The meniscus is commonly injured in sports, but can occur as a sequela of age-related degeneration. In these cases there may be no trauma, but more typically, patients give a history of a twisting injury followed by pain. This acute episode may involve locking of the knee and moderate swelling. Recurrent
episodes of pain and swelling are occasionally accompanied by complaints of mechanical symptoms such as catching, popping, or locking in the knee. The pain tends to localize along the joint line, especially with deep flexion and twisting motions.

The patient is examined for signs of an effusion, loss of quadriceps bulk, and range of motion. Tenderness to palpation along either the medial or lateral joint line is among the most sensitive signs of a meniscal tear. The collateral and cruciate ligaments are assessed to determine whether additional injury is present. Special tests for assessing the meniscus, such as the McMurray or Apley tests, are not conclusive but can aid in the diagnosis. The McMurray provocative test is performed with the patient supine, the hip flexed to 90 degrees, and the knee in forced maximal flexion. The foot is grasped by the heel, the knee is steadied, and the joint line palpated with the other hand. As the knee is slowly brought into extension, an external rotation stress will test the medial meniscus while an internal rotation stress tests the lateral meniscus. A positive test is a pain in the appropriate joint line accompanied by a thud or click. The hallmarks of a meniscal tear are presence of an effusion, joint line tenderness, as well as a positive McMurray test (Fig 38-2).

Evaluation of the meniscal tear should include routine anterior posterior (AP) and lateral x-rays of the knee. If degenerative changes are expected, standing views including a 45-degree flexion AP view should be performed to assess the degree of joint space narrowing. Although not clinically indicated in all patients, magnetic resonance imaging (MRI) plays a valuable role in the evaluation of the full range of meniscal pathology including the primary diagnosis of a meniscal tear, the detection of a recurrent tear after resection or repair, and the demonstration of associated injuries and complications (23). Although it is usually not possible to identify menisci that are amenable to repair preoperatively, magnetic resonance imaging does show the relative locations of the tears and is able to determine the presence of a meniscal tear with an accuracy of over 90% (24,25). These results support reports in the literature that MRI is an accurate noninvasive technique for evaluating meniscal tears (26).

Meniscal tears are initially treated symptomatically with protected weight bearing, modified activity, ice, and nonsteroidal anti-inflammatory medications (NSAIDs). Some meniscal tears will become asymptomatic after several months of these interventions. The best activity for the patient during this period is to use the stationary bicycle and to avoid deep or full squatting exercises. If the patients are willing to modify their activities and have full motion and no pain or swelling, then conservative management of the tear may be successful. A locked knee, however, usually represents a displaced bucket handle tear and will need surgery acutely to restore motion.

If the patient continues to have pain, swelling and giving way, then operative intervention is indicated. If there is a degenerative flap tear, then meniscectomy is the only treatment (Fig 38-4). The principle of menisectomy is to remove any unstable fragments of meniscus, to contour the edges, and to trim the remaining rim so that it is stable to probing. If,
however, the meniscal tear is amenable to repair, this can be accomplished by means of various techniques and implants. The four major methods of repairing the meniscus are: open, arthroscopic outside-in, arthroscopic inside-out, or an arthroscopic all-inside technique. Prior to the widespread use of arthroscopy, open repair techniques were performed, but arthroscopic inside-to-outside approaches evolved to decrease the morbidity and enable access to areas that are difficult to reach with an open approach. An outside-to-inside approach was later popularized, as it minimized the risk to posterior neurovascular structures. Eventually, an all-inside technique for posterior horn tears was developed which obviates posterior capsular exposure, further reducing neurovascular risk. The following sections enumerate the advantages, indications, contraindications, complications, and results of each.

A variety of implants to address meniscal tears are commercially available to the arthroscopic surgeon. These include absorbable and nonabsorbable sutures, bio-absorbable arrows, tacks, and staples, as well as a number of repair-stimulating techniques such as trephination, rasping, and implantation of a fibrin clot. Most authors who advocate the use of sutures utilize nonabsorbable sutures. By providing longer lasting and more stable fixation, nonabsorbable sutures are believed to allow more complete remodeling of the meniscal repair tissue, which allows for improved healing rates (27). Menisci repaired with permanent sutures also had a lower incidence of clinical symptoms and a much lower failure rate (39).

Patient positioning must allow circumferential access to the affected knee during meniscal repair. The leg should be prepped and draped to allow posteromedial and posterolateral incisions should they be required (Fig 38-5). This can be done with the patient supine such that the break in the table is at the level of the tourniquet and can be flexed down to allow 90 degrees of knee flexion. Alternatively, a leg holder can be used that allows the surgeon to abduct the leg away from the operating table, allowing the knee to flex as needed for access. Diagnostic arthroscopy is performed using a 30-degree arthroscope and includes an evaluation of both menisci, the articular cartilage in the knee, and the cruciate ligaments. The menisci are probed on the inferior and superior surfaces to identify any tears. In assessing meniscal stability, it is important to realize that the lateral meniscus is normally more mobile than the medial meniscus (40). The definition of an unstable meniscal tear is one that is longer than half the length of the meniscus, and subluxes under the condyle when probed with a hook. Although a tourniquet may be used to improve visualization during the procedure, some surgeons prefer to leave it deflated for the diagnostic arthroscopy in order to assess the vascularity of the meniscal tear after rasping.

Repairs of the medial meniscus are usually done in some degree of extension, depending on the location of the tear, to allow for adequate visualization and access. On the lateral side, the greatest visualization is obtained with the knee flexed and the leg in the figure-of-four position. This position is also key in protecting the peroneal nerve, which lies posterior to the biceps femoris tendon and furthest from the joint capsule with the knee in flexion.

If performing an inside-out or outside-in repair of the meniscus, a “safety” incision is usually done on the appropriate side with the knee in flexion. In the inside-out technique,
the incision is done just distal to the joint line, since the needles are passed in a cranio-caudal direction.

On the medial side, a 2 to 3 cm skin incision is performed posterior to the medial collateral ligament and then the fascia along the anterior border of the sartorius muscle is incised. The sartorius is retracted posteriorly, which protects the saphenous nerve and vein lying deep and towards the posterior border of the sartorius. Care should be taken to watch for the infrapatellar branch of the saphenous nerve, which penetrates the sartorius becoming superficial to the fascia near the joint line. With blunt dissection the interval between the posteromedial capsule and the medial head of the gastrocnemius is opened, just proximal to the semimembranosus tendon.

On the lateral side, the surgeon identifies the joint line, the lateral collateral ligament and the fibular head. With the knee at 90 degrees of flexion, an incision may be made posterior to the iliotibial band, again extending 3 cm distal from the joint line. This approach can then be continued with blunt dissection passing between the anterior aspect of the biceps femoris and the posterior aspect of the iliotibial band. If the superior lateral geniculate vessels are encountered, they can be coagulated. The biceps femoris is retracted posteriorly, protecting the peroneal nerve, which lies posterior and medial to the biceps tendon at this level. The lateral head of the gastrocnemius is identified and the dissection proceeds between the gastrocnemius and the capsule, where a retractor can be placed during the passage of sutures.

The tear should be initially probed to determine if it is suitable for repair. The edges of the tear should be debrided of fibrous tissue with a rasp or a small shaver. Abrasion of the menisco-synovial junction is also believed to improve the rate of repair regardless of repair method (41,42). Animal studies in rabbits have shown that rasping a meniscal surface to repair a tear in the avascular zone stimulates vascular induction to the tear, resulting in meniscal healing. The cytokine network on the rasped meniscal surface appears to be the key to explaining the mechanism of vascular induction and meniscal healing by meniscal rasping (43). A technique of stimulation of the meniscal synovial border with electrocautery has been described by Pavlovich (44). The principle is to lightly “burn” the synovium to produce a healing response. Zhongnan et al. (45) demonstrated that the meniscus and the rim may be trephinated to produce vascular access channels. Trephination involves the creation of vascular access channels by removal of a core of tissue from the periphery of the meniscus adjacent to the tear, thus connecting the avascular portion of the meniscus to the peripheral blood supply. Zhang (46,47) continues to champion the technique, and has shown increased healing rates and decreased symptoms when trephination is performed during repair. Some authors believe that for symptomatic stable or incomplete meniscal tears, trephination without suturing may be sufficient, and have shown good results while avoiding the complications associated with suturing (35,37).

Other techniques of biologic augmentation have been devised to improve healing rates. Arnoczky et al. (48) was the first to show that meniscal healing in the avascular zone of canine menisci can be enhanced by the use of a fibrin clot. Clinically, there have been favorable results with use of fibrin clot in repair of red-white meniscal tears (42,49,50,51,52). The technique involves withdrawal of 30 to 40 cc of the patient’s blood by venipuncture, which is then placed in a sterile glass container and stirred with a glass rod for a few minutes until a well-organized firm fibrin clot is formed (51). After rinsing the clot in sterile saline to remove serum and red blood cells, it is tied to a previously placed repair suture that has been brought out of an anterior portal by means of a cannula. A probe can be used to position the clot between the meniscus and the tibia as the sutures are tensioned (53).

The sutures and bioabsorbable devices must be placed accurately to reduce the tear and hold it until it is healed. A common approach to large bucket handle tears is to use sutures in the middle segment to reduce and hold the bucket tear, and then use the bioabsorbable devices posterior horn region because it is more difficult to access and repair. In summary, for good results in meniscal repair, the principles of meniscal repair, namely that stimulation of circulation and proper reduction of the meniscus must be adhered to.

Indications for open meniscal repair at the present time are somewhat limited. It could be used for very peripheral meniscal tears, such as meniscocapsular separation. In reality, the repair is performed open only in special circumstances, such as multi-ligament reconstruction after knee dislocation, and at the time of tibial plateau fixation.

A 3 to 5 cm incision is made longitudinally over the joint line and vertical sutures are placed from the capsule into the meniscus.

The arthroscopic inside-out suture repair originally described by Henning and Lynch (9) remains the gold standard by which other techniques are judged. A major advantage of this technique is its versatility, its ease of use, and the short learning curve. Excellent healing rates have been widely reported in the literature (54,55,56,57,58,59,60,61,62,63,64). The Zone-Specific method of inside-out meniscal repair was popularized by Rosenberg (63) in 1986, when he developed a single-lumen cannula system (Linvatec, Largo, FL) through which sutures could be passed to repair the meniscus. The system includes single-lumen cannulae with six different curvatures that allows the surgeon to direct the tip more easily to the left or right, as well as toward the
anterior, middle, or posterior part of the meniscus. The cannulae have a 15-degree curve upward, which allows the cannula to be apposed against the meniscus and allows the needle to be passed parallel to the joint line from a slightly elevated portal. The shapes of the cannulae allow placement of the device around the tibial spines and femoral condyles, and direct the needles away from the important posterior neurovascular structures.