The knee is one of the largest and most complex joints in your body, and
is often stressed. The knee joint is composed of bones as well as
tendons, ligaments, cartilage and bursae. Tendons connect the knee bones
to the leg muscles that move the knee joint. Ligaments join the knee
bones and provide stability to the knee. Two C-shaped pieces of
cartilage called the menisci act as shock absorbers between the thigh
bone and the shin bone. Numerous bursae, or fluid-filled sacs, help the
knee move smoothly.
Knee pain can be caused by:
injuries or inflammation of the tendons, ligaments and the
bursae that cushion the joint
mechanical problems such as floating cartilage or a dislocated
from conditions such as arthritis and patellofemoral pain
syndrome—pain between your kneecap and thighbone
Tendons, ligaments, cartilage and bursae can become inflamed from
injury, sports activities, wear and tear and arthritis and cause pain.
Sports that place a lot of stress on your knees, excess weight that puts
stress on your joints, a lack of strength or flexibility in the muscles
that support your knees, types of arthritis, bursitis and tendinitis and
other problems that affect the kneecap or patella, a triangular shaped
bone that covers the front of your knee are the most common causes of
Main Line Health offers free, educational Hip and
Knee Pain Seminars throughout the community where you can learn
about the causes and conditions of hip and knee pain, and the latest
treatment options to relieve your pain.
Patellofemoral Pain Syndrome
Patellofemoral pain syndrome is pain in the front of the knee. It
frequently occurs in teenagers, manual laborers, and athletes. It
sometimes is caused by wearing down, roughening, or softening of the
cartilage under the kneecap. The main symptom of patellofemoral pain
syndrome is pain, especially when you are sitting with bent knees,
squatting, jumping, or using the stairs (especially going down stairs).
You may also experience occasional knee buckling, in which the knee
suddenly and unexpectedly gives way and does not support your body
weight. It is also common to have a catching, popping, or grinding
sensation when you are walking or when you are moving your knee.
Cartilage Injuries—Torn Meniscus
Torn meniscus is a common knee injury. Each of your knees has two
menisci—one at the outer edge and one at the inner—and each is a
rubbery, C-shaped disc that cushions your knee. The menisci keep your
knee steady by balancing weight across the knee.
A torn meniscus is often caused by twisting or turning quickly, with the
foot planted and the knee bent. The tear can also occur when you lift
something heavy or play sports. The menisci get worn with aging and can
tear more easily. The injuries vary by degree of severity. In the most
serious tears, pieces of the torn meniscus can move into the joint space
causing your knee to pop or lock and you may not be able to straighten
it. Your knee may feel wobbly and give way without warning, or swell and
get stiff right after the injury or within two to three days.
Compartment syndrome is a painful condition that occurs when pressure
within the muscles builds to dangerous levels. Muscles and the nerves
and blood vessels that run alongside them are enclosed in a compartment
formed of tough membrane called the fascia. When the muscles become
swollen, they fill the compartment to capacity, damaging muscle and
interfering with nerves and blood vessels. This pressure can decrease
blood flow, which prevents nourishment and oxygen from reaching nerve
and muscle cells.
Compartment syndrome can be acute or chronic and most often occurs in
the anterior (front) compartment of the lower leg (calf). It can also
occur in other compartments in the leg, as well as in the arms, hands,
feet, and buttocks. Acute compartment syndrome is a medical
emergency. It is usually caused by a severe injury. Without treatment,
it can lead to permanent muscle damage. Chronic compartment
syndrome, also known as exertional compartment syndrome, is usually not
a medical emergency. It is most often caused by athletic exertion.
Acute Compartment Syndrome develops after a traumatic injury such as car
accident or broken bone and is a surgical
emergency. Fasciotomy is a limb-saving procedure when used to treat
acute compartment syndrome.
Chronic (Exertional) Compartment Syndrome develops after exercise.
Athletes who participate in activities with repetitive motions, such as
running, biking, or swimming, are more likely to develop chronic
compartment syndrome. This is usually relieved by discontinuing the
exercise, and is usually not dangerous.
Kneecap Dislocation and Mechanical Problems
Injury or degeneration of bone or cartilage can cause a piece of bone or
cartilage to break off and float in the joint space and affect the joint
movement. Or the ligament that extends from the outside of your pelvic
bone to the outside of your tibia becomes so tight that it rubs against
the outer portion of your femur or thighbone. This is common with
The knee cap can also become dislocated, slipping out of place to the
outside of the knee and not slip back into place. Sometimes athletes or
those with arthritis develop a chronic pain between the knee cap and the
thighbone that may be the result of the misalignment of the kneecap.
Problems with your hip or foot may change the way you walk and end up
putting more stress on the knee joint.
This condition is pain along the shin bone, the large bone in the front
of the lower leg. The pain can occur at the front outside part of the
lower leg, including the foot and ankle, or at the inner edge of the
bone where it meets the calf muscles. Shin splints are common in runners
and can occur from overuse, improper stretching or warm-up or technique,
running or jumping on hard surfaces or in shoes that do not give enough
support. They are also associated with flat feet.
Anti-inflammatory medications, orthotics and physical therapy are
typical treatments. Surgery is rare and usually because a fracture has
Baker’s cyst describes a condition where the knee produces too much of
the fluid that helps your leg swing smoothly and without friction
between the moving parts. A cyst becomes filled with this synovial
liquid and causes a bulge on the knee and a feeling of tightness behind
your knee that gets worse when you try to flex or extend the knee.
Baker’s cyst is often a result of another underlying problem with the
knee joint, such as arthritis or a cartilage tear.
Baker’s cysts may become complicated when the fluid starts leaking into
the calf, causing even more pain in the knee, swelling in the calf,
redness in the calf and a feeling that water is moving down the leg.
Because these symptoms can resemble those of other serious conditions
such as a blood clot, your doctor will test with an ultrasound or an MRI
to determine the specific cause of your symptoms. Medication, physical
therapy and fluid drainage are the typical treatment for Baker’s Cyst.
Bursitis is a painful condition that occurs when the small, fluid-filled
sacs that cushion the outside of your knee joint called bursae become
inflamed. The bursae are the buffer between hard bones and softer
tissues such as skin, tendons and ligaments, reducing friction where
there is the possibility of rubbing. When inflamed, they thicken, fill
with fluid and become lumpy and the joint may be swollen and tender.
Bursitis can also occur in people who have other medical conditions such
as gout, diabetes, rheumatoid arthritis and uremia. The bursae can also
become infected by bacteria, a more serious type of bursitis than can
spread and cause serious problems.
Traumatic bursitis occurs in athletes due to hitting an extremity
against a hard surface or from too much bending of the joint. You should
consult your doctor if you have:
Disabling joint pain, especially if it lasts more than one to
two weeks or is sharp pain when you exercise or exert yourself
Excessive swelling, redness, bruising or a rash in the affected
In most cases, bursitis pain, swelling and stiffness goes away within a
few weeks with proper treatment with medications for infection and
inflammation, injections to reduce pain and swelling, a splint to
immobilize the affected area, and physical therapy to improve range of
Recurrent flare-ups of bursitis are common and sometimes surgery may be
needed when bursitis does not respond to other treatments.
Arthritis of the Knee
Arthritis, inflammation of the knee joint, can be caused by wear and
tear through natural constant use, from trauma, or from a number of
diseases with inflammatory processes.
Osteoarthritis is the most common form of arthritis, is a progressive
degenerative joint disease that occurs when the smooth covering on the
ends of bones, the joint cartilage, becomes damaged or worn from
overweight/obesity, a history of joint injury and age. The condition
often results in bone-on-bone rubbing and affects one of the
weight-bearing joints such as the hip or knee.
Osteoarthritis of the knee cap is caused by common wear and tear in
adults over age 50, with increased pain climbing the stairs, squatting
Some arthritis of the knee is caused by rheumatoid arthritis, an
autoimmune condition that may affect your knees; gout is a type of
arthritis that occurs when uric acid crystals develop in the fluid in
the knee joint; septic arthritis occurs when the knee joint has become
Ligament Injuries—ACL, PCL, MCL and LCL
Ligaments are elastic bands of tissue that connect bones to each other
to provide stability and strength to the knee joint. Ligament injuries
in the knee are fairly common, especially injury to the anterior
cruciate ligament, or ACL. There are four main ligaments in the knee
that connect the femur or thighbone to the tibia or shin bone:
Anterior cruciate ligament or ACL – located in the center of the
knee, controls the rotation and forward motion of the shin bone
Posterior cruciate ligament or PCL – located at the back of the
knee, controls backward movement of the shin bone
Medial collateral ligament or MCL – connects the thigh bone to
the shin bone on the inside of the knee—MCL stabilizes the inner
Lateral collateral ligament or LCL – connects the thigh bone to
the fibula, the smaller bone of the lower leg on the outer side
of the knee—LCL stabilizes the outer knee
Injuries to these ligaments are common in many sports such as soccer,
football, basketball, skiing and gymnastics where the knee may twist
with the foot planted, when the knee gets hit, when it is extended too
far, when jumping and landing on a flexed knee, stopping suddenly when
running, or when suddenly shifting weight from one leg to another. Many
people who have tears to the ligaments, particularly ACL tears, opt to
have surgical treatment
to repair the tear.
Hamstring Muscle Strain Injury
The hamstring muscles that help you extend your leg straight back and
bend your knee, run down the back of the thigh. They are a common place
for injury, especially among athletes who participate in sports that
require sprinting such as track, soccer and basketball, but can also
affect runners and skaters.
A hamstring injury can be a pull or strain, partial or complete tear and
occur most often in the thick part of the muscle or where the muscle
fibers join the tendon fibers. In the most severe hamstring injuries,
the tendon tears completely away from the bone, and may even pull a
piece of the bone away with it. This can happen when there is a large
sudden overload on the muscle.
Most hamstring injuries heal with nonsurgical treatment and physical
therapy after the pain and swelling have settled down. However, the more
severe injuries require surgery to repair a tear.
A groin pull is a strain injury from putting too much stress on muscles
in the thigh and groin. If these muscles are tensed too forcefully or
too suddenly, they can get over-stretched or torn. This injury is common
in people who play sports that require a lot of running and jumping. In
particular, suddenly jumping or changing direction is a likely cause as
in football or soccer.
feel pain and tenderness in the groin and inside of the thigh,
especially when you bring your legs together or raise your knee
may also have a popping or snapping feeling during the injury
Typical treatment is more likely to include anti-inflammatory
medications, compression and physical therapy. A complete tear of the
muscle may require surgical repair.
Jumper’s Knee—Patellar Tendinitis
Jumper’s Knee is an overuse injury and a common cause of pain from
irritation and inflammation of the patellar tendon, the band of fibrous
tissue that connects the kneecap or patella to the shin bone. It often
affects athletes whose sports involve jumping, such as basketball and
volleyball, that put repetitive stress on the patellar tendon.
Other activities such as running, skiing and cycling can cause jumper’s
knee as the quadriceps muscle on the front of your thigh tighten.
Other causes include:
problems with the alignment of the hips, knees, legs and feet
wide hips, knock knees and flat feet can predispose you to
patellar tendinitis when the body mechanics put more stress on
the patellar tendon
Surgery may be
needed if the injury has not responded to other treatments as the pain
may indicate a complete tear requiring repair, or removal of damaged
Runner’s Knee and Iliotibial Band Syndrome
Pain and tenderness close to or under the kneecap at the front of the
knee and surrounding area is caused by an injury called runner’s knee.
Iliotibial band syndrome is pain on the outer side of the knee.
Both are overuse or repetitive strain injuries that can become chronic,
or the result of trauma to the knee, misaligned bones, weak or
imbalanced muscles or feet problems. They can occur together, but most
knee pain is in the front of the knee.
Anti-inflammatory medication, orthotics and physical therapy are typical
treatments, but severe cases may need surgery
for any cartilage problems or if the position of the kneecap needs to be
For more information, call 1.866.CALL.MLH.