Knee Osteoarthritis
All the information about the causes, symptoms, treatments, and prognosis of the progressive wear of the knee components.
Symptoms and causes
Knee osteoarthritis is a degenerative disease that causes joint wear. It is a condition in which the cartilage wears down, tissues degenerate, and consequently the bones become unprotected, which may also deteriorate and cause pain or stiffness.
There are four grades of knee osteoarthritis depending on tissue involvement:
- Grade I: The cartilage is softened and there is minimal joint space narrowing.
- Grade II: The cartilage is damaged, some osteophytes (bone spurs) appear, and joint space narrowing is observed.
- Grade III: Fissures in the cartilage, multiple osteophytes, and significant joint space narrowing occur. Bone deformity may also develop.
- Grade IV: The cartilage is completely worn, causing damage to the subchondral bone due to friction. Joint space is minimal, large osteophytes are present, and stiffness, inflammation, and bone deformity occur.
The knee is the most commonly affected joint because it bears the weight of the body and carried objects. While it can occur in anyone, it is more frequent in older adults due to its degenerative nature.
The prognosis of knee osteoarthritis depends on the degree of involvement and joint characteristics. Although there is no cure, treatments aim to relieve symptoms and significantly improve patients’ quality of life.
Symptoms
The most characteristic symptoms of knee osteoarthritis are:
- Pain: In early stages, it occurs only during exercise and subsides with rest. As the disease progresses, pain may occur at the start of movement and diminish after a period of activity.
- Inflammation
- Stiffness
- Reduced range of motion
- Increased sensitivity: even light touch causes pain.
- Osteophyte formation: bony deformities around the joint.
- Knee weakness
- Leg bowing
- Limping while walking
Causes
Knee osteoarthritis is usually caused by multiple combined factors, the most notable being:
- Reduced cartilage regeneration due to aging.
- Changes in knee biomechanics due to joint deformities:
- Genu valgum: knees come together, forming an X shape.
- Genu varum: knees are apart, forming a parenthesis shape.
- Previous injuries, such as:
- Trauma
- Ligament tears
- Meniscus tears
- Genetic predisposition
Risk Factors
Factors that increase the risk of knee osteoarthritis include:
- Age: more common over 50 years old.
- Sex: although the reasons are unknown, more frequent in women.
- Obesity: the joint bears excessive weight.
- Repetitive strain: occupations or sports requiring excessive and continuous knee use.
- Family history: genetic factors influence osteoarthritis development.
- Previous joint injuries or surgeries
- Diabetes: high blood sugar contributes to cartilage damage.
- Rheumatic diseases: gout, rheumatoid arthritis, or hemochromatosis can affect cartilage.
Complications
The most severe complications occur when cartilage is completely worn:
- Chronic pain
- Limited mobility
- Leg deformities
- Difficulty or inability to perform daily activities
- High dependence
- Muscle mass reduction (due to inactivity)
- Anxiety
- Depression
Prevention
Although knee osteoarthritis cannot usually be prevented, the following measures may slow its progression or reduce risk:
- Engage in low-impact physical exercise, such as swimming or short walks. Avoid jumping or running sports.
- Maintain a healthy weight.
- Avoid, when possible, stairs, kneeling, or prolonged standing.
- Wear appropriate footwear, preferably wide, flat, and with soft soles.
- Avoid carrying heavy loads.
- Maintain correct posture while walking, sitting, or lifting.
- Stand up periodically if seated for long periods.
- Follow a balanced diet and stay well hydrated.
- Avoid alcohol and tobacco.
Which Doctor Treats Knee Osteoarthritis?
Knee osteoarthritis is diagnosed and treated within the specialty of Traumatology and orthopedic surgery.
Diagnosis
Diagnosis begins with reviewing the patient’s medical history and symptoms, followed by a physical examination to assess range of motion, deformities, and pain levels.
Confirmation is made with Knee X-Ray to evaluate tissue condition and detect osteophytes. Imaging helps determine the degree of joint involvement.
A Knee Magnetic Resonance Imaging or Knee Computed Axial Tomography (CT) may be performed for detailed evaluation of bones and soft tissues and to rule out other pathologies.
Treatment
Initial treatment consists of analgesics and anti-inflammatory drugs to relieve pain and reduce inflammation. In some cases, corticosteroids are injected directly into the joint for faster but temporary relief.
Knee braces may help reduce joint load, alleviating pain and inflammation. In mild cases, braces prevent instability and facilitate daily activities.
For more advanced but not severe cases, hyaluronic acid injections improve lubrication, with symptom relief lasting about six months. Platelet-rich plasma or cultured stem cells may also be injected to reduce symptoms, but they do not halt osteoarthritis progression.
When the knee is severely damaged and movement is highly limited, surgical intervention is considered:
- Genicular Artery Embolization (GAE): a catheter delivers embolic particles to the arteries supplying the inflamed knee area. Cartilage is not repaired, but symptoms disappear.
- Arthroscopy: two small incisions are made to introduce instruments and clean cartilage in mild damage cases.
- Knee arthroplasty: partial or total joint replacement with a prosthesis.
Osteotomy: tibia or femur is cut to correct deformity and restore load alignment. Used primarily in young, active patients.
