Updated: May 5, 2022
A torn meniscus is a complicated injury that we are going to analyze, but before we look at the injury it is important to understand the anatomy and function of the meniscus. There are actually two meniscuses in each knee, your lateral and medial meniscus. Check out the image below from the American Academy of Orthopedic Surgeons
The medial meniscus is on the inner part of your knee and is the more commonly injured of the two. The reason for this is that it is less mobile, as it has attachments to the medial collateral ligament (MCL) and the joint capsule. The main goal of the menisci are to absorb shock, usually from jumping or hard ground contact. This prevents damage to the femur and tibia along with other structures of the knee.
Tearing of your meniscus can happen in two ways: acute and chronic. Chronic is typically seen in older adults and is a result of wear and tear. Many tears are actually undetected for years. A study by Englund, et al. found that 61% of subjects ages 50-90 with meniscus tears on imaging had no pain, aching, or stiffness during the previous month. We often seek to have perfect imaging as we age, but that is not realistic. Your body has structures such as the menisci to absorb force and protect other structures. This should result in wearing down of the menisci over time, but that is not necessarily a bad thing. It means that they are doing their job and protecting other areas!
Acute meniscus injuries are more common in younger, athletic populations. Typically, some form of twisting or cutting is involved to cause the injury. Remember that the menisci are designed to handle vertical stress such as from jumping or running. They are much worse at handling rotational stress from a violent twist, particularly if your foot is stuck in place. The twisting force can result in a tear, which may or may not display symptoms.
Torn Meniscus Symptoms
A torn meniscus can result in a variety of symptoms. Unfortunately, the menisci, particularly the medial meniscus, are part of your knee joint and the capsule. Therefore, swelling from damage to the meniscus can affect the biomechanics of the entire knee.
One of the main symptoms of a meniscus tear is pain with twisting. Many of the special tests used by healthcare providers are trying to twist your knee in different ways to feel for pain or catching. If you feel like twisting your knee is one of your most painful activities, then there is a higher probability of a meniscus tear.
Locking is also a common complaint with meniscus tears. This can occur with twisting, but also flexing and extending your knee. There are different types of tears, highlighted in the image below from the Florida Orthopaedic Institute.
A flap tear is a common occurrence, and it can result in a loose portion of the meniscus floating in space. This portion can get caught with flexing or extending your knee, resulting in pain and also locking. While it may sound painful, there are many people who suffer chronic tears who eventually lose their pain sensation to the area and only deal with locking. This is typically worse in the morning or after prolonged sitting, when inflammation has increased.
Feeling like your knee might buckle is another possible symptom of a meniscus tear. This can be due to several causes. Sometimes when our bodies are in pain, they shut down the involved muscles as a protective mechanism. The quadriceps muscle can frequently shut down as a result of this in knee injuries, increasing the chances of buckling. Also, the medial meniscus is connected to your hamstrings, adductor muscles, and gastrocnemius muscle in your calf. If there is irritation to the medial meniscus, these muscles can tighten as a protective response, causing lack of motion or buckling. Some medial meniscus tears result in mainly muscular soreness and tension in the listed muscles.
Torn Meniscus Surgery
There are two main surgeries that are performed for a meniscus tear: a partial meniscectomy or a meniscus repair. Both surgeries have different rationale and rehabilitation, so I will outline both.
A partial meniscectomy involves trimming the portion of the meniscus that is torn. In the above flap example, a surgeon would make a couple of small incisions and remove the damaged portion of the meniscus. This is the much quicker of the two surgeries, but it is not appropriate for all injuries. A complicated or large tear may not have the opportunity for a quick trim because there is too much damage. Also, it is unsure if trimming the meniscus results in worse outcomes later on in life including arthritis and future surgeries. Surgeons used to remove the entire meniscus, but outcomes were poor as many patients experienced arthritis and eventual joint replacements due to the stress on the joint without the cushion of the meniscus. Now, surgeons will try to remove as little of the meniscus as possible to maintain cushion. Physical therapy for this surgery is much simpler, as patients spend little if any time non-weight bearing and just need a gradual progression of loading and range of motion.
Meniscus repairs are more extensive procedures as the surgeon will typically sew the meniscus down into place. This is usually reserved for complex tears or in patients who have more time to focus on rehabilitation. A meniscus repair involves protecting the repair site, which means limited weight bearing for typically 6 weeks. During that time, you also have to be careful about active flexion of the knee, because this activates the hamstrings which are connected to the meniscus that was probably repaired. Contraction of the hamstrings can pull on the graft site and damage the repair. Rehabilitation is significantly longer after this surgery as there is less activity early on and then gradual range of motion and strength improvement. There is typically more atrophy as the leg muscles are not fully utilized for a couple of months.
Torn Meniscus Treatment
In general, treatment for a torn meniscus is based on common rehabilitation principles of avoiding exacerbation and gradually loading the tissue. The meniscus is a poorly vascularized structure, meaning there is minimal blood flow to the area. Light loading of the area can provide healing blood flow as long as it is not too stressful. This is where biking or the elliptical can be beneficial depending on patient tolerance.
Gradual loading is important for psychological and physical benefits. Psychologically, people may avoid loading the injured leg and simply shift their weight to the other side and avoid stressful exercise. While this provides temporary relief, it sets someone up for difficulty with mobility and exercise down the road. It is important to load the leg as much as is tolerated as soon as possible to decrease fear avoidance by the patient. Also, loading the leg prevents further atrophy of the muscles, making a return to exercise easier.
Meniscus Tear Recovery Time
A meniscus tear treated conservatively with physical therapy can take anywhere from 4-8 weeks to recover depending on the severity. Sometimes meniscus tears are freak accidents such as being tackled on a football field. However, there can be predisposing factors that can be addressed through physical therapy including ankle and hip mobility to take pressure off of the knee. Strengthening of the surrounding muscles are also important for force absorption and exercise tolerance.
Partial meniscectomies typically require 4-8 weeks to recover as well, which will lead some people to rush right to surgery as it is a similar timeline. As I mentioned before, it is usually better to maintain the support structures in your body whenever possible. Removal of part of your meniscus can result in issues later in life, and it should be avoided if possible. Meniscus repairs typically require 3-6 months of rehabilitation due to the 6 weeks of limited weight bearing and mobility.
Meniscus Tear Physical Therapy
A general progression for physical therapy involving a meniscus tear treated conservatively should be to decrease pain, improve range of motion, and increase strength in the nearby muscles. First, it should be determined what loading the knee can handle. At the very least, unloaded exercises like an exercise bike should be performed if possible for blood flow and mobility. As strength returns, the resistance on the bike or riding time can be increased for cardiovascular benefit.
Isometric exercises that involve no change for muscle length are typically tolerated well. Bridges are a great starting place along with wall sits for the hamstrings and other leg muscles. Holding heel raises can be a great isometric exercise for the gastrocnemius muscle as well. Eventually, more load can be added to these by holding weights.
Balance exercises fit into isometric exercises as well. Damage to the meniscus can create swelling in the knee and damage the proprioceptive nerves which tell you where your body is in space. This can be a problem if you are walking or running, as you should intuitively know where your leg is underneath you. Balancing also forces you to contract your muscles on all sides to remain in position. These exercises can be progressed with holding weights or moving your body around a stationary leg.
Deadlifts are a great exercise to begin loading the hamstrings and calves with minimal movement. Early on, you can limit how far down you go with the bar and gradually add more knee bend as you can tolerate. There is limited knee motion in a deadlift, so it is an easier exercise to return to compared to a squat. It will also provide tremendous benefit to the muscles involved with the meniscus.