Vail doc talks about how to fix a torn meniscus
August 1, 2011
A torn meniscus is a common knee injury. In younger people, the meniscus is fairly tough and rubbery. An isolated meniscus tear in a young patient is uncommon. However, young people not uncommonly tear their meniscus in conjunction with ACL tears as a result of a forceful twisting injury. I also see meniscus tears in young patients who may have torn their ACL and then have not had their ACL surgically reconstructed. Without an ACL, there is much more shear force in the knee and the meniscus is slowly overloaded and weakened by these forces and then tears.
The meniscus becomes more prone to tear as we age and as it loses some of its elasticity. Skiing the bumps for decades can take a toll on the meniscus or “shock absorber.” It is therefore not uncommon for me to see someone in their late 40s or early 50s with isolated meniscus tears. These commonly occur as the result of a fairly simple mechanism (i.e. rotating on their knee while playing tennis).
What does a torn meniscus feel like?
Patients can either tear their medial (inside of the knee) or lateral (outside of the knee) meniscus. Medial meniscus tears are much more common than lateral meniscus tears. Patients typically experience pain directly over the torn meniscus, as well as popping or catching. Squatting usually increases the pain. There is often minimal swelling present. A torn meniscus may not cause any pain when walking, but then can cause sharp, sudden pain with knee rotation.
Unlike bone or muscle, meniscus tissue has very poor blood supply. As such, it has a poor healing potential. Most patients tear along the thin, inner rim of the meniscus where there is no blood supply. These tears cannot be repaired. Instead, in order to alleviate the pain, patients often come to arthroscopy where a telescope like instrument is placed in the knee and the small torn portion of the meniscus is removed while preserving as much of the healthy, functioning portion of the meniscus as possible. In a typical meniscus tear requiring arthroscopy, 10 to 15 percent of the meniscus has to be removed. If a patient has minimal arthritis (wearing of the coating cartilage on the end of the femur and/or tibia), then the patient can expect a great outcome. If there is a meniscus tear and arthritis, then the outcome is typically inversely related to how severe the arthritis (i.e. the worse the arthritis, the less pain relief there is). There is no need for crutches or a brace after arthroscopic menisectomy and most patients recover within weeks.
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Arthroscopic meniscal repair
If the meniscus tissue is torn in the peripheral 1/3 where there is blood supply, the meniscus can be repaired and preserved. Repairing the meniscus is always my preference. So called “bucket handle tears,” where the meniscus tears longitudinally along the outer rim and then flips into the center of the knee like a bucket handle, are amenable to repair. The alternative to repairing these bucket handle tears is to remove 50 percent or more of the meniscus. Removing this amount of the meniscus, which is the “shock absorber” cartilage, is known to predispose the knee to early arthritis and this should be avoided if possible.
The gold standard for repairing the meniscus is to pass sutures “inside-out.” While viewing through the arthroscope, sutures are precisely passed through the meniscus and tied over the capsule of the knee joint. There are newer “all inside” meniscal repair devices where sutures don’t have to be passed through a small incision made outside the knee. I use these all inside devices for smaller tears or for hard-to-reach tears.
The rehabilitation after a meniscal repair is more intense than after an arthroscopic menisectomy. For a repair, the patient is kept in a knee brace with their knee locked straight whenever up and walking for 6 to 8 weeks, depending on the size of the tear. However, immediately after surgery, we encourage you to unlock the brace or remove it when sitting down and start gentle knee range of motion exercises. After 6 to 8 weeks, the brace is discontinued, but no squatting is allowed for up to 12 weeks as this places high shear stresses on the repaired meniscus, and we want to be sure it has been given every opportunity to heal.
Unfortunately, not all meniscus repairs heal despite our best efforts. This is again due to the poor blood supply and compromised healing potential of the meniscus. A MRI is somewhat helpful to see if the meniscus has not healed but more importantly, we look for symptoms of a meniscus that did not heal, which are very similar to the symptoms patients had before surgery (catching, locking, well localized pain over the meniscus).
Just as we transplant solid organs (i.e. kidneys), some patients are candidates for meniscus transplants. I recently had a 28 year old man who lost most of his lateral meniscus due to a bad injury. Given his age and activity level, he underwent a lateral meniscus transplant. This should alleviate his pain and more importantly, protect his cartilage from early degradation and arthritis.
Dr. Rick Cunningham is a Sports Medicine Orthopedist with Vail-Summit Orthopaedics. He specializes in knee and shoulder injuries, sports medicine, and partial and total knee replacements. Visit http://www.vsortho.com for more patient information on how to treat common conditions and injuries.