Discoid Lateral Menisci
What is a meniscus?
Menisci are fibrocartilaginous, rubber-like structures situated between the femur (thigh bone) and the tibia (shin bone).
What is the function of the meniscus?
They allow the rounded end of the femur to closely fit with the relatively flat top of the tibia. In cross-section, the menisci are triangular is shape but when viewed from above they appear "C"-shaped. The menisci distributes the forces across the knee more evenly and help stabilized the knee.
What is a discoid lateral meniscus?
Instead of the normal meniscal shape (triangular in cross-section and "C"-shaped). They are in the shape of a disc. Or like a hockey puck but hollow in the middle.
How does the discoid meniscus develop?
During the development of the knee join in utero, the meniscal development deviates from the normal structure into the discoid shape. At no time during normal development is the meniscus ever in a discoid shape.
Does this ever develop on the inside (medial) aspect of the knee?
Very, very rarely
How long has it been present?
Since birth
Why did it become so symptomatic so many years after birth?
Young children's bone and soft tissues are very resilient and compliant, meaning they are very strong and but forgiving. Over time, due to use, the discoid tissue gradually begins to wear down and develop tears at their edges or within the discoid meniscus itself.
When do most patients become symptomatic?
The average age of patients undergoing surgery is 11 years with average length of symptoms of up to 24 months prior to diagnosis.
What are the typical symptoms of a discoid lateral meniscus?
Knee pain, inability to fully extend or flex the knee, limping, knee giving-way, an "locked" knee, swelling, "clunking" or "popping" of the knee
What are the chances of this problem being present on the other side?
Depending on the report probably between 5% and 20% of children have both knees involved.
Is an MRI necessary?
Yes, accurate identification of the discoid meniscus is essential to make sure your child needs to undergo general anesthesia and surgery. Physical examination in the office is not very accurate or reliable in detecting these problems. Plain radiographs of the knee done in the office will visualize the discoid lateral meniscus, but can rule out other knee problems.
What is the recommended treatment?
It depends upon individual patient's symptoms. Asymptomatic discoid lateral menisci are left in place. In general arthroscopic surgery is necessary when there is pain and/or popping.
How is the surgery performed?
General anesthesia is necessary for all children undergoing knee surgery. Typically 3 small (1/2 inch) incisions are needed at the knee. A small video camera (arthroscope) is used to see the inside of the knee, and small specialized instruments are used through the other incisions.
What is done in surgery?
The goal of surgery is to contour the discoid lateral meniscus to resemble a normal meniscus. Sometimes repairs (suturing/stitching) of meniscus is necessary to correct the meniscus, and this can only be assessed during surgery. In some cases the entire meniscus needs to be excised due to un-repairable damage to the meniscus.
Will my child spend the night after surgery?
No, this is an outpatient surgery and your child will go home after surgery.
What medications will we go home with?
A prescription will be given for an oral narcotic, which is to be used as-needed. It will be either in pill or elixir form depending on the ability of each child to take oral medications. If pain is mild, the use of over-the-counter analgesics such as acetaminophen (Tylenol), Ibuprofen (Motrin), or naproxen (Aleve) is acceptable.
Will crutches be necessary after surgery?
Most children use them for several days until the knee is comfortable. However, if the meniscus is repaired (sutured) then no weightbearing (walking) can be done for 5 weeks after surgery.
Will there be a cast or brace on the knee after surgery?
No cast will ever be used. If the meniscus needs to be repaired (sutured), then a hinged knee brace will be applied to the leg in surgery and will need to be worn for 5 weeks. If used, the brace is removed for bathing.
How do we manage the knee incisions?
Remove the postoperative dressing 2 days after surgery. The child may get into the shower and let clean water run over the wounds. Do not scrub the incisions. Do not submerge the incisions in a standing pool of water, such a bathtub, pool or whirlpool/hot tub. Blot the skin dry about the knee and cover with band aids or gauze dressings until dry. When the wounds are dry they can be left open to air.
Do the sutures/stitches need to be removes?
No they are absorbable and will fall out over time. If they remain in place after two weeks postoperatively they can be removed at home. Use fingernail clippers to clip the knots to assist in their removal.
When do we return to clinic?
Call 1-3 days after surgery to set-up a visit to the office for 10-14 days after surgery.
What is the outcome after surgery?
With partial removal or "saucerization" 94% of patients have good or excellent results. Completely removing the entire meniscus early results are 84% good and excellent results and at an average of 17 years results were 72% good and excellent results.
When can sports be restarted?
At one month postoperatively, if no repair is done. If a repair is performed then sports can be resumed at 3 months after surgery.
Can discoid meniscus redevelop after surgery?
No
Will any other surgery be necessary in the future?
For the average patient only one surgery is necessary. However, each child's problems are unique, so future surgeries may be necessary.
