Knee Arthrosis: Causes, Symptoms, Diagnostic, and Treatment

Knee arthrosis, also known as knee osteoarthritis, is a chronic inflammatory condition characterized by the degeneration of the cartilage layers in the knee joint. This degeneration results in an abnormal rubbing of the femur on the tibia, leading to pain, stiffness, and reduced mobility. This blog post aims to provide a comprehensive understanding of knee arthrosis, its causes, symptoms, and available treatments.

The Anatomy of the Knee

The knee joint is a pivotal hinge joint in the human body, designed to interconnect the femur (thigh bone), tibia (shin bone), and the patella (knee cap).

At the heart of the knee's anatomy lies the articular cartilage, a smooth, slippery tissue that covers the ends of the bones in the joint. Its primary role is to minimize friction and absorb shocks, enabling seamless and pain-free movements. Surrounding the joint, the synovial membrane secretes synovial fluid, a lubricant that further reduces friction and nourishes the cartilage.

The stability of the knee is fortified by an array of tendons and ligaments. Tendons connect muscles to bones, with the quadriceps tendon attaching the quadriceps muscle to the patella and the patellar tendon linking the patella to the tibia. Ligaments, on the other hand, connect bones to bones. The cruciate ligaments (anterior and posterior) are pivotal for the anterior and posterior stability of the knee, while the collateral ligaments (medial and lateral) provide medial and lateral stability.

Embedded within the knee are synovial bags, or bursae, small fluid-filled sacs that cushion the knee structure and reduce friction between moving parts. Furthermore, the knee houses two crescent-shaped cartilages, the menisci (internal and external), which play a critical role in shock absorption and load distribution across the joint.

Together, these components synergize to bear the weight of the body, allowing for a wide range of movements from basic walking to complex actions involved in running, jumping, and squatting.

Knee Arthrosis

Knee arthrosis is a condition characterized by the chronic inflammation resulting from the gradual degeneration of the articular cartilage, as well as the cartilage of the menisci, which are vital for the smooth and frictionless movement of the knee joint. This degenerative process is not only irreversible but also progressive in nature, meaning that once the deterioration of the cartilage begins, it tends to advance over time without the possibility of a complete recovery.

The onset of knee arthrosis is often associated with aging, as the wear and tear on the joints accumulates over the years. However, it can also be accelerated by other factors such as obesity, previous knee injuries, repetitive stress on the knee joint due to certain occupations or sports, and genetic predisposition. The condition manifests through symptoms such as persistent knee pain, stiffness, especially after periods of inactivity or rest, swelling, and a decrease in the range of motion, which can significantly impair an individual's ability to perform daily activities and maintain an active lifestyle.

As the condition progresses, the cartilage continues to wear down, and in severe cases, it can lead to bone rubbing against bone, causing excruciating pain and further limiting mobility. While there are treatments available aimed at managing symptoms and improving quality of life, such as physical therapy, pain management techniques, and in some cases, surgical interventions, these measures cannot reverse the damage already done to the cartilage.

Causes of Knee Arthrosis

Knee arthrosis often arises from multiple factors rather than a single cause. One of the primary risk factors for knee arthrosis is advanced age. As individuals age, the wear and tear on joint cartilage accumulates, increasing the likelihood of developing arthrosis. This is due to the natural decrease in the body's ability to repair cartilage and maintain joint health over time.

Obesity is another significant contributor to the development of knee arthrosis. Excess body weight places additional stress on weight-bearing joints, such as the knees, accelerating the breakdown of cartilage. Moreover, adipose tissue, or body fat, is metabolically active and can produce inflammatory substances that may further damage joint tissues.

A history of knee injuries, such as ligament tears, fractures involving the joint, or meniscus damage, can predispose an individual to knee arthrosis. Injuries can cause direct damage to the cartilage or alter joint mechanics, leading to uneven distribution of forces across the joint surface and hastening cartilage wear.

Surgical interventions, particularly those involving the removal of the meniscus (meniscectomy), can also increase the risk of developing knee arthrosis. The meniscus serves as a shock absorber and stabilizer in the knee, and its removal can disrupt normal joint function and accelerate cartilage degradation.

Genetic factors play a role in the susceptibility to knee arthrosis, with certain individuals having a hereditary predisposition to developing osteoarthritis. This genetic vulnerability can influence the quality of cartilage, the body's inflammatory response, and overall joint health.

Structural anomalies of the knee, such as genu varus (bow-leggedness) or genu valgus (knock-knees), can lead to uneven loading of the knee joint and increase the risk of arthrosis. These conditions cause an imbalance in the distribution of forces across the knee, contributing to the uneven wear of cartilage.

Finally, knee arthrosis can be associated with other forms of arthritis, such as rheumatoid arthritis, or metabolic diseases like diabetes. These conditions can lead to inflammation and other changes in the joint environment that exacerbate cartilage damage.

Symptoms and Complications of Knee Arthrosis

Individuals with knee arthrosis may experience a range of symptoms that can vary in severity depending on the progression of the condition. Common initial symptoms include persistent knee pain that may worsen after physical activity or long periods of rest, joint stiffness particularly in the morning or after sitting for extended durations, and a noticeable redness over the skin surrounding the knee. Additionally, patients often report hearing cracking or grinding sounds when moving the knee, alongside swelling that contributes to a sensation of tightness within the joint.

As the condition advances, the damage to the cartilage can lead to the development of osteophytes, which are small, bony projections that form along the joint edges. These growths can contribute to an unstable knee, making it difficult for individuals to maintain balance and perform everyday tasks. Muscle atrophy, especially in the thigh muscles, may occur due to decreased mobility and use of the affected limb, further exacerbating the instability.

In the more severe stages of knee arthrosis, the structural integrity of the knee joint can be significantly compromised, leading to deformities of the lower limbs. These deformities, in turn, can severely restrict the patient's ability to engage in daily activities, such as walking, climbing stairs, and other movements that rely on knee function. The chronic pain, combined with the loss of mobility and independence, can have profound psychological effects on individuals, often resulting in feelings of depression and discouragement.

Diagnosis and Treatment of Knee Arthrosis

The diagnosis of knee arthrosis begins with a physical examination and medical history, followed by an evaluation of the family history, X-rays, and magnetic resonance imaging (MRI) of the knees. These investigations help to clarify the extent of cartilage degeneration and thinning, enabling the doctor to establish the most appropriate treatment.

Currently, there is no specific cure for knee arthrosis, and treatment is primarily focused on managing symptoms. This includes weight reduction, physiotherapy exercises, administration of painkillers and non-steroidal anti-inflammatory drugs (NSAIDs), injections of corticosteroids and/or hyaluronic acid into the knee, and the use of a specific brace for the affected knee.

In some cases, surgical intervention may be necessary. This could involve arthroscopic "cleaning" of the knee cartilages, osteotomy of the femur or tibia, or the installation of a knee prosthesis. Additionally, regenerative medicine treatments such as intra-articular infiltration of mesenchymal stem cells (MSCs) from human adipose tissue are becoming increasingly popular.

Conclusion

While knee arthrosis is a chronic condition with irreversible effects, modern medicine offers a range of effective symptomatic treatments. It's crucial for individuals to seek medical advice when symptoms such as pain and joint stiffness hinder the performance of daily activities. By understanding the causes, symptoms, and available treatments, individuals can better manage the condition and maintain a high quality of life.