KNEE PAIN

The knee comprises a strong joint that is supported by large strong muscles spanning across the ankle, knee and hip. It is also supported by a set of strong ligaments to provide control against strain. This clever design enables the knee to tolerate strain and generate forces needed for activities such as running, jumping/hopping or kicking a ball across the field.

anatomy of ligaments around the knee joint that provides passive stability in back, side, front views (anterior, posterior cruciate ligaments; lateral medial collateral ligaments, patella ligaments quadricep tendon

anatomy of muscles around the knee joint in back, side, front views (quadriceps, ITB, glute maximus and medius, hamstring)

Knee pain is a general term that can relate to any pain around the side, front and back of the knee. Specifically, it may relate to sensitive muscles, bursa, tendons and knee cap / joint.

Common medical diagnostic labels include: patellofemoral pain, Hoffa pad syndrome, pes anserinus, patella tendinopathy, patella instability, quadriceps muscle strain, iliotibial band syndrome, knee osteoarthritis. It may also be related to damage structures from a traumatic injury. Some examples include ligaments tear (anterior/posterior cruciate, medial / lateral collateral), loose osseous body from avulsion or fracture, hamstring strain or tear and Baker’s cyst. Occasionally, it may also be a referred pain down the leg that can be associated with back or hip pain.

Patellofemoral (puh-tel-o-FEM-uh-rul) pain syndrome

is pain at the front of your knee, around your kneecap (patella). Sometimes called "runner's knee," it's more common in people who participate in sports that involve running and jumping.

The knee pain often increases when you run, walk up or down stairs, sit for long periods, or squat.

Symptoms
Patellofemoral pain syndrome usually causes a dull, aching pain in the front of your knee. This pain can be aggravated when you:

Walk up or down stairs
Kneel or squat
Sit with a bent knee for long periods of time

A torn meniscus is one of the most common knee injuries. Any activity that causes you to forcefully twist or rotate your knee, especially when putting your full weight on it, can lead to a torn meniscus.

Each of your knees has two C-shaped pieces of cartilage that act like a cushion between your shinbone and your thighbone. A torn meniscus causes pain, swelling and stiffness. You also might feel a block to knee motion and have trouble extending your knee fully.

Symptoms
If you've torn your meniscus, it might take 24 hours or more for pain and swelling to begin, especially if the tear is small. You might develop the following signs and symptoms in your knee:

A popping sensation
Swelling or stiffness
Pain, especially when twisting or rotating your knee
Difficulty straightening your knee fully
Feeling as though your knee is locked in place when you try to move it
Feeling of your knee giving way

Posterior cruciate ligament (PCL) injury happens far less often than does injury to the knee's more vulnerable counterpart, the anterior cruciate ligament (ACL). The posterior cruciate ligament and ACL connect your thighbone (femur) to your shinbone (tibia). If either ligament is torn, it might cause pain, swelling and a feeling of instability.

Ligaments are strong bands of tissue that attach one bone to another. The cruciate (KROO-she-ate) ligaments connect the thighbone (femur) to the shinbone (tibia). The anterior and posterior cruciate ligaments form an "X" in the center of the knee.

Although a posterior cruciate ligament injury generally causes less pain, disability and knee instability than does an ACL tear, it can still sideline you for several weeks or months.
Symptoms
Signs and symptoms of a PCL injury can include:

Pain. Mild to moderate pain in the knee can cause a slight limp or difficulty walking.
Swelling. Knee swelling occurs rapidly, within hours of the injury.
Instability. Your knee might feel loose, as if it's going to give way.
If there are no associated injuries to other parts of your knee, the signs and symptoms of a posterior cruciate ligament injury can be so mild that you might not notice that anything's wrong. Over time, the pain might worsen and your knee might feel more unstable. If other parts of your knee have also been injured, your signs and symptoms will likely be more severe.

Osteoarthritis is the most common form of arthritis in the knee. It is a degenerative,"wear-and-tear" type of arthritis that occurs most often in people 50 years of age and older, although it may occur in younger people, too.

In osteoarthritis, the cartilage in the knee joint gradually wears away. As the cartilage wears away, it becomes frayed and rough, and the protective space between the bones decreases. This can result in bone rubbing on bone, and produce painful bone spurs.

Osteoarthritis usually develops slowly and the pain it causes worsens over time.

A knee joint affected by arthritis may be painful and inflamed. Generally, the pain develops gradually over time, although sudden onset is also possible. There are other symptoms, as well:

The joint may become stiff and swollen, making it difficult to bend and straighten the knee.
Pain and swelling may be worse in the morning, or after sitting or resting.
Vigorous activity may cause pain to flare up.
Loose fragments of cartilage and other tissue can interfere with the smooth motion of joints. The knee may "lock" or "stick" during movement. It may creak, click, snap or make a grinding noise (crepitus).
Pain may cause a feeling of weakness or buckling in the knee.
Many people with arthritis note increased joint pain with changes in the weather.

A medial collateral ligament (MCL) injury is a stretch, partial tear, or complete tear of the ligament on the inside of the knee. It is one of the most common knee injuries and results mostly from a valgus force on the knee

As with all the ligament injuries, the MCL injury is graded I, II or III (this grade is given depending on the degree of sustained tear). A grade I tear consists of less than 10% of the collagen fibres being torn, with some tenderness but no instability. Most of the patients feel pain when we apply force on the outside of a slightly bent knee, but there are no other symptoms.[5]
Grade II tears vary in symptoms and therefore they are broken down further to grades II- (closer to grade I) and II+ closer to grade III, but both of them count as having tenderness but no instability.[5] The pain and swelling are more significant than with grade I injuries. When the knee is stressed (as for grade I), patients complain about pain and significant tenderness on the inside of the knee, moderate laxity in the joint is observed.

Obviously, this means that a grade III tear is a complete rupture of the MCL, resulting in instability. Patients have significant pain and swelling over the MCL. Most of the time they have difficulty bending the knee. As stated before a grade III tear results in instability, when the knee is stressed (as described above) there is joint laxity. Grade III MCL injuries have an extra scale to measure the extent of the instability. These are described from the amount of joint separation in the 30° valgus test, more information here

Grade I and II injuries have well-defined endpoints contrary to a grade III tear that occurs a soft endpoint with valgus stress testing.[7]

A grade I tear consists of less than 10% of the collagen fibers being torn. Grade II tears vary in symptoms and therefore they are broken down further to grades II- (closer to grade I) and II+ (closer to grade III). Obviously, this means that a grade III tear is a complete rupture of the MCL.

When the knee is stressed (as for grade I), patients complain about pain, moderate laxity in the joint and a significant tenderness on the inside of the knee.
When we speak of a grade III tear of the MCL. patients have significant pain and swelling over the MCL. Most of the time they have difficulty bending the knee. Another common finding of a grade III tear is instability. When we stress the knee (as described above) there is joint laxity.

An ACL injury is a tear or sprain of the anterior cruciate (KROO-she-ate) ligament (ACL) — one of the strong bands of tissue that help connect your thigh bone (femur) to your shinbone (tibia). ACL injuries most commonly occur during sports that involve sudden stops or changes in direction, jumping and landing — such as soccer, basketball, football and downhill skiing.

Many people hear a pop or feel a "popping" sensation in the knee when an ACL injury occurs. Your knee may swell, feel unstable and become too painful to bear weight.

Signs and symptoms of an ACL injury usually include:

A loud pop or a "popping" sensation in the knee
Severe pain and inability to continue activity
Rapid swelling
Loss of range of motion
A feeling of instability or "giving way" with weight bearing

ACL injuries often happen during sports and fitness activities that can put stress on the knee:

Suddenly slowing down and changing direction (cutting)
Pivoting with your foot firmly planted
Landing awkwardly from a jump
Stopping suddenly
Receiving a direct blow to the knee or having a collision, such as a football tackle

There are a number of factors that increase your risk of an ACL injury, including:

Being female — possibly due to differences in anatomy, muscle strength and hormonal influences
Participating in certain sports, such as soccer, football, basketball, gymnastics and downhill skiing
Poor conditioning
Using faulty movement patterns, such as moving the knees inward during a squat
Wearing footwear that doesn't fit properly
Using poorly maintained sports equipment, such as ski bindings that aren't adjusted properly
Playing on artificial turf

Jumper's knee, also known as patellar tendonitis, is a condition characterized by inflammation of your patellar tendon. This connects your kneecap (patella) to your shin bone (tibia). Jumper’s knee weakens your tendon, and, if untreated, can lead to tears in your tendon.

Jumper’s knee is caused by overuse of your knee joint, such as frequent jumping on hard surfaces.

It’s usually a sports-related injury, linked to leg muscle contraction and the force of hitting the ground. This strains your tendon. With repeated stress, your tendon may become inflamed.

Following are the most common symptoms of jumper's knee. However, you may experience symptoms differently. Symptoms may include:

Pain and tenderness around your patellar tendon
Swelling
Pain with jumping, running, or walking
Pain when bending or straightening your leg
Tenderness behind the lower part of your kneecap
The symptoms of jumper's knee may resemble other conditions or medical problems.

Jumper’s knee is inflammation of your patellar tendon, the tendon that connects your kneecap (patella) to your shin bone (tibia).
Jumper’s knee is a sports-related injury caused by overuse of your knee joint.
Common signs of jumper’s knee include:
Pain and tenderness around your patellar tendon
Swelling
Pain with jumping, running, or walking
Pain when bending or straightening the leg
Tenderness behind the lower part of the kneecap
Jumper’s knee is diagnosed by taking a medical history and doing a physical exam. Sometimes an X-ray may be needed.
The best treatment for jumper's knee is to stop any activity that’s causing the problem until the injury is healed. Other treatment may include:
Nonsteroidal anti-inflammatory medicines
Rest
Elevating the knee
Ice packs to the knee (to help reduce swelling)
Stretching and strengthening exercises

Patellar instability is a condition characterized by patellar subluxation or dislocation episodes as a result of injury, ligamentous laxity or increased Q angle of the knee.
Diagnosis is made clinically in the acute setting with a patellar dislocation with a traumatic knee effusion and in chronic settings with passive patellar translation and a positive J sign.
Treatment is nonoperative with bracing for first time dislocation without bony avulsion or presence of articular loose bodies. Operative management is indicated for chronic and recurrent patellar instability.

Symptoms
complaints of instability
anterior knee pain
Physical exam
acute dislocation usually associated with a large hemarthrosis
absence of swelling supports ligamentous laxity and habitual dislocation mechanism
medial sided tenderness (over MPFL)
increase in passive patellar translation
measured in quadrants of translation (midline of patella is considered "0"), and also should be compared to contralateral side
normal motion is <2 quadrants of patellar translation
lateral translation of medial border of patella to lateral edge of trochlear groove is considered "2" quadrants and is considered abnormal amount of translation
patellar apprehension
passive lateral translation results in guarding and a sense of apprehension
increased Q angle
J sign
excessive lateral translation in extension which "pops" into groove as the patella engages the trochlea early in flexion
associated with patella alta

Osgood-Schlatter disease is a common cause of knee pain in growing adolescents. It is an inflammation of the area just below the knee where the tendon from the kneecap (patellar tendon) attaches to the shinbone (tibia).

Osgood-Schlatter disease most often occurs during growth spurts, when bones, muscles, tendons, and other structures are changing rapidly. Because physical activity puts additional stress on bones and muscles, children who participate in athletics — especially running and jumping sports — are at an increased risk for this condition. However, less active adolescents may also experience this problem.

The bones of children and adolescents possess a special area where the bone is growing called the growth plate. Growth plates are areas of cartilage located near the ends of bones. When a child is fully grown, the growth plates harden into solid bone.

Some growth plates serve as attachment sites for tendons, the strong tissues that connect muscles to bones. A bony bump called the tibial tubercle covers the growth plate at the end of the tibia. The group of muscles in the front of the thigh (called the quadriceps) attaches to the tibial tubercle.

When a child is active, the quadriceps muscles pull on the patellar tendon which, in turn, pulls on the tibial tubercle. In some children, this repetitive traction on the tubercle leads to inflammation of the growth plate. The prominence, or bump, of the tibial tubercle may become very pronounced.

Painful symptoms are often brought on by running, jumping, and other sports-related activities. In some cases, both knees have symptoms, although one knee may be worse than the other.

Knee pain and tenderness at the tibial tubercle
Swelling at the tibial tubercle
Tight muscles in the front or back of the thigh

Hoffa’s fat pad syndrome also called fat pad impingement, infrapatellar fat pad syndrome, and Hoffa's disease, is a condition characterized by anterior knee pain, pain in the center, and front of your knees, due to inflammation of the Hoffa’s fat pad.

Hoffa’s fat pad is one of three pads of fatty tissue present under the patella (kneecap). It acts as a protective layer that separates the patella from the thigh and shin bones. If Hoffa’s fat pad is compressed or injured, it swells leading to inflammation and soreness. It also tends to increase in size leading to further pinching. As this continues, pain develops in the front of the knee which is difficult to treat.

The common signs and symptoms of Hoffa’s fat pad syndrome include pain at the front and side of the knee. The other symptoms include:

Pain when straightening the knee
Pain with prolonged walking
Pain during climbing the stairs and sitting with the knee bent
Swelling below and around the knee
Occasional jolts of sharp pain

The common causes of Hoffa’s fat pad syndrome include:

Chronic knee osteoarthritis
Sudden injury, such as a direct hit to the knee
Tight quadricep muscles
Hyperextension or over-straightening the knee
Hoffa’s fat pad syndrome develops gradually if the knee is repeatedly extended beyond its fully straightened normal position.

Chondromalacia patella (knee pain) is the softening and breakdown of the tissue (cartilage) on the underside of the kneecap (patella). Pain results when the knee and the thigh bone (femur) rub together.

Dull, aching pain that is felt:

Behind the kneecap
Below the kneecap
On the sides of the kneecap
A feeling of grinding when the knee is flexed may occur. This can happen:

Doing knee bends
Going down stairs
Running down hill
Standing up after sitting for awhile

Chondromalacia patella often occurs when the undersurface of the kneecap comes in contact with the thigh bone causing swelling and pain. Abnormal knee cap positioning, tightness or weakness of the muscles associated with the knee, too much activity involving the knee, and flat feet may increase the likelihood of chondromalacia patella.

People who are at risk for developing chondromalacia patella include:

Those who are overweight
People who have had an injury, fracture, or dislocation related to the kneecap
Runners, soccer players, bicyclists, and other people who exercise often
Teenagers and healthy young adults, more often females

Bursae are small, jelly-like sacs that are located throughout the body, including around the shoulder, elbow, hip, knee, and heel. They contain a small amount of fluid and are positioned between bones and soft tissues, acting as cushions to help reduce friction.

Pes anserine bursitis is an inflammation of the bursa located between the shinbone (tibia) and three tendons of the hamstring muscle at the inside of the knee. It occurs when the bursa becomes irritated and produces too much fluid, which causes it to swell and put pressure on the adjacent parts of the knee.

Pain and tenderness on the inside of your knee, approximately 2 to 3 inches below the joint, are common symptoms of pes anserine bursitis of the knee.

The symptoms of pes anserine bursitis include:

Pain slowly developing on the inside of your knee and/or in the center of the shinbone, approximately 2 to 3 inches below the knee joint.
Pain increasing with exercise or climbing stairs
Puffiness or tenderness to the touch in this area

Several factors can contribute to the development of pes anserine bursitis, including:

Incorrect training techniques, such as neglecting to stretch, doing excessive hill running, and sudden increases in mileage
Tight hamstring muscles
Obesity
Being duck-footed or having knock knees
Osteoarthritis in the knee

A Baker's cyst is a fluid-filled cyst that causes a bulge and a feeling of tightness behind your knee. The pain can get worse when you fully flex or extend your knee or when you're active.

A Baker's cyst, also called a popliteal (pop-luh-TEE-ul) cyst, is usually the result of a problem with your knee joint, such as arthritis or a cartilage tear. Both conditions can cause your knee to produce too much fluid, which can lead to a Baker's cyst.

In some cases, a Baker's cyst causes no pain, and you may not notice it. If you do have signs and symptoms, they might include:

Swelling behind your knee, and sometimes in your leg
Knee pain
Stiffness and inability to fully flex the knee
Your symptoms may be worse after you've been active or if you've been standing for a long time.

Iliotibial band syndrome (ITBS) is a common knee injury that usually presents with pain and/or tenderness on palpation of the lateral aspect of the knee, superior to the joint line and inferior to the lateral femoral epicondyle.[1]. It is considered a non-traumatic overuse injury, often seen in runners, and is often concomitant with underlying weakness of hip abductor muscles.[2] [3]. The current theory is that this condition is likely to be caused by compression of the innervated local adipose tissue[4]. Studies have described an ‘impingement zone’ occurring at, or slightly below, 30° of knee flexion during foot strike and the early stance phase of running. During this impingement period in the running cycle, eccentric contraction of the tensor fascia latae muscle and of the gluteus maximus causes the leg to decelerate, generating tension (compression) in the iliotibial band.[5]

Our knee’s health depends on regular movements, lower limb muscle strength (hip, thigh and lower leg), and caring for general physical and psychological health. More specifically; this includes participating in physical activity regularly, keeping a healthy weight, good sleep habits and managing stress and mood well (level 1 evidence).

Physiotherapists are key healthcare providers for conservative knee care, being tasked to prevent persistent pain and disability, and facilitating a pathway to wellness and functional restoration.