Meniscus tears that can be left in situ, with or without trephination or synovial abrasion to stimulate healing

To determine which meniscus tears to leave in situ, the clinician must know whether the meniscus tear is degenerative or nondegenerative, stable or unstable, in an anterior cruciate ligament (ACL)-stable or ACL-unstable knee, and whether it is in the medial or lateral compartment. Symptomatic medial meniscus tears in ACL-intact knees are almost always degenerative in nature and should be removed. Generally, the only type of medial meniscus that can be left in situ is a peripheral, vertical, nondegenerative tear, but these tears are not displaceable, are asymptomatic, and are usually seen in a patient with an ACL tear. In the lateral compartment, most tears can be left in situ and the only tears that need to be repaired are displaceable tears that extend anterior to the popliteus tendon. Although many meniscus repair techniques and fixation devices are available, all factors related to healing and stability should be considered to determine treatment.