Knee Pain

What is Knee Pain?

Knee pain typically occurs from either a disease process like arthritis, overuse, or due to a traumatic injury. Knee pain is common and in most cases can be resolved with conservative treatments like physical therapy. Only if there is significant damage or the disease process is so advanced where it impacts daily activities like walking, would surgery be recommended.

The knee is made up of 3 bones, four ligaments, two cartilage rings, and up to 11 bursa sacs. The femur (thighbone), tibia (shin bone), and the patella (knee cap) are the bones that make up the knee. Commonly, the ligaments are known by their acronym names. The structure allows for knee flexion (bend), and extension (straight), as well as some minor rotation which is why the knee is called a hinge joint.

The ACL (anterior cruciate ligament), MCL (medial collateral ligament), LCL (lateral collateral ligament), and the PCL (posterior cruciate ligament). Finally, the knee has two cushion like rings called meniscus, which protects the knee from bone on bone contact.

Ligaments are named by their location. The ACL is in the front (anterior) of knee and attaches the patella bone to the tibia. The main purpose of the ACL to allow for rotation and forward movement of the tibia, which is the most commonly injured ligament of the knee which occurs when twisting and rotating overstretches the ligament. The highest risk sports for an ACL tear include football, basketball, and skiing.

The MCL runs along the inside (medial) of the knee where it connects to both the tibia and femur. The main purpose of the MCL to protect and stabilize the inner knee area. The LCL is on the outer side of the knee (lateral) where it connects the fibula (small bone in the lower leg) and the femur. The LCL’s purpose it to provide protection and stabilization to the outer side of the knee.

The MCL is more commonly injured, but both have been known to tear. Tears typically occur from a blunt force to the area from the outside of the knee. This type of force pushes the knee inward causing overstretching of the MCL. The highest risk sports for this type of injury is football and hockey.

The PCL is a ligament that runs in the center and towards the back (posterior) of the knee. It connects the tibia (shin bone) to the femur (thighbone). Its main purpose is to pull the knee back. This ligament is the least likely to get injured, but when it does the cause is typically due to a traumatic injury.

The meniscus rings are also known cause for pain in the knee. Meniscus pain can be from a tear, or, with years of wear and tear it may be worn down providing minimal to no protection to the knee joint.


Bursae are fluid-filled sacs within a joint which help protect the tissue and bone structures. The bursae allow for tissue (muscles, tendons, and ligaments) to glide for maximum range-of-motion of joint while also reducing the friction caused by movements.

The knee is a hinge joint with a lot of moving parts. There are four bursa sacs within the knee that are prone to injury. They include the following:

  • Suprapatellar bursa-is above the knee cap and just under the quadriceps (thigh) muscle. Repetitive movements, like with runners, can cause irritation to this bursa sac, which is commonly termed “crawlers knee,” because carpet layers are prone to this type of injury due to the prolonged and repetitive crawling affecting the bursa sac.
  • Infrapatellar bursa-actually has two bursa sacs. One sac sits near the surface just below the knee cap (patellar) while the other lies deeper between the patellar tendon and tibia (shin bone). Commonly known as the “jumper’s knee,” either sac or both can become irritated and inflamed from repetitive jumping activities.
  • Prepatellar bursa-located above the knee cap, below the skin surface and commonly known as the “housemaid’s knee.” This sac is susceptible to inflammation and injury from prolonged kneeling. Risk factor jobs include carpet layers, roofers, gardeners, and plumbers.
  • Pes Anserine bursa-located between the tibia (shin bone) and the three hamstring tendons located on the lower inside of the knee. Commonly this injury occurs from overuse or repetitive knee movements, tight hamstring muscles, poor knee mechanics, and obesity.

What causes knee pain?

Despite the knees structural design to be stable, knee injuries are common. There are various causes for knee pain including an injury, mechanical, or arthritis. Injuries typically occur with either overuse or due to a traumatic incident or “blow” to the knee.

The most common form of knee pain comes from overuse or traumatic injuries. The knee takes a sudden unexpected impact causing knee pain, whether caused by playing sports, falling, or a car accident.

Overuse typically occurs from repetitive movements in sports such as running and cycling. Runners and cyclists are susceptible to overuse due to the repetitive movements required for the sport. Continual flexion and extension movements coupled with loaded weight bearing from the body contacting the ground can inflame and irritate the knee structure. This type of repetitive injury is commonly called tendonitis, where the knee tendons (attach muscles to bones) become inflamed and irritated.

Either cause, trauma or overuse, damage can range from minor to severe. Minor may just be swelling, and irritation whereas severe damage may include torn tissue or even a fracture. Fractures can occur from a traumatic fall or during a collision while playing sports. A fracture is a broken bone, which if you suspect this has occurred, you are advised to see immediate medical attention.

Mechanical breakdown of the knee is also known to cause knee pain. Iliotibial Band Syndrome (ITBS) is where the long connective tissue that runs from your hip to the top of the tibia is irritated. Commonly this occurs in long-distance runners and is caused by the tight tissue repeatedly rubbing, or causing friction, between the connective tissue and the outer part of the femur near the knee.

Loose bodies may also be a caused by a mechanical issue. For various reasons, the piece of bone or cartilage breaks off within the knee joint space which may cause problems. The loose particle may float around without issue, but in some cases, the loose body impacts the ability of the knee to flex (bend) and extend. Commonly people will describe this as their knee “catches.”

Hip or foot pain may also cause mechanical breakdown of knee mobility. There are various reasons for hip or foot pain, but often a physical therapist will start with assessing your foot. Your feet are the foundation of good mechanics in the knee all the way up to your hips. Poor support or mechanics of the feet can lead to knee and even hip issues.

Beyond injuries and mechanical causes to knee pain, arthritis can also be a common cause of knee pain. There is a variety of arthritis conditions that exist, but there are a few that commonly impact the knee, and they are:

  • Osteoarthritisis a common form of arthritis in the knee, which occurs when the cartilage wears down so that there is little to no cushioning left.
  • Rheumatoid Arthritisis an autoimmune condition where the body “attacks” itself. This form of arthritis can be very painful and debilitating.
  • Gout-although less common in the knee, some people are more susceptible to it than others. Commonly gout occurs in the big toes, but it has been known to affect the knee, which occurs due to the build-up of uric acid crystals within the joint.

Symptoms of Knee Pain

Knee symptoms vary depending on the origin, or cause, of pain. The most common symptoms include:

  • “Buckling,” knee gives out unexpectedly
  • Difficulty weight bearing with walking, standing, or stair climbing
  • Gait pattern changes, limping
  • “Locking,” unable to bend the knee
  • Loss of range-of-motion (bending or straightening)
  • Pain from dull ache to sharp and severe
  • Popping noises
  • Redness which may include warmth
  • Swelling and stiffness
  • Tender to touch

You should seek immediate medical attention if you have the following symptoms:

  • Joint deformity
  • Immediate redness and swelling
  • Non-weight bearing
  • Visually can see bones or soft tissue

How is knee diagnosed?

The location of symptoms will clue you and your health care professional on what the cause of symptom may be. First and foremost, is there is any immediate visible trauma to the knee like swelling, redness, deformity, or even visibility of bones and tissue, you should seek immediate medical attention.

To determine the cause of your knee pain, a complete assessment of the knee is recommended. There are many structures (bone, tissue, nerves, cartilage, etc.) within the knee that may be the culprit to your symptoms. Most knee injuries are non-life threatening nor are they emergencies.

Early intervention of symptoms usually means conservative care may be appropriate. A qualified physical therapist can properly assess your knee symptoms to determine the origin of the issue, which is important to understand so the proper treatment plan is established.

Your PT will check for swelling; that may not be visible, as well as muscles strength and range-of-motion. They are trained experts in differential diagnosis which mean they know how to assess each structure within your knee to determine condition causing your symptoms.

In most states, you can be seen by a PT first, without a physician’s order. To determine if your state has direct access, please visit the American Physical Therapy Association’s website Physical Therapy Direct Access By State.

In some circumstances, your physician may need an X-Ray or MRI (magnetic resonance imaging) to assess damage to internal structures of the knee. An X-Ray will determine if there are any fractures or degenerative changes. An MRI will take a closer look at all tissue including muscles, tendons, ligaments, and cartilage. Based on the image results, your physician will establish an appropriate plan of care. If arthritis or gout is suspected, your physician may order up a blood test to verify the diagnosis.

Treatment of Knee Pain

Conservative treatment is provided for most knee injuries. Physical Therapy (PT) has been proven to be a highly valuable approach to knee treatment. Your PT will start with managing pain and swelling symptoms. Once these symptoms are managed, phase two of treatment will focus on regaining range of motion and strength without causing aggravation.

Retraining you on proper movements to perform functional activities is key to long term results. Body mechanics training with knee injuries is crucial. In some cases, shoe inserts or knee braces may be used to assist with proper alignment and prevent unwanted movement within the knee joint.

In some circumstances, an injection may be needed. One form of an injection is to remove the unwanted build of fluid within and around the knee. The extraction of this fluid will help alleviate structural stress. The other form of injection is where medication is inserted into the knee to reduce inflammation. An injection alone does not solve the structural problem with your knee. In cases where an injection is needed, when coupled with PT long term results are effective.

There are circumstances where knee surgery is needed. Depending on the issue, your surgeon will repair, remove, or replace tissue and bones. The most common knee surgeries are:

  • Meniscectomy-a part of your meniscus is removed
  • Meniscus Repair-the meniscus is fixed (not removed) when the tear is on the outer side of the meniscus
  • Meniscus Transplant-when most the meniscus is damaged; the tissue is removed, and a donor cartilage is put in its place
  • Tendon Repair-when the patellar or quadriceps tendons are fully detached from the bone; the surgeon reattaches the tissue
  • Ligament Reconstruction-when your tissue (usually from your patellar or hamstring tendon) is used to repair one of the knee’s ligaments (ACL, MCL, LCL, or PCL)
  • Full or Partial Knee Replacement-if the knee is highly damaged from trauma or arthritis, then part of, or all, the knee joint is replaced with metal and/or plastic components.

Depending on the surgery, recovery can take quite a while from months up to 1 year. PT is highly recommended after knee surgery. You will need assistance with learning to manage your symptoms and return to mobility and other functional activities safely. Your PT will guide you through the healing phases to avoid reinjury and to prevent future problems from arising.

Next Steps

Early intervention to knee pain is the key to managing the health of your knee in the long run. The sooner you address your symptoms, the more likely conservative care will work for you.

As a consumer of health care, you have a choice in finding the right provider for you. Do your homework and search for a health care provider, like a physical therapist, with excellent outcomes, great customer reviews, and can provide you the care you need for a reasonable cost.

To get started with conservative care today, you can find a highly qualified PT in your area. There are many qualified PTs, so to find one near you, please click on Find A Clinic. This link will help you find a PT that has top national rankings for treating knee pain.

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