Assessing and Treating Loss of Knee Extension Range of Motion

Assessing and treating loss of knee extension range of motion is an important component of rehabilitation following any knee surgery.  We recently discussed how loss of knee extension range of motion may be one of the biggest factors associated with the development of osteoarthritis following ACL reconstruction.

The purpose of this article is to review some of the many methods of assessing and treating loss of knee extension range of motion to help maximize outcomes following knee surgery or injury while minimizing long term complications.

 

Assessing Loss of Knee Extension Range of Motion

There are many ways to treat loss of range of motion in the knee, however, proper assessment of range of motion is even more important.  A certain degree of hyperextension is normal, with studies citing a mean of 5 degrees of hyperextension in males and 6 degrees in females.  Simply restoring knee range of motion to an arbitrary 0 degrees is not advantageous.

The most important factor in assessing loss of knee extension range of motion is looking at the noninvolved knee.  As simple as this sounds, this can not be overlooked as you need to establish a baseline for what is “normal” in each patient or client.

The first thing I look at is simply grasping the 1st toe with one hand to lift the foot off the table.  My proximal hand can stabilize the distal femur.  This is a quick and dirty assessment but I always recommend quantifying the available range of motion.

To accurately measure knee extension range of motion, you will need to use a towel roll of various height to assure the knee is fully hyperextended before taking a goniometric measurement.

Knee Hyperextension

Other aspects of assessment that should be performed when dealing with loss of knee extension range of motion should include patellar mobility, tibiofemoral arthrokinematics, and soft tissue restrictions.  Patellar mobility is especially important after ACL reconstruction using a patellar tendon autograft.  Any restrictions in patellar mobility can have an obvious correlation with restricted knee extension.  Scarring of the patellar tendon can restrict superior glide of the patella and full knee extension.

These assessments will help guide our manual therapy approach to restoring normal arthrokinematics and range of motion of the knee.

Documenting Knee Range of Motion

I took a poll of a large group of students coming through my clinic in the past and found that there was great confusion regarding how we document hyperextension of the knee.   Is + or – when defining a numerical value?

Let’s say that someone has a contracture and is sitting in 10 degrees of flexion and is unable to straighten their knee.  That would be +10 degrees of flexion, thus has to be -10 degrees of extension.  They are on two ends of the spectrum.

Still, using a + or – can be potentially confusing, so I have long taught my students that we should document range of motion using the A-B-C method.  Other authors, such as Dr. Shelbourne, recommend this method as well.

  • If a person has 10 degrees of knee hyperextension and 130 degrees of knee flexion, it would be documented as 10-0-130.
  • If a person has a 10 degree contracture and loss of full knee extension with 130 degrees of knee flexion, it would be documented as 0-10-130.
Using the A-B-C method eliminates the potential for confusion while documenting.

Treating Loss of Knee Extension Range of Motion

There are several ways to improve knee extension range of motion, however, if a person is struggling with this motion I have found that self-stretches, low load long duration (LLLD) stretching, and range of motion devices can be superior to us cranking of a already cranky knee!  Allowing gentle, frequent, and progressive load to the knee is usually more tolerable for the person, especially those that are sore or guarded in their movements.

The intent of this article is to discuss some specific independent strategies to enhance knee extension range of motion.  Other skilled treatments should focus on patellar mobility, soft tissue mobility, and other aspects of manual therapy for the knee as needed.   However, patients will need to perform stretches at home to assure good outcomes.

 

Self Stretches for Knee Extension Range of Motion

Two of the first stretches that I give patients following surgery are simple self stretches for knee extension.  The basic version simple has the patient applying a stretch into extension by pushing their distal thigh.  The second and slightly more advanced version, has the patient press down on their distal thigh while using a towel around the foot to pull up and simultaneously stretch the hamstrings.

Knee Extension Stretch

Towel Knee Extension Stretch

Similar to how we assess knee extension range of motion, you will want to use some sort of wedge under the heel to assure that you are restoring full motion.

 

Low Load Long Duration Stretching for Knee Extension Range of Motion

For the person that is having a hard time achieving knee extension, my next line of defense is usually LLLD stretching.  Several research articles have been published showing the benefit of LLLD stretching in achieving range of motion gains.

I prefer performing LLLD stretching for knee extension in the supine position rather than prone knee hangs (follow the link to learn why).  This has always been a more comfortable and thus more beneficial position for me.  To perform this exercise, place a towel roll or similar item under the heel to allow full knee extension and then a comfortable weight over the distal thigh.

Low Load Long Duration Stretch Knee

The purpose of this exercise is to be gentle and to hold the stretch for several minutes.  I typically use anywhere from 6 to 12 pounds and hold the position for at least 10 minutes.  If the person is fighting against the weight, then it is too aggressive.  Lower the weight and you’ll see better results.

Don’t forget that you can apply moist heat to the knee simultaneously for even more benefit.

LLLD Knee Stretch with Heat

Devices for Knee Extension Range of Motion

I am also quick to prescribe a range of motion restoration device for people that may be struggling with range of motion or are not moving their knee enough throughout the day.  I have tried some of the dynamic splinting in the past but found that many people would rather control and hold a sustained stretch rather than have the brace apply a dynamic stretch.

The two devices I have used and enjoyed are from Joint Active System (JAS) and End Range of Motion Improvement (ERMI).

JAS Knee Brace        ERMI Knee Brace

Both devices allow the patient to apply their own tolerable LLLD stretch at home.  This is helpful as frequent movement throughout the day is always beneficial.

Personally my criteria to use these devices is usually when I perceive the person will self-limit themselves and avoid motion.  I will get a device in their hands early so that they can move their knee more at home and have a feeling that they are controlling the restoration of range of motion.  We probably resort to using these devices when it is too late and the patient is already too stiff.

 

Conclusion

These are just some of the many ways to assess and treat loss of knee extension range of motion.  Considering how important it is to restore full knee extension after knee surgery, properly assessing early signs of loss of motion and effectively treating the knee to avoid long term loss of motion is critical.

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23 Responses to “Assessing and Treating Loss of Knee Extension Range of Motion”

  1. Thanks for listing prone knee hangs as one of your top five least favorite exercises. Who wants to lie face down with a weight on the leg forcing it into extension. I have tried these on myself and found that my hip flexors try to withstand the load based on how sore I was after just 5 minutes. The other issue is that prone hangs also cue the knee to reactively flex which defeats the entire purpose of the exercise. Next thing you know, you now have neck pain from lying prone with sore hip flexors while still battling to restore full knee extension. Prone hangs are FORBIDDEN in my facility. I typically like to just place a towel roll under the heel while icing and also use ankle weights to ensure neutral lower extremity alignment so patients dont allow the involved lower extremity to roll in to an externally rotated position which would allow the knee to fall in to an open pack position (more comfortable) which is a common tendency especially in the context of a joint effusion.

    Great post and clinical tips Mike!

    • In 17 years of practice I have never had a patient c/o hip flexor soreness from prone hangs. It not comfortable having a weight on your knee for 10 min. Most of my patients have preferred prone hangs over supine heel props from a comfort standpoint. From a clinician standpoint the prone hangs are more effective at improving knee extension. Even the total knee replacement patients end up with 3 to 5 degrees of knee hyperextension (exception being the MDs who wait 3 months before referring to PT).

      Prone shoulder endrange flexion on table or prone combo shoulder flexion with alternat hip extension (common back stabilization ex.) should have made the top 5 worst exercises.

  2. Hey Mike,

    I was wondering if you have given thought to where the external load is placed for generating the extension?

    For example, after my ACL reconstruction I talked with my therapist about where we placed the load / his hand (when it was assisted stretching) to stress the ACL the least.

    He would typically assist the extension by placing his hands on the proximal tibia and push down from there. I would do the same when I was on my own / using an external load.

    This way we minimized the ability of the tibia to anteriorly translate and thus minimized the stress on the ACL. In contrast to placing the stress on the femur. I.e. push the femur into extension and the tibia may have some anterior translation. Or at least it’s more at risk than the former method.

    That was the thought process anyways.

    • Brain, that is an interesting point. Makes sense. I havent had any issues using the femur and would assume placing the weight on the tibia would be a little less effective in establishing knee extension, but makes sense if this is a big concern for you.

      Thanks for the idea.

  3. Hey Mike, great article! Just the topic I have been more interested in lately. I had a question on your opinion (or any other reader) on any thoughts if Terminal Knee Extenseion with ther-band is effective to improve knee extension? I find patients tends to use incorrect form with this exercise and what I can do to fix the problem. I am a new grad PT, so any insight will help. Thank you!

    • @NewgradPT sounds like that is an active exercise. If they have motion restrictions, active mobility is good but they will likely need more work getting into extension. They are probably using incorrect form because the joint wont allow proper form because of their restriction.

  4. Good topic, Mike. We use a prototype of the Elite Seat at our clinic and typically have had good results with this device as well. Unfortunately, in two recent cases (one post-ACLR, one post-op scope and MUA 2/2 post-ACLR arthrofibrosis), both of whom were ideal candidates for a home extension device soon after surgery (about 0-20-90 and 0-25-90 upon eval respectively), their insurance denied coverage despite scripts from the surgeons. Both were offered to rent one for one month for $400 (by the Elite Seat manufacturer), but as you can imagine, this didn’t go over so well. Just wondering if you’ve had any better luck getting these devices covered by insurance (obviously it could just be their particular plans)? In these cases, I typically send them home with the towel stretch and a 10# cuff weight for the long stretches and hope they put in the time at home, constantly reminding them that full SYMMETRICAL motion is the goal. Thanks again for the post on a very important topic.

    • Ouch, $400 is pretty unreasonable, how much does it cost to begin with??? It is no wonder companies like this dont seem to last. I have had better success from other companies that are more affordable.

  5. I really like the self stretches and LLLD exercises as well however you need achieve the conjunct tibia external rotation necessary for the closed pack position of the knee. Stretching is great post manual therapy but I feel that stretching alone will not fully restore the proper joint mechanics of the knee necessary to prevent onset of arthritis post surgery or injury.

  6. Hi there, I’m about 5 months out of ACL surgery and stuck at 0 on the involved knee. My other knee is at about 8 degrees of hyperextension. Do you think at this stage it’s too late for the methods you described? I’m hesitant to pursue this further with my PT because she doesn’t seem concerned, though my surgeon would like to see that hyperextension restored.

  7. Dear Mike,
    The way I usually document ROM differences is different than your recommendation and I disagree with the format. I usually see clinicians document knee ROM as – 10 degrees when a patient is lacking 10 degrees of knee extension. I always suggest not to document -10 degrees, because -10 degrees means that the patient is hyperextending 10 degrees. I recommend if the patient lacks 10 degrees then we should write the starting point and ending point of the patients ROM. In other words 10-150 degrees knee flexion which means that the patient starts at 10 and ends at 150 degrees. If we write -10-0-150 this would in turn mean that the patient starts at -10 and ends at 150 degrees. Writing 10-0-130 degrees I believe is confusing. If we look at 4 quadrants we have to document ROM according to what quadrant we are measuring. 0-150 degrees are all in a positive quadrant. Hyperextension is in a negative quadrant. I enjoy reading all your logs and appreciate the ability to learn new concepts that you have shared. I have also been able apply some of these principles that you have provided in all your logs. Thanks.
    Jerry

    • Hi Jerry, thanks for the comments. There is definitely not a standardized way of documenting. That is only my suggestion, although I would disagree that -10 is hyperextension.

      In fact, we shouldn’t even use the term “hyper” extension. The knee is either flexed or extended, and they are on both ends of the spectrum.

      If the the knee is position in 10 degrees of flexion, the polar opposite would be -10 of extension.

      This is how I recommend documenting due to what I have experienced as least confusing, but no doubt there are multiple ways of documenting.

  8. Sir, I’m myself a medical student who just got a hamstring ACL reconstruction done. I’m 21 years old. Pre op, I was at 0 degrees. I couldn’t extend more, that is, as much as the other knee. I could get to 0 degrees right after surgery, on the very same day. After around a week after the surgery, I was still at 0 degrees. I came to realise the importance of hyperextension reading your articles. At that time I had some swelling. That very day I started with putting a towel near my heel, and without using weights, I pushed the heel down, with more force than I was previously doing. I gained some but not full hyperextension. But what came with this hyperextension was the pain right below the patella, which would come in in the range of motion between 0 and full hyperextension. Today is the 14th day, and now my hypertension is as much as the other knee. But the thing is, after a few extension stretches and straight leg raises with hyperextension, it starts to pain. There was no such pain before I pushed to hyperextension, just the usual tenderness that one can expect in the first week. The pain starts after the 0 degree. Can you please advice whether this is normal? Is the pain due to fatigue i. e. Decreased muscle mass of quadriceps? Was it okay that I pushed myself into hyperextension? When can I expect this pain to go?

    Thanks a lot sir, really appreciate it.

  9. My knee replacement was on June 3,”13. I am still not getting the ROM that is needed. PT is 3X per week now. Overpressure is used each time but I go back and have a 12-15 degree knee – not holding the angle. Ortho. surgeon gave me a “cranker board” to use three times/day. Ideas??

  10. I like what you guys are up too. This kind of clever work
    and reporting! Keep up the amazing works guys
    I’ve incorporated you guys to my own blogroll.

  11. Hi Mike, I wish I had read this article earlier. I had ACL reconstruction surgery last May (7 months ago), and I was not able to extend my knee beyond 10 degrees of flexation. I just had surgery today to remove arthrofibrosis. When the doctor came out, he said that he was “able to get an additional 5 degrees” of extension. If this has become a mechanical problem, and that’s the feedback I get from a surgeon after surgery, is there any way that I can get back to 0 degrees through exercise? I really like the exercises you present here, as I was tortured through 20 min prone knee hangs in which I did rotate my leg to reduce the pain. Another question on my mind right now, how high should I stack pillows under my ankle immediately after scar tissue removal surgery? The higher I stack the more pain I feel, but I am determined to do anything that I can to restore my knee to less than 5 degrees of flexation. How soon after surgery should I start the exercises you present here?

  12. Hi to all, how is everything, I think every one
    is getting more from this web site, and your views are pleasant for new people.

  13. I’m 6 weeks out of tkr and am working to straighten my leg. It’s at 6 to 8 degrees now. I just did the roll up towel with 6 pounds weights but could only last 8 minutes. How many times a day do I do these stretches? How many. Days a week? Can this hurt my recovery by doing too much?

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