Meniscectomy is still one of the most frequent cases in orthopedic surgery [4]. However, recent results favor meniscal repair over partial meniscectomy concerning either clinical outcome and/or risk for subsequent osteoarthritis [5]. Considering the amount of tissue that is removed, it is usually referred as partial, subtotal, or total meniscectomy. However, the “boundaries” for each of these categories are not very well established [32]. Partial meniscectomy has been linked to higher risk of radiographic changes toward osteoarthritis compared to repair on a recent systematic review (level I–IV studies) [5]. Considering traumatic meniscal tears, worse long-term results have been attributed to partial meniscectomy when compared to repair either in return to sports as well as risk for osteoarthritis [53].

The preservation of peripheral rim and the largest possible amount of meniscus tissue has positive implications for load transmission and contact area [54–56]. Joint instability (e.g., ACL repair) should be properly addressed once the risk of undergoing subsequent meniscectomies was decreased in patients undergoing a concomitant ACL reconstruction meniscus repair [57]. So there is a difference considering prognosis and outcome when dealing with meniscal tears by meniscectomy on a stable versus unstable knee [32]. Worse results are expected when performing isolated meniscectomies on unstable knees [32]. It has been defended that the indications for surgical repair can be widened for the medial meniscus given the increased risk of secondary meniscectomy (if “left alone”), even for small stable lesions [58]. On the opposite, for the lateral meniscus with small stable lesions, “let the meniscus alone” can be sometimes a good option given the low risk of subsequent meniscectomy [46]. An overall odds ratio of 3.50 for medial meniscal tears has been described when ACL surgery is performed more than 12 months after the ACL injury when compared to less than 12 months after ACL injury [59]. On the other hand, concerning lateral meniscus tears and the period of time comprised between ACL injury and reconstruction surgery, there was minimal to no evidence that this represents a risk factor [59]. These conclusions are in line with the documented distinctive roles of medial and lateral menisci within the knee joint.

For traumatic lateral meniscus tears approached during ACL reconstruction procedures [60], it seems plausible to provide the general recommendation to leave small tears (<1 cm) alone, repair large tears in the vascular zone, and excise only unstable, irreparable tears in the avascular zone [61]. Moreover, the risk for rapid chondrolysis after lateral meniscectomy is considerably higher when compared to medial meniscectomy [62, 63]. This is an important possible complication that patients must be informed about prior to surgery. In general, a worse outcome should be expected following a lateral meniscectomy when compared to medial [32].

It has also been demonstrated that the volume of subsequent meniscectomy after a failed meniscus repair is not more than that of the meniscectomy that would have been performed initially without repairing [64]. Despite this, partial meniscectomy has been connected to satisfactory results and faster return to activity and rehabilitation program when compared to meniscus repair [53, 65]. This creates controversy between surgeons, athletes, managers, and agents. In brief, meniscectomy remains as a possibility. However, higher risk of complications, possible lower rate of return to the same level (mainly in the lateral compartment) and a higher risk of secondary osteoarthritis must be discussed with the athlete. Nowadays, even in high-level athletes, there is an increasing strength toward the general recommendation to preserve the meniscus.

Meniscus repair techniques include all-inside [66, 67], inside-out [68, 69], or outside-in [70, 71] approaches, alone or in combination. “All-inside” refers to the fact that suture/repair devices are kept inside the joint at all times during repair. Bioabsorbable meniscal repair devices, including arrows (Fig. 14.7), screws [72], darts, and staples, have been described for all-inside use. However, most of these devices were composed of the rigid poly-L-lactic-acid (PLLA) that has been linked to some concerns related to degradability. Despite some good results described in the literature [73, 74], these devices were related to higher failure rates [75, 76] and a higher number of complications including synovitis, inflammatory reaction, cyst formation, device failure/migration, and chondral damage [76]. Given the considerable prevalence of complications, these rigid (third-generation) devices have progressively lost popularity, particularly in high-level athletes.

The most frequently used all-inside sutures are currently considered as the fourth generation of all-inside sutures. These are usually composed of suture combined with small anchors (serving as blocks) and a prettied slipknot [66]. They have low profile and permit variable compression and retensioning of the suture. A depth-limiting sleeve on the inserter is commonly used to avoid excessive penetrations of the needle, which has an inherent risk of iatrogenic complications (neurovascular structures) [77].

Inside-out (Fig. 14.8) means that the sutures come from the inner joint where they are passed through the meniscus toward the outside (capsule) where knots are tied (or equivalent). In outside-in (Fig. 14.9), the devices for passing the sutures are introduced percutaneously into the joint catching the meniscus tissue, and afterward they are also fixed over the capsule beneath the subcutaneous tissue (Fig. 14.10). Regardless of the used technique, vertical or horizontal mattress sutures can be considered. Vertical sutures are perpendicular to the circumferential fibers of the meniscus and have been stated to have higher pullout resistance [78]. Horizontal sutures are parallel to the same fibers.

In order to increase possibilities for healing, sutures combined with grasping, trephination, or augmentation with fibrin clot have been proposed [36]. As previously mentioned, meniscal sutures are not exclusive of acute traumatic tears, once some selected degenerative injuries (including some horizontal cleavage tears) might be effectively repaired [79]. Some degenerative meniscal root tears have also been successfully repaired thus preserving meniscal functions [80].

Currently, the type of tears that can be possibly suitable for suture include horizontal injuries (degenerative nature even in younger patients) [22], vertical or longitudinal tears, bucket-handle, and some radial tears (vascular zone) which are considered in the traumatic group [20]. All these can be considered as possibly repairable depending on the classification, zone, and surgeon’s experience. Flap tears (frequently traumatic) are frequently considered irreparable. This type of lesion can also be detected in complex degenerative (irreparable) lesions. Multiple factors must be considered when considering to repair a meniscus lesion [51]. These include age, activity level, tear pattern, chronicity of the tears, combined injuries (ACL injury), and healing potential/vascularization. Meniscus repair in older people provides worst outcome comparing to youngsters [81].

Several “biologic” techniques have been tried and kept under intense development aiming to enhance healing and repair of meniscus lesions even in the so-called avascular zones [18, 82]. These include fibrin clot [69, 83], fibrin glue [84], meniscal rasping, growth factors [85], and cell-based therapies [86]. Even more experimental in vivo strategies have been described. As an example, a bioabsorbable conduit has been tried to augment the healing of avascular meniscal tears by increasing vascularization (dog model) [87]. Additional tactics have been using several biomaterials such as porous polyurethane [88], porcine small intestinal submucosa [89], fascia sheaths [90], collagen scaffolds, and growth factors [82]. Tissue engineering and regenerative medicine strategies will most probably provide new answers to overcome current clinical limitations. However, this ambitious target has not yet been entirely achieved and requires ongoing research [82].

Suture/repair techniques have recently improved a lot based on increased biological and anatomical knowledge accompanied with advances in surgical techniques and medical devices [91]. So several techniques are available and can be selected according to the injury pattern, surgeon’s experience, and available resources (Fig. 14.11).

Meniscus allograft transplantation (MAT) has proven to be an effective and reproducible technique when dealing with consequences of severe meniscal loss [103, 104]. On the other hand, partial meniscus replacement by means of scaffolds (mainly acellular) has been used with promising short-term clinical outcome for chronic partial meniscus defects [82, 105–107]. The indications for both techniques are different, while, in summary, scaffold implantation requires that the meniscal roots and peripheral rim remain preserved (which is not a requirement for MAT). There is even one case report describing return to play on a professional footballer after partial lateral meniscus replacement [108]. However, we cannot find current evidence in the literature to promote such techniques in active athletes and expect consistent return to sports at the same level. Such technique, however, represents the best option in some young patients with post-meniscectomized knees as bridging procedures for more aggressive therapies (e.g., osteotomies or arthroplasties). This is quite common in footballers in the final stage of their active competitive careers.