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Meniscal Injury
Jennifer B. Schwartz, MD
image BASICS
DESCRIPTION
  • The menisci are fibrocartilaginous intra-articular structures located between the medial and lateral femoral condyles and tibial plateau.
  • Each meniscus has a body, anterior horn, and posterior horn
  • The menisci help stabilize the knee, distribute forces across the joint, and aid joint lubrication.
  • After age 10 years, the menisci begin to devascularize
    • In adults, the outer 1/3 remains vascularized.
    • The inner 2/3 is avascular and heals poorly.
Geriatric Considerations
Meniscal tears in older patients are typically due to chronic degeneration.
Pediatric Considerations
  • Meniscal injuries are rare in children <10 years old (prior to physial fusion).
  • Meniscal tears in young children are often due to a discoid meniscus (anatomic variant with thicker and wider meniscus—usually the lateral meniscus).
  • MRI is less sensitive and specific for diagnosing meniscal tears in children <12 years of age.
EPIDEMIOLOGY
  • More common in the 3rd to 5th decades of life
  • More common in males
Incidence
  • Medial meniscus more commonly injured
  • Injuries can be acute or degenerative.
    • Acute tears more likely <40 years old and due to trauma
    • Degenerative tears more likely >40 years old
Prevalence
One of the most common musculoskeletal injuries
ETIOLOGY AND PATHOPHYSIOLOGY
  • Acute tears typically occur due to a twisting motion of the knee with foot planted.
  • Degenerative tears occur with minimal trauma.
Genetics
A congenital abnormality leading to discoid meniscus increases the risk of meniscal tear among children. No specific gene locus has been identified.
RISK FACTORS
  • Increased age (>60 years), male
  • Obesity
  • High degree of physical activity (especially cutting sports like soccer, football, basketball, and rugby)
  • Anterior cruciate ligament (ACL), posterior cruciate ligament (PCL) insufficiency:
    • Waiting >12 months between ACL injury and surgery increases risk of medial meniscal tear (1)[C].
GENERAL PREVENTION
  • Treatment and rehabilitation of previous knee injuries, particularly ACL injuries
  • Strengthening and increased flexibility of quadriceps and hamstring muscles
COMMONLY ASSOCIATED CONDITIONS
  • ACL is concomitantly torn in 1/3 of cases.
  • Medial and lateral collateral ligament tears
  • Tibial plateau or femoral shaft fractures
  • Baker cyst—strong association with medial meniscal tears (2)[C]
image DIAGNOSIS
PHYSICAL EXAM
  • Pertinent findings on physical exam are the following:
    • Effusion (mild-moderate)
    • Joint line tenderness
    • Decreased range of motion, locking
    • Pain with full flexion (posterior horn tear) or extension (anterior horn tear)
  • Accuracy of special tests varies (3)[C]
    • Positive McMurray test: pain, clicking of meniscus being stressed
    • Positive Apley grind test is neither sensitive nor specific.
    • Positive Thessaly test: Patient rotates knee and body three times with knee flexed 20 degrees; has pain along joint line.
DIFFERENTIAL DIAGNOSIS
  • ACL or collateral ligament tear
  • Pathologic plica
  • Osteochondritis dissecans
  • Loose body or fracture
  • Osteoarthritis (OA)—symptoms of OA may be caused by meniscal tears (4)[C]
  • Patellofemoral syndrome
  • Gout, pseudogout, rheumatoid arthritis
DIAGNOSTIC TESTS & INTERPRETATION
  • Laboratory evaluation not indicated unless signs of septic arthritis.
  • Plain radiographs can detect fractures, loose bodies, or arthritic changes.
  • Ultrasound may help screen for meniscal tears. Less helpful for lateral tears (5)[C]
Follow-Up Tests & Special Considerations
  • MRI is the primary study to diagnose meniscal tears.
    • Increased signal within a meniscus corresponds to degenerative changes; signal contacting the articular surface indicates an acute tear.
  • Meniscal tears are often found incidentally on MRI and may not be the cause of patient's symptoms.
    • 36-76% of meniscal tears found on MRI were asymptomatic. Asymptomatic tears increase with age and in the setting of OA.
    • Patients with synovitis and displacement of meniscus on MRI may benefit from intervention (6)[C].
Diagnostic Procedures/Other
Arthroscopy may be needed if the MRI is indeterminate.
image TREATMENT
GENERAL MEASURES
  • Treatment depends on the type/location/extent of the tear, as well as age and activity level of the patient
  • Conservative treatment (RICE [rest, ice, compression, elevation], activity modification, physical therapy, intra-articular corticosteroid injections) are effective first-line options for many patients, especially those with degenerative tears.
    • No increased benefit from surgery versus physical therapy for symptomatic meniscal tears in patients with mild to moderate OA (7)[C].
    • Small, partial thickness, or peripheral tears may heal on their own or remain asymptomatic.
  • Consider surgical intervention if:
    • Mechanical symptoms, locking
    • Concurrent injuries (i.e., ACL tear)
    • Persistent symptoms following 3 to 6 months of conservative treatment
    • Young patients (<30 years) or very active patients with an acute tear
MEDICATION
First Line
NSAIDs, opioid analgesics if severe pain
ISSUES FOR REFERRAL
Surgical consult for patients meeting operative criteria or wishing surgical repair
ADDITIONAL THERAPIES
  • Rehabilitation is required for both surgical and nonsurgical patients.
  • Electrical stimulation may help improve recovery when coupled with physical therapy.
  • Weight control: Weight gain is associated with increased cartilage loss and pain in adults with medial meniscal tears.
  • Platelet-rich plasma (PRP) may or may not improve symptoms of meniscal tears (8)[C].
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SURGERY/OTHER PROCEDURES
  • Most surgeries can be performed arthroscopically.
  • Meniscectomy (partial or total) removes the injured portion of the meniscus.
    • Can lead to articular cartilage degeneration and OA. Higher risk if 40 years of age, high BMI, valgus malalignment (9)[C]
  • Meniscal repairs decrease future OA and often have better outcomes than meniscectomy (10)[C].
image ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
  • Return to play requires that the patient be pain-free, have full range of motion, and full strength.
  • Following meniscal repair, patients can generally return to all activities in 3 to 6 months.
  • Combined ACL and meniscal repair requires 6 months of postoperative rehabilitation before the patient can return to sports.
PATIENT EDUCATION
Patients should be aware of the risks and benefits of surgery compared with conservative treatment.
PROGNOSIS
Prognosis better if surgery is done within 8 weeks, patient is <30 years of age, or tear is peripheral/lateral <2.5 cm.
REFERENCES
1. Snoeker BA, Bakker EW, Kegel CA, et al. Risk factors for meniscal tears: a systematic review including meta-analysis. J Orthop Sports Phys Ther. 2013;43(6):352-367.
2. Artul S, Jabaly-Habib A, Artoul F, et al. The association between Baker's cyst and medial meniscal tear in patients with symptomatic knee using ultrasonography. Clin Imaging. 2015;39(4):659-661.
3. Smith BE, Thacker D, Crewesmith A, et al. Special tests for assessing meniscal tears within the knee: a systematic review and meta-analysis. Evid Based Med. 2015;20(3):88-97.
4. Kamimura M, Umehara J, Takahashi A, et al. Medial meniscus tear morphology and related clinical symptoms in patients with medical knee osteoarthritis. Knee Surg Sports Traumatol Arthrosc. 2015;23(1):158-163.
5. Akatsu Y, Yamaguchi S, Mukoyama S, et al. Accuracy of high-resolution ultrasound in the detection of meniscal tears and determination of the visible area of menisci. J Bone Joint Surg Am. 2015;97(10):799-806.
6. Troupis JM, Batt MJ, Pasricha SS, et al. Magnetic resonance imaging in knee synovitis: clinical utility in differentiating asymptomatic and symptomatic meniscal tears. J Med Imaging Radiat Oncol. 2015;59(1):1-6.
7. Katz JN, Brophy RH, Chaisson CE, et al. Surgery versus physical therapy for a meniscal tear and osteoarthritis. N Engl J Med. 2013;368(18):1675-1684.
8. Pujol N, Salle De Chou E, Boisrenoult P, et al. Platelet-rich plasma for open meniscal repair in young patients: any benefit? Knee Surg Sports Traumatol Arthrosc. 2015;23(1):51-58.
9. Hulet C, Menetrey J, Beaufils P, et al. Clinical and radiographic results of arthroscopic partial lateral meniscectomies in stable knees with a minimum follow up of 20 years. Knee Surg Sports Traumatol Arthrosc. 2015;23(1):225-231.
10. Xu C, Zhao J. A meta-analysis comparing meniscal repair with meniscectomy in the treatment of meniscal tears: the more meniscus, the better outcome? Knee Surg Sports Traumatol Arthrosc. 2015;23(1):164-170.
Additional Reading
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  • El Ghazaly SA, Rahman AA, Yusry AH, et al. Arthroscopic partial meniscectomy is superior to physical rehabilitation in the management of symptomatic unstable meniscal tears. Int orthop. 2015;39(4):769-775.
  • Goossens P, Keijsers E, van Geenen RJ, et al. Validity of the Thessaly test in evaluating meniscal tears compared with arthroscopy: a diagnostic accuracy study. J Orthop Sports Phys Ther. 2015;45(1):18-24.
  • Griffin JW, Hadeed MM, Werner BC, et al. Plateletrich plastma in meniscal repair: does augmentation improve surgical outcomes? Clin Orthop Relat Res. 2015;473(5):1665-1672.
  • Guenther ZD, Swami V, Dhillon SS, et al. Meniscal injury after adolescent anterior cruciate ligament injury: how long are patients at risk? Clin Orthop Relat Res. 2014;472(3):990-997.
  • Hall M, Juhl CB, Lund H, et al. Knee extensor muscle strength in middle-aged and older individuals undergoing arthroscopic partial meniscectomy: a systematic review and meta-analysis [published online ahead of print March 16, 2015]. Arthritis Care Res (Hoboken).
  • Katz JN, Brophy RH, Chaisson CE, et al. Surgery versus physical therapy for a meniscal tear and osteoarthritis. N Engl J Med. 2013;368(18):1675-1684.
  • Vermesan D, Prejbeanu R, Laitin S, et al. Arthroscopic debridement compared to intra-articular steroids in treating degenerative medial meniscal tears. Eur Rev Med Pharmacol Sci. 2013;17(23):3192-3196.
See Also
&NA;
Algorithm: Knee Pain
Codes
&NA;
ICD10
  • S83.209A Unsp tear of unsp meniscus, current injury, unsp knee, init
  • S83.249A Oth tear of medial meniscus, current injury, unsp knee, init
  • S83.289A Oth tear of lat mensc, current injury, unsp knee, init
Clinical Pearls
&NA;
  • Degenerative meniscal tears are common in patients >40 years of age and generally do not require surgical repair.
  • MRI is imaging modality of choice to identify meniscal tears.
  • Functional outcomes following meniscal injury are improved with a comprehensive plan of rehabilitation involving strengthening and stretching of knee musculature.
  • In patients opting for surgery, meniscal preservation should be the goal. Meniscal repairs have a better functional outcome and decreased risk of OA compared with meniscectomy.
  • Improving core strength, proprioception, and quadricep/hamstring flexibility may prevent knee injuries, especially in female athletes.