Knee pain is a common complaint due to the heavy load and stress to which this joint is subjected.
In this regard, it’s worth remembering that the knees not only provide stability, but also the flexibility necessary for coordination and gait. Furthermore, certain sports or jobs involve excessive strain or repeated impact on the knees, making them even more vulnerable to potential damage.
The most common causes of knee pain are injuries or degenerative processes. However, this condition can also be caused by other conditions or diseases.
The symptoms vary greatly and depend primarily on the cause of the knee pain.
Beyond pain, which can be more or less intense, other common symptoms include inflammation, stiffness, redness in the area, warmth to the touch, weakness or instability, popping or cracking sounds, and dysfunction.
Knee pain occurs when one of the structures in the joint is injured, worn, or diseased.
The cause of knee pain can also be intuited based on when it appears or worsens. For example, if the pain occurs at rest, when bending and straightening the leg, when walking, when going up and down stairs, when bending and standing, or when running.
Another determining factor when establishing possible causes is identifying the area where the pain is focused: in the front, upper, lower, or behind the knee, or in the inner, middle, or lateral area.
Determining the cause of knee pain is essential to starting the most appropriate treatment, as it will vary depending on its origin.
Knee problems increase with age and can be a source of chronic pain in older adults. However, they can appear at any stage of life and interfere with many daily activities.
Furthermore, if left untreated, they can have a significant impact on the quality of life of those who suffer from them.
Knee pain: causes
The knee is a complex joint composed of bones, cartilage, ligaments, and fluids, as well as muscles and tendons that help it function optimally.
When any of these structures are damaged, worn, or diseased, knee pain manifests.
Therefore, the causes of this condition are usually classified according to the affected area and the area where the pain is most concentrated.
Pain in the front of the knee
Knee dislocation
This is an injury in which the patella suddenly moves to the side, leaving its normal position in the anterior part of the femur.
The first knee dislocation is often accompanied by severe pain and deformity in the joint. However, bruising, tears in the patellar ligaments, and damage to the joint cartilage can also occur.
The main causes of knee dislocation are certain movements and sudden speed changes, common in sports such as soccer and basketball. However, it can also be due to trauma to the knee.
There may be subsequent episodes of dislocation that are less painful but still cause damage to the joint.
Osteoarthritis
Knee pain is one of the main causes of joint pain. It’s one of the joints most affected by osteoarthritis, a disease that causes degeneration of articular cartilage.
Knee osteoarthritis is often characterized by stiffness, swelling, pain, and even functional disability. Specifically, it can cause difficulty walking, climbing stairs, sitting, and getting up from a chair.
It usually appears from middle age onwards and is associated with joint overload as a result of certain activities such as recreational and professional sports.
Without treatment, knee osteoarthritis can lead to severe disability.
Pain in the upper part of the knee
Quadriceps tendonitis
It consists of the inflammation of the quadriceps tendon, which originates from the patella and extends towards the muscle.
Its main causes are excessive or poorly dosed training of the quadriceps and a poor position of the patella.
Suprapatellar bursitis
Behind the quadriceps tendon is a sac or bursa filled with synovial fluid, which allows the tendon to move and improves muscle function.
However, excessive physical exertion, wear and tear, quadriceps overload, or infection can cause the bursa to become inflamed and cause pain in the upper knee.
Pain in the lower part of the knee
Patellar tendonitis
Frequent overuse of the joint can cause repetitive strain on the patellar tendon. Also, certain positional disorders, such as genu varum (bowed legs) or genu valgum (inward-turning knees), can cause repetitive strain.
As a result, the tendon becomes inflamed and causes pain below the knee, especially during training or when flexing the joint.
This tendonitis, also known as jumper’s knee, can cause knee pain at rest if it is in an advanced stage.
Osgood-Schlatter syndrome
This is one of the most common causes of knee pain during adolescence and consists of an overuse injury (excessive or repetitive use) and overload.
This syndrome causes inflammation of the bone, cartilage, and/or tendon at the top of the tibia, where the patellar tendon attaches.
It primarily affects adolescents who play sports that involve running, spinning, and jumping, such as basketball, volleyball, soccer, tennis, or gymnastics.
The most affected young people are those amid their growth spurt, because during this phase, bones, muscles, and tendons grow very quickly and not always at the same pace.
In addition to knee pain, it often causes tenderness and a noticeable swelling or lump in the lower part of the knee.
Pain behind the knee
Osteoarthritis
Osteoarthritis can also cause pain behind the knee, depending on where the greatest cartilage deterioration is located.
The pain may even occur on the sides of the joint and radiate to the back of the thigh.
Baker’s cyst
Knee joint problems, such as arthritis or cartilage tears (for example, meniscal tears), can cause the knee to produce too much fluid and form a cyst.
This cyst can cause swelling and discomfort and is characterized by knee pain when the knee is fully flexed or extended.
Chondromalacia patella
This condition causes cartilage wear and tear. It typically appears in adolescence, and runners are especially prone to it.
The main cause is minor, repetitive trauma caused by a misalignment of the kneecap. This misalignment causes the cartilage to rub against other bones, resulting in a dull, aching pain around and behind the knee, without inflammation.
In this case, knee pain manifests itself primarily when climbing or descending stairs, playing sports, sitting for long periods, and running.
Pain in the middle, inner, or lateral area of the knee
Meniscus tear
Meniscus injuries are usually caused by sports involving the knees or by trauma to the joint.
However, they can also be caused by wear and tear and degeneration associated with aging.
They are characterized by a stabbing pain on the inside or outside of the knee joint and are often accompanied by functional restriction, for example, when trying to flex or extend the leg.
External lateral ligament rupture
The external or internal lateral ligaments of the knee can tear as a result of overload or tension that they cannot withstand.
It is most common in athletes, especially soccer players and skiers, but can affect anyone who suffers trauma.
In addition to knee pain, it can also cause bruising on the sides of the joint and joint instability.
Tendinitis
Tendinitis is an inflammation of one or more tendons in a joint due to irritation or overload.
Knee pain is the most prominent symptom and, in some cases, can be so intense that it makes it difficult to move the leg.
The most common tendonitis affecting the outside and inside of the knee is are fascia lata tendonitis (or band syndrome) and the pes anserine tendonitis.
In the first, the pain appears on the outside and is also known as runner’s knee, because it is typical in these athletes, as well as in cyclists.
The second, on the other hand, is characterized by pain on the inside of the knee and may be accompanied by an inability to flex and stretch the leg.
Other causes of this type of knee pain include torn cruciate ligaments, knee sprains, fractures, or conditions such as rheumatoid arthritis, gout, or fibromyalgia.
Treatment for knee pain
Before starting treatment for knee pain, it is essential to identify its cause.
For this, various physical examinations and imaging tests may be necessary.
The progression of the condition over time will also need to be taken into account, as well as other factors such as the disability it causes and the impact on quality of life.
What is applicable in all cases is a series of measures that can help prevent knee pain.
Prevent joint pain
Implementing measures to prevent knee pain is especially important for athletes. However, anyone can benefit from them.
In this sense, it’s important to wear comfortable shoes every day and avoid high heels. When playing sports, shoes should be appropriate for your gait and should be changed regularly.
People with foot malpositions or deformities, such as high or low arches (flat feet), are more vulnerable to knee pain. Therefore, they should have their shoes fitted and use orthotic insoles.
Maintaining a healthy weight also helps protect your joints, especially your knees.
A balanced diet rich in antioxidants and adequate protein levels is another strategy for preventing future injuries.
Exercises for knee pain
Performing specific stretching and strengthening exercises for the knee helps strengthen the thigh muscles and protect the joint.
In this regard, exercises that target the hamstrings (the muscles that run along the back of the thigh) are especially beneficial.
Also, those exercises with eccentric load on the quadriceps and asymmetric exercises.
Conservative therapy
When faced with knee pain, conservative treatments, meaning those without surgery, are often the best option.
These include physical therapy, drug therapy with anti-inflammatory and pain-relieving medications (only for a short period in cases of flare-ups), orthotic insoles, and the use of knee braces or supports (commonly known as ‘knee pads’) specially made to suit each individual’s needs.
The application of cold and heat for pain management has also been shown to be effective. Specifically, anti-inflammatory creams or heat patches, and cold sprays for use after exercise.
Patellar or infrapatellar straps or bands may also be recommended for use during physical activity. These act to apply pressure to the tendon, reducing the tension at the tendon insertion during exercise.
In some cases, joint injections with hyaluronic acid or platelet-rich plasma and stem cell treatments may also be indicated.
Surgical treatment
When conservative measures for knee pain do not work, surgery may be considered.
One of the most commonly used surgical procedures is arthroscopy because it’s minimally invasive. This surgery is used to repair a misaligned kneecap, injured ligaments, or a torn meniscus.
In specific cases, the implantation of an artificial joint (arthroplasty) may be considered. This joint replacement is particularly suitable for advanced osteoarthritis.
These interventions must be accompanied by physiotherapy and rehabilitation.