Each knee has two menisci, one on the inner side (medial meniscus) and the other on the outer side (lateral meniscus). The medial meniscus, located on the inner (medial) side of the knee joint, is a crucial fibrocartilaginous structure that acts as a shock absorber.
It absorbs approximately 50% of the load passing through the inner part of the knee and helps protect the joint cartilage from damage while also contributing to knee stability.
Common symptoms of medial meniscus tears include pain and tenderness in the inner knee, locking, and catching in severe tears. A diagnosis is typically confirmed through a physical examination and MRI scans.
When determining the treatment for medial meniscus tears, the key question is whether the tear can be repaired. If repairable, scheduling surgery as soon as possible before the tear enlarges is often the best course of action.
Most medial meniscus tears can be treated non-surgically with rest, physical therapy to strengthen the knee muscles, and intra-articular PRP injections. Surgery becomes necessary for medial meniscus tears that do not heal after six months of conservative treatment.
It is important to repair medial meniscus tears whenever possible. If the tear is left untreated or removed, the load on the inner side of the knee will increase, leading to cartilage damage over time.
What is the Medial Meniscus?
The medial meniscus is one of the two menisci in the knee, located on the inner side of the knee joint. Menisci are cartilage-like structures situated between the femur (thigh bone) and tibia (shin bone), playing a crucial role in knee stability, absorbing shock, and protecting the joint cartilage.
What is a Medial Meniscus Tear?
A medial meniscus tear occurs when the medial meniscus (located on the inner side of the knee) is torn. It is more common than lateral meniscus tears, as the medial meniscus is less mobile. This lack of mobility makes the medial meniscus more prone to injury from sudden impacts. The medial meniscus absorbs up to 50% of the load passing through the inner part of the knee, making it more vulnerable to injuries, especially from sports-related trauma, sudden twisting movements, or heavy loads.
How Do Medial Meniscus Tears Occur?
Like all meniscus tears, medial meniscus tears occur in two ways: traumatic injuries and degenerative wear and tear.
Traumatic Injuries:
Sudden Twisting Movements: A sudden twisting of the knee, especially when the foot is planted, can cause a medial meniscus tear. This is common in sports like soccer and basketball.
Knee Strain in a Bent Position: Sudden weight placed on the knee in a bent and fixed position can compress and tear the meniscus, which is common during weightlifting.
Direct Impact: A direct blow to the knee can also cause a meniscus tear, often resulting from car accidents or contact sports.
Degenerative Wear and Tear:
Age-Related Wear: As we age, the meniscus tissue thins and loses its elasticity, making it more prone to tearing, even with minor strain.
Repetitive Microtrauma: Over years, repetitive small stresses on the knee can gradually wear down the meniscus tissue, leading to a tear.
Types of Medial Meniscus Tears:
Longitudinal (Vertical) Tear: This tear occurs along the long axis of the meniscus and runs parallel to the edge. It is commonly seen in younger, active individuals following trauma.
Bucket Handle Tear: A subtype of the longitudinal tear, where a part of the meniscus tears away and moves within the joint, resembling a "bucket handle." This often causes knee locking and typically requires arthroscopic surgery for repair.
Horizontal Tear: This tear occurs in the horizontal plane and can extend into the meniscus. It is often a result of degenerative wear and tear due to aging.
Flap Tear: A piece of the horizontal tear breaks free and moves around the joint, causing sudden pain and catching in the knee.
Radial Tear: A radial tear runs from the free edge of the meniscus towards its center. It can severely impact the stability of the meniscus, reducing its load-bearing capacity. If untreated, it can cause further structural damage.
Complex Tear: These tears involve a combination of different tear patterns, such as both longitudinal and horizontal tears. Complex tears are usually associated with degenerative changes and are more common in older individuals. Surgical removal of the torn portion (meniscectomy) is often required.
Meniscocapsular Tears: These tears occur where the meniscus attaches to the joint capsule and can sometimes be repaired surgically, despite being complex.
Oblique Tear: These tears are diagonal in nature and typically result from trauma, extending to the joint surface.
Degenerative Tears: These tears are usually smaller and widespread, often seen in middle-aged and older individuals due to daily wear and tear. They can develop from simple activities or repetitive stress over time.
Root Tears: These tears occur where the meniscus attaches to the tibia (shin bone), affecting the biomechanical function of the meniscus. Root tears often cause severe pain, swelling, and instability. Without treatment, they can lead to early osteoarthritis and require surgical repair.
Symptoms of Medial Meniscus Tears:
Pain: Medial meniscus tears typically cause pain on the inner side of the knee.
Swelling: Acute tears can lead to swelling due to internal bleeding in the joint. Chronic tears can cause inflammation and synovitis, leading to swelling.
Locking or Catching: These symptoms often occur during deep knee bends or squats when the torn meniscus gets caught in the joint.
Instability: Large tears may affect joint stability, causing patients to feel as though their knee is giving way.
Diagnosis of Medial Meniscus Tears:
Diagnosis is made through physical examination and MRI scans. The alignment between the clinical examination and MRI findings is crucial for confirming the diagnosis of a meniscus tear and determining whether surgical repair is possible.
How Are Medial Meniscus Tears Treated?
The primary question in treating a meniscus tear is whether it can be repaired surgically. If a repair is possible, surgery should be planned promptly.
Small tears are often treated non-surgically with rest, ice application, avoiding deep knee bends, and physical therapy to strengthen the surrounding muscles. Intra-articular PRP injections may also be used to reduce pain and inflammation.
Which Types of Meniscus Tears Can Be Treated Non-Surgically?
Certain stable tears, such as non-painful, non-obstructive degenerative tears of the posterior horn of the medial meniscus, may not require surgery. These tears are often discovered incidentally on MRI scans performed for other knee conditions. In elderly patients, non-surgical treatment may be sufficient, with the possibility of PRP, PRGF, or hyaluronic acid injections if pain persists.
Medial Meniscus Surgery:
Most meniscus surgeries today are performed arthroscopically, a minimally invasive technique.
Partial Meniscectomy: This surgery is performed when the tear is irreparable. Only the damaged part of the meniscus is removed, allowing for quick recovery.
After partial meniscectomy, patients can typically walk on the treated knee immediately and begin exercises the next day. Physical therapy focusing on quadriceps activation is crucial for postoperative recovery.
Return to sports can be expected 10–20 days post-surgery, depending on the extent of the tear removed. However, those who have had significant meniscus removal may face a higher risk of developing osteoarthritis over time.
Meniscus Repair Surgery: Scientific studies have shown that in young patients with normal joint alignment and no cartilage damage, meniscus repairs have a high chance of success. Repair is typically indicated in all age groups if the tear is repairable.
Patients undergoing meniscus repair will need to use crutches for about 3 weeks to avoid putting weight on the treated leg.
Intra-articular bone marrow stimulation, PRP injections, and various stitching techniques (all-inside, inside-out, and outside-in) can further improve healing outcomes.
