Kneecap osteoarthritis can be divided into different categories:

1. Primary kneecap osteoarthritis: Develops without any recognizable external cause, usually due to age-related cartilage degradation.
2. Secondary kneecap osteoarthritis: Arises as a result of misalignments, injuries, or chronic overuse of the knee joint.
3. Local retropatellar osteoarthritis: Affects only the cartilage on the back of the kneecap.
4. Generalized osteoarthritis with retropatellar involvement: Includes both the kneecap and other parts of the knee joint.

The main causes of patellar osteoarthritis can be divided into several categories:

Mechanical overload:

Frequent stair climbing, squatting, or jumping strain the cartilage behind the kneecap.

Sports such as running or soccer can increase the risk.

Misalignments:

A misalignment of the kneecap (patellar malalignment) leads to uneven stress and cartilage wear.

Injuries:

Fractures or dislocations of the kneecap can promote osteoarthritis.

Degenerative processes:

Age-related changes in cartilage tissue lead to wear and tear of the patella.

Inflammatory diseases:

Chronic inflammations such as rheumatoid arthritis attack the cartilage and accelerate its degradation.

The symptoms vary depending on the severity of osteoarthritis, but often include:

• Pain: Pain occurs especially when climbing stairs, getting up from a squat, or sitting for long periods with bent knees.
• Movement restrictions: Difficulty fully bending or straightening the knee.
• Grinding or rubbing: Mechanical noises during knee movements, especially when straightening.
• Swelling: Recurring swelling due to inflammatory processes or fluid accumulation in the joint.
• Instability: A feeling of giving way or insecurity when walking or standing.
• Tenderness: Pain when pressing on the front of the knee, especially directly on the kneecap.

The diagnosis is made through a combination of medical history, physical examination, and imaging techniques:

• Medical History:
  • The doctor asks about typical symptoms, such as pain when climbing stairs, and possible previous injuries.
• Physical Examination:
  • Checking the mobility and stability of the knee as well as tests to locate the pain.
• Imaging Techniques:
  • X-ray: Visualization of joint space narrowing and osteophytes behind the kneecap.
  • MRI: Examination of cartilage damage and soft tissue changes.
  • Ultrasound: Assessment of fluid accumulations or inflammatory processes.

Conservative Therapy

Most cases of patellar osteoarthritis can be treated without surgery:

• Physiotherapy:
  • Exercises to strengthen the thigh muscles and improve patellar stability.
• Medication Therapy:
  • NSAIDs for pain relief and anti-inflammatory effects.
• Injections:
  • Hyaluronic acid to improve knee lubrication.
  • Cortisone for acute anti-inflammatory effects.
• Orthopedic Aids:
  • Knee braces or supports to stabilize the patella.

Surgical Therapy

In cases of advanced patellar osteoarthritis or persistent symptoms, surgery may be necessary:

• Arthroscopic Procedures:
  • Smoothing of damaged cartilage or removal of loose joint bodies.
• Corrective Osteotomy:
  • Adjustment of patellar position in cases of misalignment.
• Prosthesis Implantation:
  • Replacement of the retropatellar cartilage with a partial prosthesis.

To prevent patellar osteoarthritis, the following measures are recommended:

1. Regular exercise: Joint-friendly activities such as swimming or cycling promote knee function.
2. Strengthening the muscles: Targeted training of the thigh muscles stabilizes the kneecap.
3. Ergonomic posture: Avoiding overload through correct movement patterns.
4. Weight management: A healthy body weight reduces the strain on the knee.
5. Early detection: At the first signs of discomfort, a doctor should be consulted early.