Understanding Knee Pain: Causes, Symptoms, and Treatment Options

Causes of Knee Pain

If your knee pain is from an acute injury, you probably know where it came from. You may have twisted the knee, suffered a fall onto the knee, or received a direct blow to the knee. You may have heard a popping noise at the time of injury. This can be an important clue as to what is damaged in the knee. A noise or feeling of the knee giving way may suggest that some structure is injured or torn. An injury may cause clotting and be very painful and swollen for several days. We do not cover acute injuries in this guide.

Knee pain is very common. It is caused by a wide range of problems, from simple and temporary overuse to severe osteoarthritis. The knee is a common site for overuse injuries and other injuries, including sprains, strains, and ligament or meniscus tears. This guide will help you understand what part of the knee is causing your problem, what you can do about it, and which health professionals you may need to see.


This topic is a particularly fitting one, as over time it can be expected to touch almost everyone who has an interest in exercising for health, general fitness, or for specific sports. The increase in life expectancy, the enormous baby-boomer generation, and the graying of the population all virtually ensure that we will see a dramatic increase in the number of people with osteoarthritis (OA) of the knee, the single most prevalent joint problem in the whole population. OA is the end result of a breakdown of the protective cartilage that covers the end of the bone in a joint, and can occur in any joint. However, weight-bearing joints like the knee are the most frequently plagued. When cartilage breaks down, the underlying bone undergoes changes as well. It reacts to the loss of its usual covering with increased bony growth in an attempt to increase the area over which the joint weight is spread. At the same time, the bone just under the eroded cartilage undergoes sclerosis, or increased density. The net results are deformity of bone at the joint margins, and lessened shock absorption by the bone in areas not covered by cartilage. Deformity and excessive load on the bone are frequently translated to overlying ligaments and tendons, causing them to stretch and weaken, or to high stresses on the joint, resulting in inflammation and pain.

Ligament injuries

Typically, the treatment for an ACL tear is arthroscopic surgery to remove the torn pieces of the ACL and to restore as much stability to the knee as possible. High-level athletes may elect to have a full ACL reconstruction in order to continue competing in their sport.

During the physical examination, the knee pain doctor Singapore will look for tenderness along the joint line. This is where the ACL is attached to the bone. Range of motion will be tested as well to detect if there is any fluid that has built up within the knee. An ACL tear may also be associated with a meniscus tear.

With an ACL tear, the person will experience instability in the knee. The knee feels as though it is “giving way” and will buckle. This may occur during a specific activity or all the time, depending on how much stress the ACL can handle. A complete tear of the ACL will make the knee feel unstable.

When the ACL is torn, a popping noise may be heard and the leg will give out and not support the person’s body weight. Rapid swelling soon occurs within the knee, and within 24 hours, the knee will hurt a great deal due to the swelling. Contrary to popular belief, the swelling and pain of a torn ACL will go down with time. This is due to the fact that the ACL actually has a poor blood supply, and the body therefore has a difficult time sending the materials needed for healing to the ACL.

The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments in the knee. Approximately 80% of ACL tears occur without any direct contact to the knee. Most often, the injury occurs when slowing down from running, landing from a jump, or making a quick change in direction.

Meniscus tears

Simple tears are the most commonly occurring meniscus injury. These usually have a good prognosis as they are able to be sutured or removed successfully with arthroscopic surgery. A particular type of tear called a bucket handle tear is usually a serious injury as it can displace the meniscus and cause it to block the motion of the knee. These tears can be repaired, but unfortunately, many types of repair do not have good healing success. Complex and degenerative tears are often seen in elderly patients due to normal aging of the knee. Often, they are associated with osteoarthritis. These tears are more difficult to diagnose and have a poorer prognosis than simple tears, but arthroscopic surgery can be used to remove the torn tissue.

The changes in function of the meniscus help to explain why certain segments are more prone to tear than others. Remembering that the basic function of the meniscus is to make the knee more congruent, areas where there is increased contact stress due to malalignment of the limb are particularly susceptible to injury. An example of this would be the increased prevalence of medial meniscus tears. The medial meniscus is directly attached to the medial collateral ligament, making it less mobile than the lateral meniscus. So, when there is a force directed towards the lateral side of the knee, the increased fixation of the medial meniscus actually increases the potential for a tear to occur in the central segment of the tissue.

Meniscus tears are one of the most common knee injuries. The meniscus is a rubbery, C-shaped disc that cushions your knee and acts as a smooth surface for the joint to move on while maintaining joint stability. The meniscus is tough, rubbery cartilage. When people talk about torn cartilage in the knee, they are usually referring to a torn meniscus.

Overuse or repetitive strain

Overuse or repetitive strain occurs when you are doing an activity, let’s say for example, that without having sufficient rest between games of the same or similar intensity can play a huge role in knee pain. Jobs, tasks, hobbies or sports which require continuous stress on a particular area can take its toll and cause knee pain. It is important to identify and moderate or change the activity responsible to prevent further damage or stress. This does not mean it is not a good idea to immediately go from one extreme (rest or a totally sedentary lifestyle) to another (intense sports or work) as this can cause the area to become stiff and painful. Finding a balance and evenly spacing out activities to allow time for rest and using ice packs may be the difference between prolonged pain and a speedy recovery.

Symptoms of Knee Pain

Feelings of instability or “giving way” in the knee can be a result of many factors, depending on the severity and location of the instability. Weakness in the knee or thigh muscles can cause the knee to give out during movement, and it can be the result of an old injury to the muscles. Injuries to the knee ligaments, such as a sprain or tear, can cause varying levels of instability in the knee and often require some form of medical treatment. High-impact injuries to the knee, such as a fracture or dislocation, often cause severe instability and will require immediate medical attention.

Pain during movement of the knee is often a result of an overuse injury to the knee, such as a muscle strain or tendinitis. Movements that cause high levels of friction in the knee can irritate the tendons and ligaments or cause a tear or damage to the soft tissue. Pain in the front of the knee, just below the kneecap, can be the result of patellofemoral pain syndrome, which is caused by an irregular tracking of the kneecap during movement.

Stiffness is another common symptom of knee pain, and it can be the result of many conditions. Stiffness can be the result of overuse of the knee, which can irritate the tendons or cause the formation of scar tissue. Stiffness in the knee can also be the result of inflammation within the joint due to an underlying knee condition, such as arthritis or a cartilage tear. Osteoarthritis is a common cause of knee stiffness, and it can cause the knee to feel tight, especially after periods of inactivity.

Swelling in the knee is often the result of an injury to the knee or a symptom of an underlying condition. The most common form of swelling in the knee is referred to as water on the knee or joint effusion. Water on the knee is usually the result of an injury to the knee joint, such as a sprain or torn ligament, and can be the body’s natural response to the injury.


A severe injury, such as a ligament rupture, may cause no or very little swelling at first, whereas a minor injury, such as a meniscal tear, can cause a sudden build-up of fluid. Other conditions, such as osteoarthritis or gout, are also common causes of swelling in the knee joint. Osteoarthritis slowly wears away the cartilage and menisci of the knee, which can produce inflammation and fluid build-up. Gout is a condition where crystals build up inside joints, often the knee joint, leading to severe pain and inflammation.

Swelling occurs when there is a build-up of fluid in tissues. When the knee is injured, inflammation can occur, which causes the body to release fluid into the tissues. The body’s response to an injury can also cause an increase in the amount of fluid inside the knee joint. This can happen if the inflamed synovium (lining of the joint) produces more fluid than usual or if there is bleeding that occurs inside the joint. Often, the amount of swelling in the knee bears little relation to the seriousness of the injury.


There are two types of stiffness: inability to flex the knee and excessively flexed knee. Inability to flex the knee occurs when there is a block to the normal movement of the kneecap or thigh bone on the shin. The most common cause is damage to the articular cartilage or a torn meniscus, which prevents smooth movement within the joint. In this Instagram post, Dr. Sethi shares with us an arthroscopic video showing a case where the patient is unable to flex their knee completely. It does not take much swelling within a joint to inhibit movement, and for this reason, stiffness usually occurs with very little or no visible swelling of the knee. Excessively flexed knee stiffness is most commonly seen in elderly patients. It is often associated with degenerative arthritis of the knee. They will often complain that their knee feels “stuck” or that they are unable to straighten it, which can be very limiting in functional terms, for example, making it difficult to climb stairs. Measures to alleviate stiffness involve directly treating the cause and are some of the most rewarding aspects of knee pain management.

Pain during movement

This pain of the knee could be sudden and sharp, particularly when twisting the knee, or it could be a minor chronic ache. Sudden bursts of pain are usually the result of a tear in the cartilage or a meniscus tear. This type of pain can be so intense that it actually causes a feeling of weakness in the knee, also known as buckling, making it difficult to perform everyday activities such as walking, going up or down steps, or getting in and out of chairs. High pain and the inability to extend the knee fully can be symptoms of a more severe injury, such as a tendon rupture and muscle damage. Tendon ruptures take place at the point where the tendon attaches to bone, and if it’s near the joint, it will disrupt the normal function of the knee. This is prevalent with the back of the thigh, and pain when trying to extend the knee can be a sign of a hamstring tendon rupture. MCL and LCL injuries also cause high pain around the actual side of the ligament damage and can cause the knee to give way due to the lack of stability in the ligament. High levels of pain are associated with more acute injuries, and should they occur, it is wise to consult a medical professional for an accurate diagnosis.


The feeling of having wobbly, unstable or giving way knees can be a sign of several different problems. This describes the symptom is usually a feeling that the knee will not support the body and will give out, and may be accompanied by pain. This is often caused by damage to the posterior cruciate ligament or the collateral ligaments. Sometimes people with an injury to the anterior cruciate ligament will feel instability even though that specific symptom is not commonly associated with an ACL tear. This is because the ACL is critical to knee stability and when it is torn, its function as a stabilizer is lost. Finally, this symptom can be the result of multidirectional instability, a condition in which the muscles are unable to “coordinate” the proper movement of the joint.

Treatment Options for Knee Pain

Medications for the treatment of knee pain are usually a supplement to other modalities. It is rare that a doctor will simply write a prescription for a painkiller or anti-inflammatory medication without it being used in conjunction with another treatment. The medication can be anything from over-the-counter medications to injections that are used to treat a specific type of knee pain. An example of this would be viscosupplementation, where the patient receives injections 1-2 times over several weeks of a gel-like substance made of hyaluronic acid. Injections such as these can be used to treat arthritis in the knee. Cortisone injections are another form of medicine used to treat knee pain. Cortisone is a powerful anti-inflammatory agent that can be injected directly into an inflamed bursa or around a tendon near the knee. Cortisone helps to reduce inflammation around the area and reduce pain. Cortisone can only be used a few times in any one joint, so they are not a long-term solution for knee pain.

Physical therapy is commonly used to treat knee pain and helps to improve gait, strength, and flexibility. The therapist will look at the underlying causes that affect the knee problem and develop a rehabilitation plan. This may include only a couple of visits in order to provide instruction on a home exercise program. Other patients with more severe knee pain may require months of formal physical therapy. This will depend on the underlying cause of the knee pain. Physical therapy is something that helps the patient long after their course of treatment has ended. The therapist will help to teach the patient an exercise regimen that they can continue to use, which will strengthen the knee and help prevent degeneration and injury.

Physical therapy

Physical therapy is an individualized program of specific exercises and treatments designed to return the athlete to the highest level of function following an injury or surgery. During the onset of the acute symptoms (first 72 hrs), it is predominantly used in the treatment of traumatic injuries, where it has been shown to accelerate the healing process. By minimizing the inflammatory response and initiating early range of motion exercises, soft tissue mobility and strengthening, the injury can be managed more effectively. This will limit the amount of pain and stiffness and increase function, thereby reducing the time spent away from sport. In an athletic population, it is often possible to continue with a modified training regimen during rehabilitation. This is closely monitored and progressed accordingly to the tissue healing response, ultimately facilitating a quicker and safer return to competitive sport. In the post-acute/chronic phase, physical therapy is more conservative and aims to manage degenerative conditions, where the effectiveness of treatment is often determined by the rate of progression of the condition as opposed to full resolution. Here, the primary objective is to control symptoms and improve the biomechanical profile, thus slowing the progression of the condition and reducing symptoms. This may not always be attainable, yet it is still possible to improve function and delay joint replacement. This phase of treatment is also highly effective for injury prevention, which helps to avoid recurrence and development of new injuries.


Topical pain relief The use of topical pain medications is often overlooked and can be particularly useful for some patients. The main benefit is to provide pain relief directly over an area with minimal absorption into the bloodstream; this can greatly minimize the potential systemic side effects seen with oral medications. The most commonly used topical pain medication is a compound called lidocaine. Lidocaine is a local anesthetic and can numb the area that it is applied to. There are several preparations of lidocaine available over the counter, and there are some prescription options as well. Another topical pain medication that has grown in popularity is a preparation of the NSAID diclofenac called Voltaren Gel. This medication has been said to be as effective as some oral NSAIDs and is actually FDA approved for use on the knees.

Analgesics The main reason for being on this earth is to eliminate pain. Most people don’t care much about what is causing the pain; they just want it to stop. Thankfully, there are many pain medications available today. The main choice for pain relief is the use of acetaminophen. This drug is inexpensive and generally safe but has been said to be no more effective than a sugar pill. The best information on this drug comes from my previous post found here. As an over-the-counter medication, dosing can be different for anyone, so be sure to read the dosing information on the bottle and speak with your doctor. Acetaminophen may also be compounded with a narcotic and used for stronger pain control. These are habit-forming and best used for short-term severe pain, such as pain after surgery. For mild to moderate pain secondary to inflammation, there are many anti-inflammatory medications available. These are classified as non-steroidal anti-inflammatory drugs or NSAIDs. The most commonly used NSAID is ibuprofen, but there are many others available. These medications can potentially have serious side effects on the stomach, kidneys, etc., and their use should be discussed in detail with a physician. Lastly, there are stronger prescription NSAIDs available, and there is at least one COX-2 inhibitor still on the market. This class of medications also has potential side effects, and its use should be monitored closely by a physician.

Knee braces or supports

Patients with inflammatory forms of arthritis, such as rheumatoid arthritis or lupus, may have pain and swelling around the joint. It is possible that some patients with these conditions can benefit from the compression and support provided by knee supports, although this topic has not been well researched.

There is mixed evidence on the effectiveness of braces for knee arthritis. Because the damage from arthritis is often widespread throughout the joint, it is difficult to “unload” pressure from the most damaged area. A systematic review of research on unloader braces for knee osteoarthritis found that some patients can experience improvements in pain and function, while others will not have any benefit. It is generally believed that patients who have a previous injury and/or meniscal tear with resulting malalignment of the knee are the best candidates for unloader braces. This is because the brace can correct the alignment issue and potentially protect the knee from osteoarthritis progression.

A knee immobilizer is a special brace that is used to keep the knee from moving. Often, these braces are used after knee surgery and during injury recovery. They may be recommended for short-term use to reduce pain from an acute injury.

Knee supports are sleeves or wrap-around braces that provide general compression around the joint. The warmth and compression provided by the supports can improve comfort and help you maintain your level of activity.

There are many types of braces used for knee arthritis. “Unloader” braces are designed to redistribute weight away from a damaged part of the joint to areas with stronger, healthier cartilage. These braces may help reduce pain and slow the process of joint damage. They are custom fit for each patient and are prescribed by a doctor with instructions on wear.

Knee braces are supports that you wear for a painful or injured knee. Some people use them to prevent injuries during sports. Braces are made from combinations of metal, foam, plastic, elastic material, and straps. They work by shifting your weight off the most damaged portion of your knee to a stronger area. By improving your joint alignment, braces can help reduce pain and improve function.


Other injections which are being used increasingly are Platelet Rich Plasma (PRP) and stem cell injections. These are usually not covered by healthcare systems and are expensive. There is a lot of interest in these newer forms of injections, which use the patient’s own cells and growth factors to try and regenerate damaged tissues in the knee joint. However, at the moment, the evidence is unclear as to whether these injections are effective treatments for knee osteoarthritis, and more research needs to be done to determine this.

Injections into the knee joint can provide relief for people with osteoarthritis. The most commonly used injection is a corticosteroid, which can help relieve pain and inflammation. The relief is temporary, but for some people it is an effective treatment. Another type of injection is hyaluronic acid, which is a synthetic version of a naturally occurring substance in the joint fluid. It can act as a lubricant and shock absorber in the joint, and some studies have shown it to be effective in relieving pain in some patients.


Although it is tempting to avoid surgery, for some people knee replacement can bring dramatic pain relief and improvement in function. Knee replacement has become more common, even for younger people, and there is evidence that the results are good for those who are generally healthy and active. Usually, this will mean giving up impact-loading activities such as basketball or running, but the chance to do other activities pain-free may greatly improve the overall quality of life.

Surgery is an option to treat knee pain that is not relieved by other methods. Your doctor may recommend total or partial knee replacement. This is major surgery, and the decision to undergo it should be a well-informed one. It is important to understand what this surgery involves, what it will mean in terms of changes to your lifestyle, and what the long-term benefits will be. This may mean making an appointment with the surgeon to discuss the details and ask any questions you may have. With the exception of total knee replacement, most surgeries require a period of rehabilitation after the surgery. This may involve an extended period of using crutches or a walker and doing prescribed exercises which are designed to help you regain strength and mobility in your knee.

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