Osteochondrosis dissecans is classified according to the stage and stability of the affected fragment:

1. Stage I – Early stage: In the early stage, there is reduced blood flow to the subchondral bone without detachment occurring.
2. Stage II – Partial detachment: The cartilage-bone fragment begins to partially detach but remains attached to the surrounding tissue.
3. Stage III – Complete detachment: The fragment is completely detached but remains in its original position in the joint.
4. Stage IV – Free joint bodies: The fragment is free in the joint and can lead to blockages and mechanical discomfort.

The exact causes of osteochondrosis dissecans are not fully understood. However, it is believed that several factors play a role:

• Mechanical overload:
  • Repeated microtraumas, such as those from sports activities like jumping or running, can damage the subchondral bone structure.
• Circulatory disorders:
  • Local reduced blood flow to the subchondral bone leads to necrosis and promotes the detachment of the cartilage-bone fragment.
• Genetic predisposition:
  • A familial clustering suggests genetic factors that increase the risk of the disease.
• Growth disorders:
  • In adolescents during the growth phase, developmental disorders in the bone can promote the development of OD.
• Misalignments:
  • Misloading due to joint misalignments such as knock-knees or bowlegs favors the disease.

The symptoms of osteochondrosis dissecans depend on the affected joint and the stage of the disease:

• Load-dependent pain: Pain initially occurs only under load but can also persist at rest in later stages.
• Swelling: Recurring swelling is a common sign, especially after physical activity.
• Movement restrictions: Limitations in joint mobility due to pain or mechanical blockages.
• Instability: A feeling of insecurity in the joint, especially in advanced stages with loose fragments.
• Crunching or rubbing: Mechanical noises that can arise from the movement of free joint bodies.

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

1. Medical history: The doctor inquires about the patient's medical history, symptoms, stress patterns, and possible injuries.
2. Clinical examination: Checking for swelling, tenderness, and movement restrictions of the affected joint.
3. Imaging techniques:
   • X-ray: Shows bony changes and the condition of the fragment.
   • MRI: Provides detailed information about the condition of the cartilage and subchondral bone.
   • CT: Precise imaging of bone structures and fragments.

Conservative Therapy

In the early stages and in young patients, OD can often be treated without surgery:

• Relief:
  • Avoidance of strenuous activities through immobilization or crutches.
• Physiotherapy:
  • Exercises to strengthen muscles and improve joint stability.
• Medication Therapy:
  • Use of painkillers and anti-inflammatory drugs to alleviate symptoms.

Surgical Therapy

In advanced stages or with fragment instability, surgery is often necessary:

• Drilling:
  • Promoting blood circulation in the subchondral bone through small drill holes.
• Fragment Fixation:
  • Reattachment of the detached fragment with screws or pins.
• Removal of Loose Joint Bodies:
  • Surgical removal of detached fragments to eliminate blockages.
• Cartilage Transplantation:
  • Replacement of damaged cartilage tissue with the body's own or artificial material.

The following measures can help prevent the disease:

1. Avoidance of overexertion: Limiting intense sports activities and taking regular breaks.
2. Strengthening the muscles: Regular training to support joint stability.
3. Early detection: Timely examination for recurring joint pain or swelling.
4. Ergonomic stress: Optimization of movement sequences in sports and everyday life.
5. Control of misalignments: Treatment of joint misalignments with insoles or physiotherapy.