The Bee's Knees

The Bee's Knees

Lack of Full Knee Flexion in 2023

November 02, 2022

Lack of Full Knee Flexion
Part Four of our investigative series: Threats to a Proper Knee Replacement Recovery
by PJ Ewing

Flexion is…
We define ‘good flexion’ as a minimum of 110º bend. A lack of full knee flexion is a problem that can linger forever after a knee surgery if not solved somewhat quickly after surgery. Watch this short video to get a handle on what we’re talking about with range of motion, and why flexion/bending is a crucial part of knee surgery recovery:

Lack of Full Knee Flexion
We care about flexion because it greatly impacts our overall mobility and activity levels. Mobility is crucial to our overall well being. John McKay (RN) writes in great detail about how important mobility is in his article:  Want to Live Longer, You May Want to Start from the Ground Up.

You need good flexion to do basic things like walk up stairs, enter/exit a vehicle, play sports, garden, kneel down to play with your grandkids. Here are some benchmarks:

* Stand up from a seated position: 90º
* Sit comfortably at a dining room chair/desk: 95º
* Walk up stairs 105º

* Get in and out of a car 110º
* Ride a bike with seat in proper position: 115º
* Bend down, kneel to garden: 117º
* Dig out a tough low shot in tennis 120º

If you do not get “good flexion” what are the implications?

* Your overall mobility will be compromised
* You will move less as moving can be painful
* You will not build your strength back after surgery
* Your heart and lungs get “lazy” and less productive as there is less demand on your cardiovascular and pulmonary systems
* You will age more1 than otherwise

There is a decline in muscle strength and other factors as we age. Being mobile helps put off the impact of those conditions.

Knee Surgery Coming Up?
For those facing surgery, your pre-surgery flexion is predictive of your post-surgery flexion as demonstrated in this research by Natarajan, Narayan, and Vijayaraghavan.
In the study it is shown that “pre-operative flexion significantly influenced the post-operative flexion". Pre-operative flexion "is a good parameter for predicting the post-operative outcome.” 2
One Critical Finding
“There was a positive correlation between pre-operative and postoperative flexion; the better the pre-operative flexion, the better the post-operative flexion. However, good flexors tend to lose flexion while the poor flexors tend to gain some. TKR can produce a predictable result, not totally dictated by poor pre-operative flexion. Interestingly, restoration or even improvement in ROM for those with good pre-operative flexion may be limited by implant design and soft tissue tension."
Just think about that for a second. “Good flexors tend to lose some and poor flexors tend to gain some,” meaning that even if you have good bending before surgery you might lose ground. And if you have poor flexion before surgery there is an opportunity for gains. With a knee replacement surgery, it is not simply the new mechanical joint that can be the determining factor. Rather, it is the ligaments,