Meniscal Injury 

Updated: Apr 24, 2020
Author: Sarjoo M Bhagia, MD; Chief Editor: Ryan O Stephenson, DO 

Overview

Practice Essentials

The physician treating an athlete with a known or suspected meniscal tear needs to understand the structure and function of the meniscus and the factors involved in treating an athlete with nonoperative versus operative treatment.[1] This article presents a program for rehabilitation after meniscal injuries, meniscectomy, and meniscal repair based on current knowledge of knee biomechanics. The protocols for rehabilitation of a meniscal injury take into consideration biomechanical principles and the results of the physical examination.

Understanding of the importance of the menisci in the biomechanics of the knee has progressed steadily since 1968, when Jackson wrote, "The exact function of that structure (meniscus) is still a matter of some conjecture."[2] At that time, it was common to remove the entire substance if any doubt existed regarding the integrity of the meniscus. Today, it is known that the menisci are not optional or expendable structures; they have an integral role in normal knee joint mechanics. (See 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.

Signs and symptoms of meniscal injury

In meniscal injury, acute joint-line pain may be described. Joint effusion gradually develops over a few hours. Patients with peripheral tears of the meniscus occasionally develop effusion rapidly (in minutes), secondary to a tear that is associated with hemarthrosis and is in the vascular outer one third of the meniscus.

Locking is a common symptom after a meniscal lesion develops, usually occurring at 20-45° of joint extension.

A sensation of giving way may occur. In true meniscal lesions, the fragment becomes lodged momentarily in the knee joint, causing a sense of buckling.

Workup in meniscal injury

Arthroscopy of the knee is the criterion standard for the diagnosis of a meniscal tear.

Magnetic resonance imaging (MRI) of the knee largely has replaced arthrography as the imaging modality of choice for the menisci, as the accuracy has been shown to be greater than 90%. MRI is not routinely required for the diagnosis of meniscal tears before proceeding with arthroscopic surgery; however, MRI helps to confirm the diagnosis and provides additional information concerning the status of the ligaments and articular cartilage.[3]

Arthrocentesis can be used as a diagnostic tool and a therapeutic procedure.

Management

The protocols for rehabilitation of a meniscal injury take into consideration biomechanical principles and the results of the physical examination. Factors such as the extent and location of the lesion, the amount of articular cartilage degeneration on weight-bearing surfaces, the duration of injury, and the joint stability affect the pace and aggressiveness of the rehabilitation program.

Pathophysiology

Anatomy

The menisci are C-shaped wedges of fibrocartilage located between the tibial plateau and femoral condyles. The menisci contain 70% type I collagen. The larger semilunar medial meniscus is attached more firmly than the loosely fixed, more circular lateral meniscus. The anterior and posterior horns of both menisci are secured to the tibial plateaus. Anteriorly, the transverse ligament connects the 2 menisci; posteriorly, the meniscofemoral ligament helps stabilize the posterior horn of the lateral meniscus to the femoral condyle. The coronary ligaments connect the peripheral meniscal rim loosely to the tibia. Although the lateral collateral ligament (LCL) passes in close proximity, the lateral meniscus has no attachment to this structure.

The joint capsule attaches to the entire periphery of each meniscus but adheres more firmly to the medial meniscus. An interruption in the attachment of the joint capsule to the lateral meniscus, forming the popliteal hiatus, allows the popliteus tendon to pass through to its femoral attachment site. Contraction by the popliteus during knee flexion pulls the lateral meniscus posteriorly, avoiding entrapment within the joint space. The medial meniscus does not have a direct muscular connection. The medial meniscus may shift a few millimeters, while the less stable lateral meniscus may move at least 1 cm.

In 1978, Shrive et al reported that the collagen fibers of the menisci are oriented in a circumferential pattern.[4] When a compressive force is applied in the knee joint, a tensile force is transmitted to the menisci. The femur attempts to spread the menisci anteroposteriorly in extension and mediolaterally in flexion. Shrive et al further studied the effects of a radial cut in the peripheral rim of the menisci during loading. In joints with intact menisci, the force was applied through the menisci and articular cartilage; however, a lesion in the peripheral rim disrupted the normal mechanics of the menisci and allowed it to spread when a load was applied. The load now was distributed directly to the articular cartilage. In light of these findings, it is essential to preserve the peripheral rim during partial meniscectomy to avoid irreversible disruption of the structure's hoop tension capability.

Blood supply

The blood supply to the menisci is limited to their peripheries. The medial and lateral geniculate arteries anastomose into a parameniscal capillary plexus supplying the synovial and capsular tissues of the knee joint. The vascular penetration through this capsular attachment is limited to 10-25% of the peripheral widths of the medial and lateral meniscal rims. In 1990, Renstrom and Johnson reported a 20% decrease in the vascular supply by age 40 years, which may be attributed to weight bearing over time.[5]

The presence of a vascular supply to the menisci is an essential component in the potential for repair. The blood supply must be able to support the inflammatory response normally seen in wound healing. Arnoczky, in 1982, proposed a classification system that categorizes lesions in relation to the meniscal vascular supply.[6]

  • An injury resulting in lesions within the blood-rich periphery is called a red-red tear. Both sides of the tear are in tissue with a functional blood supply, a situation that promotes healing.

  • A tear encompassing the peripheral rim and central portion is called a red-white tear. In this situation, one end of the lesion is in tissue with good blood supply, while the opposite end is in the avascular section.

  • A white-white tear is a lesion located exclusively in the avascular central portion; the prognosis for healing in such a tear is unfavorable.

Repair of lesions in the red zone has yielded good results, according to Stone. Reports describe techniques for manufacturing a vascular access channel from the peripheral vasculature to improve the chance that tissue in the central region will repair itself.

Biomechanics

The menisci follow the motion of the femoral condyle during knee flexion and extension. Shrive et al presented a model of normal meniscal function.[4] During extension, the femoral condyles exert a compressive force displacing the menisci anteroposteriorly. As the knee moves into flexion, the condyles roll backward onto the tibial plateau. The menisci deform mediolaterally, maintaining joint congruity and maximal contact area. As the knee flexes, the femur externally rotates on the tibia, and the medial meniscus is pulled forward. Studies by Shrive, Fukubayashi, Walker, and Kurosawa state that the menisci directly influence the transmission of forces, distribution of load, amount of contact force, and pressure distribution patterns.

Mechanism of injury

Meniscal injuries, particularly sports-related injuries, usually involve damage due to rotational force. A common mechanism of injury is a varus or valgus force directed to a flexed knee. When the foot is planted and the femur is internally rotated, a valgus force applied to a flexed knee may cause a tear of the medial meniscus. A varus force on a flexed knee with the femur externally rotated may lead to a lateral meniscus lesion. According to Ricklin, the medial meniscus is attached more firmly than the relatively mobile lateral meniscus, and this may result in a greater incidence of medial meniscus injury.[7]

Epidemiology

Frequency

United States

Although the exact incidence and prevalence of meniscal injury are unknown, it is a fairly common sports-related injury among adults. Although less common than in adults, knee meniscal injuries do occur in individuals who are skeletally immature. Meniscal injuries are rare in children younger than 10 years with morphologically normal menisci.[8]

Mortality/Morbidity

Meniscal injuries usually are associated with pain that results in gait deviation and loss of time from work and/or sport.

A study by Yasuda et al suggested that medial meniscus tears cause spontaneous osteonecrosis of the knee (SONK). Specifically, the study found medial meniscus extrusion and femorotibial angle to be significantly associated with SONK stage and volume in the medial femoral condyle.[9]

Race

A correlation of race and meniscal injuries is not known to exist.

Sex

Meniscal injuries are more common in males, which may be a reflection of males being more involved in aggressive sporting and manual activities that predispose to rotational injuries of the knee.

Age

Meniscal injuries are common in young males who are involved in sporting or manual activities. A second peak of incidence is observed in elderly persons older than 55 years; this incidence is secondary to a degenerate meniscus being susceptible to injuries with minor trauma.[10] Meniscal injuries are rare in children younger than 10 years with morphologically normal menisci.[8]

 

Presentation

History

A thorough subjective history can help the examiner choose the appropriate clinical tests to include in the physical examination. A complete understanding of the exact mechanism of injury helps determine what type of meniscal involvement to look for. Initial symptoms may include the following:

  • Acute joint-line pain may be described.

  • Joint effusion gradually develops over a few hours. Patients with peripheral tears of the meniscus occasionally develop effusion rapidly (in minutes), secondary to a tear that is associated with hemarthrosis and is in the vascular outer one third of the meniscus. In 1993, Stanitski et al studied 70 young patients with hemarthrosis after acute trauma and found that 47% had anterior cruciate ligament (ACL) tears and 47% had meniscal tears. In adolescents (aged 13-18 y), the rate was 65% and 45%, respectively.[11, 12]

  • Locking is a common symptom after a meniscal lesion develops. Locking usually occurs at 20-45° of joint extension. If a torn fragment has been trapped within the joint, extension may feel limited against a rubbery resistance. Joint effusion or capsular involvement also may mimic signs of locking. A more reliable indicator of meniscal lesion is a click or snap after the joint unlocks.

  • A sensation of giving way may occur. In true meniscal lesions, the fragment becomes lodged momentarily in the knee joint, causing a sense of buckling. This finding should be distinguished from the sensation of giving way due to joint instability (eg, ACL tear) or buckling secondary to decreased activity of the quadriceps femoris muscle.

Physical

During clinical examination, use the uninvolved leg as the reference for comparison with qualitative and quantitative findings of the involved leg. Examination should include inspection, palpation, range of motion (ROM), gait, girth measurements, and tests for integrity of menisci and other structures of the knee joint.[13]

  • Inspection

    • Look for effusion, and check the state of healing of any scars or incisions.

    • Identify any signs of atrophy. Marked atrophy of the quadriceps femoris muscle, especially the vastus medialis oblique (VMO) segment, is sometimes an indication of long-standing meniscal injury because the patient may be unwilling or unable to achieve full extension, and most tension is required of the VMO muscle at or near full extension.

  • Palpation

    • Localized palpable tenderness at the joint line often is present in patients with meniscal lesions because the coronary ligaments are irritated.

    • Assess joint lines for palpable pain. The location of the tenderness is not a sure sign of the type of lesion.

    • To assess effusion, perform the fluid shift test and evaluate for the presence of the fluctuation sign. The amount of effusion does not indicate the presence or absence of a meniscal lesion.

  • ROM and gait

    • The patient may have difficulty extending the knee fully if a meniscal tear blocks the motion.

    • Full flexion, as in squatting, may be painful or impossible because of a tear.

    • Assess the gait pattern, looking for deviations or compensatory movements.

  • Girth measurements

    • Girth (circumference) measurements allow for a general assessment of effusion and atrophy.

    • Swelling within the knee joint is measured grossly by a girth measurement taken at the joint line.

    • Measurements taken at 5 cm and 20 cm proximal to the base of the patella and 15 cm distal to the apex of the patella can provide an indirect indication of atrophy in the VMO segment, quadriceps femoris muscle, and calf muscles, respectively.

  • Tests: Perform stability tests for anterior, posterior, and varus-valgus motion to rule out additional involvement of soft tissue. Several special tests may be used to assess meniscal involvement. A positive result of any test does not by itself establish the presence of a meniscal lesion, but, along with the other objective findings, such a test result can help differentiate a meniscal tear from other possible knee injuries.

    • McMurray test

      • This test indicates tears of the middle or posterior horn of the meniscus.

      • With the patient supine and the hip and knee fully flexed, apply a valgus force and externally rotate the tibia while extending the knee. An audible or palpable pop or snap indicates a medial meniscal tear.

      • Lesions of the lateral meniscus are tested by applying a varus force and internally rotating the tibia during knee extension. The snap is produced as the torn fragment rides over the femoral condyle during extension.

      • A snap in extreme flexion is indicative of a posterior horn tear; a click at 90° of flexion indicates a lesion in the middle section of the meniscus.

    • Apley test

      • This test is used to distinguish between meniscal and ligamentous involvement.

      • With the patient in a prone position, the knee flexed at 90°, and the leg stabilized by the examiner's knee, distract the knee while rotating the tibia internally and externally. Pain during this maneuver indicates ligamentous involvement.

      • Then, compress the knee while internally and externally rotating the tibia again. Pain during this maneuver indicates a meniscal tear.

    • Bragard sign

      • This test may be used if anterior joint-line point tenderness is present.

      • To test for a medial lesion, the examiner extends and externally rotates the tibia, which displaces a meniscal lesion forward, if one exists. Palpable tenderness along the anterior medial joint line is reduced with flexion and internal rotation.

    • Bounce home test

      • The patient is supine with his or her heel cupped in the examiner's hand.

      • The examiner fully flexes the knee and then passively extends the knee. If the knee does not reach complete extension or has a rubbery or springy end feel, the knee movement may be blocked by a torn meniscus.

    • Childress test

      • Instruct the patient to squat with the knee fully flexed and attempt to "duck walk."

      • If the motion is blocked, a meniscal lesion is indicated; however, pain in this position may indicate a meniscal tear or patellofemoral joint involvement.

    • Merkel sign

      • Instruct the patient to stand with his or her knees extended and to rotate the trunk. This movement causes compression of the menisci.

      • Medial compartment pain during internal rotation of the tibia indicates a medial meniscal lesion. Lateral compartment pain occurring during external rotation of the tibia indicates a lateral meniscal lesion.

    • Modified Helfet test

      • While the patient is sitting on the edge of a table with the knee flexed 90°, instruct him or her to extend the knee.

      • If knee mechanics are within normal limits, the tibial tuberosity can be seen in line with the midline of the patella in full flexion; during extension, the tibia rotates and the tibial tubercle moves into line with the lateral border of the patella.

      • Failure of the tibia to rotate during extension indicates a meniscal lesion or cruciate ligament involvement.

    • O'Donoghue test

      • With the patient prone, the examiner flexes the knee 90°. The examiner rotates the tibia internally and externally twice, then fully extends the knee and repeats the rotations.

      • Increased pain during rotation in either or both knee positions indicates a meniscal tear or joint capsule irritation.

      • With a valgus force to a flexed and laterally rotated knee, the medial meniscus, medial collateral ligament (MCL), and the ACL all may be injured, representing the O'Donoghue triad.

    • Payr sign

      • With the patient sitting cross-legged, the examiner exerts downward pressure along the medial aspect of the knee.

      • Medial knee pain indicates a posterior horn lesion of the medial meniscus.

    • First Steinmann sign

      • With the patient supine and the knee and hip flexed at 90°, the examiner forcefully and quickly rotates the tibia internally and externally.

      • Pain in the lateral compartment with forced internal rotation indicates a lateral meniscus lesion. Medial compartment pain during forced external rotation indicates a lesion of the medial meniscus.

    • Second Steinmann sign

      • This test is indicated when point tenderness is located along the anterior joint line.

      • When the examiner moves the knee from extension into flexion, the meniscus is displaced posteriorly, along with its lesions. The point of tenderness also shifts posteriorly toward the collateral ligament.

Causes

Most commonly, meniscal injuries are due to a traumatic event (especially in athletes) or degenerative changes in older individuals. Meniscal tears are caused by twisting motions with the knee in a flexed position (eg, pivoting in basketball). Chronic or repetitive stress also may cause degenerative tears of the menisci.[7, 14]

A Danish study investigated whether an association exists between meniscal injuries and occupations that require kneeling.[15] Magnetic resonance imaging (MRI) of the knees was conducted in 92 male floor layers and compared with MRI scans from referents, in this case 49 male graphic designers. (The mean age for all persons in the study was 55.6 years.) The incidence of degenerative tears of the medial meniscus was significantly higher in floor layers than in graphic designers, the odds ratio (OR) being 2.28. Medial tears in both knees also occurred more frequently in floor layers (OR 3.46). Tears in the lateral meniscus, however, were no more prevalent in floor layers than in graphic designers.

 

DDx

Diagnostic Considerations

These include the following:

  • Collateral ligament injuries

  • Loose bodies in the knee

  • Osteochondritis dissecans

Differential Diagnoses

 

Workup

Laboratory Studies

See the list below:

  • If arthrocentesis is performed (see Procedures), send the fluid for analysis, though a hemarthrosis associated with acute injury often is evacuated only for patient comfort.

    • Send nonbloody fluid to the laboratory for cell count and determination of glucose and protein levels, Gram stain, bacterial culture, and special tests (eg, crystals), as indicated.

    • Posttraumatic aspiration of bloody fluid is suggestive of a cruciate ligament tear or an injury to the peripheral vascular part of the meniscus. If the bloody aspirate is associated with fat globules, it is highly suggestive of associated fractures.

Imaging Studies

Radiographic evaluation of the knee should include standing anteroposterior (AP), lateral, tunnel, and skyline views.[16]

MRI of the knee largely has replaced arthrography as the imaging modality of choice for the menisci, as the accuracy has been shown to be greater than 90%. MRI is not routinely required for the diagnosis of meniscal tears before proceeding with arthroscopic surgery; however, MRI helps confirm the diagnosis and provides additional information concerning the status of the ligaments and articular cartilage (see images below).[3]

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.

A study by Furumatsu et al indicated that existence of the giraffe neck sign on MRI is helpful in diagnosing medial meniscus posterior root tear (MMPRT). The study found the sign in 81.7% of MMPRTs but in only 3.3% of other medial meniscus tears and suggested that a combination of giraffe neck, cleft, ghost, and radial tear signs may play an important role in the MRI diagnosis of MMPRT.[17]

Procedures

See the list below:

  • Arthrocentesis

    • Arthrocentesis can be used as a diagnostic tool and a therapeutic procedure.

    • Not all effusions require aspiration, though drainage of the bloody effusion provides symptomatic relief, improves examination accuracy, and helps confirm severity of the injury.

    • Arthrocentesis can be accomplished quickly and easily with minimal patient discomfort. The knee is prepared in sterile fashion and anesthetized with local anesthetic to facilitate the use of a large-bore needle. The choice of the site of aspiration is a matter of operator preference. Accepted locations include the level of the joint line, which is 1 cm medial or lateral to the patellar tendon when the patient is seated. Alternatively, a location 2 cm medial or lateral to the anterior-superior patella when the patient is supine can be used. An 18-gauge needle is needed for aspiration of the viscous or bloody fluid.

  • Arthroscopy of the knee is the criterion standard for the diagnosis of a meniscal tear. (See image below.)

    Arthroscopic probing of a posterior horn complex m Arthroscopic probing of a posterior horn complex meniscal tear with multiple flaps.
 

Treatment

Rehabilitation Program

Physical Therapy

A study by El Ghazaly et al indicated that in patients with symptomatic unstable meniscal tears, better treatment results can be achieved with arthroscopic partial meniscectomy (APM) than with physical therapy. The study, on 70 patients, found that although pain and swelling were reduced in the physical therapy patients, their injured knees continued to have limited range of motion, with greater knee function and treatment satisfaction found in the APM patients.[18]

On the other hand, a study by Stensrud et al reported that in middle-aged patients with degenerative meniscal tears, a 12-week supervised exercise therapy program can yield similar results to APM. Indeed, isokinetic knee extension peak torque was a mean 16% greater in the exercise group.[19]

The protocols for rehabilitation of a meniscal injury take into consideration biomechanical principles and the results of the physical examination. Factors such as the extent and location of the lesion, the amount of articular cartilage degeneration on weight-bearing surfaces, the duration of injury, and the joint stability affect the pace and aggressiveness of the rehabilitation program. No preset duration for any phase of rehabilitation is described in this section, and phases may overlap, depending upon the patient's progress and symptoms. The protocols should be adjusted to each patient's status, progress, and goals.

Rehabilitation following meniscectomy

Initial phase

When the patient first reports to outpatient physical therapy 4-7 days after surgery, he or she usually is able to bear full weight or as much weight as tolerated on the involved leg. Modalities are used as needed to decrease pain or swelling, including heat/ice contrasts, ice alone, transcutaneous electrical nerve stimulation (TENS), electric galvanic stimulation, and phonophoresis. As needed, the patient should perform flexibility exercises for the lower extremity musculature, including the hamstrings, quadriceps femoris, hip flexors, hip adductors, and calf muscles.

During the initial stage, the emphasis should be placed on overcoming any limitations to ROM. To increase passive flexion ROM, the patient should complete exercises such as wall slides. The patient uses the uninvolved leg to control the speed of descent and to push the involved leg back up into extension. The patient does not have to use the quadriceps muscle of the involved leg for this exercise, but he or she can use it if there is no pain.

After the patient attains 110-115° of flexion, he or she may substitute heel slides for supine wall slides to increase flexion ROM. Isometric exercises for the quadriceps muscle assist in strengthening the quadriceps muscle, especially the VMO segment. Electrical muscle stimulation may be used to help retrain poorly contracting VMO or quadriceps femoris muscles. Short-arc quadriceps femoris muscle exercises strengthen the quadriceps femoris muscle.

Additional exercises to strengthen the lower extremity musculature (eg, hamstrings, hip adductors, hip abductors, calf muscles) are included in the program. The patient can begin isotonic strengthening exercises for the hamstring muscles when he or she can flex the knee to at least 80-90°. Hip abduction strengthening may begin when VMO muscle contraction and strength is adequate. If the patient begins hip abduction exercises before the quadriceps femoris muscle is strong enough, the exercises may contribute to increased lateral tracking of the patella. The tensor fasciae latae muscle inserts into the iliotibial band distally, and contraction of this muscle increases the tightness of the fascial sheath, contributing to lateral patellar tracking.

Depending on weight-bearing ability and other symptoms, the patient can begin toe raise exercises to strengthen the lower leg. Proper foot placement is important, as it influences the stresses at the knee. Supination of the foot causes tibial external rotation and a varus force at the knee joint, resulting in increased pressure in the medial compartment. Pronation causes tibial internal rotation, a valgus force at the knee joint, and increased lateral compartment pressure.

Stationary bicycling may be implemented into the rehabilitation program when the patient attains 115-120° of knee flexion. This exercise increases joint lubrication, which helps to improve ROM. Tension and resistance should be adjusted according to the presence of effusion or the patient's complaints of pain. If the patient's ROM is not adequate, bicycling may cause forced motion and increased pressure, irritating the knee.

Intermediate phase

The patient should have full ROM to begin this phase. Modalities are continued as indicated by symptoms. Flexibility and strengthening exercises are continued, increasing resistance as tolerated. The patient may progress to isokinetic strength and endurance training.

The patient also may begin closed kinetic chain exercises during this phase. If the quadriceps femoris muscle is strong enough (ie, if the patient can lift 10 lb during short-arc quadriceps femoris muscle exercise), the running program may be initiated. The first stage of the running program is jogging in place on a trampoline. Unless pain or swelling occurs, the patient gradually progresses to jogging for 10-15 minutes.

Advanced phase

During the advanced phase, the patient continues to progress in strength-training exercises while beginning to return to sports activities. Track running may begin when the patient is able to run on the treadmill for 10-15 minutes at a pace of 7-8 minutes per mile (depending upon the patient's previous activity level). Once mileage on the track has reached 2-3 miles, agility drills and sport-specific activities may be performed.

Rehabilitation following meniscal repair

The program for rehabilitation following meniscus repair is similar in principle to the program that follows meniscectomy; however, more limitations are put on the patient's weight-bearing status, and the duration of each phase of rehabilitation is longer to allow for healing. Full weight bearing is postponed until 4-6 weeks after surgery to reduce the tensile and compressive forces on the repair site. During the initial phase of rehabilitation, more attention should be paid to applying modalities to decrease pain and effusion. ROM exercises are performed with caution so that the healing process is not delayed. Mobilization of the patella may be required to ensure proper mechanics of the patellofemoral joint. Stretching exercises include calf stretches to reduce the possibility of Achilles tendinitis when the patient resumes weight bearing on the involved leg. Ankle ROM exercises also may be required to maintain adequate ankle ROM before weight bearing begins.

Open kinetic chain strengthening exercises may begin during the initial phase, but caution must be used and the exercises must be reduced or suspended if the patient reports pain. Isokinetic training should not begin until the patient is able to lift 10 lb on the short-arc quadriceps muscle exercise. The running program may begin when the quadriceps femoris and hamstring muscles of the involved leg have reached approximately 70% of the strength of the same muscles of the uninvolved leg, as demonstrated by an isokinetic strength test.

Nonoperative rehabilitation

The program for nonoperative rehabilitation is similar in principle to the program that follows meniscectomy. Cryotherapy and nonsteroidal anti-inflammatory drugs (NSAIDs) play a very important role in the management of nonoperative meniscal injury. These medications help control the amount of swelling and provide some pain relief. Sometimes, aspiration is useful to decrease the effusion, and, rarely, an athlete may need a judicious 1-time corticosteroid injection. Although not routinely advocated, an injection may provide an athlete with a way to control the irritation within the knee so that performance may not falter. Maintenance of ROM of the knee is important, as are muscular strength and endurance.

A reasonable goal before return to athletic activity is strength of the injured lower extremity within 20-30% of the contralateral side. Initially, activity modification is useful, particularly in athletes who are "weekend warriors." The time frame for return to activity depends on a number of factors. Returning to competition depends on the demands and motivation of the athlete, as well as on the severity of the meniscal tear.

Surgical Intervention

Operative versus nonoperative treatment

Multiple factors are involved in making decisions regarding the management of an athlete with a known or suspected meniscal tear.[20] Factors such as the severity of the symptoms, the ability to perform one's activity, and the timing of possible surgery must be taken into account. The need for surgical management is quite evident in an individual with significant symptoms, such as a locked knee or debilitating pain with clinical or MRI evidence of a meniscal tear. A treatment decision may be much more difficult to make on an individual who has relatively mild symptoms of a meniscal tear and who is participating in a sporting event that is in the middle-to-late part of the season.

The severity of the symptoms can vary for different types of meniscal tears. A bucket-handle tear may cause the knee to lock and be quite painful, whereas a small vertical or radial tear that displaces may cause occasional symptoms of giving way and only mild pain. If the symptoms are infrequent and locking does not occur, then an initial period of conservative management may be indicated, depending on the activity level and demands of the athlete. If the athlete's ability to compete is impaired because of the symptoms, then nonoperative management is unlikely to be satisfactory and arthroscopic surgery should be helpful, although it may mean a delay of 1-4 weeks in returning to competition.

An athlete with recurrent mild symptoms but without impairment in the ability to compete may be a suitable candidate for delayed operative management. Thorough consultation between the athlete, the physician, and the athletic trainer must be undertaken before any decision is made. The athlete must be given a clear explanation of what a meniscus tear is and of what the potential ramifications of delaying surgery are. The potential ramifications of delaying surgery include the possibility of propagation of the tear or significant symptoms during a competition, which may preclude further participation at a particular event. Few published studies have examined the results of nonoperative treatment of meniscal tears, and, to the authors' knowledge, none have been performed in a prospective randomized fashion.

A study by Gauffin et al indicated that in middle-aged patients with meniscal injury, arthroscopic knee surgery combined with physical therapy brings greater pain relief than does physical therapy alone. In the prospective, randomized, single-blind trial, 150 patients aged 45-64 years who had been suffering from meniscal symptoms for more than three months were treated with physical therapy, including a three-month exercise program. Within this group, however, some patients were also treated with arthroscopic resection of meniscal injury, performed within four weeks of inclusion in the study. At 12-month follow-up, evaluation using the Knee Injury and Osteoarthritis Outcome Score determined that pain reduction was significantly greater in the patients who had been treated with physical therapy and surgery than in those treated only with physical therapy.[21]

However, a clinical practice guideline released by an international panel strongly recommended, based on a systematic review, that almost no patients with degenerative knee disease be treated with arthroscopic surgery. The panel included orthopedic surgeons, a rheumatologist, physical therapists, a general practitioner, general internists, epidemiologists, methodologists, and patients with degenerative knee disease who had or had not undergone arthroscopic treatment. It cited, with regard to the surgery, “a modest probability (< 15%) of small or very small improvement in short term pain and function that does not persist to 1 year,” as well as the postoperative limitations and, in rare cases, serious adverse effects that can occur.[22]

A literature review by Thorlund et al for the Danish Society of Sports Physical Therapy found moderate-level evidence that self-reported pain and function in degenerative meniscal tears can be improved as much with exercise as with surgery, with muscle strength improved to an even greater extent. In contrast to the Gauffin study, the investigators also stated that in cases of degenerative meniscal tears, high-quality evidence showed that using surgery in addition to exercise did not have a clinically significant impact on pain and function.[23]

Operative management

Once a decision has been made to proceed with operative management, further decisions regarding the surgical treatment of the meniscus tear need to be made (see images below). Intraoperatively, a decision has to be made whether to repair, excise, or leave the tear in the meniscus alone.

Arthroscopic probing of a posterior horn complex m Arthroscopic probing of a posterior horn complex meniscal tear with multiple flaps.
Arthroscopic view of medial meniscus after excisio Arthroscopic view of medial meniscus after excision of flap tear.

Numerous factors are involved in the determination of treatment of a meniscal tear. In assessing these factors, the clinician must be cognizant of meniscal biomechanics, including the role in load transmission and congruity of the knee joint, as discussed previously. Because of the importance of intact functional meniscus tissue, the first goal is to preserve as much of the viable tissue as possible. Many factors (eg, the location, length, pattern, stability, and chronicity of the tear; the athlete's age; presence of degenerative changes; concurrent intra-articular injuries; desired timing of return to competition) need to be taken into consideration during the decision-making process.[3, 24]

Other Treatment

When a patient is implementing nonoperative rehabilitation, an aspiration of the knee joint sometimes is useful to decrease effusion. Rarely, an athlete may need a judicious 1-time injection of a corticosteroid. Although not routinely advocated, an injection may provide an athlete with a way to control the irritation within the knee so that performance may not falter.

 

Medication

Medication Summary

The goals of pharmacotherapy are to reduce morbidity and prevent complications.

Analgesics

Class Summary

Pain control is essential to quality patient care. Analgesics ensure patient comfort and have sedating properties, which are beneficial for patients who have sustained injuries.

Acetaminophen (Tylenol, Feverall, Tempra, 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.

Nonsteroidal anti-inflammatory drugs

Class Summary

Have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known, but they may inhibit cyclooxygenase (COX) activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.

Ibuprofen (Motrin, Ibuprin)

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

Naproxen (Naprelan, Anaprox, Naprosyn)

For relief of mild to moderate pain; inhibits inflammatory reactions and pain by decreasing activity of COX, which results in a decrease of prostaglandin synthesis.

Diclofenac (Voltaren, Cataflam)

Designated chemically as 2-[(2,6-dichlorophenyl)amino] benzeneacetic acid, monosodium salt, with an empirical formula of C14 H10 Cl2 NO2 NA. One of a series of phenylacetic acids that has demonstrated anti-inflammatory and analgesic properties in pharmacological studies. Believed to inhibit COX, which is essential in biosynthesis of prostaglandins. Can cause hepatotoxicity; hence, monitor liver enzyme levels in first 8 wk of treatment.

Rapidly absorbed; metabolism occurs in liver by demethylation, deacetylation, and glucuronide conjugation. Delayed-release, enteric-coated form is diclofenac sodium, and immediate release form is diclofenac potassium. Has relatively low risk for bleeding GI ulcers.

Celecoxib (Celebrex)

Primarily inhibits COX-2. COX-2 is considered an inducible isoenzyme, induced during pain and by 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 of celecoxib for each patient.

 

Follow-up

Further Outpatient Care

See the list below:

  • Patients with meniscal injuries (operative or nonoperative) are recommended to receive outpatient physical therapy for rehabilitation. Please refer to the Physical Therapy section for appropriate treatment goals and guidelines.

Prognosis

The prognosis for pain-free return to sports is variable depending on comorbidities and severity of injury. Over the long term, meniscal injuries predispose to osteoarthritis[25] secondary to increased loads on the articular surfaces of the knee. However, the degree of correlation between meniscal injuries and osteoarthritis has not been well established in the literature.

A study by Everhart et al indicated that in middle-aged adults, meniscal tears and lateral meniscal extrusion accelerate loss of joint space. Patients with medial meniscal tears, regardless of whether or not extrusion had occurred, suffered an additional mean medial space loss of 0.05 mm/year, while those with lateral tears underwent an additional mean lateral space loss of 0.09 mm/year. Moreover, lateral extrusion was associated with an additional mean lateral space loss of 0.1 mm/year. Patients without lateral extrusion had a 0.5% annual incidence of knee arthroplasty, compared with a 1.5% rate for those with a lateral extrusion of less than 2.0 mm, and a 3.7% rate for those with an extrusion of 2.0 mm or more.[26]

A retrospective, dual-center study by Ronnblad et al of 918 patients who underwent meniscal repair indicated that surgeries using bioabsorbable arrows are more likely to fail than those employing all-inside sutures with anchors (hazard ratio [HR] = 1.8), with the failure rate also being higher for medial, rather than lateral, meniscal repairs (HR = 3.7).[27]

Patient Education

See the list below:

  • Unfortunately, most injuries to menisci occur during accidents that are, at times, not preventable. However, the following may help avoid these injuries:

    • Having strong thigh and hamstring muscles

    • Gently stretching the legs before and after exercise

    • Wearing shoes that fit properly when exercising and ensuring the shoes are appropriate for the activity being performed

    • When skiing, ensuring that ski bindings are set correctly by a trained professional so that the skis release when a fall occurs

  • For excellent patient education resources, see eMedicineHealth's patient education articles Knee Injury and Knee Pain.

 

Questions & Answers

Overview

What is a meniscal injury?

What is the anatomy of menisci relevant to meniscal injury?

What is the role of blood supply in the pathophysiology of meniscal injury?

What are the biomechanics of menisci relevant to meniscal injury?

What is the mechanism of meniscal injury?

What is the prevalence of meniscal injury in the US?

What is the morbidity associated with meniscal injury?

What are the racial predilections of meniscal injury?

What are the sexual predilections of meniscal injury?

Which age groups have the highest prevalence of meniscal injury?

Presentation

Which clinical history findings are characteristic of meniscal injury?

What is the role of the O&#39;Donoghue test in the physical exam of meniscal injury?

What is included in the physical exam to evaluate for meniscal injury?

What is the role of inspection in the physical exam of meniscal injury?

What is the role of palpation in the physical exam of meniscal injury?

What is the role of range of motion (ROM) and gait in the physical exam of meniscal injury?

What is the role of girth measurements in the physical exam of meniscal injury?

What tests are performed in the physical exam to evaluate for meniscal injury?

What is the role of the McMurray test in the physical exam of meniscal injury?

What is the role of the Apley test in the physical exam of meniscal injury?

What is the role of the Bragard sign in the physical exam of meniscal injury?

What is the role of the bounce home test in the physical exam of meniscal injury?

What is the role of the Childress test in the physical exam of meniscal injury?

What is the role of the Merkel sign in the physical exam of meniscal injury?

What is the role of the modified Helfet test in the physical exam of meniscal injury?

What is the role of the Payr sign in the physical exam of meniscal injury?

What is the role of the first Steinmann sign in the physical exam of meniscal injury?

What is the role of the second Steinmann sign in the physical exam of meniscal injury?

What causes meniscal injury?

DDX

Which conditions should be included in the differential diagnoses of meniscal injury?

What are the differential diagnoses for Meniscal Injury?

Workup

What is the role of lab testing in the workup of meniscal injury?

What is the role of imaging studies in the workup of meniscal injury?

What is the role of arthrocentesis in the diagnosis and management of meniscal injury?

What is the role of arthroscopy in the diagnosis and management of meniscal injury?

Treatment

What is the role of physical therapy in the treatment of meniscal injury?

What is the initial phase of rehabilitation following meniscectomy to treat a meniscal injury?

What is the intermediate phase of rehabilitation following meniscectomy to treat a meniscal injury?

What is the advanced phase of rehabilitation following meniscectomy to treatment a meniscal injury?

What is the rehabilitation program following repair of meniscal injury?

What is the role of rehabilitation in the nonoperative treatment of meniscal injury?

What is the difference between operative and nonoperative treatment of meniscal injury?

What is the role of surgery in the treatment of meniscal injury?

What is the role of aspiration in the treatment of meniscal injury?

Medications

What are the goals of drug treatment for meniscal injury?

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

Which medications in the drug class Analgesics are used in the treatment of Meniscal Injury?

Follow-up

What is the prognosis of meniscal injury?

What is included in patient education about meniscal injury?