While there are many reasons a person may have knee pain, there are some that occur more often. I will cover some of the most common causes in this section. But first, I want to try and explain some of the joint dynamics before we get into these problems.
Every joint in the body has an optimal position, alignment, and angle of motion. This is what we call the centric (centered) position. Sometimes a muscle imbalance can cause the alignment to become changed. For example, there is a natural balance between the quadriceps muscles and the hamstrings. There is also a natural balance between the muscles of the outer and inner leg. If the muscle strength becomes unbalanced, this changes the position of the joint as it moves through its range of motion which can cause excessive stress on the joint and some structures become more prone to injury.
The menisci (plural of meniscus) are two cartilaginous pads in the inside and outside of the knee joint. Their purpose is to protect the joint, help to make motion more fluid, and act as a shock absorber. We name these two pads by their position: the medial (inside) and the lateral (outside). Menisci can become injured during activity or simply wear out if the dynamics in the joint become altered. This usually leads to tearing and the pain is felt as a sharp or lancing sensation deep inside the joint. Altered positions of the joint are important considerations when evaluating the knee. People who are valgus (knock-kneed) tend to wear on the lateral meniscus, while people who are varus (bow-legged) tend to wear out the medial meniscus.
Medial and Lateral Collateral Ligaments
There are two collateral ligaments in the knee and they are named just like the menisci. The inside of the knee has a medial collateral ligament and the outside has a lateral collateral ligament. The purpose of ligaments is to provide stability in the joint and keep the joint from falling out of place during movements. The MCL and LCL mostly help to keep side-to-side movement in check, but also help to prevent rotation of the knee. A valgus position of the knee stresses the medial collateral ligament while a varus position stresses the lateral collateral ligament. Damage to this structure is felt more superficially as a sharp achy soreness on the inside or outside of the knee and usually causes the knee to be tender on the inside or outside aspect.
Anterior and Posterior Collateral Ligaments
Just like the ligaments above help to keep side-to-side motion in check, the anterior collateral ligament (ACL) and the posterior collateral ligament (PCL) help to keep front-to-back motion in check and also contributes to keeping rotation in check. The more common injury is to the ACL which usually happens in sports when abruptly changing the direction of motion as when breaking and cutting a run during football or soccer. This situation usually results in immediate collapse of the individual and most of the time requires surgery. The PCL is less commonly injured because it is a bit beefier than the ACL, but injury still occurs. The mechanism of injury of the PCL is typically during a tackle where a substantial amount of force is applied to the front of the lower leg while the knee is bent. Hyperextension-type injuries can also lead to PCL damage. Just like its cousin the ACL, the PCL typically requires surgery. The balance of the quadriceps and hamstring have more to do with protecting the ACL and PCL, so there is definitely training that can be done to give these structures some extra defense against injury. But… in many situations, the trauma is so great that no amount of training would have prevented the injury. Luckily a good surgeon can repair and re-pin the torn ligament the majority of the time. However, after the surgery, a good rehab program is essential for regaining functionality.
Chondromalacia Patella & Patellar tracking disorders
You may not know this, but your knee cap is not really a normal bone… It is a sesamoid bone (No, not the seeds that come on hamburger buns). A Sesamoid is a bone that develops inside of a tendon (the part of a muscle where it attaches to the bone) that helps to guide the motion of the joint and protect the tendon as the tendon glides over a groove in a bone or surface that creates a lot of stress or friction. Sesamoid bones occur in several places in the body, but the knee cap is the biggest. Without the knee cap, your tendon would fray and become damaged when you move your knee. The knee cap is shaped to fit and slide across the front of the knee joint. When you contract your quadriceps muscle, the knee straightens and the knee cap helps to guide the motion keeping the tendon centered across the front of the knee. People who have varus or valgus positions of the knee can cause scraping of the knee cap across the inside or outside of the groove. The underside of the knee cap is made of a slick cartilaginous substance that helps to reduce friction. When the knee cap tracks to the inside or outside of this joint, it can wear on that surface creating micro damage that accumulates over time and the once slick surface now becomes rough and cannot do its job of reducing friction. Over time, the damage gets bad enough that the surface is significantly changed and pain and inflammation quickly follow. The pain is felt under the knee cap and occurs especially when the knee is flexed under a load as when walking up and down stairs. Chondromalacia patella is the name we use to describe the damage under the knee cap, while patellar tracking refers to the movement of the knee cap across the front of the knee. You can now see how these two things are related.
Also known as degenerative joint disease and nicknamed the “wear and tear” arthritis, OA is the most common type of arthritis. OA can occur in any joint in the body, but is much more common in the weight bearing joints of the body. The knee is definitely one of these joints. Osteoarthritis is ALWAYS secondary to some other process. Most often that process is a joint misalignment and muscle imbalance. Just like the nickname implies, wear and tear that occurs over time is the underlying reason for all kinds of osteoarthritis. Any of the above problems if left unchecked will eventually lead to arthritis. That old trick knee or sports injury can cause enough repetitive damage in the joint that the cartilage will be lost and joint will begin to calcify and change shape. Please don’t ever tell yourself that your arthritis is just due to old age. This is not true, and usually leads to a person thinking that there is nothing that can be done, so they don’t. This is false. Maybe the joint can’t be 100%, but there is sure a lot we can do to improve the dynamics of the joint and at least stop it from getting worse.
You will note one reoccurring theme throughout this article: Knee problems are almost always due to a dysfunction in the alignment and movement pattern of the joint. Even if the injury requires surgery, rehabilitation of the knee is still necessary to address the underlying altered joint dynamics. It is much more preferable to address these joint dynamics before injury occurs rather than after. Please, if you have knee pain then make an appointment today. Let’s get to the bottom of it before the problem becomes any worse. If you have questions, I would be happy to sit down with you and talk before your examination at no cost to you. Your health and livelihood is my primary concern.