Why the difference in meniscus tear is crucial

The meniscus acts as a shock absorber and stabilizer in the knee, which is why its integrity is essential for the functionality of the joint. A meniscus tear (meniscal lesion) in the knee is one of the most common injuries to the knee joint - but not every tear is the same. The crucial difference lies in whether the tear occurred due to a sudden trauma or whether it occurred degeneratively due to years of wear and tear, often as part of early osteoarthritis. This distinction is not only important for diagnosis, but above all for choosing the right treatment.

An acute, traumatic meniscal tear in a young athlete must be treated entirely differently than a wear-related tear in an older person.

This comprehensive article examines in detail the differences between traumatic and degenerative meniscal injuries. It discusses the mechanisms of injury, affected population groups, symptoms, and corresponding treatment options. It also discusses why arthroscopy is often not effective in cases of wear-related meniscal lesions, such as those caused by osteoarthritis, and what alternatives, such as sled prosthesis, are available. Finally, the negative consequences of partial meniscectomy, which is often performed during arthroscopy, are discussed.



The Meniscus - Anatomy and Function in the Knee Joint

The meniscus is a crescent-shaped cartilage disc in the knee joint. There are two menisci per knee:

• Medial meniscus: It is less mobile and therefore tears more frequently.
• Lateral meniscus: More flexible and less frequently affected by tears.

The main functions of the meniscus:

• Shock absorber: It distributes body weight evenly on the articular cartilage.
• Stabilization: Especially during rotational movements, the meniscus provides more stability.
• Joint protection: It protects the cartilage and prevents premature wear.

A meniscus tear significantly disrupts these functions - and depending on the cause, this can have different consequences.

Traumatic meniscal tear – accident cause and typical symptoms

A traumatic meniscus tear usually occurs due to a sudden, abrupt movement of the knee - often during sports like soccer, skiing, or tennis. Classic movements that lead to a tear are:

• Twisting of the knee with a fixed foot
• Sudden changes of direction
• Hyperextension or flexion with high force

🔹 Typical symptoms of a traumatic meniscus tear:

• Acute, stabbing pain in the knee
• Swelling within hours
• Locking sensation (the knee "catches")
• Grinding or clicking in the knee
• Limited mobility

Those affected are usually young, active people and athletes.

👉 Diagnosis: To clarify a meniscal tear, a clinical examination (e.g., McMurray test) is performed. For a definitive diagnosis, an MRI (magnetic resonance imaging) is the gold standard.

Degenerative meniscus tear - wear and tear and osteoarthritis as triggers

A degenerative meniscal tear occurs due to gradual wear and tear. The tissue becomes brittle over the years and eventually tears, often during everyday movements.

🔹 Who is affected?

• Older people (from 50)
• Patients with existing osteoarthritis
• People with obesity
• People with malalignments (e.g., bowlegs)

🔹 Typical symptoms of a degenerative meniscus tear:

• Pain on the inner side of the knee
• Start-up pain after periods of rest
• Pain when climbing stairs or squatting
• Often no acute trauma in the background

👉 Diagnosis: Again, MRI is the method of choice to visualize the tear and accompanying cartilage damage.

Diagnosis of Meniscus Tear

Precise diagnostics are crucial to differentiate between a traumatic and a degenerative meniscal tear. Several examination methods are used:

Anamnesis (patient interview)

The doctor questions the patient in detail about:

• Complaints: Since when have the pain been present? Was there a specific accident or did the complaints develop gradually?
• Pain localization: Inner or outer pain, load-dependent or persistent?
• Accompanying symptoms: Feeling of instability, blockages, clicking noises?
• General medical history

👉 Important:

• Acute trauma and sudden pain indicate a traumatic meniscus tear .
• Gradual pain without a clear event is more indicative of degenerative changes.

Clinical examination

The doctor examines the knee joint for:

• Swelling (joint effusion)
• Mobility (extension and flexion restriction)
• Tenderness along the joint space

In addition, specific meniscus tests are employed:

- McMurray test

The doctor rotates the lower leg inward and outward with the knee bent. Pain or audible clicking suggests a meniscus tear.

- Apley Grinding Test

The patient lies on their stomach, the knee is bent at a right angle. The doctor presses the shin down and rotates it. Pain indicates a meniscus injury.

- Steinmann I and II test

By actively and passively rotating the lower leg internally and externally, the doctor checks if pain occurs along the joint space.

👉 Note:
In degenerative tears, the tests are often less clear. Imaging is particularly important here.

Imaging diagnostics

X-ray image

Although X-rays do not directly show meniscus injuries, they help to identify associated changes , e.g.:

• Joint space narrowing (indicative of arthrosis)
• Osteophytes (bone growths due to wear and tear)
• Axis deviations (knock knees or bow legs)

👉 Important: In cases of suspected purely traumatic meniscus injury without arthrosis, the X-ray image is usually unremarkable.

Magnetic Resonance Imaging (MRI)

MRI is considered the gold standard for diagnosing meniscus tears. It shows in detail:

• Location and extent of the tear
• Cartilage condition
• Joint effusion
• Associated injuries (e.g., cruciate ligament tears)

👉 Differences in MRI image:

• Traumatic meniscus tear: Usually a clear, localized tear pattern.
• Degenerative meniscus tear: Frayed, diffuse brightening in the meniscus tissue.

Ultrasound (Sonography)

Ultrasound is suitable for a quick assessment of a joint effusion or coarser meniscus changes. However, it is not as precise as MRI.

Treatment of meniscus tears: Which therapy is suitable for which tear?

The therapy is based on the type of tear, the patient's age, accompanying injuries, and the level of activity.

👉 Traumatic meniscus tear:

• Conservative: For small, stable tears – physiotherapy and pain therapy
• Arthroscopy with suture: In cases of fresh tears in the well-vascularized area
• Partial resection: Removal of damaged tissue (only if suturing is not possible)

Degenerative meniscus tear:

• Conservative Therapy: Pain medication, weight reduction, physiotherapy
• Arthroscopy? Usually not useful, as the cause (wear) remains
• Alternative: Partial knee replacement for advanced osteoarthritis

Konservative Therapie des Meniskusriss (ohne OP)

Especially in cases of small, stable traumatic meniscus tears and degenerative meniscus lesions a conservative treatment is often the first choice.

Goals of conservative therapy:

• Pain relief
• Reduction of swelling
• Restoration of mobility
• Building up the stabilizing musculature

👉 Conservative measures at a glance:

• Rest: Temporary relief and adjustment of activity (e.g., avoiding rotational movements).
• Cooling: Ice packs for swelling reduction (every 15-20 minutes, several times a day).
• Elevation: Supports the reduction of swelling.
• Medications: Pain relievers (e.g., ibuprofen or diclofenac) have analgesic and anti-inflammatory effects.
• Physical therapy: Targeted exercises strengthen the muscles, stabilize the joint, and improve mobility.
• Injections: Hyaluronic acid (for early osteoarthritis) or cortisone (for acute inflammation) can alleviate symptoms.

👉 When conservative therapy is useful:

• Degenerative meniscus tear without blockage or instability
• Small traumatic tears without entrapment
• Simultaneous osteoarthritis (especially in those over 50 years old)

Types of surgeries for meniscus tears

Depending on the type and location of the meniscus tear, different procedures are considered:

a) Meniscus suture (meniscus reconstruction)

In the case of fresh, traumatic tears in the well-perfused outer zone of the meniscus, it can be sutured.

Benefits:

• Preservation of the meniscus (important for long-term joint stability)
• Weniger Risiko für spätere Arthrose

Disadvantages:

• Longer rehabilitation time (3-6 months of relief necessary)
• Suture healing not always successful

👉 Suitable for:

• Young, active patients
• Fresh traumatic tears in the vascularized zone

b) Partial meniscus resection (partial removal)

Bei Rissen in der nicht durchbluteten Zone (weiße Zone) oder stark zerstörtem Gewebe wird der kaputte Teil entfernt und der Meniskus geglättet.

Benefits:

• Quick load-bearing capacity (rehabilitation often only 2-6 weeks)
• Pain relief usually occurs quickly

Disadvantages:

• Reduced buffer function → Increased risk of arthrosis
• Instability possible, especially with larger resection

👉 Suitable for:

• Traumatic tears that cannot be sutured
• Acute blockages

c) Meniscus transplantation

In cases of complete meniscus removal (e.g., after previous resection) and persistent complaints, a donor meniscus can be transplanted.

👉 Rarely performed, especially in young patients without arthrosis.

Alternative: Partial knee replacement (sledge prosthesis)

In cases of degenerative meniscus tears with existing osteoarthritis arthroscopy often does not provide long-term success — here, a partial knee replacement can be a sensible option.

What is a sled prosthesis?

It replaces only the worn-out part of the joint (usually the inner knee compartment) and preserves the healthy parts.

👉 Benefits:

• Less bone loss than with a total prosthesis
• Natural movement feeling remains preserved
• Shorter rehabilitation than with a total knee replacement

👉 Suitable for:

• Patients with unilateral cartilage wear
• Well-preserved remaining joint

Partial knee replacement as a solution for degenerative meniscus tears and osteoarthritis

A partial knee replacement (sledge prosthesis) replaces only the damaged part of the knee joint – usually the inner compartment. Advantages:

• Preservation of the healthy knee
• Faster rehabilitation
• More natural feeling of movement
• Longer durability than total prostheses with correct indication

Consequences and risks of partial meniscus resection – why the knee becomes unstable

Many think: "If the broken part is gone, the pain is gone too." Unfortunately, partial resection often leads to instability as the meniscus is missing as a stabilizer.

🔹 Consequences:

• Higher risk of osteoarthritis
• Faster cartilage wear
• Persistent pain

Long-term prognosis after meniscus tear surgery

🔹 Meniscus suture:

• Good results in younger patients and fresh, traumatic tears in the well-perfused area.
• Healing rate: 60-80 % (depending on the type and location of the tear).
• Long-term prognosis: If healing is successful, the knee remains stable and the risk of osteoarthritis is lower than after partial resection.

🔹 Partial removal (resection):

• Rapid pain reduction, but:
• The meniscus loses its cushioning and stabilizing function.
• Risk of cartilage damage and osteoarthritis increases as the load is no longer evenly distributed.
• Long-term prognosis: Mixed, depending on the size of the removed meniscus portions. Osteoarthritis often occurs earlier .

🔹 Sled prosthesis:

• Often the best option for advanced osteoarthritis and degenerative meniscus damage.
• Good durability: 15-20 years with appropriate load control.
• Prognosis: Very good in cases of locally limited joint wear – better mobility and less pain compared to total prosthesis.

Conclusion: The right therapy for the right meniscus tear

A meniscus tear is not the same as another meniscus tear. While a traumatic tear can often be well treated arthroscopically, degenerative tears require caution with surgery. Especially in advanced osteoarthritis, a sled prosthesis may be the better choice to restore mobility and quality of life.

For patients with significant osteoarthritis or advanced cartilage wear, a sledge prosthesis is the more functional and sustainable solution, as it replaces the damaged part of the knee joint – without sacrificing the entire joint.

👉 Do you have knee problems and don't know which treatment is best?

Get advice from an experienced knee specialist!