Introduction\u00a0<\/b><\/h6>\n\n- Meniscal knee injuries are commonly seen in MSK clinics and can impact athletic patients at all levels of sport or recreational activity. Injuries are seen in both young patients following acute sports injuries and older adults with underlying degenerative joint disease.<\/span><\/li>\n
- The management of these injuries has evolved alongside the latest developments on tissue function, imaging modalities, regenerative approaches, acknowledging age related changes and rehabilitation goals.\u00a0<\/span><\/li>\n
- We discuss how a community MSK focussed pathway can highlight those that need escalation to \u201cacute knee clinics\u201d, further imaging or specialist orthopaedic or sports medicine input for treatment.\u00a0<\/span><\/li>\n<\/ul>\n
The Meniscus \u2013 structure and function\u00a0<\/b><\/h6>\n
The menisci are crescent-shaped fibrocartilaginous structures located on the lateral and medial sides of the knee joint. They have primarily been thought to assist with the following within the knee joint:\u00a0<\/span><\/p>\n\n- Mechanical stability<\/span><\/li>\n
- Shock absorption<\/span><\/li>\n
- Nutrition<\/span><\/li>\n
- Lubrication<\/span><\/li>\n<\/ul>\n
Anatomical variations, injury due to trauma, or age-related wear can impact these key functions and cause changes to the articular cartilage, weight bearing surfaces of the knee and synovial fluid make-up. Typical symptoms following a meniscus tear include pain, stiffness, knee swelling, a loss of range of motion and mechanical instability or locking.<\/span><\/p>\n![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/03\/meniscus-1-300x243.png\")
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Figure 1: Meniscus anatomy (1)<\/span><\/i><\/p>\nThe menisci are acellular and relatively avascular, with the periphery and capsule supplied by the medial, middle and lateral genicular arteries.\u00a0<\/span><\/p>\n\n- As the name suggests, the medial genicular artery supplies the medial meniscus, and the lateral genicular artery supplies the lateral meniscus.\u00a0<\/span><\/li>\n
- The medial meniscus has a particularly poor blood supply, resulting in poor healing potential following surgery (2).<\/span><\/li>\n<\/ul>\n
Histological studies have described age-related changes to the make-up and function of the menisci with increased age and tears associated with; a decreased rate of collagen turnover, increased cytokine and inflammatory signals (3), reduced microvascular blood supply (4), accumulation of glycation end products and reduced mechanical properties (3).\u00a0<\/span><\/p>\nMechanisms of injury\u00a0<\/b><\/h6>\n
Acute meniscal tears typically result from a twisting force applied to a weight bearing, flexed knee. In sport, this may be due to contact but can also occur due to sudden changes in direction or when landing from a jump.\u00a0<\/span><\/p>\nOn the other hand, degenerative tears often occur without a single clear causative event.<\/span><\/p>\nAs with other soft tissues, the meniscus is liable to age-related changes that increase the risk of a degenerative tear. Typically, these tears occur due to repetitive stress on a failing tissue, subject to high physical loads and in the context of metabolic risk factors, with little or no history of trauma (5).\u00a0<\/span><\/p>\nMeniscal injuries in the sporting patient: just how common are they?\u00a0<\/b><\/h5>\n
Acute meniscus tears are primarily observed in younger individuals and athletes, frequently occurring during sport or physical activity. Often, they will present with an associated ACL injury.<\/span><\/p>\n\n- A five-year cohort study found an<\/b> incidence of 5.1 meniscus tears per 100,000 athlete exposures<\/b> (training or competitive matches) in high school athletes (6).<\/span><\/li>\n
- Ligamentous lesion? Lateral likely<\/b>\n
\n- 66.7% of acute ACL injuries have been found to have an associated lateral meniscus tear, while only 4.6% had an associated medial meniscus tear and 6.0% had simultaneous tears of both menisci (7).<\/span><\/li>\n
- Such concomitant injuries tend to affect the posterior horn, and are often longitudinal ramp lesions (8).\u00a0<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- A key area for injury prevention: knee injuries in the female athlete<\/b><\/li>\n<\/ul>\n
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\n- In recent years the high incidence of ACL tears in female athletes has been an important point of discussion in sport.<\/span><\/li>\n
- The risk of ACL injuries in females is 2.8 times higher in football and 3.5 times higher in basketball than males (9).<\/span><\/li>\n
- Hormonal changes during the menstrual cycle have been proposed as a potential cause (surge in oestrogen during the late follicular phase)(10,11).<\/span><\/li>\n
- Given the high incidence of meniscus tears associated with ACL injury, it raises questions on whether a similar pattern exists for meniscus tears.<\/span><\/li>\n
- 68% of meniscus tears in high school athletes were suffered by males, however most of these injuries originated from boys’ American football, a sport in which no female equivalent was considered. In gender-comparable sports (football, basketball, lacrosse, softball), female athletes had more than double the risk of meniscal injury than male counterparts (6).<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/03\/meniscus-2-212x300.png\")
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Figure 2: Risk factors for meniscus tears<\/span><\/i><\/p>\nThe degenerate tear: what do we know about graceful ageing of the meniscal tissue?<\/b><\/h6>\n
Degenerative meniscus tears will typically present in patients aged over 50. Unlike acute tears, the onset of symptoms is chronic, gradually worsening with age. High BMI and repetitive trauma are also known risk factors for degenerative meniscus tears (12). They are also strongly associated with knee osteoarthritis (13).\u00a0<\/span><\/b><\/p>\n\n- Medial Meniscus is more frequently affected<\/b><\/li>\n<\/ul>\n
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\n- Usually found to be horizontal tears (14).<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Chronic ACL laxity is a risk factor for degenerative meniscus tears\u00a0<\/b><\/li>\n<\/ul>\n
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\n- Due to the increased pressure on the meniscus.\u00a0<\/span><\/li>\n
- Unlike acute ACL injury, chronic ACL insufficiency often results in a medial meniscus tear (8,15).<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Part of a wider degenerative process in the knee<\/b><\/li>\n<\/ul>\n
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\n- A 10-year cohort study indicated that individuals with a baseline medial meniscus injury exhibited substantially more advanced osteoarthritis on radiographic assessments compared to those without any meniscus injury.<\/span><\/li>\n
- The presence of osteophytes on knee X-Rays were associated with increased progression of meniscus tears (16).<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Subchondral insufficiency fractures of the knee (SIFK)<\/b>\n
\n- Strongly associated with degenerative meniscus tears and osteoarthritis (17).<\/span><\/li>\n
- Increased suspicion of SIFK may arise when a patient can specifically pinpoint a moment when sudden knee pain began, particularly if there is a background of\u00a0 osteoporosis and meniscal symptoms (18,19).<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
Meniscal tear grading<\/b><\/h6>\n
Several grading criteria exist for meniscal tears, however a clear descriptive report on the size, location and type alongside the following risk factors can help to guide treatment:\u00a0<\/span><\/p>\n\n- What is the tear type, size and location?<\/span><\/li>\n
- Is it acute or degenerative?<\/span><\/li>\n
- Are there any other associated soft tissue of cartilage injuries?<\/span><\/li>\n
- What is the patient’s age and healing potential of the tear?<\/span><\/li>\n
- Are there symptoms of instability or a risk of secondary injury or OA in the future?<\/span><\/li>\n<\/ul>\n
![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/03\/meniscus-3-212x300.png\")
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Figure 3: Management options for meniscus tears<\/span><\/i><\/p>\n\n\n\nTear Type<\/b><\/td>\n Appearance<\/b><\/td>\n Description<\/b><\/td>\n<\/tr>\n\nPeripheral Tear<\/span><\/td>\n ![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/03\/peripheral-tear-300x169.jpeg\")
<\/td>\nLesion of the outer rim of the meniscus, known as the peripheral zone.\u00a0<\/span><\/p>\nThis area has a rich blood supply, so has good healing potential.<\/span><\/td>\n<\/tr>\n\nHorizontal Tear (Cleavage tear)<\/span><\/td>\n ![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/03\/horizontal-tear-300x169.jpeg\")
<\/td>\nTears are horizontal and parallel to the tibial plateau.<\/span><\/p>\nThese tears are often degenerative and more likely to be found in older patients.<\/span><\/td>\n<\/tr>\n\nVertical Tear Repair<\/span><\/td>\n ![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/03\/vertical-tear-300x265.png\")
<\/td>\nTears extend in a vertical orientation and are more likely to occur acutely in younger patients following trauma.<\/span><\/p>\nThese are often associated with ACL injuries.<\/span><\/td>\n<\/tr>\n\nBucket handle tear\u00a0<\/span><\/td>\n ![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/04\/bucket-handle-tear-300x169.jpeg\")
<\/td>\nCentral tear of the meniscus. Peripheral ends are still attached to the knee, thus resembling a \u2018bucket-handle\u2019.<\/span><\/p>\nThe lower image and video show a flipped bucket handle tear \u2013 the meniscal tissue has been flipped into the joint between the femoral condyle and the tibial plateau.<\/span><\/p>\nThese are more common in younger patients following an acute tear.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nTable 1: Types of meniscus tears<\/span><\/i><\/p>\nMSK services should develop close links with orthopaedics to offer fast track referrals to \u201cacute knee\u201d clinics and have the capacity to offer rehab and discuss cases via integrated virtual clinics. An example of a community referral pathway is included below.<\/span><\/p>\n![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/04\/referral-pathway-191x300.png\")
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Figure 4: Community referral pathway for meniscus tears<\/span><\/i><\/p>\nVarious clinic-based examinations can be performed to aid the identification of meniscus tears. Findings from these tests should be taken in the context of the background and history of the presenting complaint. The sensitivities and specificities of these are highlighted below:<\/span><\/p>\n![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/04\/meniscus-assessment-300x300.png\")
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Figure 5: Clinic based tests to aid identification of meniscus tears<\/span><\/i><\/p>\nImaging:\u00a0MSK imaging options to consider for meniscal knee injuries<\/strong><\/h6>\nX-ray\/<\/b>Weightbearing films<\/b><\/p>\n
Can be used to assess for underlying osteoarthritis. (Kellgren-Lawrence criteria).\u00a0<\/span>The addition of Rosenberg views can improve sensitivity.\u00a0<\/span><\/p>\nMRI (See below for MRI examples)<\/b><\/span><\/i><\/p>\nMRI 2-slice-touch rule (using knee arthroscopy to verify diagnosis):<\/span><\/p>\n\u00a0 \u00a0Medial meniscus tear:<\/span><\/p>\n\n- 92% sensitivity<\/span><\/li>\n
- 90% specificity<\/span><\/li>\n<\/ul>\n
\u00a0 \u00a0Lateral meniscus tear:<\/span><\/p>\n\n- 80% sensitivity<\/span><\/li>\n
- 95% specificity (20)<\/span><\/li>\n<\/ul>\n
Ultrasound<\/b><\/span><\/i><\/p>\n\n- Initial screening test to assess for associated soft tissue injuries (MCL, LCL, parameniscal cyst, effusion).<\/span><\/li>\n
- Cannot accurately detect intracapsular injuries\/vertical tears of the inner zone of the meniscus.<\/span><\/li>\n
- Sensitivity of 97% and specificity of 86% for detecting meniscal cysts (21).<\/span><\/li>\n<\/ul>\n
MRI Examples<\/b><\/p>\n
![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/04\/MRI-1-300x178.png\")
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Figure 6: Flipped medial meniscus into the anterior compartment<\/span><\/i><\/p>\n![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/04\/MRI-2-300x169.png\")
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Figure 7: Radial tear of the inner margin of the lateral meniscus<\/span><\/i><\/p>\n![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/04\/MRI-3-300x169.png\")
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Figure 8: Double PCL. Flap tear of the posterior third of the medial meniscus that has flipped into the intercondylar notch<\/span><\/i><\/p>\n![\"\"](\"https:\/\/blogs.bmj.com\/bjsm\/files\/2024\/04\/MRI-4-300x194.png\")
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Figure 9: Oblique tear through the middle third of the medial meniscus<\/span><\/i><\/p>\nDeciding on operative vs non operative management\u00a0<\/b><\/h6>\n\n- Patients are commonly referred into MSK\/orthopaedic clinics to discuss treatment options as part of a shared decision-making process.\u00a0<\/span><\/li>\n
- A personalised approach should be used to counsel patients, with a focus on pain and function.\u00a0<\/span><\/li>\n
- Any meniscus tears should be put in the context of underlying osteoarthritis and the health of the underlying joint.<\/span><\/li>\n<\/ul>\n
\n\n\nNon-operative options\u00a0<\/span><\/td>\n Operative options\u00a0<\/span><\/td>\n<\/tr>\n\n\n\n- Lifestyle changes<\/span><\/li>\n<\/ul>\n
\n- Physiotherapy<\/span><\/li>\n<\/ul>\n
\n- Injections\u00a0<\/span>(Steroid, hyaluronic acid, PRP)<\/span><\/i><\/li>\n<\/ul>\n
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\n- Dietary advice\/ Weight management.<\/span><\/i><\/li>\n<\/ul>\n<\/td>\n
\n\n- Arthroscopy (repair or resection)<\/span>\n
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The Meniscus \u2013 structure and function\u00a0<\/b><\/h6>\n
The menisci are crescent-shaped fibrocartilaginous structures located on the lateral and medial sides of the knee joint. They have primarily been thought to assist with the following within the knee joint:\u00a0<\/span><\/p>\n Anatomical variations, injury due to trauma, or age-related wear can impact these key functions and cause changes to the articular cartilage, weight bearing surfaces of the knee and synovial fluid make-up. Typical symptoms following a meniscus tear include pain, stiffness, knee swelling, a loss of range of motion and mechanical instability or locking.<\/span><\/p>\n Figure 1: Meniscus anatomy (1)<\/span><\/i><\/p>\n The menisci are acellular and relatively avascular, with the periphery and capsule supplied by the medial, middle and lateral genicular arteries.\u00a0<\/span><\/p>\n Histological studies have described age-related changes to the make-up and function of the menisci with increased age and tears associated with; a decreased rate of collagen turnover, increased cytokine and inflammatory signals (3), reduced microvascular blood supply (4), accumulation of glycation end products and reduced mechanical properties (3).\u00a0<\/span><\/p>\n Acute meniscal tears typically result from a twisting force applied to a weight bearing, flexed knee. In sport, this may be due to contact but can also occur due to sudden changes in direction or when landing from a jump.\u00a0<\/span><\/p>\n On the other hand, degenerative tears often occur without a single clear causative event.<\/span><\/p>\n As with other soft tissues, the meniscus is liable to age-related changes that increase the risk of a degenerative tear. Typically, these tears occur due to repetitive stress on a failing tissue, subject to high physical loads and in the context of metabolic risk factors, with little or no history of trauma (5).\u00a0<\/span><\/p>\n Acute meniscus tears are primarily observed in younger individuals and athletes, frequently occurring during sport or physical activity. Often, they will present with an associated ACL injury.<\/span><\/p>\n Figure 2: Risk factors for meniscus tears<\/span><\/i><\/p>\n Degenerative meniscus tears will typically present in patients aged over 50. Unlike acute tears, the onset of symptoms is chronic, gradually worsening with age. High BMI and repetitive trauma are also known risk factors for degenerative meniscus tears (12). They are also strongly associated with knee osteoarthritis (13).\u00a0<\/span><\/b><\/p>\n Several grading criteria exist for meniscal tears, however a clear descriptive report on the size, location and type alongside the following risk factors can help to guide treatment:\u00a0<\/span><\/p>\n Figure 3: Management options for meniscus tears<\/span><\/i><\/p>\n This area has a rich blood supply, so has good healing potential.<\/span><\/td>\n<\/tr>\n These tears are often degenerative and more likely to be found in older patients.<\/span><\/td>\n<\/tr>\n These are often associated with ACL injuries.<\/span><\/td>\n<\/tr>\n The lower image and video show a flipped bucket handle tear \u2013 the meniscal tissue has been flipped into the joint between the femoral condyle and the tibial plateau.<\/span><\/p>\n These are more common in younger patients following an acute tear.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Table 1: Types of meniscus tears<\/span><\/i><\/p>\n MSK services should develop close links with orthopaedics to offer fast track referrals to \u201cacute knee\u201d clinics and have the capacity to offer rehab and discuss cases via integrated virtual clinics. An example of a community referral pathway is included below.<\/span><\/p>\n Figure 4: Community referral pathway for meniscus tears<\/span><\/i><\/p>\n Various clinic-based examinations can be performed to aid the identification of meniscus tears. Findings from these tests should be taken in the context of the background and history of the presenting complaint. The sensitivities and specificities of these are highlighted below:<\/span><\/p>\n Figure 5: Clinic based tests to aid identification of meniscus tears<\/span><\/i><\/p>\n X-ray\/<\/b>Weightbearing films<\/b><\/p>\n Can be used to assess for underlying osteoarthritis. (Kellgren-Lawrence criteria).\u00a0<\/span>The addition of Rosenberg views can improve sensitivity.\u00a0<\/span><\/p>\n MRI (See below for MRI examples)<\/b><\/span><\/i><\/p>\n MRI 2-slice-touch rule (using knee arthroscopy to verify diagnosis):<\/span><\/p>\n \u00a0 \u00a0Medial meniscus tear:<\/span><\/p>\n \u00a0 \u00a0Lateral meniscus tear:<\/span><\/p>\n Ultrasound<\/b><\/span><\/i><\/p>\n MRI Examples<\/b><\/p>\n Figure 6: Flipped medial meniscus into the anterior compartment<\/span><\/i><\/p>\n Figure 7: Radial tear of the inner margin of the lateral meniscus<\/span><\/i><\/p>\n Figure 8: Double PCL. Flap tear of the posterior third of the medial meniscus that has flipped into the intercondylar notch<\/span><\/i><\/p>\n Figure 9: Oblique tear through the middle third of the medial meniscus<\/span><\/i><\/p>\n <\/p>\n <\/span><\/i><\/li>\n\n
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Mechanisms of injury\u00a0<\/b><\/h6>\n
Meniscal injuries in the sporting patient: just how common are they?\u00a0<\/b><\/h5>\n
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<\/p>\nThe degenerate tear: what do we know about graceful ageing of the meniscal tissue?<\/b><\/h6>\n
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Meniscal tear grading<\/b><\/h6>\n
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\n Tear Type<\/b><\/td>\n Appearance<\/b><\/td>\n Description<\/b><\/td>\n<\/tr>\n \n Peripheral Tear<\/span><\/td>\n <\/td>\nLesion of the outer rim of the meniscus, known as the peripheral zone.\u00a0<\/span><\/p>\n \n Horizontal Tear (Cleavage tear)<\/span><\/td>\n <\/td>\nTears are horizontal and parallel to the tibial plateau.<\/span><\/p>\n \n Vertical Tear Repair<\/span><\/td>\n <\/td>\nTears extend in a vertical orientation and are more likely to occur acutely in younger patients following trauma.<\/span><\/p>\n \n Bucket handle tear\u00a0<\/span><\/td>\n <\/td>\nCentral tear of the meniscus. Peripheral ends are still attached to the knee, thus resembling a \u2018bucket-handle\u2019.<\/span><\/p>\n <\/p>\n<\/p>\nImaging:\u00a0MSK imaging options to consider for meniscal knee injuries<\/strong><\/h6>\n
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<\/p>\n<\/p>\n<\/p>\n<\/p>\nDeciding on operative vs non operative management\u00a0<\/b><\/h6>\n
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\n Non-operative options\u00a0<\/span><\/td>\n Operative options\u00a0<\/span><\/td>\n<\/tr>\n \n \n \n
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