Knee arthritis
Lateral and medial meniscus anatomy
Lateral and medial meniscus anatomy

What is a meniscus?

A healthy knee joint contains two C-shaped cartilage like structures,  each one called a meniscus.  The one on the inside of the knee is the medial meniscus and the one on the outside is the lateral meniscus.  Each meniscus is smooth, flexible, and rubbery, and acts to provide both stability and shock absorbing protection to the precious knee cartilage lining the joint, also known as the hyaline cartilage.  Loss or damage to this hyaline cartilage, for whatever reason, is known as arthritis, so the meniscus is essential to the health of the knee and the prevention of arthritis.

What are meniscus tears?

Meniscus tears are one of the most common knee injuries, affecting approximately 1 million people in the US each year.1,2  The meniscus can tear from acute injury or trauma to the knee.  In addition knees that begin to degenerate over time with age can see changes to both the hyaline cartilage and meniscus, and though changes here are often termed meniscus tears, more accurately they fall more into the category of degeneration, and therefore should be treated differently to acute tears.   An acute tear may happen during sports activities or other knee trauma such as twisting injuries.    They frequently occur in combination with other knee injuries, particularly cruciate ligament tear (ACL tears).  For many of these surgical treatment may be considered.

A degenerative tear is more subtle, and may develop gradually as the quality of the  hyaline cartilage and meniscus weaken and thin with age.  Many of these are not initially symptomatic or bothersome.  Often a degenerative meniscus will be labelled as “torn” when imaged by MRI but this is a bit of a misnomer.  Though the meniscus structure may not be normal, it is not considered a tear in the conventional sense, in that most times we do not consider these in need of surgical repair.  A degenerative meniscus can however undergo acute tearing,  and it may be reasonable to consider repair, but in these cases the meniscal tissue quality may be too degenerated to allow a good repair, and so many of these are still treated non-operatively.

What are common symptoms of meniscus tears?

The most common symptoms of a meniscus tear include joint pain and stiffness, swelling of the joint, limited range of motion of the knee, and knee joint locking, catching, or sometimes an audible clicking sensation of the knee or a feeling of it “giving way”.  Any combination of these symptoms may be present.

How are meniscus tears diagnosed?

These are best diagnosed by a health care professional.  A person experiencing any of the common symptoms should consult a sports medicine physician or surgeon for a thorough examination.  At the visit, the doctor will do a thorough review the patient’s symptoms and medical history.  In addition, the doctor will physically examine and manipulate the injured knee to check for signs of a meniscus tear and other associated pathology. While the diagnosis is often relatively clear from the history and exam, most times an MRI will provide the more definitive picture.  X-Rays to look at the overall status of the bones, and in particular to look for arthritis, are frequently done too.

What is the treatment for a meniscus tear?

The doctor will recommend the best treatment option based on your particular situation: the type of meniscus tear, it’s size, location, stability, and consideration for your general knee condition, relative age, sports and activity levels.  The treatment must be matched to your specific situation, not all types of tears are treated the same in all people.  Often times, and particularly with degenerative type tears, surgery is not needed and physical therapy, braces, ice, anti-inflammatory medications and various types of injections may help improve symptoms and return activity and function over time. 

If surgery is indicated, it is usually for mechanical or structural type tears, that without surgical repair could lead to loss of the protective and stabilizing effects of the meniscus, or where pieces of the meniscus are unstable and causing catching, locking and damage to the joint. Typically your doctor will recommend a minimally invasive procedure called arthroscopy.  Arthroscopy allows your doctor to see inside your knee via small incisions to gain access to your knee and meniscus and evaluate it fully before proceeding with definitive surgery.  At that point the choice for the doctors is to perform either a meniscus repair where the meniscus is surgically repaired and its shape and function are restored, or a procedure called a meniscectomy, where the damaged section of the meniscus is removed.

What is meniscus repair?

Meniscus repair is done by suturing the tear together by various different techniques and devices.  This attempts to restore the natural shape of the meniscus and preserves the tissue, allowing it to perform its normal function of protecting and preserving the knee joint.  It does require and extended rehabilitation with crutches and brace and not all meniscus tears will heal when repaired, which in turn may lead to a second surgery.

What is meniscectomy?

Meniscectomy, or meniscus removal, involves the permanent removal of the torn tissue in part or whole and does not preserve the normal shape or volume of the meniscus.  In general meniscectomy is associated with decent short term symptom improvement, as well as relatively rapid recovery from surgery, but increased potential for accelerated arthritis and higher risk for knee replacement in less than 5 years.3,4 In select cases meniscectomy does provide good longer term results. 

Which is better:  meniscectomy or meniscus repair?

Repairing the meniscus to its original configuration (meniscus repair) rather than removing any part of it (meniscectomy) has obvious advantages, and where possible most surgeons would prefer to repair than resect.  However meniscus tissue is somewhat unpredictable in its healing, predominantly due to its variable blood supply and the forces it experiences in the knee.  So repair failure rates remain higher than most surgeons like (between 10-30 percent depending on the tear)  The post-op rehab for repairs is also considerably more difficult and longer than with meniscectomy.  Repair surgery itself also takes longer and is overall more expensive than resection.  Lastly, degenerative meniscus has poor structural quality, blood supply and healing ability, so repair is seldom possible or recommendable for tears in this situation.

For these reasons the far the more common procedure at this time is meniscectomy.  However as recognition of critical type of tears (such as the so called “root tear”) have  improved, and as repair techniques and outcomes continue to progress,  repair has become more and more common and meniscectomy rates decline yearly at this point.   While this general trend of less meniscectomies being performed is a welcome development, it must be pointed out that meniscectomy can still be a good choice under the  right circumstances, and results from meniscectomy in those cases can be quite satisfying (11)  

How does my doctor decide between meniscectomy or meniscus repair?

Many times this decision is clear from the outset, as the history, exam and imaging are consistent and point to either meniscectomy or meniscus repair as being the definite choice in that situation.   However quite frequently the final decision has to be made at the time of surgery, as it is only under direct visualization of the knee and the meniscus itself under the arthroscope, that the true nature and extent of the tear can be evaluated.  In those cases the doctor will have discussed both options with the patient and the relative likelihood of performing either one, as well as the “game time” decision making process in these cases.

What does the clinical research show for meniscus repair vs. meniscectomy?

A number of clinical studies have compared each of the treatment options with strong support for meniscus repair.  Studies looking at the consequences of meniscus tissue removal or meniscectomy paint a negative picture, but in select cases good longer term results can be obtained. (11)  But no high level direct comparison studies of each approach exists.   All the studies suffer from a lack of generalizability as the multiple types of meniscus tears that exist all behave very differently.   Meniscus repair is associated with improved long-term outcomes and overall cost savings relative to meniscectomy, but higher rates of re-operation.  Meniscus removal may lead to diminished long-term sports performance, mobility, and total knee health, though in some cases can be very effective treatment .6 ,11

What is the typical recovery following meniscus repair surgery?

Protocols following meniscus repair surgery will depend on the type of tear and the repair itself, as well as other factors.  Your surgeon will have a detailed plan after the surgery is completed, suited to your specific situation.  Generally following meniscus repair surgery, patients typically wear a brace for 2-6 weeks, and usually need crutches for all or part of that time.  Heavy lifting, and excessive knee bending may be restricted during this time.  Regular rehabilitation exercises are commonly prescribed to restore knee mobility and strength. Generally, patients return to near normal active lifestyles after surgery and rehabilitation.

References

  1. Brinker MR, O’Connor DP, Pierce P, Woods GW, Elliott MN. Utilization of orthopaedic services in a capitated population. J Bone Joint Surg Am. 2002 Nov;84-A (11):1926-32.
  2. New Hampshire Outpatient Surgery: Knee arthroscopy data. Vol. 2008. New Hampshire Comprehensive Health Care System; 2006.
  3. Chung et.al. Arthroscopy 2015 Oct; 31(10):1941-50.
  4. Knee Surg Sports Traumatol Arthrosc. 2017 Feb;25(2):335-346. Epub 2017 Feb 16
  5. Feeley B, et.al. The Cost-Effectiveness of Meniscal Repair versus Partial Meniscectomy: A Model-based Projection of Clinical Outcomes and Costs
  6. Chahla et.al. Am J Sports Med. 2018 Jan;46(1):200-207
  7. Brophy Arth 2015 Dec;31(12):2295-2300
  8. Brophy et.al. AM J Sports Med. 2009 Nov;37(11):2102-7
  9. Chahla et.al. AM J Sports Med. 2017 Nov;746(1):200-207
  10. Stein et.al. Am J Sports Med. 2010 Aug;38(8):1542-8
  11. Feeley BTLau BCJ Am Acad Orthop Surg. 2018 Dec 15;26(24):853-863.