Though initially reported by Annandale" in 1885, meniscus repair did not receive widespread attention and acceptance until the last 2 decades. This attention has been the result of increasing awareness of the functional significance of normal menisci, documentation of the consequences of meniscus loss, increasing awareness of the healing potential of certain meniscus tears, and the development of reliable open and arthroscopic repair techniques.
MENISCUS HEALING King" documented that healing occurred in meniscus tears in dogs if there was communication with the peripheral blood supply. Subsequently, other experimental and clinical studies have documented that the peripheral meniscal blood supply produces a healing response similar to that generated by other connective tissues."1." The initial healing is accomplished by the formation of fibrovascular scar tissue, which gradually modulates into more normal-appearing fibrocartilage over a period of several months."' Most of the experimental and clinical healing studies have addressed vertical, longitudinal tear types, but experimental studies have shown that radial lesions that extend to the synovium also heal by the same process." Biomechanical function of menisci after healing of complete radial tears is doubtful, however, as restoration of the peripheral circumferential fiber arrangement has never been documented. Newman et al.') reported that even with successful gross and histologic healing, the ability of a repaired meniscus to transmit load was no different than after total meniscectomy in control animals.

• Address correspondence and reprint requests to Kenneth E. DeHaven, MO, University of Rochester Medical Center, Department of Orthopaedics. 601 Elmwood Avenue, Box 665, Rochester, NY 14642. Neither the author not his related institution has received any financial benefit from research in this study.
Meniscus tears known to be suitable for repair with high expectation for success are traumatic lesions within the vascular zone in which the peripheral circumferential fibers remain intact and there is minimal damage to the meniscus body. In addition, the tear should be of significant length (generally greater than 8 mm), as shorter tears are more likely to heal spontaneously and even if they persist are likely to be asymptomatic. The most com-mon tear types that fit these criteria are peripheral, or near peripheral, vertical, longitudinal tears. In addition, anterocentral osseous detachments are also suitable re-pair candidates. These are rarely encountered clinically, but this was the lesion initially repaired by Annandale.' Other types of meniscus tears can be repaired but must be considered questionably suitable candidates. These include tears that are clearly in the avascular zone or where the vascularity is in question. When repairing tears of this type, it is advisable to consider using one or more of the healing enhancement techniques described later in this article. Other questionably suitable tear types include complete radial tears that extend to the meniscosynovial junction and tears that result in extensive damage to the body of the meniscus. Even if clinical healing occurs, the ultimate biomechanical function of these repaired menisci remains in question. Recognition of potentially repairable meniscus tears preoperatively is helpful for both the surgeon and the patient, particularly in cases not requiring ligament re-pair or reconstruction procedures. This preoperative recognition facilitates surgical planning and patient preparation for different aftercare requirements compared with those of partial meniscectomy. Patient profiling can be helpful. Our patients undergoing repair are young (aver-age age, 21 years) and active (acute or chronic ACL tears in 72%).' Quite often, the presence of a meniscus tear can be accurately predicted from the history and physical ex-amination, but potential repairability cannot be deter-mined clinically. Diagnostic studies such as arthrography and MRI can be helpful in making this determination.