Examples of tear types

A torn meniscus will usually cause pain on the side of the knee that is localized to the meniscus (at the level of the joint line between the femur and tibia). Swelling of the joint may occur although meniscal tears by themselves usually don't cause a large, tensely swollen knee. Typically low-level swelling sets in the next day after the injury and is associated with stiffness and limping.

Sometimes the knee becomes "locked" in a bent position and is quite painful with attempts to straighten it. This scenario is often caused by the mechanical blockage of the joint from a displaced bucket handle type meniscal tear. The torn fragment actually acts like a wedge to prevent the joint surfaces from moving, hence the knee appears locked.

Any twisting, squatting or impacting activities will pinch the meniscus tear or flap and cause pain. Often the pain may improve with rest after the initial injury so that the limping resolves but as soon as aggressive activity is attempted the pain recurs. Meniscal tissue doesn't heal (with the exception noted above) due to its lack of a blood supply so symptoms are persistent until the tear is treated.

The diagnosis of a tear is made based on the history and joint line findings. A physician can often stress and manipulate the knee joint in a way that provokes the meniscal tear to snap or cause pain which makes the diagnosis likely. Other times an MRI scan will be obtained to visualize the meniscus and assess its integrity. A good MRI scanner has a very high accuracy rate in determining if a tear is present.

About MRI scans           David's Discoid Meniscus

Once a meniscal tear has been diagnosed it should be treated. This doesn't have to be done urgently although patients with a painful locked knee may want surgery as soon as scheduling permits. Arthroscopic surgery is the only way to treat the tear since there are currently no medications, braces, or physical therapy treatments that have been shown to promote healing in the avascular tears. As explained above it's conceivable that a short (<1 cm) stable tear limited to the outer 20% of the meniscus where the blood supply is could heal with a period of immobilization but this a rare circumstance.

Arthroscopic surgery is performed on an outpatient basis. The surgeon initially inspects the whole knee joint to see if  there are any other problems (e.g. arthritic areas, ligament tears or tears of the other meniscus) and then evaluates the meniscal tear by inspecting it with a blunt probe. Based on the location and geometry of the tear the decision is made to either remove or repair the tear(s). Removing the tear (called a meniscectomy) is accomplished by using a variety of small instruments that cut and suck out only the the torn portions of the meniscus. The remaining meniscal rim is then balanced and contoured to provide a gradually tapered transition into the area of the resection. The surgeon tries to leave as much normal meniscal cartilage as possible since this is an important shock-absorbing structure.

Arthroscopic probing of a posterior horn complex meniscal tear with multiple flaps

After arthroscopic removal of flap tears and contouring of remaining meniscal rim

Most meniscal tears need to be removed because they involve areas of the tissue that do not have the ability to heal (even if sewn together). On the other hand, if there is a vertical tear at the peripheral rim of the meniscus which is confined to the zone of meniscal blood supply, it is possible and desirable to repair the meniscus. A repair allows the entire meniscus to be saved and retained whereas removing a peripheral tear would require resection of a very large portion of the meniscus. The key to a successful repair is that the meniscus must be able to heal itself; the repair serves only as a means of securely holding the tissue together long enough for this biologic process to occur.

There are a variety of surgical techniques available for repairing a torn meniscus. Initially surgeons used to do an open repair (outside-in) sewing the meniscus back together through an incision, however in recent years the technology has progressed so that these repairs are now routinely done arthroscopically.

One arthroscopic technique is an inside-out method that uses curved guide tubes called cannulas to direct a pair of long needles into the meniscus and out through a small incision in the back of the knee. The suture thread ends connected to the needles are then tied together on the outside of the knee capsule layer to firmly bring the meniscal tear together.

This technique works well but note that it does require a 11/2 - 2" incision to access the area where the knots need to be tied down.

There are now a variety of methods available to the arthroscopic surgeon that permit a true inside-in repair and avoid having to make an incision at all. Some of these include bioresorbable T-arrows and dissolving meniscal "staples" which can each be applied from within the joint arthroscopically. At Orthopaedic Associates of Portland we often prefer to use the T-Fix® system for meniscal repair since in our hands it seems to give a strong and tight re-approximation of the meniscus to its rim. The T-Fix® sutures have an anchor that acts like a wall anchor and is deployed after placing the suture through the meniscus, the tear and the peripheral rim . Multiple sutures pairs are placed through long hollow needles and are tied together from inside the joint using a knot pusher instrument that securely snugs the meniscus down and provides an excellent repair.

Peripheral meniscal tear in the zone of blood supply
	Knots are pushed down after placing suture anchors               Close up of knot pusher
	Arthroscopic view of a meniscus repaired with the T-Fix® system