Meniscus injuries of the knee
By: Dale J. Buchberger, PT, DC, CSCS, DACBSP
A meniscus tear is a common knee injury. The meniscus is a rubbery, C-shaped disc that cushions your knee. Each knee has two menisci (plural of meniscus), one at the outer edge of the knee (lateral meniscus) and one at the inner edge (medial meniscus). The menisci keep your knee steady by balancing your weight across the knee. A torn meniscus can prevent your knee from functioning correctly.
A meniscus tear is usually caused by twisting or turning quickly and forcefully often with the foot planted while the knee is flexed. Meniscus tears can occur when you lift something heavy or during sporting events that involve stop and go movements. The risk is particularly high for athletes, especially those who participate in contact sports, such as football, or activities that involve pivoting and sudden stops, such as soccer, tennis, or basketball. As you age, your meniscus will begin to degenerate and wear. This can make the meniscus more susceptible to a tear. Even kneeling, deep squatting, or lifting something heavy can sometimes lead to a torn meniscus. In older adults, degenerative changes of the knee may contribute to a torn meniscus. If a meniscus is degenerated, simply rolling over in bed can result in a tear.
Larger tears can cause pain at the side or center of your knee. Swelling gets progressively worse over 2 or 3 days. This may make your knee feel stiff and limit how you can bend your knee, but walking is usually possible with a noticeable limp. You might feel a sharp pain when you twist your knee or attempt to squat down. These symptoms may resolve in 3 or 4 weeks but can recur if you inadvertently twist or overuse your knee. The pain may come and go for years if the tear is not treated or rehabilitated.
When severe tears occur, pieces of the torn meniscus can break loose and move into the joint space. This can cause your knee to catch, pop, or even lock. You may not be able to fully straighten or bend your knee. Your knee may feel “unstable” or “give way” when weight bearing on the injured leg. It will usually swell and become stiff right after the injury or within 24 hours of suffering the injury.
If you are older and your meniscus is degenerated, you may not know what you did to cause the tear. For example, you may only remember feeling pain after you got up from a squatting position. Pain and slight swelling are often the only symptoms.
A torn meniscus can lead to knee instability, inability to move your knee normally or chronic knee pain. You also may be more likely to develop osteoarthritis in the injured knee several years following the injury.
A Baker’s cyst is a fluid-filled pouch that can develop behind the knee and is commonly associated with a meniscus tear. It is named after doctor William Baker who is reported to first describe this condition in approximately 1877. It is also sometimes referred to as a popliteal cyst. The cyst can vary in size from a very small cyst to a large cyst that is a number of centimeters across. It is although possible, uncommon for a Baker’s cyst to develop behind both knees at the same time.
A Baker’s cyst can develop if there is an underlying problem within the knee, such as arthritis (including osteoarthritis and rheumatoid arthritis), or a tear in a meniscus. This type of Baker’s cyst is the most common and may be referred to as a secondary Baker’s cyst.
In a secondary Baker’s cyst, the underlying problem within the knee joint causes too much synovial fluid to be produced within the joint. As a result, the pressure inside the knee increases. This has the effect of stretching the joint capsule. The joint capsule bulges out into the back of the knee, forming the Baker’s cyst that is filled with synovial fluid. This results in limited ability to bend the knee, especially with attempting to squat down. The Bakers cyst can expand and shrink over time. Generally surgery is not indicated for a Baker’s cyst, but draining it is an option.
Meniscus tears that prevent full function after conservative treatment (Physical therapy, strengthening program, Active Release Techniques, Extra-corporal Shock Wave Therapy, etc.) for 6-8 weeks may require arthroscopic surgery. While no one wants surgery sometimes surgery is necessary to regain full function. Meniscus tears commonly fall into this category. Once the meniscus tear is either debrided or repaired supervised physical therapy will quicken your return to your pre-injury level of activity. Remember, it’s your right as the patient, to choose which physical therapist you see!