The decision between minimally invasive arthroscopy and the use of a knee prosthesis poses a challenge for many patients and doctors. While arthroscopy is considered a gentle procedure, a knee prosthesis promises a sustainable solution for advanced damage. But when is which method really sensible? In this comprehensive guide, we highlight the differences between isolated meniscal injuries and degenerative damage due to osteoarthritis, provide therapy recommendations for different patient groups, and explain why arthroscopy often does not promise success in the presence of osteoarthritis. In addition, we go into detail on partial joint replacement, such as sled prosthesis, and show when this represents an effective alternative to arthroscopy or total joint replacement.

1. Anatomy and Function of the Knee Joint

To better understand the various treatment options, it is worth taking a look at the anatomy of the knee. The knee is one of the largest and most complex joints in the human body. It consists of:

• Femur (thigh bone)
• Tibia (shinbone)
• Patella (kneecap)
• Meniscus – two crescent-shaped cartilage discs that act as shock absorbers
• Ligaments (cruciate and collateral ligaments) for stabilization
• Articular cartilage, which enables smooth movements

Damage to one of these components can cause pain, limited mobility, and instability. Depending on the cause of the symptoms, different therapies come into consideration.

Difference between isolated meniscus injuries and degenerative damage due to osteoarthritis

The knee joint is one of the most heavily stressed joints in the human body and is therefore susceptible to various injuries and degenerative changes.

Isolated Meniscus Injuries:

The meniscus acts as a shock absorber between the femur and tibia. Acute injuries, for example through sports, can lead to tears. Typical symptoms are sudden pain, swelling and limited mobility. In such cases, arthroscopy can be useful to repair the tear or remove the damaged part.

Degenerative damage due to osteoarthritis:

Osteoarthritis is a chronic, progressive condition in which the articular cartilage is gradually worn away. Causes can include overuse, malalignment, or genetic factors. Symptoms include pain, stiffness, and limited mobility. Unlike acute injuries, osteoarthritis develops over the course of years.

2. Isolated Meniscus Injuries and Degenerative Damage: The Key Differences

2.1 Isolated Meniscus Injuries

Isolated meniscus injuries often occur due to sports accidents or abrupt movements. The meniscus can tear, leading to sudden pain, swelling, and blockages in the knee. Typical symptoms include:

• Stabbing pain, especially during rotational movements
• Feeling that the knee "catches" or locks
• Swelling after strain

👉 Treatment option: In younger patients or those with fresh tears, arthroscopic meniscus repair may be useful to preserve the meniscus.

2.2 Degenerative damage due to osteoarthritis

Osteoarthritis is a gradual, progressive wear and tear of the articular cartilage. Typical symptoms are:

• Start-up pain
• Weight-bearing pain
• Morning stiffness
• Grinding in the knee

👉 Treatment option: Conservative measures (physiotherapy, pain medication, hyaluronic acid) can slow disease progression. However, in advanced osteoarthritis, joint replacement is often unavoidable.

Therapy options: Isolated injuries vs. degenerative damage

Isolated Meniscus Injuries:

• Acute complaints: In cases of sudden injuries without prior knee problems, arthroscopy can be a sensible option. This minimally invasive procedure enables a quick restoration of function.
• Young patients: In young, active individuals, arthroscopic repair is often preferred to preserve natural joint function.

Degenerative damage due to osteoarthritis:

• Chronic Complaints: In cases of prolonged pain and advanced osteoarthritis, conservative measures such as physiotherapy, pain medication, and weight reduction are the first choice.
• Older patients: In older individuals with significant impairment, joint replacement, such as unicompartmental knee arthroplasty, may be considered.

3. When is knee arthroscopy useful?

Knee arthroscopy was a common procedure for osteoarthritis for a long time. Studies have shown, however, that it does not provide long-term benefits for degenerative changes. Today, arthroscopy is primarily used in:

• Fresh meniscal tears (especially in younger patients)
• Loose joint bodies (e.g., cartilage fragments that block the joint)
• Knee joint effusions of unknown cause

👉 In osteoarthritis? No longer recommended! The cartilage damage remains, and symptoms usually return.

Arthroscopy for existing osteoarthritis: Why often not effective?

Studies have shown that arthroscopy in patients with knee osteoarthritis does not provide long-term benefits. Neither pain nor joint function is sustainably improved. Therefore, this procedure is no longer recommended as a standard treatment for existing osteoarthritis.

Partial knee replacement: Unicompartmental knee arthroplasty as an effective solution

In cases of unilateral osteoarthritis that affects only one part of the knee joint, a partial prosthesis can be a gentle alternative to a full joint replacement. Here, only the affected joint section is replaced, resulting in faster rehabilitation and a more natural feeling of movement. The prerequisite is that the knee ligaments are stable and there are no malalignments.

4. Knee replacement: Total vs. Partial joint replacement

In advanced osteoarthritis, knee replacement is a long-term solution. There are two main types:

4.1 Total Knee Endoprosthesis (Knee TEP)

Here, the entire knee joint is replaced. Useful for:

• Complete cartilage destruction
• Pronounced malalignment (knock knees or bow legs)
• Pain in multiple knee compartments

👉 Benefit: Pain relief, long-term solution

👉 Disadvantage: Longer rehabilitation time, more bone substance must be removed

4.2 Partial prosthesis (unicompartmental knee arthroplasty)

A partial prosthesis replaces only the damaged part of the knee – usually the inner side. Prerequisites:

• Only unilateral osteoarthritis
• Stable ligaments
• No pronounced malalignments

👉 Advantage: Less bone removal, faster recovery, natural feeling of movement

👉 Disadvantage: Not suitable for advanced osteoarthritis in multiple knee sections

5. Which therapy for whom? A detailed guide

The choice between knee arthroscopy, partial joint replacement (e.g., sled prosthesis) or total knee replacement depends on various factors. Here is a detailed consideration:

5.1 Isolated meniscus injuries

Typical patient: Younger, sportively active people or persons of middle age with sudden, load-dependent pain after trauma.

Recommended therapy:

• Knee Arthroscopy: In cases of acute, clearly defined meniscus tears without cartilage damage, minimally invasive arthroscopy can be useful. The tear is sutured (if favorably located) or the damaged meniscus portion is removed (partial resection). It is crucial to preserve as much meniscus tissue as possible to minimize the risk of later osteoarthritis.
• Rehabilitation: Return to sports is possible within a few weeks, especially after partial resections. After suturing, a longer period of relief is recommended.

Prognosis: Good for isolated tears without additional damage. Caution with degenerative changes - arthroscopy is usually not very promising here.

5.2 Degenerative damage and osteoarthritis

Typical patient: Older patients (>50 years), persons with persistent pain, increasing mobility restriction and X-ray findings with cartilage wear.

Recommended therapy:

• Knee arthroscopy: In this case, it is rarely useful. Studies show that arthroscopy usually does not bring long-term improvement in osteoarthritis. It is therefore no longer routinely recommended.
• Partial knee replacement (unicompartmental knee arthroplasty): If only one compartment of the knee (usually the inner side) is affected, a unicompartmental knee arthroplasty can be a good solution. This preserves the healthy part of the joint, allowing for faster rehabilitation and a more natural feeling of movement.
• Knee replacement: In advanced osteoarthritis in several compartments, total knee replacement remains the last option. Here, the entire joint is replaced.

Rehabilitation:

• Sled prosthesis: Patients can often walk well again after a few weeks, many even without walking aids.
• Total Knee Replacement: Full recovery often takes several months, but it offers long-term pain relief and functional improvement.

Prognosis: Improved mobility and pain relief with correct indication. Particularly, partial prosthesis offers good long-term results in localized osteoarthritis.

5.3 Acute vs. Chronic Complaints

• Acute pain after trauma: Here, an accurate diagnosis should be made first (MRI, X-ray). In cases of isolated meniscus tears or loose joint bodies, arthroscopy can be helpful.
• Persistent complaints: In cases of chronic pain, especially with existing osteoarthritis, arthroscopy is usually no longer indicated. In these cases, joint-preserving measures such as partial prostheses or, in advanced osteoarthritis, knee replacement are more suitable.

5.4 Younger vs. older patients

• Younger patients: Here, preserving the joint is the priority. Arthroscopy for isolated injuries or a joint-preserving partial prosthesis is preferred to delay a full prosthesis.
• Older patients: In older age and advanced osteoarthritis, knee replacement offers long-term pain relief and better mobility. Unicompartmental knee arthroplasty remains an option if osteoarthritis is limited to one area.

5.5 Summary: The Path to the Right Treatment Decision

The choice of the right treatment depends on many individual factors - age, activity level, pain intensity and joint condition. Isolated arthroscopy is usually no longer useful in degenerative damage. Partial prostheses, such as the sled prosthesis, often offer a gentle alternative with faster rehabilitation and a natural feeling of movement. In advanced osteoarthritis, the knee prosthesis remains the reliable option for long-term pain relief.

An individual consultation with an experienced orthopedic surgeon is essential to choose the right therapy and avoid overtreatment.

Conclusion

The choice of the right therapy for knee problems depends on the type of injury or disease, the duration of the complaints, and the age of the patient. While arthroscopy can be useful for isolated meniscus injuries, it often shows no success in cases of existing osteoarthritis. In such cases, a partial knee replacement, such as a unicompartmental knee arthroplasty (UKA), can be an effective solution to improve the patient's quality of life.

Arthroscopy or Prosthesis?

Arthroscopy is particularly suitable for acute meniscal injuries - but not for osteoarthritis. In degenerative knee changes, partial prostheses such as the unicompartmental prosthesis offer a good alternative to total joint replacement if only one section of the knee is affected.

A thorough diagnosis and individual consultation by experienced orthopedic surgeons is crucial to find the best possible treatment.

👉 Question for you: Do you have knee problems and are unsure which therapy is suitable for you? Please feel free to schedule a consultation appointment!