Meniscus Injuries 

Updated: Oct 12, 2018
Author: Bradley S Baker, MD; Chief Editor: Craig C Young, MD 

Overview

Practice Essentials

Meniscal injuries may be the most common knee injury. Meniscus tears (see the image below) are sometimes related to trauma, but significant trauma is not necessary. A sudden twist or repeated squatting can tear the meniscus.

Magnetic resonance imaging scan showing a torn med Magnetic resonance imaging scan showing a torn medial meniscus.

Signs and symptoms

Most meniscal injuries can be diagnosed by obtaining a detailed history. Important points to address include the following:

  • Mechanism of injury (eg, twisting, squatting, changes in position)

  • Pain (commonly intermittent and usually localized to the joint line)

  • Mechanical complaints (eg, clicking, catching, locking, pinching, or a sensation of giving way)

  • Swelling (usually delayed, sometimes absent; degenerative tears often manifest with recurrent effusions)

Physical findings that are significant in the examination of a patient with a possible meniscus injury include the following:

  • Joint line tenderness (77-86% of patients with a meniscal tear)

  • Effusion (~50% of patients presenting with a meniscal tear)

  • Impaired range of motion – A mechanical block to motion or frank locking can occur with displaced tears; restricted motion commonly results from pain or swelling

Provocative maneuvers that may elicit characteristic results in the presence of a meniscal tear include the following:

  • McMurray test – Pain or a reproducible click

  • Steinmann test – Asymmetric pain with external (medial meniscus) or internal (lateral meniscus) rotation

  • Apley test – Pain at the medial or lateral joint

  • Thessaly test – Pain or a locking or catching sensation at the medial or lateral joint line

  • Similar tests, including those that elicit the Bragard, Böhler, Payr, Merke, Childress, and Finochietto signs

See Presentation for more detail.

Diagnosis

Imaging studies that may be considered include the following:

  • Plain radiography – Anteroposterior weight-bearing view, posteroanterior 45° flexed view, lateral view, and Merchant patellar view

  • Arthrography – Once the standard imaging study for meniscal tears but now largely supplanted by magnetic resonance imaging (MRI)

  • MRI – Criterion standard for imaging meniscus pathology and all intra-articular disorders

Abnormal meniscal signals on MRI are classified into the following groups:

  • Grade I – Small area of increased signal within the meniscus

  • Grade II – Linear area of increased signal that does not extend to an articulating surface

  • Grade III – Abnormal increased signal that reaches the surface or edge of the meniscus (indicative of meniscal tearing)

  • Root tears – Meniscal extrusion of at least 3 mm in the mid-coronal plane[1]

In competent hands, arthroscopy is the best tool for meniscal tear diagnosis, with sensitivity, specificity, and accuracy approaching 100%. Being both therapeutic and diagnostic, it offers the option of immediate treatment of most disorders.

See Workup for more detail.

Management

Conservative treatment should be attempted in all but the most severe cases. In the acute phase, such treatment may include the following:

  • Home physical therapy program

  • Simple rest with activity modification

  • Ice

  • Nonsteroidal anti-inflammatory drugs (NSAIDs)

If conservative treatment does not lead to resolution, surgical treatment is considered. Surgical options (arthroscopic or open) include the following:

  • Partial meniscectomy – The treatment of choice for tears in the avascular portion of the meniscus or complex tears that are not amenable to repair

  • Meniscus repair – Recommended for tears that occur in the vascular region (red zone or red-white zone), are longer than 1 cm, root tears, involve greater than 50% of the meniscal thickness, and are unstable to arthroscopic probing

  • In cases of previous total or subtotal meniscectomy, meniscus transplantation – A relatively new procedure for which specific indications and long-term results have not yet been clearly established

In the recovery phase, physical therapy may involve the following:

  • Partial meniscectomy – Low-impact or nonimpact workouts on postoperative day 1, advancing rapidly to preoperative activities; this can usually be accomplished without formal physical therapy, but such therapy should be initiated if deficits persist

  • Meniscus repair – More intensive rehabilitation; one option is avoidance of weight bearing for 4-6 weeks, with full motion encouraged; the authors prefer to allow full weight bearing with the knee braced and locked in full extension for 6 weeks, while encouraging full motion when the knee is not bearing weight

Medical therapy can be used during trials of nonoperative management with associated rest, ice, and a rehabilitation program. If surgical treatment is indicated, medical therapy is valuable in postoperative management.

See Treatment and Medication for more detail.

Background

Our understanding of the meniscus has changed radically in the last century. In 1887, Sutton described the meniscus as "the functionless remains of a leg muscle."[2] Not until 1948 did Fairbanks appreciate that "meniscectomy is not wholly innocuous," in his classic report of postmeniscectomy radiographic changes.[3] Research and knowledge of the meniscus has continued. The critical importance of the meniscus of the knee joint is now understood.

Note the contrasting images below.

Magnetic resonance imaging scan showing a normal m Magnetic resonance imaging scan showing a normal meniscus.
Magnetic resonance imaging scan showing a torn med Magnetic resonance imaging scan showing a torn medial meniscus.

For patient education resources, see the Foot, Ankle, Knee, and Hip Center and Arthritis Center, as well as Knee Pain and Knee Injury.

Frequency

United States

See the list below:

  • Meniscal injuries may be the most common knee injury. The prevalence of acute meniscal tears is 61 cases per 100,000 persons.

  • The overall male-to-female incidence is approximately 2.5:1. The peak incidence of meniscal injury for males is in those aged 31-40 years. For females, the peak incidence is in those aged 11-20 years.

  • In patients older than 65 years, the rate of degenerative meniscal tears is 60%.

  • Root tears are observed in 28% of medial meniscal tears.[4]

  • Surgical procedures of the meniscus are performed on an estimated 850,000 patients each year.[5]

International

Estimates indicate that at least twice the number of meniscus procedures in the United States are performed worldwide.

Functional Anatomy

The menisci are 2 semilunar wedges in the knee joint positioned between the tibia and the femur. They are essentially extensions of the tibia that act to deepen the articular surfaces of the otherwise relatively flat tibial plateau to accommodate the relatively round femoral condyles. The superior surfaces are concave and in contact with the femoral condyles; the inferior surfaces are flat and conform to the tibial plateaus. The peripheral, convex borders of the menisci are thick and attach to the joint capsule; the opposite border tapers inward to a thin, free edge centrally. Therefore, menisci have a triangular shape in cross section. Each covers approximately two thirds of the corresponding articular surface of the tibia. The medial and lateral menisci each have distinct, individual anatomic characteristics.[6, 7, 8]

The medial meniscus is semicircular or C-shaped and approximately 3.5 cm in length from anterior to posterior. It is asymmetric with a considerably wider posterior horn than anterior horn. Peripherally, the medial meniscus is continuously attached to the joint capsule, with the middle portion being more firmly attached via connection with fibers of the deep medial collateral ligament. It is anchored to the tibia by the coronary (meniscotibial) ligaments.

The posterior horn of the medial meniscus inserts in the posterior intercondylar fossa directly anterior to the posterior cruciate ligament. The anterior horn attachment is more variable, distributed in a 6- to 8-mm area anterior to the anterior cruciate ligament (ACL) tibial attachment in the anterior intercondylar fossa. Some anterior fibers attach over the anterior periphery of the tibial articular surface, and some posterior fibers of the anterior horn merge with the transverse meniscal ligament that connects to the lateral meniscus.

The lateral meniscus is more nearly circular or O-shaped and covers a larger portion of the tibial plateau surface than the medial meniscus. Its length from anterior to posterior is slightly less than the medial meniscus, and it has an almost uniform width. There is attachment to the joint capsule peripherally, except in the region of the middle one third, where there is no attachment but rather a hiatus for the popliteal tendon.

Unlike the medial meniscus, there is no attachment of the lateral meniscus to the lateral collateral ligament, but the lateral meniscus is anchored to the tibia via coronary (meniscotibial) ligaments. Posteriorly, the lateral meniscus is uniquely attached to the medial femoral condyle by meniscofemoral ligaments. These ligaments are highly variable and pass anterior (ligament of Humphrey) and/or posterior (ligament of Wrisberg) to the posterior cruciate ligament. The posterior attachment to the tibia is just anterior to the medial meniscus attachment in the posterior intercondylar fossa. The anterior horn inserts anterior to the lateral tibial spine and in close proximity to the ACL tibial insertion. Some fibers actually may blend into the ACL.

Despite their attachments, both menisci have mobility. The medial meniscus, with excursion of approximately 5 mm, is half as mobile as the lateral meniscus, whose mobility may exceed 10 mm. The anterior horns are more mobile than the posterior horns. This mobility allows for improved conformity of the tibiofemoral joint. Because the posterior horn of the medial meniscus has the least movement, it is at greatest risk for disruption.

The microanatomy of the meniscus is dense fibrocartilage composed of cells and an extracellular matrix of collagen fibers in network. The cells are termed fibrochondrocytes because they appear to be a mixture of fibroblasts and chondrocytes. These cells are responsible for the synthesis and maintenance of the extracellular fibrocartilaginous matrix.

The most abundant component of the menisci is collagen (75%)—mainly type I collagen (>90%) but it also contains types II, III, V, and VI. Collagen fibers are arranged mostly along a longitudinal or circumferential direction, with some interwoven radial and oblique fibers. The circumferential fibers are related directly to the menisci's functional ability to dissipate compressive loads. The other fibers act primarily as ties to enhance structural rigidity and to help prevent longitudinal splitting. The extracellular matrix also includes proteoglycans, glycoproteins, and elastin.

Most meniscal tissue is avascular and depends on passive diffusion and mechanical pumping to provide nutrition to the fibrocytes within the meniscal substance. Arnoczky and Warren demonstrated the important vascular anatomy of the menisci.[9, 10] The limited peripheral blood supply originates from the medial and lateral inferior and superior geniculate arteries. Branches from these vessels give rise to a perimeniscal capillary plexus within the synovium and joint capsule, which, in turn, supplies the meniscus periphery.

Studies have shown that 10-30% of the periphery of the medial meniscus and 10-25% of the lateral meniscus receives a vascular supply; the remainder receives its nutrition from the synovial fluid from passive diffusion and mechanical pumping. A few terminal branches of these vessels, along with the middle geniculate artery through the synovial covering of the anterior and posterior horn attachments, supply increased vascularity to the meniscal horns. The potential for vascular ingrowth is essential for successful meniscal healing and surgical repair. Various zones of the meniscus are described based on the blood supply; the red zone is the well-vascularized periphery, the red-white zone is the middle portion with vascularity peripherally but not centrally, and the white zone is the central avascular portion.

The neuroanatomy of the meniscus is not well described. However, the distribution of neural elements has been demonstrated in essentially the same anatomic distribution as the vascular supply. The anterior and posterior horns are the most richly innervated, and the body innervation follows the pattern along the periphery. Although not entirely clear, these nerve endings are believed to play a role in sensory feedback and proprioception. The greater innervation of the horns of the meniscus reflects the need for feedback at the extremes of flexion and extension, when the meniscal horns are compressed and neural elements are activated.[6, 7, 8]

The meniscus has unique anatomic properties. An understanding of this anatomy is essential to comprehending its important functions, which include load bearing, load and force distribution, joint stability, joint lubrication, and proprioception.[6, 7, 11] One of the primary functions is to provide load bearing across the knee joint. Fifty percent of the compressive load in the knee is transferred by the menisci in extension, whereas up to 85% of the load is transferred at 90° of flexion. The collagen orientation makes this load bearing possible by converting the compressive forces to tensile forces.

Load and forces are distributed across a much larger surface area because of the menisci, which (1) decrease focal contact pressure by increasing the contact area and (2) protect the underlying articular cartilage. Resection of 15-34% of a meniscus may increase contact pressure by more than 350%. Normal knees have 20% better shock-absorbing capacity than meniscectomized knees.

Joint stability is increased because of meniscal structure, which allows increased congruence and conformity between the femoral condyles and tibial plateaus.[6, 7] The wedge-shaped meniscus attached to the tibia serves as a secondary stabilizer. For example, the posterior horn acts as a shim to resist anterior tibial translation relative to the femur. Meniscectomy alone may not increase knee laxity, but it has been shown that in association with ACL deficiency, anterior laxity is increased. Meniscal lubrication occurs by fluid exudation across the surface, much like articular cartilage.

The classification of meniscal tears provides a description of pathoanatomy. The types of meniscus tears include the following:

  • Longitudinal tears that may take the shape of a bucket handle if displaced

  • Radial tears

  • Parrot-beak or oblique flap tears

  • Horizontal tears

  • Root tears

  • Complex tears that combine variants of the above

 

Presentation

History

Most meniscal injuries can be diagnosed by obtaining a detailed history. Important points to address include the following:

  • Mechanism of injury

    • Meniscus tears are sometimes related to trauma, but significant trauma is not necessary. A sudden twist or repeated squatting can tear the meniscus. The timing of the injury is important to note, although patients often cannot describe a specific event.

    • Meniscus tears typically occur as a result of twisting or change of position of the weight-bearing knee in varying degrees of flexion or extension.

  • Pain

    • Pain from meniscus injuries is commonly intermittent and usually the result of synovitis or abnormal motion of the unstable meniscus fragment.

    • The pain is usually localized to the joint line. Meniscal root tears usually cause posterior knee pain.

  • Mechanical complaints: Patients often provide nonspecific descriptions, but these include reports of clicking, catching, locking, pinching, or a sensation of giving way. Root tears however, rarely cause mechanical symptoms.[12]

  • Swelling

    • Swelling usually occurs as a delayed symptom or may not occur at all. Immediate swelling indicates a tear in the peripheral vascular aspect.

    • Degenerative tears often manifest with recurrent effusions due to synovitis.

Physical

A complete examination, including that of the lower spine, ipsilateral hip and thigh, patellofemoral joint, and tibiofemoral joint, is essential when evaluating knee pain. Associated findings such as a perimeniscal cyst or ligamentous laxity suggest a higher likelihood of a meniscus injury. Important findings when examining a patient with a possible meniscus injury include the following:

  • Joint line tenderness

    • Joint line tenderness is an accurate clinical sign.[13] This finding indicates injury in 77-86% of patients with meniscus tears. Despite the high predictive value, operative findings occasionally differ from the preoperative assessment.

    • The examiner must differentiate collateral ligament tenderness that may extend further toward the ligament attachment sites, above and below the joint line.

  • Effusion

    • Effusion occurs in approximately 50% of the patients presenting with a meniscus tear.

    • The presence of an effusion is suggestive of a peripheral tear in the vascular or red zone (especially when acute), an associated intra-articular injury, or synovitis.

  • Range of motion

    • A mechanical block to motion or frank locking can occur with displaced tears.

    • Restricted motion caused by pain or swelling is also common.

  • Provocative maneuvers: These techniques cause impingement by creating compression and/or shearing forces on the torn meniscus between the femoral and tibial surfaces.

    • The McMurray test

      • This maneuver usually elicits pain or a reproducible click in the presence of a meniscal tear. The medial meniscus is evaluated by extending the fully flexed knee with the foot/tibia internally rotated while a varus stress is applied. The lateral meniscus is evaluated by extending the knee from the fully flexed position, with the foot/tibia externally rotated while a valgus stress is applied to the knee. One of the examiner's hands should be palpating the joint line during the maneuver.

      • Only 57% of meniscal root tears result in a positive McMurray test.[12]

    • The Steinmann test

      • Tibial rotation is performed with the patient seated and the knee flexed 90º. Asymmetric pain is created with external (medial meniscus) or internal (lateral meniscus) rotation.

    • The Apley test

      • This maneuver is performed with the patient prone and the knee flexed 90º. An axial load is applied through the heel as the lower leg is internally and externally rotated. This grinding maneuver is suggestive of meniscal pathology if pain is elicited at the medial or lateral joint.

    • The Thessaly test

      • This maneuver is performed with the patient standing on one leg and the knee flexed to 5º and 20º while holding the examiner’s hand for balance. From this position, the patient is asked to internally and externally rotate the knee. Pain or a locking or catching sensation at the medial or lateral joint line is suggestive of meniscal tears.

    • Similar tests, including those that elicit the Bragard sign, Böhler sign, Payr sign, Merke sign, Childress sign, and Finochietto sign, are based on the provocative principle.

 

DDx

 

Workup

Imaging Studies

See the list below:

  • Plain radiography: An anteroposterior weight-bearing view, posteroanterior 45º flexed view, lateral view, and Merchant patellar view should be obtained to rule out degenerative joint changes (arthritis) or fractures.

  • Arthrography: Historically, arthrography was the standard imaging study for meniscal tears, but it has been replaced by magnetic resonance imaging (MRI).

  • MRI: This is the criterion standard imaging study for imaging meniscus pathology and all intra-articular disorders.[14, 15]

    • Normal menisci have a homogeneous low signal. Abnormal meniscal signals are classified into the following 3 groups:

      • Grade I – Small area of increased signal within the meniscus

      • Grade II – Linear area of increased signal that does not extend to an articulating surface

      • Grade III – Abnormal increased signal that reaches the surface or edge of the meniscus

    • Grade I and II changes are common in older patients as evidence of the normal aging degenerative process and in young patients as normal perforating vascular channels. Grade I and II changes are not usually seen arthroscopically and do not represent meniscal tears. Grade III changes are meniscal tears.

    • MRI has proven to be an effective technique for evaluating menisci.

      • Average sensitivity – 95% medial, 81% lateral

      • Average specificity – 88% medial, 96% lateral

      • Average accuracy – 92% medial, 92% lateral

    • Meniscal root tears are directly or indirectly diagnosed by MRI by assessing the amount of meniscal extrusion, defined as at least 3 mm of coronal translation beyond the margin of the tibia.[1, 16]

Procedures

See the list below:

  • Arthroscopy

    • In the hands of a competent arthroscopist, arthroscopy is considered the best tool for meniscal tear diagnosis, with sensitivity, specificity, and accuracy approaching 100%.

    • Arthroscopy is therapeutic and diagnostic and thus offers the advantage of immediate treatment of most disorders.[15, 17, 18]

 

Treatment

Acute Phase

Rehabilitation Program

Physical Therapy

A home physical therapy program or simple rest with activity modification, ice, and nonsteroidal anti-inflammatory drugs (NSAIDs) is the nonoperative management of possible meniscus tears. The physical therapy program goals are to minimize the effusion, normalize gait, normalize pain-free range of motion, prevent muscular atrophy, maintain proprioception, and maintain cardiovascular fitness. Choosing this course of treatment must include consideration of the patient's age, activity level, duration of symptoms, type of meniscus tear, and associated injuries such as ligamentous pathology. A trial of conservative treatment should be attempted in all but the most severe cases, such as a locked knee secondary to a displaced bucket-handle tear.

Medical Issues/Complications

The main complication at this stage of treatment is the absence of healing and failure of symptoms to resolve. The natural history of a short (< 1 cm), vascular, longitudinal tear is often one of healing or resolution of symptoms. Stable tears with minimal displacement, degenerative tears, or partial-thickness tears may become asymptomatic with nonoperative management.[19]

Most meniscal tears do not heal without intervention. If conservative treatment does not allow the patient to resume desired activities, his or her occupation, or a sport, surgical treatment is considered. Surgical treatment of symptomatic meniscal tears is recommended because untreated tears may increase in size and may abrade articular cartilage, resulting in arthritis (see Treatment, Acute Phase, Surgical Intervention).

Surgical Intervention

If symptoms persist, if the patient cannot risk the delay of a potentially unsuccessful period of observation (eg, elite athletes), or in cases of a locked knee, surgical treatment is indicated.[20]

The basic principle of meniscus surgery is to save the meniscus.[21] Tears with a high probability of healing with surgical intervention are repaired. However, most tears are not repairable and resection must be restricted to only the dysfunctional portions, preserving as much normal meniscus as possible.

Surgical options include partial meniscectomy or meniscus repair (and in cases of previous total or subtotal meniscectomy, meniscus transplantation). Arthroscopy, a minimally invasive outpatient procedure with lower morbidity, improved visualization, faster rehabilitation, and better outcomes than open meniscal surgery, is now the standard of care. One study found that arthroscopic pullout repair of a medial meniscus root tear provided better results than partial meniscectomy.[22]

Partial meniscectomy is the treatment of choice for tears in the avascular portion of the meniscus or complex tears that are not amenable to repair. Torn tissue is removed, and the remaining healthy meniscal tissue is contoured to a stable, balanced peripheral rim.

Meniscus repair is recommended for tears that occur in the vascular region (red zone or red-white zone), are longer than 1 cm, are root tears, involve greater than 50% of the meniscal thickness, and are unstable to arthroscopic probing. A stable knee is important for successful meniscus repair and healing. Thus, associated ligamentous injuries must be addressed.

The most commonly associated ligamentous disruption is complete tear of the ACL, which must be reconstructed to prevent recurrent meniscal tears. Fortunately, the increased blood and growth factors in the knee during meniscal repair combined with cruciate reconstruction significantly improves the outcome of the meniscal repair. In ACL-intact knees with isolated meniscal tears, healing rates are less than those in ACL-reconstructed knees, but they are higher than those in ACL-deficient knees.

The principles of repair include smoothing and abrading the torn edges and bordering synovium to promote bleeding and healing. Likewise, needle trephination of the meniscal body (poking holes to create vascular channels) can be performed.

Meniscus repair fixation techniques are numerous and variable. Fixation can be accomplished with outside-in, inside-out, or all-inside arthroscopic procedures.[6, 23, 24, 25] The outside-in and inside-out methods are usually performed with sutures and require additional incisions. Suture repair can be accomplished with vertical or horizontal stitches. The all-inside method is very popular, and a plethora of commercially available meniscus repair devices are available (eg, biodegradable arrows or darts, sliding knot sutures with extracapsular anchor fixation).

Over the past decade, there have been multiple laboratory and clinical studies investigating the efficacy and safety of third- and fourth-generation all-inside devices. The current literature on the efficacy of the all-inside technique is best summarized by 3 independent systematic reviews.[26, 27, 28]

In a 2007 systematic review of the all-inside technique, Lozano et al reported a failure rate of 0-43%.[26] There were no significant differences in efficacy noted among the different all-inside devices included in the review.

In a 2012 systematic review that compared the all-inside and outside-in techniques in isolated meniscal tears (eg, without concomitant ACL reconstruction), Grant et al reported the failure rates of the all-inside and outside-in techniques were 19% and 17%, respectively.[27] The final Lysholm and Tegner activity scores were similar between the techniques.

In the same year (2012), Nepple et al provided the most comprehensive systematic review of all meniscal repair techniques to date, in which they pooled outcomes data at greater than 5 years of these procedures, and observed no difference in outcome among the open, outside-in, inside-out, and all-inside techniques.[28] The pooled clinical failure rate of open repair was 23.1%; inside-out, 22.3%; outside-in, 23.9%; and all-inside, 24%.

Prospective, randomized controlled trials are lacking; ultimately, they are necessary to determine the most effective method of surgical repair.

In recent years, meniscal root tears have been investigated as a unique type of meniscal tear that requires special attention. Multiple biochemical studies have shown that the joint contact mechanics of a posterior root tear is almost identical to that of a complete meniscectomy, and that repair restores normal mechanics.[29, 30] The global loss of circumferential hoop tension caused by root tears is believed to be the source of the increased joint contact forces observed in affected patients. Therefore, there has been an increased focus to surgically repair root tears more aggressively.

Surgical repair of root tears, however, poses a unique challenge in that the meniscus must be repaired to bone. The root is fixed to bone by either arthroscopically-assisted bone suture anchors (all-inside technique) or an intraosseous suture technique ("pullout technique").[31, 32, 33, 34, 35]

In a study comparing the results of the pullout technique with partial meniscectomy, investigators showed that repair improved functional outcomes and decreased progression of arthritic changes.[36] A separate study that compared the results of the all-inside and pullout techniques showed no difference in function or repair characteristics between the 2 techniques[37] : Complete structural healing was observed in 86% of patients who underwent the all-inside technique and 65% of those who underwent the pullout technique (P >0.05). In another study, investigators assessed the results of the all-inside repair and reported significant improvement in the amount of sagittal extrusion; however, improvement of coronal extrusion was not observed.[38]

Future prospective, randomized controlled trials are needed to compare the effectiveness of these techniques with respect to healing rates and prevention of arthritic changes.

A systematic review and meta-analysis found that arthroscopic surgery for patients with degenerative meniscal tears and mild or no osteoarthritis provided no benefit when compared with nonoperative management.[39]

A study by Kise et al that included 140 adults looked to determine if exercise therapy is as effective as arthroscopic partial meniscectomy for knee function in middle aged patients with degenerative meniscal tears. The subjects were randomly assigned to the treatment groups. The study found no differences at 2 years between the exercise therapy group and the arthroscopic surgery group in knee function and found greater muscle strength in the exercise group at 3 months and 12 months.[40, 41]  The results from this study led to the formation of an expert multidisciplinary panel to review the literature for or against the use of arthroscopy for patients with degenerative knee disease. The panel issued a strong recommendation against arthroscopy for most patients with degenerative knee disease.[42]  Another study by Sihvonen et al that included 146 adults with symptoms for degenerative medial meniscus tear without knee osteoarthritis who were randomized to arthroscopic partial meniscectomy or placebo surgery reported no statistically significant differences between the two groups.[43]

 

Human allograft meniscal transplantation is a relatively new procedure but is being performed increasingly frequently. Specific indications and long-term results have not yet been clearly established. Meniscus transplantation requires further investigation to assess its efficacy in restoring normal meniscus function and preventing arthrosis.

Recovery Phase

Rehabilitation Program

Physical Therapy

Physical therapy during recovery is directed toward the same goals as those in the acute phase. For partial meniscectomy, patients may return to low-impact or nonimpact workouts such as stationary cycling or straight-leg raising on the first postoperative day and may advance rapidly to preoperative activities. In most patients, this can usually be accomplished without formal physical therapy. However, evidence suggests that the quadriceps remains weaker than that of the contralateral side for up to 12 weeks; therefore, therapy should be initiated if deficits persist.

When a meniscus repair is performed, the rehabilitation is typically more intensive. Many different protocols are described in the literature. Three main issues are considered in the rehabilitation of meniscus repairs: knee motion, weight bearing, and return to sports.[25] A common protocol is avoidance of weight bearing for 4-6 weeks, with full motion encouraged. A more aggressive approach is promoted by some surgeons. The authors' protocol is to allow full weight bearing with the knee braced and locked in full extension for 6 weeks, while encouraging full motion when the knee is not bearing weight. Note that meniscal rehabilitation must not interfere with concomitant ACL rehabilitation.

Medical Issues/Complications

Reported complication rates for arthroscopic meniscectomy range from 0.5-1.7%, and these can occur intraoperatively or postoperatively. Intraoperative complications include anesthetic problems, articular cartilage damage, vessel or nerve injury, or instrument failure. Postoperative complications include anesthetic concerns, thrombophlebitis, hemarthrosis, infection, stiffness, persistent pain, effusion, or synovitis.

Reported complication rates for meniscus repairs range from 1-30%. The list of complications is the same as that for meniscectomies, with a greater concern for neurovascular injury. Additionally, failure to heal or meniscal reinjury can occur.

 

Medication

Medication Summary

Medical therapy is used in the treatment of meniscal injuries. It can be used during trials of nonoperative management with associated rest, ice, and a rehabilitation program. If surgical treatment is indicated, medical therapy is valuable in postoperative management.

Nonsteroidal anti-inflammatory drugs

Class Summary

NSAIDs are a first-line medical therapy. The goal with the use of these agents is to reduce pain and inflammation during early attempts at conservative management of meniscal tears or during the postoperative period following surgical treatment. Myriad drugs are available. A few are listed below, including the newer cyclooxygenase (COX)-2 inhibitors. The COX-2 inhibitors are more specifically directed at inflammation and pain without the gastrointestinal (GI) toxicity.

Ibuprofen (Motrin, Ibuprin)

DOC for mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Celecoxib (Celebrex)

Inhibits primarily COX-2, which is considered an inducible isoenzyme; induced during pain and inflammatory stimuli. Inhibition of COX-1 may contribute to NSAID GI toxicity. At therapeutic concentrations, COX-1 isoenzyme is not inhibited; thus, GI toxicity may be decreased. Seek lowest dose for each patient.

Analgesics

Class Summary

Analgesics are an alternative therapy to NSAIDs with similar indications. These agents are directed primarily at controlling pain and do not have an anti-inflammatory effect.

Acetaminophen (Tylenol, Feverall, Aspirin-Free Anacin)

DOC for pain in patients with documented hypersensitivity to aspirin or NSAIDs, with upper GI disease, or who are taking oral anticoagulants.

Narcotic analgesics

Class Summary

Narcotic analgesics should be used sparingly in the conservative treatment period. The use of these agents is warranted only in special cases in which intolerable pain is present that cannot be controlled by the first-line drugs. However, these drugs are commonly used in the postoperative period when surgical treatment is necessary. Many options are available, and narcotic analgesics are commonly combined with drugs from the above categories. Common examples are listed.

Hydrocodone and acetaminophen (Vicodin, Lortab, Norcet)

Drug combination for moderate to severe pain.

Oxycodone (Roxicodone, OxyContin, OxyIR)

Indicated for moderate to severe pain.

 

Follow-up

Return to Play

Return to play after a meniscus injury is expected. The timing varies and depends on the injury, treatment, and rehabilitation protocol. In many cases, athletes can return to their sport as soon as 2-3 weeks status post arthroscopic partial meniscectomy or 6-8 weeks status post meniscal repair.

Complications

Complications are discussed under Recovery Phase, Medical Issues/Complications. In the long term, meniscal repairs fail to heal in 5-10% of patients. Failure rates are lower when the tears are repaired in patients with concomitant ACL reconstruction.

In patients with untreated tears, enlargement of the tear and arthrosis are common. In patients who are status post partial meniscectomy, arthrosis is also a concern. However, arthroscopists are hopeful that long-term outcome studies will demonstrate that a partial meniscectomy can delay or prevent the degenerative changes noted by Fairbanks in patients who had open total meniscectomy.[3]

Prevention

Prevention of recurrent problems is accomplished best by reestablishing and maintaining knee fitness with strength, flexibility, and proprioception.

 

Questions & Answers

Overview

What are meniscus injuries?

What should be the focus of history in the evaluation of meniscus injuries?

Which physical findings suggest a meniscus injury?

Which provocative maneuvers are performed in the exam for meniscus injuries?

What is the role of imaging studies in the diagnosis of meniscus injuries?

What is the role of MRI in the grading of meniscus injuries?

What are the benefits of arthroscopy in the diagnosis of meniscus injuries?

What is the initial treatment for meniscus injuries?

What are the surgical options for treating meniscus injuries?

What is included in physical therapy following surgery for meniscus injuries?

What is the role of medical therapy in the treatment of meniscus injuries?

What is the appearance of a meniscus tear on MRI?

What is the prevalence of meniscus injuries in the US?

What is the global prevalence of meniscus injuries?

What is the functional anatomy relative to meniscus injuries?

What is the functional anatomy of the medial meniscus?

What is the functional anatomy of the posterior and anterior horn of the medial meniscus?

What is the functional anatomy of the lateral meniscus?

What are the mobilities of the lateral and medial menisci?

What is the microanatomy relative to meniscus injuries?

What is the most abundant component of the menisci?

What is the vascular anatomy relevant meniscus injuries?

What is the significance of vascular supply in meniscus injuries?

What is the neuroanatomy relevant to meniscus injuries?

What is the role of the meniscus in load and force distribution in the knee?

How does meniscectomy affect load and force distribution in the knee?

What are the joint stabilizing forces in the meniscal structure?

How are meniscus injuries classified?

Presentation

What should be the focus of the history in the evaluation of meniscus injuries?

Which physical findings suggest a meniscus injury?

DDX

What are the differential diagnoses for Meniscus Injuries?

Workup

What is the role of imaging studies in the workup of meniscus injuries?

What is the role of arthroscopy in the workup of meniscus injuries?

Treatment

What is the role of nonoperative management of meniscus injuries?

What is the efficacy of nonoperative management of meniscus injuries?

What is the role of surgery in the treatment of meniscus injuries?

When is surgery indicated for meniscus injuries?

What is the basic principle of surgical intervention to treat meniscus injuries?

What are the surgical options for treating meniscus injuries?

What is the role of partial meniscectomy in the treatment of meniscus injuries?

What is the role of meniscus repair in the treatment of meniscus injury?

What is the role of the ACL in the treatment of meniscus injuries?

What are the principles of meniscus injury repair?

How is fixation accomplished during meniscus injury repair?

What is the efficacy of all-inside technique for the treatment of meniscus injuries?

What is the treatment approach for meniscal root tears?

What is the challenges of meniscal root tear surgical repair?

What is the efficacy of pullout techniques to treat meniscus injuries?

What is the efficacy of arthroscopic surgery for degenerative meniscus tears?

What is the efficacy of exercise therapy in the treatment of degenerative meniscus tears?

What is the role of allograft transplantation in the treatment of meniscus injuries?

What are the goals of physical therapy in the treatment of meniscus injuries?

What is included in the physical therapy for meniscus injuries during the recovery phase?

What are the complication rates for arthroscopic meniscectomy?

What are the complication rates for meniscus repairs?

Medications

What is the role of medical therapy in the treatment of meniscus injuries?

Which medications in the drug class Narcotic analgesics are used in the treatment of Meniscus Injuries?

Which medications in the drug class Analgesics are used in the treatment of Meniscus Injuries?

Which medications in the drug class Nonsteroidal anti-inflammatory drugs are used in the treatment of Meniscus Injuries?

Follow-up

When can athletes return to play following surgical treatment of meniscus injuries?

What percentage meniscal repairs fail to heal?

What are the complications of untreated meniscus injuries?

How are recurrent meniscal injuries prevented?