What hurts? - Knee
The knee is the largest joint in the body and one of the most commonly injured. It is a complex joint made up of many components. The boney components are the thigh bone (the femur), the shin bone (the tibia) and the knee cap (the patella). Additionally there are four large ligaments that help control the motion of the knee and connect the two bones and another well known structure in the knee is the meniscus, which is a C-shaped disc of cartilage between the femur and tibia and it acts as a shock absorber to cushion and protect the cartilage on the ends of the bones. The cartilage on the ends of the bones is known as articular cartilage.
Causes of Knee Pain
Because of the knees fairly complex anatomy and numerous components, there are several injuries that can occur in or around the knee. These include: muscular strains, ligament sprains or tears, torn cartilage, bursitis, tendonitis, and arthritis. For further information about fractures in the knee you can refer to the fracture section.
Knee pain quick links:
Strains occur when there are forces on the muscles that cause injury to the muscle. Commonly this will result in thigh pain, either in the hamstrings or quadriceps, occasionally in the outside of the thigh, in an area known as the iliotibial band and also a calf strain (gastroc muscle) might occur. Hamstring and quadriceps tears or strains often occur with sporting activities as a result of not warming up and stretching enough. The reason these sets of muscles are so commonly strained is because they cross two joints. The quadriceps and the hamstring muscles cross both the hip and the knee joint and the calf muscles cross the knee and the ankle joint. These injuries can be a small pull, partial tear or a complete tear. Grade One is mild and usually heals within a week or two and Grade Three is a complete tear and sometimes this may even require surgery and it often takes months to completely heal. If the tear is significant enough, it can cause bruising and swelling. Usually with rest, ice, generally stretching and sometimes physical therapy, as well as over-the-counter medications such as Tylenol and an anti-inflammatory the symptoms will often resolve within a few weeks. If the pain persists beyond this time period, it may mean that something more serious is occurring and you should see one of our physicians for further evaluation.
Sprains occur when a ligament is injured. A ligament is a tissue that connect two bones, where as a tendon connects a muscle to a bone. The common ligaments in the knee are the anterior cruciate ligament (ALC), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and lateral collateral ligament (LCL). The medial and lateral collateral ligaments help protect the knee in the side to side fashion, and when they are torn or sprained they result in looseness with the knee moving side to side. The anterior and posterior cruciate ligaments crossed in the center of the knee and they provide stability to the knee in a front to back motion. This topic will be discussed in much greater depth later.
The two most common forms of tendonitis about the knee are quadriceps tendonitis and patellar tendonitis. This is inflammation of the tendons. It may also cause partial tearing in those tendons. These types of tendonitis often occur in people that participate in activities that require a lot of running and jumping.
Treatment of tendonitis may include rest, elevation, anti-inflammatories, stretching and formal physical therapy. Surgery is sometimes required if the patient doesn’t respond appropriately to the conservative treatments mentioned above. This is something that can be discussed with your orthopedic surgeon. Imaging studies and x-ray are helpful for evaluation of torn tendons because you can sometimes see a small fleck of bone that has pulled away from the normal bone with the torn tendon. Sometimes the kneecap be seen to not be in an appropriate position and this would result from the tendon being torn. An MRI can be helpful to evaluate the tendon itself, especially for persistent tendonitis or if a doctor is suspicious of a partial tendon tear.
Muscle is connected via tendon and sometimes that tendon can be torn away from the bone or torn in half. These tendons are pulled or torn because they are overloaded and stretched beyond their normal capacity; often times with a sudden quick load. This often happens when someone is running and the muscle is forced to length as it contracts. It can also occur when one becomes inflexible, when there is muscle in balance, such as one group of muscle is stronger than the opposing muscle, or if the muscles are poorly conditioned. Often times, imaging studies such as X-rays or MRI’s (Magnetic resonance imaging) are not needed for these injuries, but occasionally they can be helpful, for instance an x-ray may show a small piece of bone that is pulled off along with the tendon and an MRI may show the tear in the soft tissue itself.
Almost always surgical treatment is necessary to repair a torn tendon or a tendon that has pulled away from the bone. If the torn tendon is not repaired, the patient will not be able to straighten their knee against gravity. Complete tear within the tendon can be closed back together with stitches as well at times. Common tendon tears about the knee are the quadriceps tendon which attaches the quadriceps muscles to the kneecap or the patellar tendon which attaches the kneecap to the shin bone. The Achilles’ tendon attaches the leg muscle to the heal bone and is commonly torn.
Left: X-ray showing the upward displacement of the knee cap that occurs when the patellar tendon is ruptured. This patient also has arthritis and bone spurs on his knee cap.
Right: X-ray showing the normal position of the knee cap.
Similar to the strains in a muscle, ligament injuries are called sprains and they have different grades. Grade 1 is a mildly damaged ligament, it is stretched, but it is not torn and it is still able to keep the knee stable. Grade 2 means it is partially torn and the knee is a little less stable in that direction. Grade 3 is when the ligament is completely torn and is unable to provide stability to the knee in that plane of motion.
Anterior Cruciate Ligament (ACL)
One of the most common ligament injuries in the knee occur with the anterior cruciate ligament (ACL). This often happens when someone has a forced excessive flexation injury, a hyperextension injury, a twisting injury, a sudden stopping injury and sometimes with a direct contact or collision that can occur in sporting activities.
A person who injures their anterior cruciate ligament often feels or hears a pop in their knee and they have significant swelling in their knee that sometimes happens immediately, and sometimes it happens within a few hour or overnight. Many times it results in loss of motion, pain around the joint, pain with weight barring or difficulty with weight barring. Additionally, when people are able to bear weight on their knee it often times feels unstable and wants to give out. If any of these symptoms are occurring then it is important to see your doctor within a day or two and potentially an orthopedic surgeon first. During that visit the doctor will talk to you about how this injury occurred, some of your symptoms, they will do a physical exam to check all the structures of your knee. Often times this is difficult to do because of the pain. X-rays and, often times, an MRI will be ordered to look for other injuries.
MR images showing an intact ACL on the left and a torn ACL on the right.
Treatment for anterior cruciate ligament is variable. Many people with anterior cruciate ligament injuries are active individuals and are unable to go back to their activity because of instability in their knee. Generally this leads to surgical reconstruction of their torn ligament. Occasionally the patient will not have instability or will not be overly active and if they can resume their normal actives without instability, then aggressive physical therapy and bracing may be all that is needed. Some older patients that have torn their anterior cruciate ligament may not want to undergo the extensive physical therapy and rehabilitation and they elect not to do surgery. If patients elect non-surgical treatment the torn anterior cruciate ligament generally does not heal without surgery. Despite the ligament not truly “healing”, many patients, depending on their level of activity, can do well with a torn anterior cruciate ligament, by modifying their activity, strengthening their leg, and sometimes bracing.
Surgical treatment can be addressed in a variety of different ways. Historically it has been found that anterior cruciate ligaments cannot be sutured back together and generally need to be reconstructed and rebuilt with other tissue. The exception to that is if the ligament is torn off of the femur bone, but the ligament itself remains intact. Dr Stedman and his partners at the Stedman Hawkin’s clinic developed a procedure called the Healing Response where holes are poked into the bone where the anterior cruciate ligament use to be attached to the thigh bone, that causes the bone to bleed, and as it bleeds new growth factors come out of the bone and help cause scarring between the end of the anterior cruciate ligament and the bone, and for some people, it can lead to very good results.
A more conventional approach to surgical treatment of anterior cruciate ligament injuries is reconstruction of the ligament itself and rebuilding of the ligament. This can be done with a variety of different grafts. The most common graft utilized is the central third of the patellar tendon, which is harvested from the body, along with a small piece of bone from the knee cap and shin bone. That entire unit is taken and used to rebuild the ACL. Another commonly used set of tendons, are the hamstring tendons, which can be taken from a small incision down by the knee and the tendons themselves are detached from the shin bone and removed from the muscle and those can be used to rebuild the ACL. The quadriceps tendon can also be used. A cadaver graft of either the patellar tendon, quadriceps tendon or a heel cord tendon can all be used. All these tendons are reattached to the thigh and shin bone, in the same place the original ACL was attached. This often requires drilling of holes in the shin bone and thigh bone and then the grafts are stabilized in those bone tunnels with screws or some other fixation device. Most of the time surgery is not done right away because it has been found that if a patient goes to surgery while they do not have their full range of motion and the knee is very swollen, following the surgery they have a much more difficult time regaining their motion and strength. If we allow the swelling to subside and the patient to regain the motion before surgery, their recovery after surgery is a little easier. Whether surgery is performed or not on the ACL, extensive rehabilitation and physical therapy are required for the patient to regain their strength and full range of motion and return to their desire level of function. With surgery it is at least six months before patients are allowed to return to activities that require cutting or twisting.
Posterior Cruciate Ligament tears (PCL)
The PCL works with the ACL to keep your thigh and shin bone stable in relationship to each other. If the PCL is torn, the shin bone can move backwards in relation to the femur. This injury is much less common than an injury to the ACL. It often occurs when there is a backwards force applied to the shinbone, i.e. when the shin bone hits the dashboard in a car accident or a direct fall into the knee during sports. If you have injured your PCL, your knee will be very swollen and stiff. You may experience instability as well. You should see your orthopedic surgeon if you think you have torn your PCL or if you have significant swelling and stiffness in your knee. Your doctor will do a physical exam, ask you questions about your injury, get x-rays, and may order an MRI.
Treatment of an isolated PCL tear can often be accomplished without surgery. It includes ice, rest, Tylenol and anti-inflammatories, bracing, and physical therapy. If the PCL is torn with other ligaments, it may require surgical reconstruction and can be discussed with your orthopedic surgeon. If you need surgery it will take 6 – 12 months to recover from this injury.
Medial and Lateral Collateral Ligament tears (MCL and LCL)
The medial collateral ligament (MCL) is on the inner side of your knee and connects the thigh and shin bone, while the lateral collateral ligament (LCL) is on the outside of your knee and connects the femur to the little bone in your leg called the fibula. These ligaments protect your knee in the side to side motions. The MCL is injured when your knee is forced sideways towards your other knee. For instance, if you are playing football and your knee is hit on the outside and is pushed toward your other knee, you will injure your MCL. This also can easily occur while skiing if you are turning and catch an edge. Similarly, the LCL can be torn, but this requires a force applied to the inside of the knee forcing it outwards. The MCL is torn more commonly than the LCL, probably because it is easier to get it on the outside of your knee and apply a force, than it is to get it on the inside of your knee and apply an outward force.
These injuries, generally, cause more localized symptoms and less swelling than does a tear to the ACL. Unfortunately these ligaments can be torn with other ligaments and may have lots of generalized swelling and pain. It is best to see your orthopedic surgeon for evaluation if you think you have injured one of these ligaments. The doctor will do a physical exam, ask you questions about your injury, get x-rays, and may order an MRI.
Isolated injuries to the MCL or LCL will cause swelling and tenderness on the inside or outside of your knee respectively. If they are isolated, they can be treated without surgery. Ice, bracing, medications such as Tylenol and anti-inflammatories, and physical therapy may be required. Surgery may be indicated if more than one ligament is torn. A thorough discussion and examination with your orthopedic surgeon will help determine the need for surgery.
The meniscus is a c-shaped disc in the knee. There are 2 menisci, one on the medial (inside) and one on the lateral (outside) of the knee joint. The menisci are cartilage discs that sit between the thigh and shin bones and act as a shock absorber to protect the cartilage on the ends of the bone. They are rubbery, tough structures and can help the ligament provide stability for the knee. The outer rim of the meniscus has a good blood supply and therefore tears in this region can be fixed. The inner two-thirds of the meniscus doesn’t have a very good blood supply and tears in this region generally can’t be fixed (see more below). Menisci can be torn by sudden twisting injuries. Sometimes deep flexion activities may also result in a tear. These are referred to as acute tears. Degenerative tears occur as we age. As the cartilage ages, it becomes thinner and weaker and is more apt to tear with less aggressive activity. People with a meniscus tear often complain of pain, swelling, stiffness, catching, locking, popping, and inability to fully straighten or bend their knee. Sometimes they complain of instability also. If you have these symptoms you should see your doctor or orthopedic surgeon. The doctor will get a history of the injury from you, do a physical exam, get x-rays, and may order an MRI at some time. This isn’t always done, especially at the 1st visit.
MR images showing a normal lateral meniscus on the left and a torn lateral meniscus on the right.
Treatment will depend on your age, activity, and the acuteness of the tear. In young patients, when the tear is in the outside of the meniscus (where there is a good blood supply and there is good potential for healing) your surgeon may talk about surgery and repair of the torn tissue. This is probably the best option for treatment because it will preserve the meniscus and help protect the knee from future wear and tear. If the tear in this outer region is small, it may heal on its own with rest, ice, Tylenol, anti-inflammatories, and therapy. If the tear is in the inner two-thirds of the meniscus (where there is not a good blood supply), or you are older with a more degenerative tear, the meniscus doesn’t heal very well and therefore removal of the torn tissue may be needed. Often times these tears can become asymptomatic with the non-operative treatments discussed above, especially in the patient over 45 or 50 years old. If however, you continue to have popping, catching, swelling, pain, or instability you may need surgery.
The surgery for a torn meniscus is one of the most common surgeries done by orthopedic surgeons. This is done arthroscopically, generally through three small incisions in your knee and with a small camera and instruments inserted into these incisions. Your surgeon can repair or remove the torn tissue. If the tissue is repaired, the recovery could take 4-6 months before you are performing all your activities. If the torn tissue is removed, then you can generally return to all your activities as tolerated. This may take anywhere from 3-4 weeks or 3-4 months depending on the severity of the tear and surgery. This is all something that you, your family, and your orthopedic surgeon can discuss to determine what is best for you.
A bursa is a small lubricating sac that is located between tendons and bones (Pes bursa) or the skin and the bone (Prepatella bursa). These sacs function to decrease the friction between the bone and the tendons or skin. Bursitis occurs when the sac becomes inflamed and filled with fluid. Pes bursitis occurs in athletes and older patients with arthritis. It is characterized as pain 2-3 inches below the inside of your knee. It is tender to the touch, and may be more painful with walking and exercise, especially walking up or down stairs.
Treatment generally includes ice, rest, anti-inflammatories, such as ibuprofen or naprosyn, physical therapy, and possibly an injection by your orthopedic surgeon.
Prepatellar bursitis occurs on the front of the knee and generally can be seen in people that do a lot of kneeling, carpet layers, tilers, plumbers, or someone just cleaning the house.
Treatment consists of rest, ice, compression, and avoidance of kneeling. If the swelling persists, your orthopedic surgeon may discuss an aspiration where the fluid is removed with a needle and syringe. If the swelling and pain persist, or if the bursa gets infected, then surgical drainage or removal of the bursa may be indicated. Signs and symptoms associated with an infected bursa include pain, fevers, chills and increased warmth and redness. This should all be discussed with your surgeon.
There are many causes of anterior knee pain including malalignment of the knee cap, dislocation of the knee cap, overuse, and Osgood-Schlatter Disease.
Malalignment of the Knee Cap
Pain in the front of the knee may be caused by malalignment of the knee cap. The pain is often a dull achy pain that is made worse stairs, hills, kneeling, squatting, and sitting for prolonged periods of time (in a movie theater). When you come see the doctor he/she will ask about the timing of your symptoms and what makes them worse and what makes them better, and will examine your knee and your gait. X-rays will often be ordered. Fortunately, the causes of anterior knee pain can usually be treated without surgery. Your doctor will likely recommend rest and avoidance of the aggravating activities, stretching, ice, anti-inflammatories such as ibuprofen and naprosyn, home exercises, and/or physical therapy, and sometimes special braces and orthotics. If surgery is needed, it can sometimes be done arthroscopically through small incisions and a special camera that looks inside your knee. Sometimes the knee cap needs to be realigned but cutting the bone and repositioning it. Generally surgery is only needed after the patient fails to respond to an extensive rehabilitation program and continues to have pain.
Left x-ray shows mostly normally aligned knee caps that are centrally located in the groove of the thigh bone, while the x-ray on the right shows knee caps that are very tilted and not well located in the groove.
Dislocation of the Knee Cap
The knee cap normally sits in a groove in the femur bone and slides within that groove as a person bends and straightens their knee. The knee cap can be forced out of this groove with some kind of traumatic event. These events include direct blows, twisting and bending of the knee in the wrong way. When this happens the knee cap can spontaneously pop back into place or it can get stuck sitting out of its normal groove. This can be very painful and your knee may be stuck in a bent position. The knee cap may need to be put back by a doctor. Again, your doctor will ask you questions about your injury and pain, do a physical exam, order x-rays and maybe even an MRI. The MRI is helpful to determine if you knocked any of the cartilage off the end of the bones and have a loose body floating in your knee.
Treatment usually starts with bracing, ice, elevation, and rest and then physical therapy after the knee cap has been put back where it belong. If there is a loose body floating in the knee, arthroscopic surgery is often required to remove the loose body and to try to fix the defect that was created when the piece of cartilage was knocked out of place. If the patient continues to have pain and problems with stability, a stabilizing procedure may need to be done and should be discussed with your doctor.
This is an overuse injury seen in active adolescents. It’s more common in males and more common in running or jumping sports such as basketball, soccer, and gymnastics. The patient complains of pain with activity where the patellar tendon attaches to the shin bone. There is a growth plate there that the patellar tendon attaches to and it gets inflamed and painful. The pain is worst during the sporting activity and usually decreases with rest. In addition to a history of your symptoms and a physical exam, your doctor may order x-rays.
Treatment is generally symptomatic, with rest, ice, and anti-inflammatories such as ibuprofen and naprosyn. Most kids may continue their sporting activities during this time; however, if the symptoms are too bad or worsen, then prolonged rest and avoidance of aggravating sports may be indicated. Symptoms may last 2-3 years and generally resolve as the growth plate closes and stops growing.
Arthroscopic surgery is one of the most common surgeries performed by the orthopedic surgeon. It allows your doctor to clearly see the inside of your joint (knee, shoulder, hip, etc) and treat any pathology that is seen. Many of the ligament and meniscal injuries discussed here are addressed with arthroscopic surgery. This surgery is done through small incisions that allow insertion of a small camera and small surgical instruments that the surgeon uses to treat your problem. The surgical team visualizes the inside of the joint on computer-like monitors in the operating room. Today, many of these are high definition monitors and allow excellent visualization and clarity. Arthroscopic surgeries are generally day, or outpatient surgeries. Your surgeon will discuss the surgery with you as well as the expected recovery.
There are many types of arthritis: osteoarthritis, rheumatoid arthritis, and post-traumatic arthritis are probably the most common types. Osteoarthritis is the most common type of arthritis in the knee. It is generally a slow progressive type of arthritis that is often present as we age and is commonly thought of “wear and tear” arthritis. There may be a genetic predisposition, but weight, workload, activity, and prior injury all play a role in the development of osteoarthritis. It occurs as the cartilage on the ends of the bones starts to wear out and get thin. Eventually, the cartilage wears out completely and the thigh bone rubs on the shin bone. Post-traumatic arthritis is very similar to osteoarthritis and results from a prior injury to the knee such as torn ligaments or cartilage, or a fracture involving the joint. Rheumatoid arthritis is an inflammatory arthritis that is usually an autoimmune disease that destroys the cartilage in many joints in the body. It can be often treated/controlled with medication for a period of time.
When the cartilage deteriorates, there are no more smooth surfaces to rub on each other during motion. The cushioning effect is also lost, which leads to shin and thigh bone rubbing on one another. While bone is well suited to weight bearing, it does not work well as a surface through which motion occurs. It’s analogous to the rim of a wheel being well-suited to the loads of a car provided it’s surfaced with a tire. Without the tire, the rim does not function well. At any rate, in the absence of cartilage, the joint undergoes a cascade of events including the release of chemicals and cells within the joint, disruption of normal joint fluid content, formation of bone spurs, development of cysts within the bones, and even the formation of loose bits of bone floating loose within the joint (loose bodies). These abnormalities are likely the causes of the pain associated with arthritis.
Patients usually complain of a deep achy pain, sometimes it may be localized to only one part of the knee joint, but it may also involve the entire joint. It may even cause thigh or shin pain occasionally. It starts slowly, generally with increased activity, and progresses over the years to pain that may even occur at rest and may keep patients from sleeping. In the early stages it limits vigorous activity, but eventually may limit every day activities such as putting on one’s shoes and socks and climbing stairs. In addition to pain, patients may complain of catching or locking of their knee, and they may even experience buckling of their knee. They will likely have swelling.
In addition to discussing your symptoms, the doctor will do a physical exam and get x-rays. Standing, or weight-bearing x-rays are very useful and show the loss of space between the shin and thigh bone that occurs as the arthritis worsens. MRI’s are usually not needed for the diagnosis of arthritis.
Most of the time the first treatments for arthritis do not include surgery. Often times the early treatments include activity modification, such as ride a bike, swim, or walk instead of run, and other activities that do not hurt. Exercises including strengthening and stretching and maybe even physical therapy may be helpful. Weight loss, if needed, can be very helpful for some patients. Braces and orthotics might also help to decrease one’s pain. Other alternative therapies that may or may not help your symptoms include acupuncture, massage, herbalism, and magnetic therapy. The success of these treatments is usually short-lived in our experience and, while the number of such options available to patients is great, the research supporting their use as a cure is weak.
Often times ice and over the counter medications such as Tylenol, ibuprofen and naprosyn are helpful during this time and can allow patients to remain active. Other prescription anti-inflammatory medications may also be prescribed, for example Celebrex or Relafen. Another over the counter medication that is very helpful to some patients, and completely not helpful to others, is glucosamine and chondroitin. These are oral supplements and the two molecules are found in normal cartilage. Rather than building new cartilage, they may act to decrease the swelling and thus reduce the pain, again, only in some patients. They may interact with your other medications, so make sure to check with your doctor or pharmacist to make sure it is ok to take if you are on other medications. Some side effects include nausea, vomiting, and headaches. Another thing your doctor may recommend is an injection, either “cortisone” or viscosupplementation. Both of these have some anti-inflammatory affect and help to decrease the pain. They help some patients, sometimes for several months, but they don’t help everyone. A cortisone shot is a one shot deal that can be repeated a few times a year, while viscosupplementation is more commonly given as a series of three shots, each one week apart. There is a new formula that can be given as one shot. These can be repeated in 6-8 months if they gave the patient excellent relief. Despite all these nonsurgical options, none of them actually treats the underlying cause of the arthritis, the loss of cartilage, and therefore the patient eventually may want and need surgery. A discussion with your doctor can help determine which, if any, of these treatments is best for you.
Eventually, activity modification and the above methods of treatment will no longer provide adequate pain relief, and you and your doctor will discuss surgery. Depending on the extent of your arthritis, the entire joint may be replaced; or, if the arthritis is only in part of your knee, you might only need that part replaced. This is known as a unicompartmental (one compartment only) knee replacement. Another option if only part of your knee is worn out is a realignment procedure. In these procedures your thigh or shin bone are cut and realigned to put more pressure on the part of the knee that is not arthritic and to allow the arthritic part to have less pressure.
In knee replacements, the worn out ends of the bones are removed and replaced with metal and plastic inserts. The metal is often attached to the bone with cement; but sometimes the metal is such that it allows the bone to grow into it, thus stabilizing it to the underlying bone. The surgery requires an incision 5–7 inches and takes approximately 1.5–2.5 hours to perform. Patients are usually in the hospital 3 nights before they are comfortable going home. Total recovery takes at least 3-6 months before patients are back doing most things they want. A discussion with your surgeon can help determine what is best for you.
Click here or select the image above to watch A Patient's Guide to Knee and Hip Replacement, video provided by Durango Orthopedics in Colorado for patient education.
More information may be obtained on any of these subjects at the American Academy of Orthopedic Surgeons website under patient information.
Go to http://aaos.org/ and choose patient information on your left.
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