophy. It is important to quickly regain volitional quad control in order to walk normally and begin strengthening.

Quad strength at 12 weeks following surgery is correlated to long term strength and function. Early strengthening is critical for long term success which is why regaining volitional quad control is so important in the early phase of rehab.

Neuromuscular electrical stimulation (NMES) is a device used in the clinic that sends signals to the nerves to elicit muscle contraction. We use this in combination with isometric quad sets to restore active quad contraction and achieve full knee extension. NMES can also be paired with straight leg raise and knee extension for optimal quad contraction with movement.

Patellar Mobility

The patella (knee cap) plays an important roll in the ability to bend and straighten your knee. The patella moves slightly downward when you bend your knee and moves slightly upward when you straighten your knee. Limited patellar mobility can contribute to overall knee joint stiffness. Swelling can initially impair patellar mobility and if not quickly restored, adhesions and scar tissue can develop under and around the patella. This is of increased significance if a patellar tendon or quad tendon graft is used for reconstruction. See our previous blog post ‘ACL Graft Selection’ to learn more about the different types of grafts.

Soft tissue massage and mobilizations are used to restore and maintain patellar mobility.

Gradually Progress Knee Flexion

Regaining full knee flexion is not as important as immediate restoration of knee extension. However, it should not be ignored. Progressing knee flexion can be done more gradually with the initial help of gravity. Sitting at the edge of a table with the leg relaxed is a gentle way to progress knee flexion to roughly 80-90 degrees. Heel slides are another technique to progress knee flexion that allows the patient to be in control. Ideally, we want to see about 90 degrees of knee flexion by week 2 and full restoration of knee flexion equal to the other side by week 4-5.

Normalize Gait

It is important to instill normal walking mechanics shortly after surgery. Walking around with a limp and bent knee can lead to continued pain and swelling and possibly cause dysfunction in other areas of the body.

Once full knee extension is restored with active quad control and moderate bending of the knee, the patient can begin to walk without limitations.

There are a variety of techniques we use in the clinic to help patients achieve normal walking with and without the use of crutches.


We understand that recovery after ACL surgery is tough both physically and mentally.  Starting physical therapy within the first 2-3 days after surgery promotes decreased pain and increased function.  Pain, swelling, knee extension, and quad control are all related to each other. As one improves, it facilitates the improvement of others. However, if neglected, a vicious cycle of pain, swelling, impaired joint mobility and function can snowball downhill. Our therapists are here for you every step of the way to provide safe and effective treatment in a positive, energetic atmosphere. Let us know if you are scheduled for or considering ACL surgery and have any questions about the recovery process!

Written by Hannah Sweitzer, DPT, OCS

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