Types of Meniscus Tears

Before we discuss the types of tears, it is important to understand how the location of the tear can affect treatment choice. The location and tissue quality of a meniscus tear play crucial roles in determining the potential for repair and subsequent healing. The meniscus is divided into two zones: the outer, vascularized “red” zone and the inner, avascular “white” zone. Tears in the red zone have a higher potential for healing due to its blood supply, while those in the white zone are less likely to heal because of the lack of blood vessels. Additionally, the integrity and quality of the meniscal tissue itself can influence the success of a repair. Fresh, clean tears in healthy tissue often have a better prognosis for repair compared to degenerative or frayed tears in aged or compromised tissue.

Horizontal tears occur when a tear forms parallel to the joint line. These types of tears often occur due to wear and tear, and they may not cause as much instability as other tear types. However, they can increase contact pressures within the knee, potentially leading to early degenerative changes. Treatment often includes arthroscopic partial meniscectomy, where the torn segment is removed, or in some cases, a meniscus repair might be appropriate.

Vertical tears, often seen in younger patients, can be quite detrimental to the biomechanics of the knee. They increase contact forces dramatically and can cause significant instability, depending on the tear’s location and size. These tears are often amenable to repair, which is preferred when possible to preserve meniscal tissue.

Bucket-handle tears are a specific type of vertical meniscal tear, characterized by a torn piece of meniscus that flips over, resembling the handle of a bucket. These tears are commonly large and involve a significant portion of the meniscus. Due to their size and location, they can cause a mechanical block to knee motion, often leading to a ‘locked knee’ where individuals have difficulty fully straightening their leg.

The flipping of the torn meniscal fragment dramatically changes the biomechanics of the knee, leading to significant increases in contact forces and potentially causing further damage to the articular cartilage.

Bucket-handle tears are generally considered severe meniscal injuries, and their treatment often requires surgical intervention. The goal of treatment is to save as much of the original meniscus as possible to preserve its shock-absorbing function and prevent long-term joint degeneration.

When the tear is fresh and involves the peripheral, vascularized portion of the meniscus, a meniscal repair can often be performed, where the torn meniscus is sutured back together. This procedure allows for the possibility of healing and restoration of the normal meniscal shape and function but requires a longer recovery period with restrictions on weight-bearing and knee bending activities to allow the meniscus to heal.

In cases where the tear is not amenable to repair due to factors such as tear chronicity or location in the more central, avascular portion of the meniscus, a partial meniscectomy may be performed. In this procedure, the flipped and torn segment of the meniscus is removed to relieve the block to motion. However, as this results in less meniscal tissue to distribute forces, there may be an increased risk of knee joint degeneration over the long term.

Radial tears are vertical tears that extend from the inner edge of the meniscus towards the outer edge. These tears essentially split the meniscus into two, greatly compromising its load-bearing capacity and causing increased contact forces in the knee. The outer part of the meniscus may be repairable if the tear extends there due to the better blood supply, but the inner portion often requires partial meniscectomy. These tears are very unstable, and require prolonged protection to heal.

Meniscus root tears occur at the meniscus’s attachment points to the tibia. These tears can cause the meniscus to become “non-functional,” leading to significantly increased contact forces and a rapid progression of knee arthritis. Given the implications, these tears are typically treated aggressively, often with root repair to restore the normal function of the meniscus.

RAMP tears refer to a tear in the peripheral attachment of the posterior horn of the medial meniscus. Often associated with ACL injuries, these tears can significantly impact the stability of the knee and may go unnoticed on standard MRI scans. RAMP tears are usually repaired to restore stability and normal knee kinematics.

Complex tears involve a combination of tear patterns, making the meniscus look shredded or “crabmeat-like.” These tears can destabilize the knee and increase contact forces. However, due to the extent of damage, these tears are often not amenable to repair and may require partial or total meniscectomy.

Degenerative meniscus tears occur due to wear and tear over time, often without a specific injury. These tears can cause increased contact forces in the knee, leading to pain and swelling. Treatment often starts with conservative measures such as physical therapy and anti-inflammatory medications. If symptoms persist, arthroscopic partial meniscectomy or repair may be considered.