Rhizarthrosis is classified according to severity and clinical symptoms:

1. Early stage: Mild pain during exertion, especially during gripping movements.
2. Middle stage: Increasing pain even at rest, accompanied by swelling and limited mobility.
3. Late stage: Joint deformities, loss of thumb function, and chronic pain.
4. Primary rhizarthrosis: Age-related wear without identifiable pre-existing conditions.
5. Secondary rhizarthrosis: Result of injuries, misalignments, or inflammatory diseases.

The causes of rhizarthrosis are diverse and include both degenerative and mechanical factors:

- Degenerative processes:

- Age-related wear of the joint cartilage.

- Mechanical overload:

- Repeated gripping and twisting movements, as occur in some professions or hobbies.

- Genetic predisposition:

- Familial accumulation of osteoarthritis diseases.

- Traumatic injuries:

- Previous injuries such as fractures or dislocations.

- Inflammatory diseases:

- Accompanying diseases such as rheumatoid arthritis can accelerate joint wear.

The symptoms vary depending on the stage of the disease, but typically include:

- **Pain:** Initially dependent on stress, later also at rest.

- **Movement restrictions:** Difficulties with everyday activities such as writing, opening jars, or grasping objects.

- **Loss of strength:** Reduced grip strength, especially with pinch grips.

- **Deformities:** Visible misalignments and swelling of the thumb saddle joint.

- **Crepitus:** Crunching noises during joint movements.

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

- Medical history:

- Assessment of symptoms, duration, and dependency on stress.

- Physical examination:

- Palpation of the thumb saddle joint for tenderness.

- Functional tests such as the grind test to check joint mobility.

- Imaging:

- X-ray: Visualization of joint space narrowing, osteophytes, and deformities.

- MRI: Rarely required, but helpful for early cartilage damage.

- Ultrasound: Assessment of soft tissue changes.

Conservative Therapy

Most patients initially benefit from non-surgical measures:

• Medication Therapy:
  • NSAIDs: To relieve pain and inflammation.
  • Injections: Hyaluronic acid or cortisone to improve joint function and relieve pain.
• Physiotherapy:
  • Special exercises to strengthen the thumb muscles and improve mobility.
• Orthoses:
  • Use of thumb splints to stabilize and relieve the joint.
• Pain Management:
  • Local applications such as heat or cold therapy.

Surgical Therapy

In severe cases or failure of conservative measures:

• Resection Arthroplasty: Removal of the affected joint and replacement with soft tissue.
• Partial Prosthesis: Replacement of the joint with an artificial prosthesis.
• Arthrodesis: Surgical fusion of the joint to eliminate pain.
• Minimally Invasive Techniques: Gentle procedures to reduce postoperative rehabilitation. 

To prevent and alleviate symptoms, the following measures are recommended:

1. Ergonomic adjustments: Avoidance of repetitive strain through suitable aids.
2. Regular exercise: Promotion of joint function through targeted training.
3. Joint protection: Use of orthoses during strenuous activities.
4. Early treatment: At the first symptoms, to prevent the progression of the disease.