“Why does my knee hurt?” Some Common Knee Issues Explained.

Knee pain is one of the more common issues we treat in Physical Therapy.  In fact, it is probably one of the big three areas of the body we treat along with the shoulder and the spine.  When it comes to knee pain though, there is a lot of variability in the frequency of the symptoms, the location of the symptoms, and the intensity of the symptoms.  Some people report dull aches in their knees at rest that can get worse with an approaching storm, others will note increased pain every time they do stairs, and still others will say their pain only bothers them sometimes on the stairs and other times not.  Let’s take a look at some of the more common knee injuries now.

Mechanical Issues

Knee osteoarthitis

Here is an X-ray that indicates knee osteoarthritis on the inside of both knee joints. You can tell because there is no space between the femur above and the tibia below on that side compared to the outside of the knee. © Puwadol Jaturawutthichai | Dreamstime.com

Osteoarthritis(OA): Oseteoarthritis, or OA, is what we think of when we talk about arthritis.  It typically presents as deep knee pain and stiffness accompanied with knee pain while weight bearing. Pain presents throughout the knee or it could be localized to one side of the knee or the other.  It will typically worsen with prolonged activities that require increased weight bearing through our legs like walking or standing.  However, it may also increase with prolonged rest. Usually common in elderly or people with mechanical alterations of the knee. People may present with loss of range of motion.  Often times people with knee arthritis will state that their knee pain can help predict when inclement weather in on the way based on their pain intensity.

Bursitis: Throughout our body wherever there is a location that multiple muscles or tendons run over a bony prominence we have Bursae sacs.  These Bursae sacs act as ball bearings for those muscles and tendons when the move over the bone to prevent any tearing or breakdown.  However, at times those bursae sacs can become inflamed and painful.  This is called bursitis.  

In the knee bursitis usually presents with local pain, heat and swelling over the involved bursa.  Typically acute onset can occur after trauma or repetitive actions such as kneeling.  More frequently though, bursitis is due to overuse injuries as a chronic condition.  Pain may limit knee bending and there may be pain with walking.

Illiotibial band syndrome (ITB syndrome ): The Iliotibial band is a long tendon that extends from the lateral aspect of our hip down the lateral thigh, crosses past the lateral side of the knee, and ends on the fibular head.  It often occurs  in runners from overuse. It is an irritation caused by the rubbing of the ITB over the lateral part of the femur. Typically runners will note pain with downhill running but eventually pain begins to occur anytime the knee gets to about 30 degrees of knee flexion.  Typically people that have this pain will begin to walk “stiff legged”  in an attempt to avoid the pain they get at the 30 degree angle.

Patellofemoral pain syndrome (PFPS) aka chondromalasia patella: This syndrome is somewhat of a ‘catchall’ phrase for any pain around the kneecap that is thought to be due to a tracking problem.  At the end of the femur is a groove between the medial and lateral condyles. The kneecap sits in this groove. On a certain type of X-ray the condyles will look like two mountain peaks and the kneecap should be sitting in the valley of those two peaks.  If the patella fails to track properly in the valley of the femur by hitting either of those two mountain peaks you will get pain.  

Patellafemoral pain syndrome

Patellafemoral Pain Syndrome (PFS) occurs when the kneecap is out of alignment over the knee joint. ©pivotalmotion.physio

In the beginning pain is noted in the first 30 degrees of knee flexion but as it continues to get worse people begin to note increasing pain with stair climbing, prolonged sitting (moviegoer’s sign), squatting,  jumping, or running.  Prolonged rubbing of the underside of the kneecap along those two peaks can wear away the cartilage and create patellar chondramalacia (in English…arthritis under your kneecap). 

It most common in girls between the ages of 13 to 22, especially athletes or girls who have increased hip weakness as it is thought that weak hip musculature will contribute to the femur changing positions under the kneecap creating the tracking problem.

Meniscal injuries

Meniscus tears

Six of the most common meniscus tears seen in PT. ©Acer2020| iStock.com

The way we injure our meniscus has a lot to do with which side we injure as both sides have slightly different mechanisms of injury.  For the medial meniscus, we typically injure it with sudden extension or  twisting of the knee while the knee is flexed.  For the lateral meniscus, typically the injury is caused when we have sudden extension, medial rotation, and adduction of the knee while it is flexed, while the lower leg is rotated inwards and the foot is flexed.  

Regardless the symptoms tend to be joint line tenderness, your knee will give out when you step on uneven ground, you can have pain at end range in flex/ext or in weightbaring (like when you are going up or down stairs) which people will often time describe as a popping with pain.  Often times there is gradual swelling in the knee with greater activity or more popping.

Ligament injuries

A Note on Grades

Knee sprain grading system

The three Grades of a ligament sprain. ©knee-pain-explained.com

Complicating matters more is that some of the structures in our knee have a grading system for how bad the injury is.  Each grade in that system corresponds to a different level of pain and decreased function.

A grade 1 injury is like when we twist our ankle, it hurts for a couple days and gets better.

A grade 3 injury is often times a complete tear of the structure.  Typically you get a shot of signifiant pain at the moment of injury (some have described that it felt like they got shot) and then the pain goes away pretty quickly.  Unfortunately, when they begin to move again they will note significant instability in the knee and possibly some buckling.

A grade 2 injury is everything in between.  They become the most difficult to figure out because depending on the severity they can range from a grade 1 injury that just lingers for 2-4 weeks all the way to significant pain and some instability similar to a grade 3 injury.

In the knee the most common injuries that require the grading system are our ligaments.  If you remember form our knee anatomy post, our knees have 4 ligaments that generate the stability of the knee.  Based on their location and what they do, each can be injured in a different way as well.

Common knee ligament injuries

Robert Griffin III tore (a grade 3 sprain) his ACL and further injured his LCL on this fateful play on Jan 6, 2013. He was wearing the brace to support his already injured LCL (he was already diagnosed with a grade 2 sprain) but this play tore the LCL in addition to his ACL.

    ACL: The ACL injury is one of the most common knee injuries we see in PT.  It typically results from twisting of the knee while changing directions, can happen with hyperextension, or hyperflexion of the knee with foot in plantarflexion. Most of the time there is an audible pop with immediate swelling.  A lot of people report having intense pain at the posterior lateral tibia. Once they get up the feel like their knee is unstable in weight bearing.  With greater force there is a greater liklihood of having a medial meniscus injury as well.  More girls/women will have a non-contact ACL rupture where a quick change of position with the knee in a compromised position will tear the ACL causing her to fall.  In contrast most boys/men will tear their ACL due to a lateral hit to the knee when their knee is in a compromised position.

    PCL: In contrast the PCL Injury is not nearly as common.  The most common way we injure our PCL is in a motor vehicle accident (MVA) when the dashboard blows into the anterior shin with the knee flexed at 90 degrees.  In sports the PCL will get injured when the athlete falls onto the knee with foot pointed down.  There is usually minimal swelling, Bruising may appear days later. tenderness in the back of the knee and pain with kneeling are common complaints.  Sometimes the lower leg of the injured knee will sag towards the floor if a person is lying on their back with their knees bent and feet flat on the floor. 

    LCL: Probably the least common ligament injury is the LCL.  This injury results from a medial stress resulting in overstretching or tearing of the ligament. It typically results in a warm and swollen lateral knee. Range of motion may not be effected.

    MCL:. The MCL is the second most common knee ligament injury after the ACL.  It typically occurs as a result of some lateral stress resulting in overstretching or tearing of the ligament.  It also can occur as a result of lateral tibia rotation with knee flexed or hyperextended (the foot twists away from the body while the knee is flexed or when it is hyperextended).  Results in limited knee bending to 90 degrees, inability to fully straighten the knee, and pain along the medial aspect of the knee.  

Due to the nature of how ACL tears occur, with our knee twisting or from a blow to the lateral side of the knee, our MCL can also be effected.  The greater the force of the ACL injury, the more our knee will rotate laterally or overstretch the MCL, resulting in not only tearing the ACL but also the MCL too.  In fact, if the force of the injury is great enough one could tear their ACL, MCL, and tear their meniscus…All in the same injury!  this is called the Unhappy Triad.   Not good.


If you are having any symptoms described in this article or have a new pain, numbness, stiffness or tingling in any part of your body, arms or legs, contact us today!  With Direct Access in NJ we can get you in for an evaluation without you having to see your Doctor, probably quicker than you could get that appointment, while also saving you both time and money!  

Please, call us to schedule your evaluation at one of BeneFIT’s locations, Bridgewater (908.203.5200) or Chester (908.879.5700)  with one of our highly trained Doctors of Physical Therapy!