DEFINITION

A meniscus tear results in mechanical disruption of the gross structure of the medial or lateral meniscus or both.

The goals of meniscus repair are to preserve and optimize meniscus function and to restore joint biomechanics, ultimately resulting in protection and preservation of the articular cartilage.

 

 

ANATOMY

 

The medial meniscus and the lateral meniscus are crescentshaped and triangular in cross-section.

 

The medial meniscus is C-shaped. It covers about 64% of the tibial plateau. Its width varies from anterior to posterior, with an average of 10 mm (FIG 1).

 

The lateral meniscus is more circular. It covers about 84% of the tibial plateau, with an average width of 12 to 13 mm.

 

The menisci are fibrocartilaginous structures made up of collagen (90% type I and the remainder made up of types II, III, V, and VI), fibrochondrocytes, and water.

 

The collagen fibers are arranged in a circumferential pattern in the peripheral third, whereas the inner two-thirds is organized with a combination of radial and circumferential fibers (FIG 2).

 

The collagen fiber arrangement is integral in transforming axial force into a circumferential force within the meniscus. Three layers within the meniscus each have particular fibril arrangements.

 

Within the most superficial zone are fibers arranged in a meshlike pattern. The middle zone has fibers in a random array, whereas the deepest layer contains circumferential fibers. These deep zone fibers are cross-linked with radial fibers and function to prevent longitudinal tears (ie, bucket-handle tear). If a tear in the deep

layer exists, the distribution of forces is subsequently altered and may lead to meniscal extrusion.14

 

 

 

FIG 1 • Anatomy of the meniscus, showing the average sizes of the components of the medial and lateral meniscus with the average amount of tibial plateau coverage.

 

 

 

 

 

FIG 2 • A cross-section of the meniscus showing the radial and circumferential collagen fiber orientation. Also shown are blood vessels penetrating the peripheral one-third of the tissue and the location of chondrocytes.

 

 

The menisci function to deepen the articular surface of the tibial plateau, providing shock absorption and compensating for gross incongruity between the articulating surfaces, acting as joint stabilizers. They provide

 

joint lubrication and maintenance of synovial fluid and assist in providing nutrition of articular cartilage.39 The vascular supply comes from the perimeniscal capillary plexus supplied by the medial and lateral inferior

and superior geniculate arteries. The plexus penetrates the meniscus peripherally and its abundance decreases as it crosses centrally. This difference in vascularity creates the red-red, redwhite, and white-white

zones.5

 

The meniscus contains free nerve endings and corpuscular mechanoreceptors, providing pain and proprioception in the knee joint.39

PATHOGENESIS

 

Acute tears typically occur in younger patients from compression and rotational injury of the knee joint as it moves from a flexed to an extended position.

 

Degenerative tears are typically chronic in nature, are found in older patients, are complex, and are usually irreparable.

 

Medial meniscus tears most often occur in the stable knee or chronic anterior cruciate ligament (ACL)-deficient knee, whereas lateral tears occur more often in younger patients with acute ACL tears.

 

Associated injuries are often found. The “terrible triad” consists of tears of the lateral meniscus, ACL, and medial collateral ligament (MCL). It is often sustained from a hyperextension with a valgus stress, such as during a “clipping” injury in football.

 

 

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Tears may be classified according to anatomic zone (as described by Cooper et al13), vascularity (red-red, red-white, white-white), or by tear pattern.

 

Tear patterns are described as horizontal, radial, longitudinal, bucket-handle, oblique, or complex.13

 

NATURAL HISTORY

 

Walker and Erkman49 in 1975 found that with loads up to 150 kg, the lateral meniscus bore most of the weight bearing in that compartment, whereas the medial meniscus shared about 50% of the load with the articulating surfaces of the tibiofemoral joint.

 

Partial and total meniscectomy has been shown to increase the contact stresses exerted on the articular cartilage, resulting in its degeneration and ultimately osteoarthritis.

 

After partial meniscectomy, femoral-tibial contact areas decrease by about 10%, with peak local contract stresses (PLCS) increasing by about 65%. After total meniscectomy, contact areas decrease about 75% and

PLCS increases about 235%.7

 

Lee et al24 demonstrated significantly decreased contact areas and increased mean and peak contact stresses compared to the intact meniscus for tears involving 50% radial width, 75% radial width, segmental, and total meniscectomy.

 

Vertical tears of the meniscus were found to have contact areas and pressures similar to total meniscectomy, with repair yielding values near to the normal meniscus.31

 

The menisci also contribute to joint stability, especially in the anteroposterior (AP) plane. In a cadaver study, a longitudinal tear of the posterior horn of the medial meniscus in the ACL-deficient knee was found to result in a

significant decrease in AP joint stability compared to the ACL-deficient knee with intact meniscus.2 Repair of the meniscus restored kinematics to the ACL-deficient, intact meniscus level.

PATIENT HISTORY AND PHYSICAL FINDINGS

 

The history should include location of pain (joint line tenderness), recent traumas, prior injuries and surgery, as well as evidence of effusions, locking, catching, or instability (which may indicate associated ligamentous pathology).

 

In addition, questions should be asked about the patient's age, function, activity level, occupation, goals, expectations, and other pertinent medical problems. These will help the surgeon decide on nonsurgical versus surgical treatment and resection versus repair.

 

A complete examination of the knee should be performed, including evaluation for the following:

 

 

Anterior and posterior ligament injury: Lachman, anterior and posterior drawer, pivot shift, along with a history of hearing a “pop” with injury and acute swelling

 

Posterolateral corner injury: injury of the popliteus tendon, iliotibial band, popliteofibular ligament, biceps, and posterior capsule. Asymmetry on the dial (external rotation) test is the most sensitive examination.

 

Collateral ligament injury: Medial and lateral collateral ligament injuries may be assessed by palpation and widening with varus-valgus stresses at 30 degrees and at full extension.

 

The examiner should also

 

 

Inspect for effusion. The presence of diffuse joint effusion is not specific enough. A localized swelling at the joint line may indicate a parameniscal cyst.

 

Palpate all ligament and tendon insertions as well as the patellofemoral joint; this may indicate associated pathology.

 

Evaluate range of motion. Loss of extension or locking may relate to a displaced or bucket-handle tear. Pain with squatting may indicate a posterior horn tear.

 

Perform the McMurray test—flex the knee, bring knee into extension with external rotation and valgus while palpating the medial joint line, or bring the knee into extension with internal rotation and varus while palpating the lateral joint line. Pain or popping/clicking is indicative of a meniscal tear.

 

Perform the Apley test to look for a meniscus tear—place patient prone, flex knee to 90 degrees, apply an axial load while internally and externally rotating the knee. Relief on distraction is found if a meniscus tear is the only pathology, but no relief will be found if a concomitant collateral ligament injury is present.

 

Perform the Childress test—have the patient assume a squatting position and either repeatedly squat or walk while squatting. The test is positive if the patient has pain or mechanical blocking; this may indicate a meniscus tear.

 

While assessing for the Merkel sign, pain with internal rotation of tibia is consistent with a medial meniscus tear; pain with external rotation is consistent with a lateral meniscus tear.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Plain radiographs should be taken to evaluate for bony pathology, extremity alignment, arthritis, chondrocalcinosis, or findings consistent with associated injuries such as a Segond sign (ACL injury), osteochondritis dissecans lesion, or osteochondral fracture.

 

Typically, four views are obtained: a 30- or 45-degree posteroanterior flexion weight-bearing view, a true lateral view, a notch view, and a patella skyline view.

 

Magnetic resonance imaging (MRI) is not always indicated to evaluate for meniscal pathology, but it is typically used and helpful in evaluation of associated injuries when a meniscus tear is suspected. The sensitivity of

 

MRI for meniscus tears is reported as high as 96%, with a specificity of 97%.26 MRI classification is as follows:

 

 

 

Grade 1: small focal area of increased signal, not extending to the joint surface Grade 2: linear area of increased signal, not extending to the joint surface Grade 3: linear area of increased signal extending to the joint surface

 

A linear abnormality is identified as extension to the articular surface on two consecutive images and is considered to have a high likelihood of being a true tear (FIG 3A).

 

A bucket-handle tear may be identified by the “double PCL” (posterior cruciate ligament) sign (FIG 3B,C).

 

Evaluation of the meniscus postoperatively presents a challenge because the repair site becomes filled with fibrous scar and may continue to produce abnormal magnetic resonance signal on postoperative imaging.

Currently, the best method of evaluation is with a gadolinium-enhanced MRI.

 

 

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FIG 3 • A,B. Lateral and posteroanterior MRIs of meniscus tears. C. MRI of medial bucket-handle meniscus tear and double PCL sign. D,E. Sagittal and coronal MRIs of discoid lateral meniscus tears.

 

 

A discoid meniscus may be evident on MRI as a rectangular meniscus on all slices as opposed to the wedge shape typically seen. It is more commonly found in the lateral meniscus (FIG 3D,E).

 

DIFFERENTIAL DIAGNOSIS

 

ACL or PCL tear

 

 

 

Medial or lateral collateral ligament tear Osteochondritis dissecans lesion Patellofemoral syndrome

 

 

Osteoarthritis Chondrocalcinosis

NONOPERATIVE MANAGEMENT

 

Conservative treatment options include physical therapy, nonsteroidal anti-inflammatory medications, steroid injections, and activity modification.

 

 

Typically, a stable longitudinal tear in the periphery less than 10 mm is likely to heal on its own. Bracing usually is not indicated in the treatment of meniscus tears.

 

The expected result of nonoperative treatment is improved symptoms in 6 weeks, with return to full activities by 3 months.

 

SURGICAL MANAGEMENT

 

Intervention may proceed after failure of conservative treatment or more urgently if the patient shows mechanical symptoms such as locking or catching. These may represent loose bodies or an unstable torn meniscus (ie, bucket-handle tear), which can cause significant articular damage if left untreated.

 

 

With all meniscus pathology, the goal is to preserve as much meniscus as possible. Repair versus resection

 

The potential long-term benefit of repairing the meniscus is chondroprotection.

 

The surgeon should consider tear location, pattern, vascularity, tissue viability and ability to hold repair sutures, and associated pathology when determining whether to repair or resect the meniscus.

 

The surgeon should consider the patient's age, activity level, overall health, and compliance with a limited postoperative activity regimen.

 

 

When resection is performed, all efforts should be made to preserve as much viable meniscus as possible. Mobile, unstable meniscus fragments should be resected, leaving a smooth contour.

 

The peripheral rim of meniscal tissue should be carefully assessed and measured to determine the “rim width.” This is the area where the circumferential collagen fibers are located and function to provide the ultrastructural integrity to resist joint compressive hoop stresses and should be preserved.

 

The surgeon should consider leaving a stable tear alone. An unstable tear will be easily mobilized, displaced at least 7 mm, and/or will have the ability to “roll” (FIG 4).

 

Preoperative Planning

 

Before surgery, all radiologic studies should be reviewed and clinical correlation must be confirmed. Comprehensive patient counseling should also be performed.

 

 

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FIG 4 • Intraoperative evaluation of the ability to roll the meniscus.

 

 

The knee should be examined under anesthesia before beginning the surgery in an attempt to detect associated pathology.

 

The healing potential for a meniscus repair in conjunction with an ACL reconstruction is far superior to that of a repair alone.

 

The surgeon should discuss with the patient the risks and benefits of the surgery as well as the principle of informed consent.

 

All patients should be apprised of the possibility of meniscus resection versus repair. They should understand the implications of each in terms of short- and long-term consequences, including risks of failure and rigors of postoperative rehabilitation protocols.

 

The surgeon may discuss the potential for associated pathology and may obtain a better understanding of the patient's treatment preferences before entering the operating room. This may be a particularly crucial conversation with an elite athlete who would prefer to undergo a resection in an attempt to return to competitive sport faster.

 

The anesthesia used is typically decided on by the anesthesiologist and orthopedist before entering the operating room. General anesthesia or a laryngeal mask airway (LMA) may be used.

 

We prefer to have the anesthesiologist provide sedation in conjunction with a local anesthetic administered by the surgeon.

 

We typically use a mixture of 0.5% Marcaine and 1% lidocaine with epinephrine in equal proportions. About 30 to 40 mL is injected intra-articularly, and about 5 mL is injected into each portal site.

Positioning

 

Typically, the patient is lying supine.

 

There are two methods for using an intraoperative leg support device to facilitate coronal plane valgus joint distraction; these include the use of a knee holder or a lateral post.

 

The knee holder should be placed perpendicular to the position of the femur at a level above the patella and portals that allows for a valgus force on the knee.

 

The end of the table is dropped down below 90 degrees from horizontal to allow both legs to hang freely from the knees.

 

The lateral post should be placed above the patella and angled outwardly to allow for a valgus force on the operative knee. This technique is performed without dropping the end of the table.

 

The surgeon should check that the knee may be taken through a range of motion by abducting the leg against the lateral post with flexion of the knee off the side of the table.

 

A tourniquet may be placed on the upper thigh if bleeding is suspected, such as in débridement of hypertrophic synovitis or a hypertrophic fat pad.

 

Padding of the contralateral leg is used to prevent pressurerelated injury to the bony prominences or superficial nerves.

 

Approach

 

The typical portal sites are anteromedial and anterolateral (FIG 5).

 

In addition, a superomedial portal can be made proximal to the superior pole of the patella in line with the medial border of the patella (medial to the quadriceps) and is directed in an oblique manner to the joint.

 

This portal is typically used for outflow or inflow.

 

The anterolateral portal is created by making a small (about 6 mm) stab incision 1 cm proximal to the joint line and 1 cm lateral to the patella tendon.

 

This area can be identified as the “soft spot.” This portal is used for insertion of the arthroscope.

 

The anteromedial portal is considered the working portal for insertion of instruments. It is typically made under direct visualization by inserting a spinal needle into the medial soft spot 1 cm medial to the patella tendon and 1 cm proximal to the joint line.

 

Accessory portals are useful depending on tear patterns and repair strategies and may include superolateral, posteromedial, posterolateral, midpatella, central, far medial, or lateral (FIG 5).

 

Meniscal tears may be stimulated to heal with either rasping or trephination. Rasping may be performed with either an arthroscopic shaver or a meniscal rasp that lightly abrades both the tibial and femoral edges of the tear site, as well as the meniscosynovial junction, to stimulate vascularity.

 

 

 

FIG 5 • Placement of the standard (superolateral, anteromedial, and anterolateral) and accessory arthroscopic portals in the knee.

 

 

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Trephination is performed by inserting a long 18-gauge needle either percutaneously or through the arthroscopic portals across the meniscus tear to create vascular channels.

 

The surgeon should avoid perforation of the meniscus surface, causing further injury.

 

 

 

FIG 6 • Visualization before (A) and after (B) MCL pie-crusting.

 

 

The MCL pie-crusting technique can be performed to avoid articular cartilage damage/scuffing in the tight medial compartment. An 18-gauge needle or arthroscopic awl is used to create multiple punctures in the deep MCL while a valgus force is applied. The punctures should begin posteriorly and advance anteriorly until

adequate visualization is obtained6 (FIG 6).

 

 

TECHNIQUES

• Inside-Out Technique

  This technique requires passage of double-loaded 2-0 or 0 nonabsorbable and/or high-strength sutures with long flexible needles passed arthroscopically and directly through low-profile contoured suture cannulas (TECH FIG 1A-E).

  It is best used for posterior horn, middle third, peripheral capsule, and bucket-handle tears.

  Before passage of the sutures, an incision is made posteromedial or posterolaterally to capture the needles as they exit through the capsule. In this manner, all neurovascular structures are protected.

  For passage of a needle through the medial compartment, the knee is placed in 20 to 30 degrees of flexion to avoid tethering the capsule.

  A 4- to 6-cm posteromedial incision is made just posterior to the MCL, extending about one-third above and two-thirds below the joint line.

  Dissection is continued anterior to the sartorius and semimembranosus musculature, deep to the medial head of the gastrocnemius.

  The posterolateral incision is made with the knee in 90 degrees of flexion to allow the peroneal nerve, popliteus, and lateral inferior geniculate artery to fall posteriorly.

  A 4- to 6-cm incision is made just posterior to the lateral collateral ligament, anterior to the biceps femoris tendon, extending one-third above and two-thirds below the joint line.

  Dissection is continued between the iliotibial band and the biceps tendon and then proceeds deep and anterior to the lateral head of the gastrocnemius.

  On exposure of the capsule, a popliteal retractor is placed against the capsule retracting the gastrocnemius muscle tissue posteriorly to safely visualize, deflect, and capture the exiting repair needles.

   

  A single- or double-lumen cannula is passed through the arthroscopic portals to the site of the tear.

   

  Long flexible needles are then passed through the cannula, piercing the meniscus above and below the tear site and creating vertical mattress sutures.

   

   

  The needles are captured one at a time by an assistant who is retracting on the capsule (TECH FIG 1F). Care is taken not to pull either suture all the way through until both needles are passed.

   

  The sutures are then tensioned and tied to the capsule while viewing the repair arthroscopically.

   

   

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  TECH FIG 1 • Inside-out repair technique. A. Diagram of technique. B. Skin incision on medial side. C. Skin incision on lateral side. D. Intraoperative image and popliteal retractor in place. E. The cannulae used to pass the needles. F. A proprietary system including a curved cannula and needle catching retractor (Protector Meniscus Suturing Set, Arthrex).

   

   

   

• Outside-In Technique

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  This technique is performed by passing multiple long 18-gauge spinal needles percutaneously from outside of the knee to inside the knee joint (TECH FIG 2).

   

   

  This technique is best performed on tears of the anterior and middle third as well as radial tears. Needles should be spaced about 3 to 5 mm apart.

   

  The needle should enter the joint through the periphery to achieve a vertical and horizontal mattress suture configuration.

   

  An absorbable monofilament suture is passed into the joint which can be used to shuttle a nonabsorbable and/or highstrength suture of choice.

   

   

   

  TECH FIG 2 • Outside-in repair technique. A. Illustration of horizontal mattress technique without intraarticular knots using spinal needles and threaded wire. B. External placement of needles. C,D.

  Arthroscopic views of intrameniscal passage of needles.1 E. Arthroscopic view of mattress suture with outside-in technique.

   

   

  A second needle with a 3-0 wire retriever trocar is passed through the tear to retrieve the suture.

   

  After tensioning of the mattress suture, a 3- to 5-mm skin incision is made near the suture strands and blunt dissection carried down to the capsule with a hemostat.

   

  A probe may be used to retrieve the sutures and tie them down to the capsule under direct visualization, taking care to avoid incarceration of any neurovascular structures.

   

  The Meniscal Mender II (Smith & Nephew, Andover, MA) uses a proprietary suture capture loop and offers both curved or straight needles for better access to the tear, thereby minimizing the risk of damage to nearby neurovascular structures.

• All-Inside Nonsuture Fixation Technique

   

  These devices have become much less popular due to concern over device complications and need for further surgery.

   

  Multiple proprietary fixation devices are available with variations on the popular reverse-barbed fishhook design (eg, Meniscus Arrow [ConMed, Linvatec, Largo, FL]; BioStinger [ConMed]; Dart [Arthrex, Inc.,

  Naples, FL]).

   

  They are commonly referred to as first-generation arthroscopic fixators.

   

   

  These devices are best used in vertical longitudinal tears in the red-white zone of the posterior horn. They are typically made of bioabsorbable copolymers such as poly-L-lactic acid and poly-D-lactic acid.

   

  After identification of tear site, accurate measurement of the size of the meniscus is performed with an arthroscopic measuring device.

   

   

  Insertion of the fixator must be performed perpendicular to the tear and parallel to the tibial surface. Fixators can be placed at 3- to 5-mm intervals.

   

  Care must be taken to implant the fixator so that it is seated flush or countersunk to the meniscus surface while spanning the tear equally on both sides to appropriately compress the tear.

   

   

  Multiple published studies have reported implant breakage, chondral scoring and injury, and unpredictable resorption and degradation profiles.15,22,45

   

• All-Inside Suture Fixation Technique

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  The fourth generation of meniscal fixation devices highlight the importance of meniscal repair without further damage to the chondral architecture. These flexible and suture-based devices allow for compression and retensioning across the tear (TECH FIG 3A).

   

  The suture fixators are designed to allow repair of the meniscus with mattress suture using all-arthroscopic methods.

   

  The devices deploy two absorbable or nonabsorbable suture anchors with attached nonabsorbable highstrength sutures or use all-arthroscopic suturing methodologies.

   

   

   

  TECH FIG 3 • A. All-inside meniscal repair devices. (A) NovoStitch; (B) OmniSpan; (C) FasT-Fix 360; (D) MaxFire and MaxFire MarXmen; (E) Sequent; (F) Meniscal Cinch; (G) CrossFix II. B. A proprietary slotted cannula system to ease device insertion (FasT-Fix 360 Meniscal Repair System. C,D. Placement of arthroscopic sutures in mattress configuration. E. The “self-tying” arthroscopic knot thrown with a suture fixator. F. Circumferential repair achieved using the NovoStitch device.

   

   

  The sutures can then be arthroscopically tied or they may come pretied or may come in a knotless design.

   

  After preparing and débriding the tear in the standard manner, the delivery device should be inserted usually through the contralateral portal.

   

  A portal skid can facilitate arthroscopic access and also serve as an arthroscopic “retractor.”

   

  Use of a curved needle provides the surgeon with more options compared to the straight needle with regard to position and reduction and insertion angles. Insertion of the needle through a portal insertion device, sheath, or insertion cannula prevents the delivery system from getting caught on loose tissue (TECH FIG 3B).

   

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  The surgeon starts the repair from the center reducing the unstable tear fragments and works outward. This avoids gapping, puckering, and tissue coaptation incongruence—“dog-ears.”

   

  The use of an outside-in stay suture using an 18-gauge spinal needle may aid in holding the reduction, particularly of a displaced bucket-handle tear, until the mattress sutures can be placed.

   

  The devices are placed perpendicular to the tear, and optimally, double vertical or horizontal mattress suture configurations should be placed because they result in the strongest repair construct (TECH FIG 3C-E).

   

  The first anchor should be placed superiorly and posteriorly and the second should be placed inferiorly and anteriorly across the tear to create a vertical mattress.

   

  The knot pusher is used to slide and manually assist in cinching down the knot; however, the surgeon should avoid overtightening and puckering the repair.

   

   

  The devices are placed about 4 to 5 mm apart. Multiple proprietary designs exist:

   

  FasT-Fix/FF 360 (Smith & Nephew)—has a pretied sliding knot; device is made to pierce the meniscus twice in a mattress configuration.

   

  Meniscal Cinch (Arthrex)—pretied sliding knot; gun handle configuration

   

  CrossFix II (Cayenne Medical, Scottsdale, AZ)—pretied sliding knot; all suture design that does not use plastic implants

   

  NovoStitch (Ceterix Orthopaedics, Menlo Park, CA)—low profile; suture can be reloaded, allowing for multiple passages; can achieve circumferential repair (TECH FIG 3F)

   

   

  OmniSpan (DePuy Mitek, Raynham, MA)—pretied sliding knots; fires two implants (TECH FIG 3A) Knotless designs are also available:

   

  MaxFire MarXmen (Biomet, Warsaw, IN)—has a strand of suture that is woven through itself twice in

  opposite directions.25 This allows the surgeon to cinch down the suture with a variable amount of tension to the repair and does not require a knot to be tied.

   

  Sequent (ConMed Linvatec)—a knotless system that can create up to six continuous stitches (TECH FIG 3A).

• Biologic Augmentation Methods

   

  After meniscal injury, preserving the meniscus is important for lifelong joint preservation. Because of the healing complexities of the menisci, due to incomplete vascularity, adjunct techniques can assist meniscal

  repair and improve clinical results.3

   

  With a better understanding of the natural healing mechanisms of a meniscus, development and application of biologic enhancement of meniscal repairs is much stronger today.42

   

  It is accepted that results of meniscus repair are improved when performed in conjunction with ACL reconstruction. The reason for the success is theoretically secondary to the release of growth factors and cytokines when bone tunnels are drilled.

   

  Several methods have been used in an attempt to recreate that biologic advantage.

   

  Mechanical enhancement including trephination or rasping may be performed in an attempt to increase vascularity delivered to the tear site.

   

  The addition of blood into the joint is considered optimal, and shaving or perforating the bone surface of

  the notch has been described as a practical and cost-effective method for creating a hemarthrosis.

   

  The use of fibrin clot or platelet-rich fibrin matrix attempts to deliver biologically active factors directly to the repair site. The fibrin clot provides a chemotactic and mitogenic stimulus to the reparative process as

  well as a scaffold where fibrous tissue may form.42

   

  The platelet-rich fibrin matrix technique is a variant of platelet-rich plasma (PRP) delivery. The technique is performed by obtaining a sample of autologous blood intraoperatively (about 10 mL) and placing it in a centrifuge. After centrifugation is completed, the fibrin-clotting cascade is activated with an agent such as calcium chloride, and the sample is placed through a second centrifuge step. This process minimizes platelet activation and traps inactivated platelets in the fibrin matrix, allowing sustained release of

  cytokines.40 The matrix is then placed into the meniscal repair site. Proprietary technology is available to perform this method (TECH FIG 4).

   

  Growth factors within platelets that are associated with enhanced healing include platelet-derived growth factor, vascular endothelial growth factor, transforming growth factor-β, fibroblast growth factor, and epidermal growth factor.

   

  Multiple studies demonstrate promising results with PRP use and chronic tendinopathy, including epicondylitis and Achilles tendon pain. However, there are no randomized controlled trials investigating PRP usage and meniscal repair.

   

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  TECH FIG 4 • A. A prepared fibrin clot. B. The fibrin clot during insertion. C. Final insertion position.

   

  PEARLS AND PITFALLS

   

  Indications ▪ Repair of red-white and red-red tears optimally

  • If concurrent pathology is present, meniscus tears should always be repaired in conjunction with ACL reconstruction.

 

Tear site management

• The tear should be approached from an anterior portal that allows perpendicular access to suturing the tear site. Use of a contralateral portal can facilitate suture delivery.

• Preparation of the tear site with abrasion, débridement, or trephination is essential and is facilitated by the use of lowprofile arthroscopic shavers, meniscal rasps, and 18-gauge spinal needles.

• The tear should be reduced accurately and reduction should be maintained during fixator placement.

• Tears should be bisected with reduction and centrally based index suturing to avoid a dog-ear result.

• An anchoring stitch may assist with tear reduction.

• Hybrid techniques are very effective using all-arthroscopic, inside-out, and outside-in methods.

• Accessory portals improve access and fixation configuration.

   

  Fixation placement

  • Implants should be separated by about 3-5 mm.

  • Implants should be placed perpendicular to the tear site.

  • Implants should not be left proud.

     

    Suture techniques

  • Vertical mattress sutures are used when possible.

  • Skin incisions are made in 90 degrees of flexion for posteromedial and posterolateral approaches.

  • Sutures are passed in 20 degrees of flexion for medial tears and 90 degrees of flexion for lateral tears.

 

Rehabilitation ▪ Programs should be individualized for each patient and tear pattern and repair construct in terms of protection, weight bearing, range of motion, and return to activities.

 

 

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POSTOPERATIVE CARE

 

Postoperative care must be individualized based on tear geometry, repair construct strength, associated surgical procedures, and surgeon preference.

 

In the operating room, our patients are placed in a knee immobilizer or hinged brace locked in extension.

 

 

 

A patient with an isolated meniscus repair will remain partially weight bearing with crutches for about 1 month. Early range of motion is performed passively from postoperative day 1.

 

Typically, range of motion is limited to 90 degrees for the first 3 weeks for nondisplaced meniscus tears and 4 to 6 weeks for displaced bucket-handle tears.

 

Crutches are discontinued when the patient shows good quadriceps function and no antalgia.

 

Return to pivoting sports ranges from 4 to 6 months or when the patient has no point tenderness or effusion and can show full extension and painless terminal flexion.

 

OUTCOMES

Repair with and without Anterior Cruciate Ligament Reconstruction

 

The long-term success rate of meniscus repair has been found to be between 75% and 85%, with a higher likelihood of success when repair is performed in conjunction with an ACL reconstruction.32

 

A systematic review of all meniscal repair techniques by Paxton et al34 found a reoperation rate of 20.8% in 145 patients with follow-up more than 10 years. The reoperation rate was 14% in patients who had a meniscal repair in conjunction with ACL reconstruction versus 24% with isolated meniscal repair.

Additionally, 78% of meniscal repairs had no degenerative changes on x-ray versus 64% of partial meniscectomies.

 

Recently, the results of a Canadian registry with 988 matched pairs of patients who underwent either

meniscal repair alone or in conjunction with ACL reconstruction was published.50 An average of 9.7% of patients who had meniscal repair with ACL reconstruction required reoperation within 2 years of the index procedure compared to 16.7% in the isolated meniscal repair patients.

Long-term Results

 

Brucker et al10 described the-long term results of 26 patients who had isolated open meniscal repair, with an average follow-up of 21 years. Eighteen of the 26 patients had no re-tear of the meniscus (69.2%), and 17 of the patients had good or excellent subjective outcome.

 

Excellent clinical results were shown in 42 patients with 10-year follow-up after inside-out repair with

concomitant ACL reconstruction.28 An average of 86.2% of the patients had a Lysholm score between 80% and 100%, and these patients had better functional scores when compared to a matched cohort group that had undergone partial meniscectomy and ACL reconstruction.

 

Outside-in repair was found to have an 87.8% success rate in 41 patients with an average of 11.7 years

of follow-up, with failure defined as needing further surgery.1 A study of 88 patients with outside-in repair and an average of 10 years follow-up showed a success rate of 72.7% based on clinical and subjective

parameters.27

All-Inside Repair Outcomes

 

Studies have shown inside-out vertical mattress suture placement to be the strongest fixation technique, whereas the all-inside suture fixators provide excellent repair strength. The all-inside first-generation fixators have shown inferior results compared to the newer fixators.22,23,45

 

A study of 61 menisci repaired with the FasT-Fix found, at an average follow-up of 18 months, a 90%

success rate.20 ACL reconstruction was performed in 62% of cases. Excellent or good clinical results were found on Lysholm knee scoring in 88% of patients.

 

Another study of FasT-Fix repair demonstrated that 30 of 31 patients were asymptomatic at an average of 3 years follow-up.12 Forty-two percent of patients had concomitant ACL reconstruction. The Lysholm

and Tegner activity scores significantly improved from preoperative values, and there were no neurovascular or other major complications.

 

A systematic review found no difference in clinical failure rate or subjective outcome between inside-out

and all-inside meniscus repair techniques, but this included first-generation all-inside fixation.15 All-inside fixation had more implantrelated complications and the inside-out method had more nerve-related complications, but there was no difference in the overall complication rate.

 

Laboratory studies have found that the second-generation all-inside fixators are just as strong as inside-out constructs.

 

Biomechanical testing in cadaver longitudinal meniscal tear model showed a mean load to failure of inside-out vertical mattress Ethibond suture to be 73 N; OrthoCord (Depuy, Warsaw, IN) vertical mattress, 88 N; OmniSpan, 88 N; Cinch (Arthrex), 71 N; MarXmen/MaxFire, 54 N; Sequent, 66 N; and

FasT-Fix 360, 60 N.8 There was no significant difference between the various devices.

 

A recent study by Pujol et al38 demonstrated the results of all-inside repair using the FasT-Fix device in 31 patients with a mean follow-up of 9.7 years. Ninety-two percent of patients had good International Knee Documentation Committee (IKDC) scores, 12.9% required additional surgery, and 26% displayed changes of osteoarthritis.

Repair of Chronic Tears and Failed Meniscal Repairs

 

The definition of a chronic meniscal tear has been described as the presence of a tear for anywhere from 3 months to greater than 1 year.

 

A healing rate of 84% was found with the repair of meniscal tears with a median time to surgery of 27

months using the FasT-Fix device in 25 patients.35 The median follow-up was 20 months and 1 patient (4%) required additional surgery.

 

Recently, the same authors published the results of tears greater than 3 months' duration using outside-

in or all-inside FasT-Fix repair techniques.36 Clinical healing was found in 85.7% of patients with an average of 18.5 months of followup. Time to surgery of greater than 1 year had a significantly higher rate of failure.

 

Primary repair has become the treatment of choice for amenable meniscal tears, with the goal of retaining as much native meniscal tissue as possible.

 

Repeat meniscal repair has a survival rate of roughly 72%, which is lower than that seen in primary

repairs.48 These re-repairs were able to withstand a return to prerepair function levels; however, longer follow-up studies are needed to better understand their impact on degenerative changes within the joint.

 

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Pujol et al37 reported their findings regarding the amount of meniscal resection performed after a failed meniscal repair. In this study, the size of the initial meniscal tear was documented, and 37 out of 295 repairs required repeat surgery. At the time of the second arthroscopy, the amount of meniscus resected was compared to the amount of meniscus that would have initially been resected had repair not been attempted, and there was no difference found between the two quantities.

Patient Age and Repair

 

There is no consensus regarding an age limit to attempting meniscal repair for a tear at an amenable site. Meniscal tissue in patients older than 40 years of age has been found to have a decreased healing

response and less cellularity than in younger patients.29 In addition, issues including poor tissue viability, complex degenerative tear patterns, and reduced compliance with postoperative recovery protocols all

contribute to decision making regarding when to repair and when not to repair meniscal tears in patients older than the age of 40 years.

 

Noyes and Barber-Westin33 showed an 87% success rate in a case series of inside-out repair in 29 patients ages 40 years and older with a mean follow-up of 33 months.

 

Barrett et al9 published the results of inside-out repair in patients older than age 40 years and demonstrated that 86.5% were asymptomatic at an average of 26 months of follow-up.

 

Kalliakmanis et al18 reported no difference in the rate of failure of meniscal repair with concomitant ACL reconstruction between patients older or younger than age 35 years.

Pediatric Meniscal Repair

 

Meniscal injury in children, once considered a rarity, is increasing in incidence likely due to an increase in recognition as well as a true increase in pediatric knee injuries.

 

Carter and Kocher11 pointed out the importance of intraoperative decision making particularly with meniscal pathology in comparison to that of an adult. Because of the well-documented negative effects of meniscectomy on long-term knee function, one must consider preservation of meniscal tissue to be of utmost importance.

 

Reparative techniques of meniscal tears are similar in the pediatric population as in adults; however, care must be taken with the all-inside technique to avoid iatrogenic neurovascular injury due to the small leg size.

 

Two recent studies have demonstrated good clinical outcomes with repair of meniscal tears at any site in the pediatric population, including those in the white-white zone.

 

Twenty four of 29 (82.8%) full-thickness meniscal tears were found to be asymptomatic at an average follow-up of 2.3 years after repair with either all-inside or outside-in technique, regardless of the zone or

site of the tear.21

 

Vanderhave et al47 demonstrated excellent clinical outcomes in 43 of 45 pediatric patients (95.6%) who underwent inside-out repair of a meniscal tear at any site, with an average follow-up of 27 months.

 

COMPLICATIONS

The overall incidence of complications from arthroscopic meniscus surgery is 0.56% to 8.2%.44

 

 

 

 

FIG 7 • Thorough knowledge of the structures around the knee is necessary to prevent injury or tethering during meniscal repair. In this axial MRI cut at the level of the knee, the lateral and medial menisci are outlined. On the medial side of the knee, the MCL (A) and saphenous vein and nerve (B) are at risk. On the lateral side of the knee, the iliotibial band (C), lateral collateral ligament (D), popliteus tendon (E), and peroneal nerve (F) are at risk. Posteriorly, the popliteal artery (G) and tibial nerve (H) are in proximity to

the posterior horn of the lateral meniscus.16

 

 

Meniscus repair surgery has a higher complication rate than meniscus resection, with reports as high as 18%.43

 

Commonly discussed complications include infection, deep vein thrombosis, vascular injury, and neurologic complications (FIG 7).

 

The rate of infection is 0.23% to 0.42%, with an increasing incidence associated with extended operating time, extended tourniquet time, performance of multiple concurrent procedures, and a history of prior

surgeries.4

 

There is no clear consensus on the use of prophylactic perioperative antibiotics.

 

There are published reports of an increased incidence of infection associated with intra-articular corticosteroid injections given intraoperatively.30

 

When an infection has been diagnosed after a repair, it is appropriate to leave the implant or sutures in place; however, there is a higher failure rate associated with it.

 

The incidence of deep vein thrombosis ranges from 1.2% to 4.9% after arthroscopic knee surgery.17 No clear consensus exists with regard to perioperative anticoagulation.

 

The overall incidence of vascular complications is 0.54% to 1.0%, with complications including popliteal artery injury, pseudoaneurysm, and arteriovenous fistulas.19

 

Neurologic complications include direct or indirect nerve injury or complex regional pain syndrome. The overall incidence is 0.06% to 2.0%.41

 

Medial meniscus repairs using an inside-out or outsidein technique can result in saphenous neuropathy or neurapraxia, with reports of up to 43% of cases.46

 

A systematic review by Grant et al15 reported a 9% incidence of nerve irritation/injury with the inside-out technique versus 2% for all-inside techniques including first-generation devices. All-inside techniques had a higher rate of local soft tissue irritation, swelling, and implant migration or breakage.

 

The first-generation all-inside devices have been associated with chondral damage secondary to implant abrasion.15,22

 

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FIG 8 • A,B. Superficial irritation/skin breakdown due to an implant.

 

 

The all-inside fixators have more implant-related complications. It is possible for devices to misfire, launch inaccurately, or break. These may lead to excessive chondral loss or a loose body or fragment within the joint. Other complications include inflammation superficial to the subcutaneous anchor, especially medially overlying the MCL as well as cyst formation (FIG 8).

 

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