Knee meniscus injuries: symptoms, diagnosis, and treatment

The menisci are semilunar cartilaginous structures that distribute loads between the femur and tibia, increasing stability and protecting articular cartilage. A meniscus tear occurs with a sudden twist on a fixed foot, landing after a jump, a direct blow to the knee, and also due to age-related degeneration. Clinically, this results in pain along the joint line, swelling, limited flexion and extension, and a sensation of "locking" or instability. [1]

Current guidelines emphasize the priority of organ-preserving strategies: if the tissue is viable, preference is given to meniscal suturing and attachment repair, as fragment removal increases contact loads and the risk of subsequent osteoarthritis. For degenerative tears without pronounced mechanical symptoms, a stepwise conservative program is recommended. [2]

In recent years, clinical guidelines for acute isolated meniscal pathology have been updated, clarifying the indications for imaging, patient selection criteria for surgery, and principles of rehabilitation and return to sports. The emphasis has shifted to criteria-based rehabilitation and minimizing resections, particularly in young and active patients. [3]

Certain types of injuries require specialized tactics: root ruptures, posteromedial "ramp segment" injuries, "watering can handle" injuries, complex and radial tears. For these, specific consensus guidelines and approaches have been developed for restoring meniscal attachments and tension in order to preserve knee biomechanics. [4]

Code according to ICD-10 and ICD-11

In the International Classification of Diseases, Tenth Revision, acute meniscal injury is coded in the S83.2 block with detailed subtypes by tear side and configuration, including "watering can handle," peripheral, complex, and unspecified variants. For sequelae of old tears and malunion, the M23.2 family is used. This is important for reporting and comparability of studies. [5]

The eleventh revision includes a section NC93, "Dislocations, strains, and ruptures of ligaments and elements of the knee," where the actual meniscal tear is reflected by the code NC93.3 with subtypes NC93.30 for the medial meniscus and NC93.31 for the lateral meniscus. In ICD-11, the entry may be expanded with a cluster of additional codes to clarify the side, mechanism, and anatomy. [6]

Table 1. Examples of codes for meniscus tears

Classifier	Code	Formulation
ICD-10	S83.2	Meniscus tear, current injury, with specification of configuration and side
ICD-10	M23.2	Meniscus dislocation due to an old tear or injury
ICD-11	NC93.30	Current tear of the medial meniscus
ICD-11	NC93.31	Lateral meniscus tear, current
ICD-11	NC93.3Z	Meniscus tear, current, unspecified

Epidemiology

Meniscus injuries are among the most common intra-knee injuries in athletes and active middle-aged individuals. In younger individuals, traumatic tears due to rotational mechanisms are more common, while in older individuals, degenerative tears arising from everyday activities are more common. The overall proportion of meniscus injuries among sports-related knee injuries is high, but the frequency varies depending on the method of measurement and the sport. [7]

Systematic reviews show that tissue preservation is associated with better long-term outcomes and a lower risk of osteoarthritis compared with resection. Therefore, there is a population-based shift toward organ-preserving surgery and expanded indications for suture in appropriate patients. [8]

In young patients, isolated arthroscopic partial meniscectomy does not demonstrate advantages over an exercise and education program in some patients with traumatic tears without significant locking, which is reflected in current research and influences the choice of tactics. [9]

Consensus rehabilitation guidelines indicate a significant percentage of successful return to sport with a properly designed program and adherence to eligibility criteria. The timeframe depends on the type of intervention, location, and complexity of the tear. [10]

Reasons

The primary injury mechanism is rotation of the torso on the supporting leg with a bent knee, often during a sudden change of direction in team sports. Additional scenarios include landing after a jump and a direct blow to the knee. These movements create shear forces and compression along the joint line, causing a tear of the meniscus fibers. [11]

Degenerative tears develop gradually due to decreased hydration and elasticity of the cartilage tissue, microcracks, and associated chondropathy. These tears are often accompanied by moderate pain and recurrent effusion without a history of obvious trauma. [12]

Specific mechanisms include meniscal root avulsions, leading to loss of hoop tension and a sharp increase in contact loads, as well as "ramp injuries" of the posteromedial segment with an accompanying rupture of the anterior cruciate ligament. These variants significantly alter biomechanics and require specific diagnostics. [13]

Combined injuries with elements of instability, including ligamentous ruptures, increase the risk of chronic symptoms and accelerated degeneration, which determines the need for early detection and comprehensive tactics. [14]

Risk factors

Modifiable factors include a lack of strength and control in the hip and gluteal muscles, poor landing technique, excessive training volume without recovery, and excess body weight. Correcting these factors reduces peak loads on the menisci and the risk of injury. [15]

Non-modifiable factors include age and anatomical features, such as a high tibia or variations in meniscus shape. In older individuals, the incidence of degenerative tears increases due to pre-existing changes in articular cartilage. [16]

Prior meniscal surgery, particularly extensive resections, increases the long-term risk of symptoms and structural progression, including the development of osteoarthritis within several years after surgery. This argues for tissue preservation in primary treatment. [17]

The presence of concomitant knee instability, such as anterior cruciate ligament (ACL) rupture, increases the risk of secondary meniscal injuries, particularly the ramp segment, requiring simultaneous management of the instability.[18]

Pathogenesis

The meniscus distributes loads and provides hoop tension due to the continuity of its collagen fibers. A traumatic tear disrupts the transfer of load from the femur to the tibia, increasing point pressure on the articular cartilage, which accelerates wear over time. Maintaining or restoring fiber continuity is critical for biomechanics. [19]

Root rupture is functionally equivalent to total resection: circumferential tension is eliminated, the contact area is reduced, and peak loads are increased. Early anatomical root fixation restores tension and reduces the risk of structural progression. [20]

Radial and complex tears cross the circumferential fibers, dramatically reducing the meniscus's ability to distribute loads, whereas longitudinal peripheral tears in the "red zone" have a high healing potential with reliable suturing. This explains the differences in the choice of surgical technique. [21]

In degenerative tears, in addition to biomechanics, the inflammatory component is significant, contributing to pain sensitization and effusion. Here, gradual physical therapy and load modification before cartilage and meniscus dissection play a major role. [22]

Symptoms

The most common symptoms include pain along the joint space, swelling after exercise, clicking, episodes of "locking" when turning, and a feeling of instability. Pain may occur when squatting and descending stairs, as well as limited flexion or extension. Symptoms range from episodic to constant. [23]

Mechanical symptoms such as blocking and "sticking" increase the suspicion of a torn fragment or "watering can handle," especially in young, active patients. In such cases, early surgical treatment with an attempt at organ-preserving repair is often indicated. [24]

In degenerative ruptures, recurrent moderate pain and effusion after everyday activities without episodes of "blocking" predominate. A conservative approach with clear progression criteria is preferable here. [25]

In cases of combined injuries with instability, symptoms may be masked by manifestations of ligamentous damage. This requires careful in-person diagnosis and planning of interventions within a unified strategy. [26]

Classification, forms and stages

Based on their origin, tears are classified as traumatic or degenerative. By location, they involve the medial and lateral meniscus, anterior, middle, and posterior segments. By configuration, they can be longitudinal, radial, horizontal, "watering can handle," flap, root, or complex. These characteristics determine the treatment strategy and prognosis. [27]

Particularly noteworthy are root ruptures, leading to loss of circumferential tension, and "ramp injuries" of the posteromedial segment, often associated with anterior cruciate ligament rupture. Specific indications for early anatomical fixation and rehabilitation protocols have been formulated for these conditions. [28]

Based on the duration of the injury, acute injuries are distinguished, lasting up to three to six weeks, and chronic injuries after this period, when secondary changes and scarring appear, which may require reconstructive techniques. The duration of the injury influences the choice between suturing and resection. [29]

Table 2. Types of Gap and Key Decisions

Type of rupture	Biomechanical significance	Basic tactics
Longitudinal peripheral in the "red zone"	High healing potential	Suture with early protected rehabilitation
Radial and complex	Loss of hoop tension	Consider reconstruction, avoid wide resection
Watering can handle	Risk of blocking	Reposition and suture with viable tissue
Root rupture	Total resection equivalent weight-bearing	Early anatomical root fixation

Complications and consequences

Extensive meniscal tissue resection is associated with a higher incidence of osteoarthritis in the years to come compared to suture, especially in younger patients. This highlights the importance of a strategy to "preserve as much meniscus as possible."[30]

Undiagnosed root and ramp lesions perpetuate abnormal kinematics and cartilage overload, increasing the risk of chronic pain, recurrence, and the need for repeat interventions. Timely restoration of these structures improves outcomes. [31]

After suturing, there is a risk of leakage requiring revision; however, in the long term, repair is associated with more favorable structural preservation of the joint compared to resection. The frequency of reinterventions depends on the type of tear and the technique used. [32]

Prolonged immobilization increases the risk of contractures and atrophy, so rehabilitation should begin early, but in a measured manner, with a focus on protecting the suture and achieving functional milestones. [33]

When to see a doctor

Immediate consultation is necessary in cases of acute knee locking, inability to straighten the leg, severe swelling, and pain following injury. These signs indicate a probable rupture with a torn fragment and require early imaging and a decision on repositioning and suturing. [34]

A specialist should be consulted if there are recurring episodes of "sticking" and instability, increasing effusion after exercise, or decreased tolerance to walking and squatting. Early diagnosis accelerates recovery and reduces the risk of structural complications. [35]

If the pain is moderate and occurs without obvious injury but persists for several weeks, an in-person assessment and a phased rehabilitation program with milestones are required. If progress is lacking, the diagnosis and treatment plan are reevaluated. [36]

In patients with knee instability or after ligament surgery, if posteromedial line pain occurs, evaluation for a ramp lesion is necessary, as missing this pathology worsens reconstruction outcomes. [37]

Diagnostics: step-by-step algorithm

The examination includes localization of pain along the joint line, assessment of effusion, range of motion, and provocative tests with rotation and compression. However, the isolated accuracy of individual tests is moderate and highly dependent on the experience of the performer, so the results are interpreted holistically. [38]

Standard radiography is essential to exclude fractures and gross bone pathology, although a meniscal tear itself does not visualize it. It is useful for basic screening and assessment of associated changes. [39]

Magnetic resonance imaging is the method of choice for confirming rupture, refining the configuration, and identifying associated lesions. Modern meta-analyses demonstrate high sensitivity and specificity overall, with caveats for individual scenarios and areas. [40]

Ultrasound in experienced hands can be useful for identifying medial tears and dynamic monitoring, but is used selectively and does not replace magnetic resonance imaging in complex cases. Arthroscopy remains the gold standard for concurrent treatment. [41]

Table 3. Diagnostic methods and indicative capabilities

Method	Role	Key Notes
Clinical tests	Screening and localization of pain	Moderate accuracy, depends on the experience of the physician
X-ray	Exclusion of bone pathology	The gap itself is not visible, the method is basic level
Magnetic resonance imaging	Confirmation, type and associated damage	High accuracy, limitations in certain scenarios
Ultrasound examination	Available dynamic control	Useful for medial tears, selectively

Differential diagnosis

Meniscal tears should be differentiated from chondral lesions, synovial folds, pes anserinus syndrome, and painful conditions of the anterior knee. The nature of the pain, provocative tests, and imaging findings are important. [42]

In cases of combined instability, associated ligament tears, particularly of the anterior cruciate ligament, are suspected, which changes the treatment and rehabilitation plan. Identification and simultaneous correction increase the chances of returning to sports. [43]

Root rupture mimics rapid pain progression without obvious blockage and requires targeted evaluation of the posterior horns using magnetic resonance imaging and arthroscopy. Failure to recognize this diagnosis leads to rapid loss of function. [44]

Table 4. Distinctive features of related conditions

State	What's alarming	Confirmation
Meniscus tear	Pain along the joint line, mechanical symptoms	Magnetic resonance imaging, arthroscopy
Chondral injury	Pain in the load zone, crepitus	High-quality magnetic resonance imaging
Ramp damage	Posteromedial pain with instability	Targeted arthroscopy, magnetic resonance imaging
Root rupture	Rapid deterioration, swelling, decreased tolerance	Magnetic resonance imaging, arthroscopy

Treatment

The first stage for most degenerative and some traumatic non-blocking tears is a conservative program. This includes pain and swelling management, progressive strength and motor control exercises, balance training, activity modification, and body weight. This approach is justified as a "first-line treatment," especially in the absence of gross mechanical symptoms. [45]

For traumatic ruptures in young patients with severe blockage, a large displaced fragment, or a longitudinal peripheral rupture in a well-vascularized area, an organ-preserving suture is indicated. Current evidence and practice recommend repair where tissue is viable to preserve biomechanics and reduce the risk of osteoarthritis. [46]

Arthroscopic partial meniscectomy is considered for irreparable tears with poor tissue quality, but its extent should be kept to the minimum necessary. Studies show no advantage of early resection over rehabilitation in some young patients without locking, as well as a higher risk of subsequent degeneration compared to repair. [47]

Root rupture requires anatomical fixation with restoration of hoop tension, usually through bony canals to the tibial plateau. Early root restoration is associated with better clinical and radiographic outcomes than resection or delayed intervention.[48]

Posteromedial "ramp" lesions during anterior cruciate ligament reconstruction require targeted assessment and, if unstable, suturing, as their correction improves biomechanics and protects the ligament graft. The question of repairing stable lesions is decided on an individual basis. [49]

Post-suturing rehabilitation is structured around a combination of time-based and criterion-based stages. Consensus recommends early but protected restoration of extension, graduated loading, then progression of strength and proprioception, and re-entry into running and sports based on functional criteria. Timelines depend on the type of tear and the extent of the intervention. [50]

After partial resection, return to running activity is possible significantly sooner than after suturing, but this tactic carries a higher risk of long-term structural changes. The choice should take into account the patient's age, type of tear, activity requirements, and expectations. [51]

Pharmacotherapy is supportive: short-term painkillers and anti-inflammatory agents, local methods, and swelling control. Injectable biological approaches for degenerative tears are discussed individually, but convincing advantages over well-structured rehabilitation are still lacking. [52]

Return to sport criteria include the absence of pain and swelling, symmetry of strength and jump tests, quality landing patterns, and patient confidence. For meniscal repairs, consensus suggests a return to sport of several months, and for complex reconstructions, up to nine months. Decisions are made based on the achievement of functional milestones. [53]

Table 5. Choice of tactics based on the clinical situation

Situation	Preferred tactics	Alternative
Degenerative rupture without blocking	Conservative program	Limited resection if ineffective
Traumatic peripheral longitudinal rupture	Meniscus suture	Limited resection with poor tissue quality
Watering can handle with lock	Reposition and suture	Minimal resection when repair is not possible
Root rupture	Anatomical fixation	Resection when repair is contraindicated
Ramp damage during instability	Suture for ligament reconstruction	Observation during stability

Table 6. Rehabilitation after intervention

Stage	Goals	Examples
Protected phase	Control pain and swelling, restore extension	Orthosis according to indications, cryotherapy, isometry
Early progression	Normalization of gait, range of flexion	Closed chain exercises, exercise bike
Power	Increased strength and endurance	Single-leg squats, bridges, deadlifts, balance
Preparing for sports	Plyometrics, change of direction	Jump tests, functional test batteries

Prevention

Injury prevention programs include developing quadriceps and hamstring strength, gluteal training, neuromuscular control, and proper landing and braking techniques. Regular work on balance and proprioception reduces peak stress on the menisci. [54]

Periodization of loads, sufficient recovery and early correction of discomfort reduce the likelihood of overload conditions turning into a rupture, especially in older athletes and with high competitive activity. [55]

Return to play should be criteria-based: no pain or swelling, symmetry of strength, successful functional testing, confident movement without compensatory strategies. This reduces the risk of recurrent injuries. [56]

Patient and trainer training to recognize early signs of strain, as well as standardized referral algorithms, reduce the proportion of advanced cases and the need for extensive resections. [57]

Forecast

With appropriate management, most patients return to daily activities and sports. The best long-term results are demonstrated by strategies that preserve meniscus tissue with anatomical repair and criteria-based rehabilitation. [58]

After limited resection, recovery is faster in the short term, but the risk of structural changes is higher over several years. This risk should be discussed preoperatively, especially in young patients. [59]

Root repair and correction of "ramp lesions" improve cartilage stability and load-bearing capacity, reducing the likelihood of repeat interventions and early arthrosis. Return to sports time varies from person to person and depends on the complexity of the repair. [60]

The presence of concomitant ligamentous injuries and cartilaginous pathology worsens the prognosis and prolongs rehabilitation, but with an integrated approach it is possible to achieve high levels of function and participation in sports. [61]

FAQ

Does everyone with a meniscus tear need surgery?
No. For degenerative and some traumatic tears without locking, the initial approach is a rehabilitation program with load modification. Surgery is considered for mechanical symptoms, the ineffectiveness of conservative treatment, and for tear types favorable for repair. [62]

Which is better: suture or partial resection?
If the tissue is viable, repair is preferable, as it preserves biomechanics and is associated with a lower risk of developing osteoarthritis compared to resection. Resection is indicated for irreparable tears with low healing potential. [63]

How long does rehabilitation last?
After a partial resection, returning to running is possible much sooner, whereas after a suturing procedure, especially in cases of complex and root ruptures, it's based on criteria and often takes several months. Current consensus recommends focusing on functional milestones rather than a calendar. [64]

Is it true that magnetic resonance imaging is always accurate?
Magnetic resonance imaging has a high average accuracy, but it is not ideal for certain areas and scenarios, and interpretation depends on the quality of the examination. Diagnosis is confirmed using a combination of clinical examination and, if necessary, arthroscopy. [65]

Table 7. Comparison of the main surgical strategies

Approach	Advantages	Restrictions	Who is it suitable for?
Meniscus suture	Preservation of biomechanics and tissue, better joint structure in the long term	Risk of insolvency, longer rehabilitation	Young and active, peripheral longitudinal, "watering can handle"
Partial resection	Rapid relief of symptoms, short rehabilitation	Higher risk of degeneration progression	Irreparable tears with poor fabric quality
Root fixation	Restoring ring tension, protecting cartilage	Technical complexity, longer protection	Symptomatic root ruptures without pronounced arthrosis