Meniscus Injuries of the Knee

Disease/Disorder

Definition

The meniscus is a crescent-shaped fibrocartilaginous wedge located between the femoral and tibial condyles of the knee that serve as shock absorbers to optimize load transmission across the knee joint. Each knee has two menisci, one medial and one lateral.¹ Injury to the meniscus occurs when there is acute or chronic damage to the structure of the meniscus.¹

Etiology

A meniscal tear is caused by a combination of axial loading and rotational forces that create shearing stress on the meniscus. Acute tears are often secondary to direct trauma to the knee, and degenerative tears are often secondary to age-related stress/deterioration.¹

Epidemiology including risk factors and primary prevention

Knee meniscal injuries are common with an incidence of 61 cases per 100,000 people. Risk factors include male sex and over 40 years of age. Individuals participating in activities or sports with frequent squatting and kneeling such as soccer, rugby, football, basketball, baseball, skiing, and wrestling are at increased risk of meniscal tears. Medial meniscal tears are more common than lateral.²

Patho-anatomy/physiology

The menisci distribute axial load, stabilize the knee during rotation, and facilitate joint lubrication. The medial meniscus is crescent-shaped and less mobile due to its firm attachments to the medial tibial condyle. The lateral meniscus is more C-shaped and mobile and attaches to the lateral tibial condyle. The menisci are secured to bone by ligament-like structures called meniscal roots.¹

Meniscal tissue is composed of roughly 75% water and 25% solid matrix—including Type I collagen, proteoglycans, glycoproteins, and elastin—and is organized into three histological layers. The outer layer contains lubricated collagen fibers that reduce friction. The middle layer features a lamellar, radially oriented collagen network that distributes compressive stress, while the inner layer is made up of circumferential fibers that resist tensile stress during axial loading. The peripheral 10-35% of the meniscus receives blood supply from branches of the popliteal artery. The outer one-third (“red-red zone”) is vascular and has excellent healing potential; the adjacent intermediate zone (“red-white zone”) has limited vascular supply and moderate healing potential; and the inner two-thirds (“white-white zone”) is avascular and has poor healing capacity.¹

Classification

Table 1. Morphology of Meniscal Tears.

Specific secondary or associated conditions and complications

Acute meniscal tears frequently accompany injuries to nearby ligaments, muscles, and bone following high‑energy knee trauma. Tears of the lateral meniscus are more common with acute ACL ruptures, whereas chronic ACL deficiency predisposes to medial meniscal injury.² Tibial‑plateau and femoral‑shaft fractures often coexist with meniscal damage.³ Peri‑articular tendon or muscle tears (e.g. quadriceps or patellar tendon) are also markers of high‑force mechanisms that can shear the meniscus.²

Chronic meniscal pathology is often linked to degenerative joint disease and connective‑tissue disorders. Age‑related osteoarthritis weakens the meniscal matrix and alters load distribution, leading to degenerative meniscal tears.⁴ Chronic synovial inflammation in rheumatoid arthritis can erode meniscal integrity and provoke tears. Inherited hypermobility syndromes such as Ehlers‑Danlos increase tear risk through capsular laxity and excessive joint motion.⁵

The discoid meniscus is a congenital variant more often occurring in the lateral meniscus. It has a unilateral prevalence of 3–5%, and bilateral prevalence of 20–25%. Although often asymptomatic in childhood, this condition predisposes children and adolescents to snapping, popping, and tearing even in the absence of trauma. Symptomatic discoid menisci are typically managed by partial meniscectomy.¹

Essentials of Assessment

History

Meniscal tears present variably depending on the mechanism and extent of injury. Typical symptoms include pain, swelling, and stiffness. Pain may be described as sharp or stabbing over the lateral or medial joint line. Pain and swelling develop relatively quickly after trauma or gradually with degenerative tears. Pain is often exacerbated by twisting movements and improves with rest.² Associated mechanical symptoms include clicking, catching, locking, buckling, or an inability to fully extend the knee. Patients may describe participating in high-risk activities including kneeling, squatting, carrying or lifting heavy weights, jumping, and activities requiring rapid acceleration/deceleration, or change of direction just prior to the onset of pain.² Direct trauma to the knee can also lead to meniscal injury but typically concomitantly with other ligamentous or bony injuries.² 

Physical examination

Evaluation should begin with inspection of the lower extremity including assessment of skin, edema, muscle bulk, knee alignment, and gait. Measure active and passive range of motion of the knee, comparing injured and noninsured sides. A large meniscus tear or intra-articular loose body may limit passive motion.⁶ Palpate the entire knee, including bony and soft tissue structures of the medial, lateral, anterior, and posterior knee with particular focus on temperature, edema, and localized tenderness. Joint-line tenderness and effusions commonly occur with meniscal tears. A neurologic examination of the lower extremities including manual muscle testing (with special attention to muscles around the knee joint), sensory testing of the knee and surrounding areas, and reflexes should be conducted. Absent reflexes or decreased sensation may suggest associated nerve injury.⁶Special tests (provocative maneuvers) to evaluate the meniscus are described in Table 2. Proximal and distal structures (e.g. spine, hip, femur, tibia/fibula, ankle) should be examined as appropriate to exclude alternate pain generators. The entire clinical picture must be considered as no single test is sufficient for definitive diagnosis.⁶

Table 2. Special Tests for Assessing Meniscal Tears.

Imaging

Radiographs do not allow for visualization of the meniscus but are obtained as part of the initial work-up. In patients over 50 years old, radiographs can evaluate for associated osteoarthritis.⁷ In cases of acute knee injury, radiographs are recommended particularly to rule out fractures if a patient meets one of five Ottawa Knee Rules:⁸

• Age 55 years or older
• Isolated tenderness of the patella
• Tenderness at the head of the fibula
• Inability to flex to 90 degrees
• Inability to bear weight for four steps immediately and in the emergency department

Magnetic resonance imaging (MRI), the “gold-standard” imaging, is the most accurate, non-invasive method for diagnosing meniscal injuries. MRI allows for visualization of the meniscus in all spatial planes and characterization of lesions according to type, while also enabling evaluation of cartilage and subchondral bone.⁷ According to Kim et al., sensitivity and specificity of MRI in detecting lateral and medial meniscal tears is 80.8% and 85.4%, and 91.8% and 79.9% respectively.⁹

Computed Tomography (CT) arthrography can be used to diagnose meniscal and cartilage injuries in patients unable to tolerate MRI. Contrast is injected into the knee joint and continuous rotation scanning is conducted to obtain high quality 2D multi-planar reconstructions of internal knee joint structures.⁷ CT arthrography has a sensitivity and specificity between 86-100% for evaluation of meniscal lesions.⁷ In general, CT arthrography is not preferred over MRI due to exposure to ionizing radiation and intravenous contrast administration. 

Ultrasound shows promise for diagnosing meniscal injury. By adjusting the patient’s position and repositioning the probe, ultrasound could be used to identify tears in the anterior, body and posterior regions of the medial and lateral menisci.¹⁰ Sensitivity and specificity for detecting meniscal pathology is estimated to be 91.2% and 84.2%, respectively. Cook et al. found ultrasonography performed by trained musculoskeletal ultrasonographers was two times more likely than MRI to correctly determine the presence or absence of meniscal pathology confirmed by arthroscopy.¹⁰ Potential advantages over MRI include point-of-injury assessment, reduced cost, and increased patient comfort and safety.¹⁰

Supplemental assessment tools

Arthroscopic knee surgery is the gold standard in diagnosis and treatment of meniscal injuries. However, diagnostic arthroscopy in isolation is not appropriate for evaluation of meniscal pathology as pre-operative imaging is recommended prior to invasive procedures.⁷

Early predictions of outcomes

Meniscal injuries accelerate cartilage degeneration, predisposing patients to osteoarthritis, chronic pain, and decreased function.¹¹ Meniscectomy has fallen out of favor as loss of the load-sharing, shock-absorbing, and lubricating meniscus has been shown to promote early-onset osteoarthritis.¹¹ One study found patients who underwent arthroscopic partial meniscectomy were over 10 times more likely to require a total knee arthroplasty (TKA) within 15 years, with those aged 30-39 being nearly 40 times more likely to undergo TKA compared to the general population.¹²

Environmental

There is some evidence that occupational knee-straining activities are associated with increased risk of meniscal lesions. These activities include squatting, kneeling, climbing stairs, and lifting or carrying heavy weights greater than 10 kg, common in professions such as construction, plumbing, and emergency/first response. Certain strategies, such as the use of knee pads, leg supports, and tools that allow workers to complete tasks in an upright position can minimize risk of meniscal injury in the workplace.¹³

Professional issues

Occupational groups such as floor layers, coal miners, and professional football players are at increased risk of meniscal injury. Prevention of knee disorders at work may be beneficial in reducing work-related health care costs and reducing time away from work.¹³

Rehabilitation Management and Treatments

Current Guidelines

Conservative management is appropriate for most patients with degenerative tears and some simple traumatic meniscal tears. Physical therapy is the mainstay of conservative treatment but additional techniques such as activity modification, knee bracing, quadriceps strengthening, and endurance activities like biking and swimming should also be employed.¹¹ Supervised exercise focused on improving strength, flexibility, and proprioception for eight weeks has been shown to improve outcomes in patients with degenerative medial meniscal tears, non-inferior to surgical management. Surgery may be appropriate in patients who continue to have pain, impaired function, and persistent and/or disabling mechanical symptoms after conservative treatment.^{11, 14}

Operative management is generally favored for healthy patients <40, tears in the vascular zone, complex meniscal tears >1cm, acute tears <6 weeks, and concurrent ACL injury.¹¹ Meniscal repairs, performed via open or arthroscopic approach, are most advantageous for traumatic tears in the vascular zone.¹¹

Partial meniscectomy may be performed in patients with refractory mechanical symptoms after 3 months of conservative treatment or those with meniscal tears that are not repairable. Total meniscectomy, or complete removal, is rarely performed due to significant negative impact on knee function and risk of osteoarthritis.¹¹ Early surgical intervention may be preferred in young athletes to accelerate return to play; however, research suggests that 12-month outcomes may be similar between surgical and nonsurgical groups.¹⁵

Post-operative rehabilitation aims to promote healing and return to function. Rehabilitation protocols have historically focused on protecting the surgical repair by avoiding weight-bearing in the first 6-8 weeks and prioritizing range of motion followed by progressive strengthening.¹⁶ However, newer research suggests early weight-bearing 0-2 weeks post-op results in no difference in healing rate or repair failure rates compared to more restrictive rehabilitation protocols.¹⁶

Patient & family education

Initial management of meniscal injury includes rest, ice, compression, and elevation (R.I.C.E). Oral medications, such as NSAIDs and Tylenol may be prescribed to help control pain and swelling.¹¹ Meniscal tears are common injuries, and treatment depends on factors such as tear type, location, and patient activity level. Many cases can be managed non-surgically with physical therapy, including a tailored home exercise program and activity modification. However, because meniscal tears increase the long-term risk of osteoarthritis, ongoing follow-up is essential to manage symptoms and optimize outcomes.¹¹

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

• Preserve the meniscus when possible. Meniscus preservation (repair or nonoperative care) results in better long-term outcomes than meniscectomy, which increases osteoarthritis risk.¹¹
• Start with rehab in younger patients. In adults under 40, structured rehab yields similar outcomes to early surgery at 12 months.¹⁵
• Use accelerated rehab after repair. Early weight-bearing and motion do not increase failure risk and improve strength and function.¹⁶
• Support shared decision-making. Explain that rehab often matches surgery in outcomes; use plain language, confirm goals, and offer surgery if rehab fails.
• Prioritize function over imaging for return to play. Using functional tests can help create an individualized rehabilitation protocol for return to sport.¹⁷

Cutting Edge/Emerging and Unique Concepts and Practice

Orthobiologics are becoming increasingly popular as a therapy to promote meniscal repair and improve surgical outcomes.¹⁸ Cell-free therapies include platelet-rich plasma (PRP), hyaluronic acid, and biomimetic gels. PRP is a concentrated autologous processed blood-based product that delivers a high concentration of growth factors and bioactive proteins to stimulate an inflammatory response and promote angiogenesis in the injected tissue. In the meniscus, PRP promotes blood flow into otherwise avascular tissue and thus allows for the healing of a meniscal tear.¹⁸

Cell based therapies, such as mesenchymal stem cells and scaffolds cell therapies hold great promise for regenerating damaged tissues, but they have not yet reached clinical practice.¹⁸

New techniques are being explored combining biomaterials and biomimetic constructs with stem cells to aid in cellular regeneration.¹⁸ A tissue-engineered construct (TEC) has shown promise in preclinical testing regenerating hyaline cartilage, as a potential adjunct to meniscal repair by promoting cartilage regeneration at the tear site.¹⁸

Gaps In The Evidence-Based Knowledge

Further research is needed to guide how tear type and repair technique can inform post-operative rehabilitation protocols. While stem cell therapies hold promise, there is currently limited clinical evidence to support their use. Rigorous studies on mesenchymal stem cells and scaffold-based approaches are essential before these treatments can be widely implemented.¹⁸

References

1. LaPrade RF, Chahla J. Evidence-Based Management of Complex Knee Injuries: Restoring the Anatomy to Achieve Best Outcomes. Elsevier; 2021.
2. Raj MA, Bubnis MA. Knee Meniscal tears. StatPearls [Internet]. July 17, 2023. Accessed April 22, 2025. https://www.ncbi.nlm.nih.gov/books/NBK431067/.
3. Malik S, Herron T, Mabrouk A, Rosenberg N. Tibial Plateau fractures. StatPearls [Internet]. April 22, 2023. Accessed May 7, 2025. https://www.ncbi.nlm.nih.gov/books/NBK470593/?utm.
4. Ozeki N, Koga H, Sekiya I. Degenerative meniscus in knee osteoarthritis: From pathology to treatment. Life (Basel, Switzerland). April 18, 2022. Accessed May 7, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC9032096/.
5. Ericson W, Wolman R. Orthopaedic management of the Ehlers–Danlos syndromes. American Journal of Medical Genetics Part C Seminars in Medical Genetics. February 13, 2017. Accessed May 7, 2025. http://onlinelibrary.wiley.com/doi/10.1002/ajmg.c.31551/full.
6. Malanga GA, Mautner KR. Musculoskeletal Physical Examination: An Evidence-Based Approach. Elsevier; 2017.
7. Lefevre N, Naouri JF, Herman S, Gerometta A, Klouche S, Bohu Y. A current review of the meniscus imaging: Proposition of a useful tool for its radiologic analysis. Radiology research and practice. February 11, 2016. Accessed April 28, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC4766355/#:~:text=MRI%20is%20the%20most%20accurate%20and%20least%20invasive%20tool%20for,and%20characterizing%20the%20meniscal%20lesion.
8. Still I, Greenberg G, Wells G, et al. Prospective validation of a decision rule for the use of radiography in acute knee injuries. JAMA. February 28, 1996. Accessed April 28, 2025. https://pubmed.ncbi.nlm.nih.gov/8594242/.
9. Kim SH, Lee H-J, Jang Y-H, Chun K-J, Park Y-B. Diagnostic accuracy of magnetic resonance imaging in the detection of type and location of meniscus tears: Comparison with arthroscopic findings. Journal of clinical medicine. February 5, 2021. Accessed April 28, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC7914628/.
10. Cook J, Cook C, Stannard J, et al. MRI versus ultrasonography to assess meniscal abnormalities in acute knees. The journal of knee surgery. January 28, 2014. Accessed April 28, 2025. https://pubmed.ncbi.nlm.nih.gov/24474166/.
11. Luvsannyam E, Jain MS, Leitao AR, Maikawa N, Leitao AE. Meniscus tear: Pathology, incidence, and management. Cureus. May 18, 2022. Accessed May 7, 2025. https://www.cureus.com/articles/98347-meniscus-tear-pathology-incidence-and-management#!/.
12. Abram S, Judge A, Beard D, Carr A, Price A. Long-term rates of knee arthroplasty in a cohort of 834 393 patients with a history of arthroscopic partial meniscectomy. The bone & joint journal. September 2019. Accessed May 12, 2025. https://pubmed.ncbi.nlm.nih.gov/31474146/.
13. Bahns C, Bolm-Audorff U, Seidler A, Romero Starke K, Ochsmann E. Occupational risk factors for meniscal lesions: A systematic review and meta-analysis. BMC musculoskeletal disorders. December 15, 2021. Accessed April 28, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC8672613/.
14. Mordecai SC, Al-Hadithy N, Ware HE, Gupte CM. Treatment of meniscal tears: An evidence based approach. World journal of orthopedics. July 18, 2014. Accessed May 7, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC4095015/.
15. Skou S, Hölmich P, Lind M, et al. Early Surgery or Exercise and Education for Meniscal Tears in Young Adults. NEJM Evidence. January 25, 2022. Accessed May 7, 2025. https://evidence.nejm.org/doi/pdf/10.1056/EVIDoa2100038.
16. Spang III R, Nasr M, Mohamadi A, DeAngelis J, Nazarian A, Ramappa A. Rehabilitation following Meniscal Repair: A systematic review. BMJ open sport & exercise medicine. February 9, 2018. Accessed May 7, 2025. https://pubmed.ncbi.nlm.nih.gov/29682310/.
17. Calanna F, Duthon V, Menetrey J. Rehabilitation and return to sports after isolated meniscal repairs: A new evidence-based protocol – Journal of Experimental Orthopaedics. SpringerOpen. August 17, 2022. Accessed May 9, 2025. https://jeo-esska.springeropen.com/articles/10.1186/s40634-022-00521-8.
18. Shimomura K, Jacob G, Hanai H, Nakamura N. Utilization of orthobiologic augmentation for meniscal repairs: Current concepts and future perspectives. Journal of Cartilage & Joint Preservation. November 17, 2022. Accessed May 9, 2025. https://www.sciencedirect.com/science/article/pii/S2667254522000531.

Original Version of the Topic

Christopher T. Plastaras, MD and Jerry Fang, MD. Meniscus injuries of the knee. 9/20/2013.

Previous Revision(s) of the Topic

Brian Pekkerman, MD; Puneet Ralhan, MD; and Richard G. Chang, MD, MPH. Meniscus injuries of the knee. 8/7/2017

German Valdez, MD, Abid Haque, MD, and Richard G. Chang, MD, MPH. Meniscus Injuries of the Knee. 12/22/2021

Author Disclosure

Jasmin Johnson, MD
Nothing to Disclose

Mona Amin, MD
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Laura Malmut, MD, MEd
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