Knee Pain and Rehabilitation Overview

Author Dr. Zach Cullen

Many patients seeking care here at Move Better complain of pain and dysfunction surrounding the knee. The symptom presentation can vary from a traumatic rupture of the quadriceps tendon all the way to chronic arthritis/degeneration where patients have been unfortunately told that they are “bone on bone”. While these two presentations certainly justify the need for a tailored approach, there are underlying principles and criteria that any patient will need to strive for if they are going to overcome knee pain in the long term. To understand the destination however, we need to understand where we are starting from which entails both a pathophysiological diagnosis and then a functional/biomechanical diagnosis.

Pathophysiological diagnosis is a big fancy phrase us doctors like to throw around to make ourselves feel better about our ever looming student loan debt. In all seriousness though, this phrase can be defined as simply being the belief about what structure we think is generating the symptoms of pain. During the examination, the provider will use a variety of orthopedic tests designed to stress specific tissues within the knee to key into what anatomical structures are creating the discomfort. For example, the medial collateral ligament (MCL) is located on the inside of the knee and can be physically palpated from the outside by a well trained practitioner. Applying inward force on the outside of the knee to stress the inside of the knee would also target the MCL. If touching the MCL is tender (and affirmed to be the familiar sensation of the pain the patient normally feels) in addition to stress testing the MCL also recreating the discomfort, we can reliably infer with a high probability that the pain generating structure within the knee is the MCL. This would conclude that the pathoanatomical diagnosis is a strain of the MCL.

Biomechanical/Functional diagnosis is the process of evaluating the movement behaviors, activities, or stabilization strategies an individual exhibits that may explain why the pathophysiological diagnosis came to fruition. In my opinion, this diagnosis is much more important because if we know why the problem is happening then it is much easier to fix. Knowing what the problem is is irrelevant if you don’t know why it’s happening and therefore how to fix it. While our clinic focuses on both the pathophysiological and functional diagnosis, a much larger portion of our evaluation process and care plan is concentrated towards the later.

For the vast majority of patients seeking care for knee pain, the structural integrity of the knee is intact. Many patients come to the clinic with an x-ray or MRI that reveals signs of “degenerative arthritic changes”, “osteoarthrosis”, or “generalized effusion/edema” and understandably become convinced that their knee is beyond repair. Receiving imaging for a region of the body that hurts can be a bit of a double edged sword in this way. On one end of the spectrum, if there is a serious injury or trauma inflicted onto a region of the body, receiving imaging can be a crucial step in escalating to the proper management of the injury. A patient may need a surgical procedure or pharmaceutical intervention to properly treat the area of concern. On the other hand however, imaging can sometimes report on findings that speak a narrative of tissue damage that can lead to patients becoming fearful or hyperfixating on a structural finding that very well could have no direct impact on their symptoms.

I can speak from experience here. Years ago I had an MRI performed on my low back and found there to be a disc bulge at L5/S1. When I first received the report I immediately spiraled into fear and helplessness that my back was forever going to hurt and that I would not be able to get back to normal physical activities. After years of treating patients, receiving my Doctoral degree, and having first hand experience of rehabilitating my low back I came to realize that the vast majority of individuals can completely eliminate pain or dysfunction within a given region of their body even when imaging shows structural compromise.

All of this is to say that if imaging shows a structural change within the region of complaint, knowing WHY the structures have altered is more important than knowing what has been damaged and can oftentimes result in a reduction of symptoms if intervened on. This is fascinating to me because while symptoms of pain subside, it is extremely unlikely to see any visible changes if a follow up MRI/CT/X-ray were to be performed after the patient started to feel better.

So now that we know what frame of focus is most likely to help patients feel better, what are some of the most common movement dysfunctions we observe in patients coming to the clinic with knee pain?

-Compromised midline stabilization
-Insufficient support function on the symptomatic leg
-Poor knee tracking through multi joint movement patterns
-Knee dominant recruitment patterns through multi joint movement patterns

Let’s break down each problem and talk about how we approach solving them when patients come to the clinic.

Midline stabilization is a concept that explains how the core or center of our body stabilizes in any given movement scenario. Properly stabilizing the core of the body when interacting with movements involving the extremities allows for proper alignment as well as proper load distribution across the entire kinetic chain. When this is not functioning properly, the knee can become destabilized due to not having an adequate fixed point to move against. A good way to think about this would be to think about how a crane operates. The body of the crane acts as the “core” that the neck can freely move against to perform tasks. If the body of the crane was not structurally stable then the neck of the crane would topple the entire crane over whenever it went to pick up an object. We see very often that independently improving midline stability, bracing, and core activation can lead to immediate improvements in knee pain without interacting with the local knee structures AT ALL.

Support function is a concept that explains the difference between a muscle functioning in either a closed chain or open chain system. A closed chain movement is when the distal segments of the body are in a fixed position and the rest of the body moves around this fixation point. An open chain movement is when the distal segment of the body is unfixed and moves freely relative to the middle of the body being the fixed point. When a muscle is acting in support function, it is working in a closed chain movement system. A good example of a support function would be the seemingly simple act of walking. One leg is fixed to the ground and the other leg swings forward and is temporarily displaced in mid air before striking the ground. The leg that is in contact with the ground that helps to propel the body forward is working as the trunk of a tree to root you to the ground as the swing leg acts as a branch extending from the base of the tree. It is very common to see that when performing movements that challenge support function (single leg movement variations) that there is a high correlation between observing a relative increased instability on the side that a patient complains of having knee pain on. Support function compromise can be an issue of how the foot, ankle, or hip below or above the knee is functioning to assist the knee in stabilization. By improving control and competency in movements that challenge support function, many patients have a significant improvement in their knee pain.

Knee tracking refers to the positioning of the knee when challenged through various ranges of motion that involve the knee. This touches on a concept called joint centration. Joint centration is the theoretical position of a segment of the body where all of the forces around the joint are perfectly evenly distributed in all planes of motion. When a joint becomes decentrated, the risk for tissue damage becomes higher due to an asymmetrical force distribution. For example, if a patient explains that they experience knee pain when they squat down to the floor, then evaluating how their knee is tracking from point A to point B within a squat can give a lot of information. If a patient complains of knee pain on the inside when squatting and then when asked to squat shows that their knee tracks towards the inside, a strong suspicion can be made that the pain in their knee is due to the asymmetrical load being imposed upon it when the knee destabilizes. Improper knee tracking can be a result of compromised support function or poor midline stabilization integration. This can turn into a chicken or the egg debate however. Instead of trying to assume the origin of the knee destabilization we simply accept that we cannot know which is the cause or the effect and treat all dysfunctions we see to cover our bases.

Knee dominant loading patterns describe how a patient subconsciously organizes their body to perform any given movement task. Many movements can be performed in a way that biases load distribution more or less towards certain areas of the body. For example when someone squats, they can hinge forward and have a greater amount of the movement generated to achieve the bottom of their squat come from the hips or initiate with bending of the knees first, keep a very upright torso, and have the motion be mostly manifested from movement at the knees. A knee dominant loading pattern would be the patient being more likely to load their knees to a greater degree in a given movement than another region. This can lead to what we call a load management issue. Outside of any obvious technical dysfunction of interacting with movement involving the knee, it is simply an issue of using the knees too much to perform movement actions that can be performed with a dominance of load on other parts of the body. Part of our treatment for knee pain would be to evaluate without prompting to see how you subconsciously decide to perform certain movements. We do this to evaluate how much knee dominance you rely on. If it is determined that you do indeed have a knee dominant loading bias, then teaching you how to rely on other parts of your body to perform a multitude of movement tasks would in theory reduce your knee pain by offloading its working demands.