Back to Blog

A Commonly Missed Impairment After ACL Reconstruction

acl reconstruction recovery

Let's talk about one of the most commonly missed impairments after ACL reconstruction --  loss of knee flexion range of motion. To me, this is defined as getting the ischial tuberosities all the way back to the heels (researchers define it as within 5 degrees compared to the contralateral side). 

Researchers tell us that if you don't get full knee range of motion, you're more likely to re-tear the graft, as well as have long-term osteoarthritis. Here's a summary of a couple of studies:

Loss of normal knee motion after anterior cruciate ligament reconstruction is associated with radiographic arthritic changes after surgery

  • 780 patients at a mean of 10.5 + 4.2 years after surgery
  • Normal range of motion if extension was within 2 degrees of the opposite knee including hyperextension and knee flexion was within 5 degrees
  • Logistic regression showed that abnormal knee flexion at early follow-up, abnormal knee extension at final follow-up, abnormal knee flexion at final follow-up, partial medial meniscectomy, and articular cartilage damage were significant factors related to the presence of osteoarthritis on radiographs

Clinical Tests Can Be Used to Screen for Second Anterior Cruciate Ligament Injury in Younger Patients Who Return to Sport

  • Patients with a flexion deficit of 5 degrees had over two times the odds of sustaining a graft rupture (odds ratio, 2.3; P < .05)

So the bottom line is that full knee flexion ROM is really important.  However, nearly all of the patients who see me from another provider at 6 months, a year or even 2 years post ACL reconstruction are limited in knee flexion, particularly in the quadruped position.

We must start working on getting this back ASAP post-operatively. One of my favorite ways to get it back is simple hands and knees rocking.  We're going to have the patient come back until they feel a stretch . . . not a pain, not a pinch . . . because this is something that will come back on its own gradually if you work on it in this position consistently until the range of motion is fully restored. When you're doing the stretch, hold it about 10 seconds, back off of it, and each time try to come back a little bit farther.   

Again, the real question of this is not if we should do this exercise, it's when . . . with bone patellar tendon bone graft, we've got to wait for harvest site healing.  With a hamstring graft, we can do it a little bit earlier.  

 If you are interested in learning more about ACL reconstruction, check out our course series ACL Reconstruction Rehabilitation: Beyond the Protocol on MedBridge.


Shelbourne KD, Benner RW, Gray T. Results of Anterior Cruciate Ligament Reconstruction With Patellar Tendon Autografts: Objective Factors Associated With the Development of Osteoarthritis at 20 to 33 Years After Surgery. Am J Sports Med. 2017 Oct;45(12):2730-2738. doi: 10.1177/0363546517718827. Epub 2017 Aug 14. PMID: 28806096.

Shelbourne KD, Gray T. Minimum 10-year results after anterior cruciate ligament reconstruction: how the loss of normal knee motion compounds other factors related to the development of osteoarthritis after surgery. Am J Sports Med. 2009 Mar;37(3):471-80. doi: 10.1177/0363546508326709. Epub 2008 Dec 4. PMID: 19059893.

Webster KE, Feller JA. Clinical Tests Can Be Used to Screen for Second Anterior Cruciate Ligament Injury in Younger Patients Who Return to Sport. Orthop J Sports Med. 2019 Aug 6;7(8):2325967119863003. doi: 10.1177/2325967119863003. PMID: 31431901; PMCID: PMC6685123.


Are you looking to gain confidence in taking athletes from injury to high level performance? Looking to simplify the process and gain clarity? Wish you had a community to ask questions and bounce ideas off of? Check out the Coaches Club.

Don't Miss Out on the Latest Research and Insights!

Sign up for The Huddle


By entering your info, you’ll become a member of The Huddle– with FREE access to a weekly newsletter, return to sport and discharge checklists, free content and offers delivered to your inbox. (Unsub anytime in a click.) You also agree to our Terms of Use and Privacy Policy.

This is a blog and information website and it is not intended to replace the advice or care from a healthcare provider. If you are a healthcare provider, this blog and website are not designed to replace formal education or give you authority to practice outside of your jurisdiction’s practice act. It contains my opinion (based on the best available evidence where possible) and may even be wrong. The information also may not be complete or timely. It does not cover all diseases, physical conditions, ailments, or treatments. The information should NOT be used in place of visiting with your healthcare provider or formal continuing education on the subject matter, nor should you disregard the advice of your healthcare provider because of any information you obtain on this website. Discuss any activities presented on this website with your healthcare provider before engaging in the activity. Links and posts by others do not imply my endorsement of the material and the link might not even be the correct one. Any information, content, products, services, advertising or other materials presented on or through such websites is not under my control or my responsibility.
Disclosure of Material Connection: Some of the links in the post above are “affiliate links.” This means if you click on the link and purchase the item, I will receive an affiliate commission. Regardless, I only recommend products or services I use personally and believe will add value to my readers. I am disclosing this in accordance with the Federal Trade Commission’s 16 CFR, Part 255: “Guides Concerning the Use of Endorsements and Testimonials in Advertising.