With more than 35,000 participants the Indianapolis “Mini” Marathon is known for being the only way most people will ever set foot on the track at the Indianapolis Motor Speedway. For me, it was my first half marathon and the day I ran eight miles on a torn lateral meniscus.
The incidence of meniscus tears has been reported to be 12% to 14%. This number may be as high as 50% as we age. Meniscus tears are the second most common injury to the knee. These tears used to be thought of as a condition that necessitated surgery but recent recommendations suggest surgery should be delayed in the absence of mechanical symptoms.
Lateral knee meniscus anatomy
The knee presents as a simple joint but is rather complex in its function. The articular surfaces of the femur and tibia are not congruent and thus, rely on soft tissue structures for stability. The four main providers of stability are the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments.
The menisci are fibrocartilaginous, semilunar structures that attach to the tibia and femur via coronary ligaments and the joint capsule. The “O” shape of the lateral meniscus covers more articular surface than the smaller “C” shaped medial meniscus. According to Jackson and Dandy, meniscus tears may be categorized as incomplete, complete, stable, or unstable.
Menisci serve two purposes in the knee: (1) improve load distribution and (2) maintain joint health and stability. These functions are the primary reason for the shift in thinking when it comes to early surgical intervention- the more meniscus that can be preserved, the less the chance of developing osteoarthritis. The lateral meniscus is the workhorse of the two, shouldering 70% of the load through the knee. When working together, the medial and lateral meniscus together transmit as much as 85% of the load when in 90 degrees of knee flexion.
The medial and lateral meniscus can be divided into three zones: red, red-white, and white. The “red” zone is the outer portion of the tissue and named for its good blood supply. The “red-white” zone is the middle third of the meniscus and has some vascularity while the “white” zone is the innermost portion with no blood supply. These zones are critical in determining the likelihood of a tear healing without surgical intervention; healing becomes more likely as you move from the inside out because of the increased vascularization in the peripheral portion of the tissue.
The menisci are subject to a small amount of consequent motion due to their ligamentous attachments. When the knee is moving into extension, the menisci move forward. While the knee moves into flexion, the menisci are drawn backward. This is both a common injury mechanism and a surgical precaution after meniscus repair as the posterior horns of the menisci may become pinched between the femur and the tibia with deep flexion angles.
There are some anatomical predispositions to lateral meniscus injury. Valgus stress is associated with the risk of lateral meniscus damage while varus stress seems to lead to medial meniscus injury and degeneration. An increased Q-angle, which also causes valgus position at the knee, can put excessive pressure on the lateral compartment and lead to lateral meniscus pathology.
A discoid lateral meniscus is an anatomical condition that is unique to the lateral meniscus and may require surgery correction. Meniscus, from the Greek word “meniskos”, translates to “crescent” which is the general shape of the tissue. A discoid meniscus is the most common anatomical variant and is described as thickened meniscus tissue that covers more of the tibial plateau than the normal meniscus. A discoid meniscus can be symptomatic or asymptomatic.
Symptomatic cases typically have associated knee pain and functional limitations that require surgical intervention to correct. As with other meniscus procedures, the correction of discoid lateral meniscus has become more conservative over time; historically, total meniscectomy was performed. Following surgery, most patients developed early degeneration of the lateral compartment which is undesirable. Currently, arthroscopy is used to perform a partial meniscectomy where the remaining tissue is reshaped to more closely resemble the normal lateral meniscus.
What causes a lateral meniscus tear? Who are at risk?
Traumatic meniscus tears may result from torsional or axial loads. The most common mechanism of injury is a quick change from flexion to full extension where the meniscus gets pulled back into the space between the femur and tibia. This is the motion that occurs during the midstance phase of running or when returning to the upright position or coming out of “the hole” during a squat. In the non-athletic population, this motion can occur when transitioning from stooping to standing or even when stepping off a curb.
Lateral meniscus tears can happen in contact and non-contact injury situations. In sports such as football or soccer, a contact meniscus tear can happen if an athlete is hit by an opponent with their foot planted; an open-field tackle in football or a slide tackle in soccer would be an example of this. Non-contact meniscus tears often occur in sports when an athlete’s foot is planted while changing directions. This pivoting or twisting motion causes a rotary force that leads to meniscus injury.
Torsional force meniscus injuries can also happen in non-contact situations such as dancing, gymnastics, Zumba, and step aerobics where twisting to change direction is common. As noted above, axial load meniscus injuries happen in deep flexion or when moving from flexion to extension. This type of meniscus tear happens in athletes participating in sports that involve running, jumping, or unstable surfaces such as volleyball or cross country. This can also occur during squatting with heavy weights or getting out of a chair.
Those who are working in professions that require prolonged stooping or deep squatting such as plumbers, cable technicians, and auto mechanics may be more likely to experience tears from the axial load incurred in these positions or the repetitive motion of moving in and out of the deep squat position.
Meniscus tears are categorized by some combination of their shape and location. Longitudinal lesions, the most common type, can be horizontal or vertical depending on their orientation to the tibial plateau; horizontal tears are parallel to the plateau while vertical tears are perpendicular to it. Radial tears start at the inner free portion of the meniscus and are perpendicular to the tibial plateau and the long axis of the meniscus. Bucket handle tears are longitudinal with the added element of a central flap that can flip up and get stuck (like a bucket handle moving from one side of the bucket to the other). This is not an all-encompassing list but rather a brief description of the most common types of tears. Nguyen, et al. is an excellent resource for a more in-depth description of the classification of meniscal tears.
Medial vs. lateral: difference between lateral meniscus and medial meniscus injuries
Both medial and lateral meniscus tears present with the same symptoms. Differentiating which meniscus is involved lies in the location of the symptoms. Joint line tenderness, pain during special testing (McMurray’s, Thessaly, etc.), and pain with functional activity will usually localize to the side of the injured meniscus.
For example, a torn lateral meniscus will produce pain in the lateral joint line, pain with McMurray’s test when the tibia is internally rotated and varus stress is applied, and pain at the lateral aspect of the knee with functional activities such as walking, climbing stairs and squatting. Conversely, a medial meniscus tear will present with medial joint line pain, pain at the medial aspect of the knee with special testing, and pain at the medial aspect of the knee during activities of daily living.
There does seem to be some difference in the way posture is altered by medial and lateral meniscus tears. Lee et al., measured postural stability using stabilometry in 24 patients with medial meniscus tears and 18 patients with lateral meniscus tears. Anteroposterior, mediolateral, and overall stability were measured. In the three indices, poorer postural stability was found in both involved and uninvolved knees of individuals with lateral meniscus tears. Though not a validated special test, having an individual perform single leg stance testing may help confirm a suspected meniscus tear.
Lateral meniscus tear symptoms
Meniscus tears may be acute or degenerative. Most acute meniscus tears present to the clinic with a classic set of signs and symptoms. These injuries are often sustained during sporting events that involve cutting, pivoting, or twisting motions. Patients will likely endorse an associated snap or pop along with sharp, local pain. There may be an effusion with acute meniscus tears that takes some time to develop (unlike the immediate swelling seen with tears of the anterior cruciate ligament) which can limit both flexion and extension range of motion. If a bucket-handle or flap tear is present, the patient may also note mechanical locking.
Degenerative, or chronic, meniscus tears tend to present similarly to knee osteoarthritis. These patients may report generalized knee pain and swelling as well as intermittent clicking, popping or locking. Patients with degenerative tears tend to be male, over 60 years-old, or work-related from kneeling, squatting, or climbing.
In both acute and degenerative tears, the most consistent clinical exam finding for lateral meniscus tears is lateral joint line tenderness. This pain is present with palpation as well as when the knee is moved into full flexion or extension. Mohan and Gasol retrospectively examined the reliability of clinical diagnosis in meniscal tears. One hundred thirty patients included in the study were diagnosed with a torn meniscus in the clinic using joint line tenderness and McMurray’s test.
Following the diagnosis of meniscus tear, all participants underwent arthroscopic surgery where the diagnosis was either confirmed or rejected. Eighty-eight percent of medial meniscus tears and 92% of lateral meniscus tears were correctly identified using clinical tests alone. These findings suggest a clinical exam that includes joint line tenderness and McMurray’s test is a reliable method for diagnosing a meniscus tear.
Ruling out other structures that could be involved in diagnosing meniscus tears can be lengthy. Acute anterior cruciate ligament tears are more often associated with lateral meniscus tears while chronic anterior cruciate ligament injury can drive medial meniscus tears. Severe injury to the medial collateral ligament is likely to involve the medial meniscus because two structures are firmly attached to one another. Conversely, isolated injury to the lateral collateral ligament is possible as the lateral meniscus is separated from the ligament by a fat pad.
Posteriorly, a hamstring strain, Baker’s cyst, or posterior cruciate ligament injury may be the source of pain rather than a lateral meniscus tear. A hamstrings strain will cause pain and soreness at the posterolateral aspect of the knee but this pain will likely change with activity (improve with rest, worsen with activity) whereas meniscus pain is consistent regardless of the amount or intensity of activity.
Meniscus tears are often associated with Baker’s (popliteal) cysts. It is believed that these cysts are formed by one-way valves that are the body’s way of regulating the hydraulic pressure in the knee when an effusion is present as the size of the cyst is directly related to the size of the effusion. A Baker’s cyst isn’t likely to be mistaken for a torn meniscus but finding one could indicate a meniscus tear or other intra-articular lesion is present.
Similar to a popliteal cyst, deep vein thrombosis (DVT) is unlikely to be mistaken for a meniscus tear but it can be mistaken for the sequelae of such an injury. Severe meniscus injuries can lead to significant gait impairments and pain behind the knee. If an individual is unable to fully extend their knee they will adopt a plantarflexed ankle position and a toe-touch gait that can create unusual calf pain. If this is accompanied by redness, heat, or cramping, deep vein thrombosis should be ruled out before treatment commences.
It is possible, albeit unlikely, that a torn meniscus could cause anterior knee pain. In the case where jumper’s knee and patellofemoral pain syndrome have been ruled out but anterior knee pain persists, a meniscus tear may be suspected.
Lateral meniscus surgery: do you need it?
To operate or not to operate on meniscus tears is quite the question. To date, there is no consensus as to when, or if, arthroscopic surgery is indicated. Historically, orthopedic surgeons were quick to perform partial meniscectomies on symptomatic patients but over the past decade, the fast-track to meniscus surgery has fallen out of favor and been replaced by a meniscus sparing or meniscus preservation approach.
A host of well done randomized control studies have reported no difference in outcomes between patients who undergo arthroscopic surgery and those who don’t at one-year follow-up, especially in cases of degenerative meniscus tears. Partial meniscectomy should be reserved for patients who fail conservative treatment (physical therapy, medication, injection) or those with significant mechanical symptoms (ie. locking that alters gait or causes instability). When possible, a meniscal repair is performed in an attempt to preserve the tissue. Meniscal repairs also tend to have good clinical outcomes.
Individuals with meniscus tears who have partial meniscectomies report excellent results immediately following the procedure. More than 80% of patients report their knees are normal or near-normal after meniscus surgery however when the lateral meniscus is involved, these positive results aren’t as long lasting. Repeat lateral meniscus surgery is indicated 14% of the time due to continued impact on activity. Prognostic factors for good outcomes following surgery include which meniscus is involved, the size of the tear, amount of tissue resected, age, and cartilage health. Regardless of which meniscus is involved, osteoarthritis is common after arthroscopic intervention which is one of the reasons meniscus preservation has gained traction.
A 2020 systematic review by Smoak et al., found that meniscus tears are often identified during reconstruction of the anterior cruciate ligament; this is particularly true in cases where surgery is delayed six months or more or there are several incidences of instability. When the meniscus is addressed at the same time as the anterior cruciate ligament repair, the likelihood of developing osteoarthritis is increased.
Though performed in patients with medial meniscus tears, the work of Sihvonen et al. is worth mentioning. The group conducted a double-blind, randomized, sham-controlled study in 146 patients who had medial meniscus tears without knee osteoarthritis. Participants were randomly assigned to either the arthroscopic partial meniscectomy group or the sham surgery group. Following surgery, the sham group reported higher scores on the Lysholm and Western Ontario Meniscal Evaluation Tool outcome measures. On both outcome measures, higher scores indicate fewer symptoms. In fairness, both groups had significant improvement at the end of the study but the patients in the surgical intervention group had no more improvement than those in the sham group.
Chirichella et al., in a recently published narrative review, noted that randomized control trials support the notion that both surgical and non-surgical treatments are better than nothing but no study has been able to effectively determine that surgical intervention is superior to conservative management in degenerative meniscus tears. Notably, in degenerative tears, the British Journal of Medicine is strongly against the use of arthroscopy in most patients.
As a physical therapist, I find that many of the patients I see who have meniscal tears are frustrated when they are advised to try conservative management because it is so well known that this condition has traditionally been addressed surgically.
Most of the time, the patient’s pain and function improve within a couple of visits which tends to lead them away from surgical intervention as their preferred treatment (which is good!). They must realize that surgery cannot be undone and that even the most minimally invasive procedure has risks associated with it and long term changes that occur.
My clinical practice mirrors the research in that I see no difference in outcomes between patients who complete surgical vs conservative treatment by the end of their course of therapy. Also, like the research, I find that patients with significant mechanical symptoms at their initial evaluation are unlikely to improve with physical therapy and tend to have surgery in the end.
Lateral meniscus tear treatments
When appropriate, conservative management is the preferred treatment option for lateral meniscus tears. Patients with severely limited range of motion, clicking, popping, locking, or instability are not good candidates for non-surgical treatments. Initial management of an acute meniscus tear should include controlling pain and swelling and restoring range of motion.
The R.I.C.E. (rest, ice, compression, elevation) approach may be employed after an injury to help mitigate pain and swelling. Gentle, pain-free range motion exercises should be introduced when comfortably tolerated. Someone with an acute meniscus tear may benefit from an assistive device such as crutches or a cane so that they can ambulate with minimal gait deviations and offload the injured area as needed. Additionally, an offloading brace can be used with meniscus tears to normalize gait, decrease pain, or both.
Physical therapy for lateral meniscus tears should focus on decreasing pain and increasing range of motion during the immediate post-injury phase. The next phase of the rehabilitation program should focus on improving lower extremity strength, particularly the quadriceps, hamstrings, and gluteal muscle groups. The final progression in physical therapy should be to plyometrics, dynamic proprioceptive training, and eventually sport-specific exercise as indicated.
The ability to bear weight, minimal swelling, and good range of motion favor success in physical therapy following a torn lateral meniscus.
An additional treatment option for lateral meniscus tears is orthobiologics. Orthobiologics are substances used to enhance or assist the body’s own ability to repair and regenerate musculoskeletal tissue.
Evidence for the use of platelet-rich plasma injections after meniscal tears is scarce but promising. The multiple anabolic growth factors found in platelet-rich plasma may play a role in healing meniscal lesions, particularly in the avascular white-zone. Platelet-rich plasma is also strongly supported in the literature as a treatment for knee osteoarthritis which is often a co-diagnosis in patients with meniscus tears, as it inhibits the inflammatory effects of osteoarthritis on the cells found in cartilage.
Mesenchymal stem cells are a group of stem cells that have been extracted from bone marrow, periosteum, trabecular bone, adipose tissue, skeletal muscle, and teeth. These cells can participate in several cellular processes including homeostasis of tissues, remodeling, and repair. Adipose-derived stem cells are another subset that has been isolated for their role in restorative processes. Adipose-derived stem cells are easier to isolate and are more abundant in the body than mesenchymal stem cells. Though research is limited, both have shown encouraging results in the treatment of knee pain and meniscus tears.
Despite showing good results, orthobiologics are not currently covered by Medicare or other insurers so physical therapy remains the road most traveled as the out-of-pocket costs for platelet-rich plasma and stem cell treatments can be prohibitive. Without a direct comparison of the treatment options, it is impossible to know if one is superior to the other but the good news for those with meniscus tears is that they all seem to help.
As with any medical condition, musculoskeletal or otherwise, readers should consult with a physician or qualified medical professional to determine the best course of treatment for their condition. This article should not be considered a substitute for professional advice or care.
Meniscus tear recovery time without surgery
Although it depends on the size, shape, and chronicity of the tear most meniscus tears heal in four (orthobiologics) to twelve (physical therapy) weeks with conservative therapies. Research defining physical therapy elements or timelines after meniscus tear is scarce. The link between degenerative meniscus tears and osteoarthritis of the knee has led clinicians to use the plentiful osteoarthritis research to guide meniscal tear treatments.
Lateral meniscus tear prevention
A 2018 consensus statement from the British Journal of Sports Medicine identified several risk factors for meniscal tears. Twenty individual studies contributed to the statement. The risk of meniscus injury is increased in individuals who are overweight and male but it is unclear if age is a risk factor for injury. Participation in sports, generalized hypermobility, and heavy labor jobs are also associated with increased risk of meniscus tears. In individuals with torn anterior cruciate ligaments, the time from injury to surgery is also indicative of greater risk of meniscus involvement.
Maintaining a healthy weight, safe sports participation, and attention to body mechanics in physically demanding work situations may reduce the risk of developing meniscal tears.
Massage therapy and lateral meniscus tear
Massage therapy recommendations for lateral meniscus tears follow the physical therapy evidence in that they rely on knee osteoarthritis findings. The meniscus itself can not be the target of massage but the surrounding tissues can. Meniscus tears are often associated with an antalgic gait which may lead to tight hamstrings, gastrocnemius, or soleus.
The hamstrings often become tight when the knee remains in the less painful flexed position. In the case of gastrocnemius and soleus, the tightness can be driven by maintaining plantar flexion to account for the decrease in leg length that occurs when the knee is flexed.
The lateral hip may also become tight if the individual externally rotates from the hip to decrease knee motion during the swing phase of gait. In this situation, external rotation creates a functional shortening of the leg which can allow them to clear the floor without the typical knee flexion and extension seen in normal gait.
Hamstring tightness is often addressed with classic massage techniques. Hopper et al. compared classic massage to dynamic massage and found that those who received dynamic massage gained more flexibility than those in the other group. Moderate pressure massage has proven useful in lateral hip pain as well.
Field et al. investigated the effects of weekly 20-minute massages and found decreased pain as well as improved stiffness, function, mood, and sleep. These individuals continued to benefit from the effects of massage at one-month follow-up.
Massage therapy is a widely accepted treatment for patients with knee osteoarthritis. A systematic review of randomized controlled trials on the use of massage therapy in patients with arthritis found that massage improved walking function in individuals with osteoarthritis of the knee. The review also found that increasing quantities of massage led to more reduction in pain and improved self-reported function.
In a review by Field et al., the aggregate data suggest the use of massage focused on the quadriceps and hamstrings muscle groups is an effective way to improve knee range of motion and improve range of motion-related pain. Notably, this review also endorses self-massage on the days between sessions to enhance the overall effects of massage.
Self-massage using a foam roller or roller massager has been found to have wide-ranging effects. Monteiro et al. had 18 active males perform foam rolling or roller massage to their anterior thigh. Range of motion assessments taken before and after the intervention revealed increased range of motion immediately and at 30-minute follow-up. These short-term effects make this type of self-massage perfect for use before a workout or as part of the preparatory phase during a physical therapy session.
At the end of the day, it was easy for me to decide to have surgery. In fact, the mechanical symptoms of my bucket-handle tear made the decision for me. In situations where this decision is not as clear, it is advisable to exhaust all conservative treatment options before electing to undergo surgical intervention.
Feature photo: LeoCastrum via Pixabay.