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Knee Pain Causes

zCauses of knee pain

Causes of knee pain | Understanding symptoms | Nonsurgical treatments | Surgical options | Knee prevention

Knee Anatomy

The knee joint is comprised of four bones.  The largest of these is the femur, or thigh bone.  Also found in the knee is the tibia, sometimes called the shin bone.  Alongside the tibia, on the outside of the leg, is the fibula. knee pain rhode island, causes of knee pain rhode island, knee anatomy rhode island, orthopedic center rhode island

The fourth bone found in the knee is the patella or kneecap. It’s cradled within the patellar tendon, and lies directly in front of the femur. This patella assists in knee extension, increasing leverage by lifting the quadriceps and patellar tendons away from the joint.

The lower end of the femur is rounded into two knob- shaped masses known as condyles.  These move against the upper end of the tibia, which is flat.  Both the lower end of the femur and upper end of the tibia are covered with  articular    cartilage, a smooth rubbery material, which allows one surface to glide one upon the other with minimal friction.  Sandwiched between the two joints are two distinct masses of fibrocartilaginous material called menisci, which acts as an additional cushion for the joint.

In addition to the meniscus, there is articular cartilage covering the ends of the femur, the top of the tibia, and the back of the patella.  Articular cartilage is found throughout the body anywhere two bones meet and glide against each other. The point of meeting and movement for bones is described as the point of articulation, hence the name “articular cartilage.”

Knee - Common Injuries

Athletes can be used to feelings of slight discomforted and occasional pain, but sometimes this can be the warning sign of a more serious injury. Some of the most common injuries that occur to football players and athletes are lower leg and knee injuries.

Knee injuries can become a common occurrence for anyone that is exposed to a lot of activities involving repetitive twisting, stopping, starting, and jumping. Football players are at high risk for knee injuries because of the probability of a sideways blow to the knee while a cleated foot is planted.

While knee pain can occur for a variety of reasons, most knee problems come from four main areas:

1. Pain from the kneecap. Those with kneecap pain typically notice an increase in pain when going up or down stairs, when running downhill, or even while sitting.

2. Torn meniscus. The bottom of the femur (thigh bone) and the top of the tibia (shin bone) that come together in the knee joint, are covered by cartilage which enables the bones to glide against each other with a minimal amount of friction. But if the knee is twisted, or banged, the cartilage can become damaged or loosened out of its normal position. A common symptom of this type of injury is that the knee may “catch” or grind at a certain point as it moves through its normal range of motion.

3. Ligament problems. If you think of the knee as a hinge between the upper leg and lower leg, it is the awesome work of the supporting muscles, ligaments, and tendons to make sure that it is supported and working properly—often while the leg is twisting, turning and absorbing shock from jumping. There are four key ligaments that can be injured in the knee:

Anterior cruciate ligament (ACL) is often the victim of noncontact injury, where the knee is twisted while the foot is planted. You may feel a pop, and the whole knee may give way.

  • Posterior cruciate ligament (PCL) injuries can be caused by a blow to the knee, or when the knee is forced backward.
  • Medial collateral ligament (MCL) can be injured from a blow to the outside area of the knee.
  • Lateral collateral ligament (LCL) injury can be caused by a blow to the inside area of the knee.

4.Tendon problems. Sometimes the tendons that attach the kneecap (patella) to the shinbone (tibia) can become inflamed.

Meniscus

knee pain rhode island, fractured knee rhode island, knee surgery rhode islandAs the largest of joints, and the one bearing the heaviest burden, our knees are fortified with an extra layer of cartilage just between the femur and tibia. The menisci protect the articular cartilage by spreading out the forces placed on the joint surfaces during movement. To imagine how valuable this function is, consider that forces on the knee range from about twice our body weight during normal walking, to more than four times our body weight during running activities.

The meniscus also plays a role in shock absorption. Considering the meniscal layer is only about one-fourth of an inch thick, this padding does a remarkable job of softening impact and vibration when our feet hit the ground walking, running, and jumping. Knees with the menisci in top form have a shock absorption capacity that is 20 percent higher than knees in which the menisci have been removed. This underscores the importance of injury prevention when it comes to the knee. Once you damage the shock absorber, you are that much more susceptible to arthritis and damage to the joint.

Menisci also aid the knees in maintaining stability. If you placed a ball on a flat surface, you’d have a pretty good idea of what the knee would be like without the meniscus. Except for the ligaments, there would be nothing to keep the femur from rolling right off the tibia. When we are young, menisci are tough but can tear as a result of a sports injury. As we reach our fifth decade of life, menisci can become fragile and often tear with just a slight twist.

Meniscal tears stem from sports-related injuries or even from seemingly innocuous activities such as squatting. Athletes who play football, basketball, and tennis are especially prone to meniscus tears. The type of movement that most often causes meniscal injury is one in which the foot is firmly planted on the ground while the knee is twisted. Shoes with cleats often contribute to this type of injury by anchoring the lower leg into the ground and preventing it from moving with the knee.

During arthroscopic surgery of the knee, a knee surgeon will attempt to clean up and remove the torn part of the meniscus, while at the same time trying to preserve as much of it as possible.

In addition to the meniscus, there is articular cartilage covering the ends of the femur, the top of the tibia, and the back of the patella. Articular cartilage is found throughout the body anywhere two bones meet and glide against each other. The point of meeting and movement for bones is described as the point of articulation, hence the name “articular cartilage.”

Knee - Meniscus Tears

Meniscal tears can occur at any age. In the younger age group, they are usually sports-related and result from violent trauma. Contact sports like football account for a large number of tears. The type of movement that most often causes meniscal injury is one in which the foot is firmly planted on the ground while the knee is twisted. Shoes with cleats often contribute to this type of injury by anchoring the lower leg into the ground and preventing it from moving with the knee.

Along with other sports, which call for cutting, pivoting, or decelerating, basketball and tennis can also lead to meniscal tears. Traumatic meniscal injuries may also be accompanied by the tearing of a ligament, such as the anterior cruciate ligament.

For those forty and older, meniscal tears are less likely to be due to sports injury. With age the meniscus weakens and becomes more fragile. Individuals in this age group can tear a meniscus by performing simple activities, such as squatting.

Meniscal tears come in a variety of sizes and shapes. Often torn fragments lodge between the tibia and femur causing mechanical obstruction and pain. When this happens, the knee is said to “lock up” which means that the patient is unable to extend the knee fully outward. Fluid accumulates as the result of an inflammatory process, and walking becomes difficult.

Menisci lack blood supply except at their outer rim. Once torn, they heal poorly, if at all, and function is lost. Symptoms often vary in intensity depending upon the level of one’s activity.

Ligaments

Ligaments interconnect the bones of the knee.  They are made up of tough collagen fibers, which themselves are relatively inflexible.  However, they are arranged with a crimp design that straightens when force is applied and permits the ligaments to endure large internal stresses during normal joint motion.  Ligaments are attached to bone in such a manner that there is progressive increase in stiffness as they blend into bone.

The way that ligaments become part of a bone is also important to their function. Ligamentous tissue and bone meet together in a graduation of fibrocartilage and mineralized fibrocartilage, which provides the increasing stiffness as ligament blends into bone.

The four major ligaments of the knee are:

  • the anterior cruciate ligament
  • the posterior cruciate ligament
  • the medial collateral ligament
  • the lateral collateral ligament

The stability of the knee is largely due to their combined efforts.  They are the structures that ultimately hold the tibia and femur together, while permitting motion.

The anterior cruciate ligament (ACL) is deep within the knee.  It crisscrosses the posterior cruciate ligament (PCL) and keeps the tibia from sliding too far forward in relation to the femur.  The PCL does the opposite.  It prevents the tibia from sliding excessively backwards.  The PCL is further supported by two minor ligaments:  the ligaments of Humphry and Wrisberg.

The ligaments that provide sidewise stability to the knee are the medial collateral ligament (MCL) and lateral collateral ligament (LCL).  These ligaments limit side-to-side motion.

Chronic pain

Pain is broken down into two categories: acute or chronic. If you fall down and hurt your knee or twist your knee, that is called "acute" knee pain. Chronic pain is something that occurs more gradually over time, often getting worse as weeks and months go by.

Unlike acute pain which can be linked to a specific event or time - like when you fall or twist your knee - chronic pain is more like an ache that is not linked to any event. The knee specialist will ask when and how your pain started to learn more about the potential cause of pain.

Knee - Anterior cruciate ligament

The anterior cruciate ligament (ACL) is deep within the knee. It crisscrosses the posterior cruciate ligament (PCL) and keeps the tibia from sliding too far forward in relation to the femur. The PCL does the opposite. It prevents the tibia from sliding excessively backwards. The PCL is further supported by two minor ligaments: the ligaments of Humphry and Wrisberg. The ligaments that provide sidewise stability to the knee are the medial collateral ligament (MCL) and lateral collateral ligament (LCL). These ligaments limit side-to-side motion.

When the ACL is torn, it is often because the leg rotates while the foot stays planted on the ground. Often times an ACL tear is accompanied by a loud popping sound from the knee and the support of the knee gives way. A posterior cruciate injury happens when the knee is forced backwards or when it receives a hard impact. A medial collateral ligament injury most commonly occurs when the knee is hit from the outside while a lateral collateral ligament injury occurs when the knee is impacted from the inside.

Knee - ACL Tears

Certain ligaments are especially vulnerable. The ACL and MCL are the most commonly torn. Frequent causes of ligament injuries include twisting or changing direction rapidly, slowing down when running, and landing from a jump. Specific athletes at risk are those who ski, play basketball, soccer, or football.

Why are ligaments so easily damaged?

Consider the average size of the ACL or PCL. They’re smaller than you might think. The ACL is about one centimeter wide and has a range of eight to thirteen millimeters wide, while the PCL is thirteen to sixteen millimeters. Both of these ligaments are only about four centimeters in length.

The sound of an ACL as it tears is distinctive, and the feeling unforgettable. Here’s what happens. The anterior cruciate ligament tightens as the knee is twisted. But when the knee is forced past the normal straightened position, or when the tibia is twisted excessively outward on the femur, or frequently when the knee is struck from the side, the ACL may be stretched beyond its breaking point. Those nearby will notice a distinctive popping sound, and the afflicted individual will experience a sudden burst of pain and instability. Often the knee buckles, causing a fall to the floor. Swelling appears promptly.

Swelling and pain may subside, but after returning to sports, there will be a sense of instability with any twisting maneuver. While not commonly the case, bleeding may occur in the knee. Because the knee is now rendered unstable, repeated injury can now damage the menisci or articular cartilage and ultimately lead to arthritis.

ACL - Treatment and Surgery

Treatment for an ACL tear varies depending upon the patient’s individual needs. A torn ACL will not heal without surgery. To surgically repair the ACL and restore knee stability, the ligament must be reconstructed. Your orthopaedic surgeon will replace the torn ligament with a tissue graft that acts as scaffolding for a new ligament. Non-surgical treatment might be beneficial for older patients or low activity level. If the stability of the knee is undamaged, the doctor may recommend other non-surgical options.

Surgical treatment is most often recommended for people with ACL tears accompanied with other injuries. The foremost likely candidates for surgery are active individuals who pivot and push off the knee. Surgery is additionally recommended for people with unstable knees or injuries combined with damage to the menisci, cartilage or ligaments.

Surgery to rebuild an anterior cruciate ligament is done with an arthroscope using small incisions. Arthroscopic surgery is a less invasive technique, with the benefits of less pain from surgery, less time spent in the hospital, and quicker recovery times.

The Anterior Cruciate Ligament (ACL) works a lot like a guy wire that keeps the femur and the tibia stable. When an athlete tears their ACL, usually it is from a sudden impact that can cause an audible pop or at least a great deal of pain.

Generally speaking, a partially torn ACL stands a chance of recovery without surgery. If the ACL is completely torn, most will need surgery to repair the ligament. Many of those with a torn ACL will need surgery to get back to activity. The procedure itself takes about one hour.

The more you expect to play aggressive sports in the future, the more likely you will need knee surgery to repair a fully torn or partially torn ACL. If you are professional athlete, chances are you will need surgery to get back to full activity.

If you have a torn ACL, the good news is that the problem is fairly common as knee injuries go, and in the hands of a surgeon who specializes in knees, the post surgical knee can be as effective as the knee prior to injury. But most of that depends on the willingness of the athlete to invest the time to rehabilitate and strengthen the knee.

Repairing a torn ACL does NOT involve sewing two torn ends together. Think of your ACL as a rubber band. Once it snaps, it cannot be sewn together. Instead, you have to replace the rubber band completely. And that is exactly what the knee surgeon does. They attach a new rubber band to your shin, thread it through your knee and anchor it your femur.

You should ask your physician HOW they repair the ACL. Some knee surgeons use a patellar tendon while many others use a hamstring ligament. There are pros and cons to each.

Harvesting a patellar tendon from the front of the knee makes for a more painful recovery and painful rehabilitation. However, professional athletes who are used to pain from training are more able to tolerate this approach, especially considering that the patellar tendon is viewed by some surgeons to be a higher performance replacement for the torn ligament than the hamstring. Using a hamstring ligament is less painful on rehab of the knee, and some surgeons feel that for most people, the strength of the ligament is sufficient.

Overall, most surgeons would agree that the performance of the knee after ACL replacement is directly linked to how much commitment is given to strengthening the knee with exercises. With the right knee specialist, and with specialized knee rehab, a professional athlete can regain their competitive form and play professional sports again.

Using an arthroscope, the knee surgeon can repair the knee through two tiny half-inch incisions instead of a longer incision that requires a longer recovery and causes a bigger scar. The surgeon will remove a strand from the patellar tendon or hamstring, which will ultimately become the new ACL. A hole is then drilled through the shin bone and a new ACL is threaded through. The new ligament is prepared and secured into place. A plastic dowel locks the new ACL into place. About 30 minutes later, the anesthesia will wear off and the patient is dismissed from the hospital.

During the recovery process, a patient will start off by walking around. Physical therapy focuses on returning motion to the joint and surrounding muscles, and is followed by a strengthening program designed to protect the new ligament. This strengthening process gradually increases the stress across the ligament. A few months later golf is acceptable. After five or six months, the patient is usually allowed to play sports without restriction.

Knee - Tendons, Muscles, Nerves, and Blood Vessels

Tendons are cords of strong, fibrous tissue, which connect muscle to bone. Muscle power is transferred across tendons to bones. The primary muscle groups associated with the knee are the quadriceps and hamstring muscles. These muscles are at work when the knee is extended, flexed, or rotated.

The easiest way to understand how the muscles in the leg operate is to imagine two large rubber bands, one that runs down the front, and another that runs down the back. The front rubber band pulls the leg straight, or extends it. The rear rubber band causes the leg to do the reverse, or flexes it.

The quadriceps mechanism is the strongest muscle in the leg, allowing us to walk and run. The quadriceps mechanism includes:

1. Quadriceps muscle
2. Quadriceps tendon above the patella
3. Patella
4. Patellar tendon

The quadriceps tendon connects the quadriceps muscle to the patella, while the patellar tendon connects the patella to the tibia. The hamstring muscles at the back of the thigh, as well as the calf muscles, enable the knee to flex.

Working together, the muscles, tendons, and ligaments of the knee work fluidly. Turn to any sports channel on a Sunday afternoon and pay attention to the slow motion videos of a wide receiver running a complex pass route, jumping through the air to snatch a football, and then changing directions and accelerating into the end zone. Or watch a skier charge through a slalom course, knees pumping as they work the edges of their skis through the gates.

That’s when everything is working perfectly. Things change after a wide receiver takes a blow to the side of the knee, or when that downhill skier catches an edge and tumbles.

Now that you have an understanding of the gears and moving parts that make up the knee joint, we start to understand what can go wrong.

Knee - Strains, Sprains, and Tears

Strains are common and occur when a muscle is overworked or overstretched. When you suddenly dive into a new activity or exercise program, you often strain a muscle or tendon by overworking it. A strained muscle is what we sometimes call a “pulled” muscle. A strain is characterized by a sharp pain or “stitch” at the time of injury. The area becomes sore and stiff within a few hours or moments of straining. Pain accompanies further movement but often subsides within days.

Strains often occur when, after months of inactivity, we throw ourselves into a new exercise routine. If you are out of shape and haven’t carefully stretched your muscles, think twice before zealously jumping on the treadmill and powering it up to a high-speed performance level. When the machine starts racing, your legs might race right out from under you, and in that case, you’ll be lucky if a strain is the only injury suffered.

Sprains are more serious than strains. A sprain occurs when a ligament is overstretched or partially torn. Since ligaments hold bones together, their close proximity to the bone may lead to the suspicion of a fracture. The signs of a sprain include joint pain, inflammation, tenderness and swelling. These may be associated with black and blue discoloration. Sprains in the knee involve partial tears to the ACL, PCL, MCL, and LCL.

The location of the injury should clarify any confusion over whether it’s a sprain or strain. Strains occur in the muscles of the neck, back, thighs, and calves. Sprains are found around joints—knees, ankles, or wrists.

Tears are more severe than strains or sprains. When muscles, ligaments, or tendons are torn they are actually disrupted. The torn ends grossly disrupt the continuity of their structure.

What Is Inflammation?

The word “inflammation” literally means to “set on fire.” Its characteristics are swelling, reddening, pain, and heat. Inflammation is a defensive reaction to injury. There are hundreds of inflammatory processes, as indicated by the “-itis” suffix. Tendinitis, bursitis, and arthritis are conditions which bring about inflammation in the knee.

What’s good about inflammation? Each characteristic of inflammation provides a clue. The reddened appearance of inflamed tissue is a result of an increased blood supply. This carries white blood cells to the affected tissues. These are the agents which release enzymes to aid in healing or destroy germs.

This extra concentration of blood cells and fluid causes the area to swell, while increased local metabolism increases warmth. Pain occurs as a result of these processes and often prompts one to seek care. Inflammation may be present both in acute or chronic knee problems.

Chondromalacia

“Chondro” indicates cartilage, while “malacia” means softening. Consequently, chondromalacia together means softening of the cartilage.

But chondromalacia really refers specifically to softening of the under surface of the patella, or kneecap. It is a degenerative condition that occurs as the result of chronic wear of the kneecap against the femur. The articular cartilage gradually softens and then frays.

At other times, a traumatic blow around the knee is the cause of chondromalacia. Symptoms of chondromalacia include pain in front of the knee, especially when walking up and downhill, stiffness after prolonged sitting, and a grinding or clicking sensation as the knee is flexed and extended.

Symptoms typically vary according to the level of activity and may limit one’s participation in sports. As problems progress, patients may also lose speed and strength, and notice swelling. The condition is increasingly common in middle age. For reasons unknown, it occurs most in women, and may begin as early as the teenage years.

It has even been suggested that some people may be predisposed to chondromalacia. Women suffer most from this condition possibly due to muscle weakness in the extension mechanism and anatomical factors, which cause the kneecap to slip out of alignment. Symptoms may be especially severe with repetitive activities like running or aerobics, although cyclists are not immune to the problem.

Ligament Problems

An increase in interest in sports seems to have been the catalyst for more and more ligament problems every year. In fact, there are more than 50,000 hospital admissions for ligament repair. Interestingly, women are 8 times more likely to have an ACL tear than men. Some experts theorize it may relate to high heals or anatomy. The ACL (anterior cruciate ligament) and the MCL tend to be particularly susceptible to injury during sports. The cause is generally turning quickly and twisting the knee, slowing down when running, and landing from a jump. High risk sports include soccer, skiing, basketball, and tennis.

Pain from Meniscus Tears

Meniscal tears stem from sports-related injuries or even from seemingly innocuous activities such as squatting. Athletes who play football, basketball, and tennis as well as adults over the age of 40 are especially prone to meniscus tears. The type of movement that most often causes meniscal injury is one in which the foot is firmly planted on the ground while the knee is twisted. Shoes with cleats often contribute to this type of injury by anchoring the lower leg into the ground and preventing it from moving with the knee.

Fractures

A bone can break for a number of reasons. A traumatic injury such as a car accident can cause a bone to break. Other causes for bones breaking can be "stress" fractures where a bone is used repetitively and because of compression, it breaks.

Dislocation

Sometimes, especially while doing something physically strenuous, we can throw a joint out of alignment with the bone. Although nothing breaks, the alignment is off. This is called dislocation.

Arthritis

Arthritis: Osteoarthritis

This is a degenerative joint disease stemming from wear and tear on the knee usually affecting those in middle age and older. Osteoarthritis causes the cartilage to erode away. Symptoms include pain, stiffness, and swelling that at first happens once in a while but can progress to chronic pain.

Arthritis: Rheumatoid Arthritis

Unlike osteoarthrits, this type of arthritis does not erode the cartilage slowly, rather it inflames the joint (usually many joints at one time) until the joints are ruined. Rheumatoid arthritis is most common in middle aged women, but can affect people of all ages.

Arthritis: Crystaline Arthritis

Inflammation of the joints can occur when a small granual of sodium urate (related to gout) or calcium phosphorate (related to chondrocalsinosis) gets lodged in the joint. The effect is similar to getting a piece of sand trapped in your eye. It irritates the surrounding inflammation. Middle-aged men are most prone to this sort of arthritis.

Pre-Patellar Bursitis

Between the tendon and the skin are small sacs called bursae which allow the skin to smoothly and painlessly slide over bones. When the bursae become inflamed, any knee movement can cause pain. In the knees, one function of the bursae is to allow the knee cap to move around freely without pain. Repetitive kneeling and/or direct impact on the knee can cause the bursae to swell and cause pain. Those in professions where the knees are often bent such as masonry, house cleaning, carpet layers, and electricians are more likely to experience post-patellar bursitis. At other times, the condition can occur when the sacs become infected. Usually for this ailment surgery is not necessary (although may be called upon in extreme cases) and treatment includes avoiding bending of the knees and relieving pressure to the knee cap.

The Four Most Common Knee Problems

  • Knee cap pain - the pain usually become most noticeable when walking up stairs, going down stairs, running or sitting.
  • Pain from a torn meniscus - the meniscus is the cartilage that keeps the femur (the thigh bone) and the tibia (the shin bone) from hurting or grinding when they rub against each other. If the meniscus is torn, stretched or out of place, pain may occur when the joint is moved.
  • Pain from ligament problems - there are four ligaments in the knee: the anterior cruciate ligament, the posterior cruciate ligament, the medial collateral ligament, and the lateral collateral ligament. When the ACL is torn, it is often because the leg rotates while the foot stays planted on the ground. Often times an ACL tear is accompanied by a loud popping sound from the knee and the support of the knee gives way. A posterior cruciate injury happens when the knee is forced backwards or when it receives a hard impact. A medial collateral ligament injury most commonly occurs when the knee is hit from the outside while a lateral collateral ligament injury occurs when the knee is impacted from the inside.
  • Pain from tendon problems - inflamed tendons that connect the knee cap to the shin bone can cause pain.