Last updated: December 30, 2009
Active children and teenagers sometimes can have structural injuries to their knees. The meniscus which is a shock-absorbing cartilage in the knee can tear; often these painful injuries are treated surgically using a minimally-invasive procedure called arthroscopy. Using arthroscopy surgeons can repair or trim torn meniscus cartilages which can relieve pain and often return the child or teen to a high level of athletic function.
The knee is made up of the femur (thigh bone) the tibia (leg or shin bone) and the patella (knee cap) which are held together by ligaments. Between the femur and the tibia are two rings that are like bumpers one on the medial (inner) side of the knee called the medial meniscus (Figure 1) and one on the lateral (outer) side of the knee called the lateral meniscus (Figure 2). The meniscus functions to improve the fit between the femur and the tibia to absorb shock and distribute weight in the knee and to help move lubricating fluid around the knee. The meniscus is made of a type of cartilage which gives it a rubbery texture. However within the meniscus there are also fibers of collagen that help maintain the shape of the meniscus. The meniscus has blood supply only at its outer attachments. In adolescents and adults about 4/5 of a meniscus has no blood supply and so tears in this inner 4/5 of meniscus will usually not heal. In younger children more of the meniscus has a blood supply so tears have a greater potential to heal. Tears larger than about one centimeter in length also have a low chance of healing on their own so repair of the torn tissue is an excellent and often necessary way to help nature’s healing along. Trimming of a torn meniscus that has a low capacity to heal even with the help of sutures or other repair devices is the next best treatment to repair when repair is unlikely to be successful.
Tears are usually caused by sudden twists of the knee though sudden bending forces from the side of the knee may also cause injury to the meniscus. A torn meniscus can cause pain with standing walking or bending of the knee. In the long term a knee with a large meniscal tear and a knee missing some meniscus because of surgical removal both have a greater chance of developing arthritis. Meniscal tears usually cause swelling of the knee and they may cause the knee to be locked in one position or merely decrease the total flexion and extension of the knee (Figures 3 and 4).
Meniscal tears larger than about one centimeter or located in the inner or more central portion of the meniscus often do not heal on their own so surgery is likely the quickest way to return an athlete to their sport or a person to their normal daily activities.
Meniscal repair whenever possible is always recommended for patients as it may decrease the risk of future arthritis. Meniscal repair in children may also have a greater likelihood of success because of the better blood supply to the meniscus and blood brings healing factors to the tear. The result of a meniscal repair is typically pain-free function of the knee.
A patient with a knee locked from a piece of torn meniscus in the joint should experience a return to more normal function after repair. If a repair is not possible because of the location of the tear or the condition of the piece of torn meniscus trimming or removal of the torn piece of meniscus is the next-best treatment allowing an earlier return to sports — but at the risk of earlier wear-and-tear arthritis in the knee.
|Characteristics of meniscal tears in the knee of adolescents and children
Meniscal tears usually occur following a twisting injury. The tears produce knee swelling and stiffness and may result in locking (when the knee gets stuck in one position) or catching (when the knee does not move smoothly went bent and straightened) and are often accompanied by pain with standing walking running and especially squatting.
During a physician examination patients with a meniscal tear may experience discomfort with full flexion (bending) or full extension (straightening) of the knee. The knee is also often tender along the joint line between the thigh and leg or shin bones. In addition patients may experience discomfort when their knee is flexed and gently twisted.
TypesMeniscal tears may occur along the outer edge of the meniscus allowing a strip of meniscus (attached at either end to the tibia.) to flip upward into the knee joint like the handle of a bucket. The tears may occur in the front or the back of the knee (anterior or posterior tears). The tears may be a flap shape or a simple vertical or horizontal split or the be result of an abnormal formation of the meniscus which is called a “discoid meniscus” (Figures D and E).
Normally the meniscus should look like a C-shaped ring broad on the outside edge and thin on the inside. A discoid meniscus is a piece of cartilage shaped like a pancake or disc where a ring ought to be. This pancake shape tends to lead to frequent meniscal tears. They are found in the lateral side of the knee in approximately 5 percent of people of western European heritage and 10 to 15 percent of those of Asian heritage.
Anterior knee pain may have many similar symptoms as meniscal tears but the knee rarely swells with anterior knee pain. The discomfort in a patient with anterior knee pain often lies under the knee cap and is frequently the result of tight quadriceps and hamstring (thigh) muscles.
As young athletes play more sports at greater intensity meniscal tears are now being seen more than ever before. Those playing cutting or rapid direction-changing sports (such as soccer basketball tennis skiing and gymnastics) are at greater risk for meniscal tears.
Examination by a physician of the patient’s knee swelling tenderness between the thigh bone and leg bone pain during knee movements as well as the level and location of pain when squatting will help a physician diagnose meniscal tears. An MRI (magnetic resonance image) study of the knee is often used to help diagnose meniscal tears.
In some cases when the patient’s history and exam suggest a tear but an MRI does not reveal it the surgeon may suggest a diagnostic arthroscopy for patients whose condition doesn’t improve through physical therapy.
Medications may relieve the discomfort temporarily associated with meniscal tears but they would not be expected to lead to healing of the tear. Meniscal tears may heal on their own if they are small enough and are located in the outer edge of the meniscus.
ExercisesExercise can be helpful in some cases of meniscal tears. Some tears (i.e. small tears near the edge of the meniscus) may heal on their own and may become asymptomatic over time. Studies suggest that knee arthritis may occur later in a knee with a torn meniscus that is left untreated than a knee with a trimmed or repaired meniscus. Thus if a patient can perform his or her sports of choice without undue discomfort with a torn meniscus that may be preferable to surgery. Quadriceps and especially hamstring strengthening may help a patient return to their activities sooner. However a torn meniscus is at risk for further tearing potentially causing greater disability to a knee. This should be considered when deciding whether to pursue treatment.
Possible benefits of minimally-invasive surgery for a torn meniscus in athletic childrenRepairing a torn meniscus when possible and trimming a torn meniscus when necessary may improve the range of motion of a knee the comfort of the patient and the overall function of the limb. However these treatments may also increase the risk of early arthritis.
Types of surgery recommendedArthroscopic surgery is commonly performed for meniscal tears. Repairs may require moderate-sized incisions to tie knots in the suture passed through the meniscus and knee joint or may be performed with no additional incisions at all — through a technically demanding “all-inside” technique. The incision and its size will be determined by the surgeon based on the patient’s condition the location of the tear(s) and the surgeon’s preference. Some surgeons use special barbed devices that hook together the sides of the meniscal tear without requiring the large incisions of a sewn repair.
Who should consider minimally-invasive surgery for a torn meniscus in athletic children?Patients with suspected meniscal tears with marked loss of motion should consider surgery as should those with near normal motion but who are making little progress alleviating symptoms through exercise.
What happens without surgery?A torn meniscus may function adequately but it may lead to further loss of motion and cause pain with activities. It may also lead to a progressive tear and more severe loss of function. If the tear involves a large portion of the meniscus it may put the patient at risk for early arthritis.
Surgical optionsMeniscal tears may be treated with large (open) incisions through which repair or more commonly trimming or complete removal of the meniscus might occur. Complete removal of a meniscus was a common orthopedic procedure performed 30 to 50 years ago for a mensical tear. Now we understand that removing a whole meniscus too often results in early arthritisis and so it is avoided whenever possible.
EffectivenessFor those who undergo repair patients typically use crutches for six weeks and restrict squatting for six months. After six months following meniscal repair the patient is allowed to fully participate in sports though they typically have experienced full relief of symptoms many months prior to this.
Patients often experience immediate relief of symptoms after trimming of a meniscal tear. They are usually cleared to return to sports in three weeks.
The success rate of meniscal repairs is estimated to be 75 percent in patients under 20 years of age though 87 percent of these patients rated their knees as “very good” suggesting that even patients with incompletely healed tears after repair may still experience good knee function.
UrgencyThe urgency related to meniscal tears depends on the patient’s symptoms.
Those who have a locked knee should undergo the procedure as soon as is possible ideally within one to two weeks of diagnosis. Patients with a locked knee should use crutches so that they can keep weight off of the knee until they can be seen and treated by a physician.
Those patients who do not have a locked knee but have stiffness swelling or pain may follow an exercise program until a more permanent solution is identified. Crutches should be used if putting weight on the leg is painful.
RisksThe early risks for arthroscopy for meniscal tears in order of frequency are:
Managing riskThe following is recommended if risks occur:
PreparationPrior to arthroscopy for meniscal tears for patients who do not have a locked knee an exercise program to improve hamstring and quadriceps strength is recommended. This program will make rehabilitation easier for the patient.
TimingPrior to arthroscopy for meniscal tears for patients who do not have a locked knee an exercise program to improve hamstring and quadriceps strength is recommended. This program will make rehabilitation easier for the patient.
Surgical teamArthroscopy for meniscal tears is a technically demanding procedure that should be performed by an experienced orthopedic surgeon in a medical center accustomed to performing arthroscopy at least several times a month. In the case of children the surgeon should be well versed in performing the procedure on the skeletally immature body of a growing child with smaller joint spaces and pristine cartilage surfaces.
Finding an experienced surgeonIt is unlikely that every community has an experienced pediatric orthopedic surgeon who performs many arthroscopies for meniscal tears each year or who have sports medicine specialists who routinely treat children. Surgeons specializing in arthroscopies for meniscal tears in children and adolescents may be located through university schools of medicine county medical societies or state orthopedic associations such as the American Academy of Orthopedic Surgeons (AAOS). A regional children’s specialty hospital would also likely have surgeons experienced in these techniques.
FacilitiesArthroscopies for meniscal tears are usually performed in a major medical center that performs these procedures on a regular basis. These centers have surgical teams and facilities specially designed for this type of procedure. They also have nurses and therapists who are accustomed to assisting patients in their recovery.
On the day of the surgery the patient checks into the surgery center and meets the anesthesiologist the doctor who is in charge of keeping the patient comfortable and medically stable during the procedure. After general anesthesia is administered the surgeon performs an exam of the knee as a means to thoroughly assess the injury. The limb is then washed drapes are placed and the arthroscopy is performed. “Arthroscopy” means that the joint is examined and probed using small instruments through small incisions or portals while the action inside the knee is viewed on a large monitor like a TV screen. The surgeon decides where to place and move the instruments in the knee depending on what is seen on the viewing monitor. Ultimately three or more small incisions are made around the knee of a size just big enough to accept instruments the diameter of a pencil. The instruments are then inserted into the knee – a tube to collect the overflow of fluid a tube for the camera and a magnifying lens and an incision for probes shavers and suturing or sewing needles or other instruments (Figure 5). The probes are small hooked devices that help the surgeon tug on the meniscus to see where it may be torn; shavers come in different sizes and help trim the edges of torn a torn meniscus and a variety of different small scissor type instruments may be used to trim the edges of meniscal tears.
There are numerous ways to repair a torn meniscus. The meniscus may be sewn with absorbable or non-absorbable suture or thread it may be hooked together with a small device with barbs or small hooks that either absorb over time or stay permanently within the knee or the sides of the tear may be pinched together with a pair of special winged washers pushed out through the tear and the back of the meniscus onto which suture material is attached to allow for knot tying on the front of the meniscus.
When the meniscus is sewn using an “inside-out” technique long sewing –type needles are introduced through the small incisions or portals in the front of the knee to stitch together a repairable meniscal tear (Figure 6). These needles are usually pulled out of the knee through larger incisions 4-6 centimeters in length on the inner or outer back side of the knee and the thread on the ends of the needles is then tied over the capsule or joint covering. When the repair is completed the knots from the stitches of the repaired meniscus are covered as these larger wounds in the back of the knee are closed. All sutures in the skin are absorbable so no stitches need to be removed at future clinic visits. The stitches holding the sides of the torn meniscus together can be seen on the surface of the inner edge of the meniscus (Figure 7). In this particular case the suture or thread used was non-absorbable to protect the repair in case of slow healing.
Trimming of a meniscus is the preferred treatment when the torn piece is not repairable either because the tear is more central with a poor blood supply or the pieces of meniscus are deformed and unable to be returned to their normal position and function. Instruments used in trimming include small scissors shavers and special large biting clippers that can cut-off large chunks of meniscus with each bite.
Most patients undergo arthroscopy for meniscal tears under general anesthesia though sedation with a local or regional anesthetic are both possible alternatives.
Time for this procedure depends on the size and location of the tear as well as the tightness of the knee. These procedures may take anywhere from one to three hours.
Pain is relieved in part by oral pain medications usually a combination of mild narcotics such as Tylenol with codeine or hydrocodone and a non-steroidal anti-inflammatory such as ibuprofen. In addition the use of cold therapy may also greatly reduce discomfort. Plastic bags of ice placed over the dressings for 15 minutes out of every hour provide fair cooling of the knee though more controlled and less labor intensive cooling may be achieved with the use of a cooling cuff placed by the surgeon under the dressing. The cooling cuff attaches to a thermos mixed with ice and water.
Most patients who have had a meniscal tear repaired arthroscopically will stay overnight in the hospital. Pain medications may be administered orally with intravenous supplementation of more powerful medicines if necessary. Usually oral medicines and cold therapy together provide adequate pain relief within 12-24 hours and narcotic pain medicines can often be stopped within a week.
Patients who have had their meniscus trimmed often feel well enough to go home later that same day. In this case oral pain medicines and cold therapy together provide adequate relief within 1-2 hours of surgery and narcotic pain medicines can often be stopped within a week.
Oral pain medicines and cold therapy may greatly reduce discomfort though if a patient does not elevate their foot above their knee and their knee above their heart for the first three to five days after surgery the pain experienced may not be well controlled.
Nausea and vomiting may occur early after surgery though these side effects of the general anesthesia and potent intravenous narcotics often wear off within 12 to 24 hours. Post-operatively any nausea may be lessened when pain medicines are not taken on an empty stomach. Should a patient experience these symptoms with the oral pain medicines despite taking the medicines on a full stomach a change in medicines may be necessary. Using oral or rectal anti-nausea medicines may help break the cycle of nausea and vomiting that can accompany use of oral narcotic pain medicines.
For patients whose meniscus is repaired an overnight stay is often recommended to ensure adequate pain control.
Patients are often discharged from the hospital the same day if the meniscus is only trimmed should their level of discomfort be tolerable with oral pain medications.
For those who have undergone repair patient should use crutches and keep the weight off their knee for six weeks. Motion is encouraged during this period of time as well as isometric quadriceps and hamstring strengthening exercises. These exercises are usually taught to the patient at the pre-operative visit and reviewed at an early post-operative visit. At six weeks the patient is allowed to stand fully on the leg though no squatting is permitted for six months. This approach often precludes any participation in contact sports for six months. Though this seems like a long period of time to stay out of sports such a delay increases the chances of the torn meniscus healing decreasing the likelihood of early arthritis in the knee.
If the patient has had only a trimming of the meniscus without repair then he or she may put as much weight on the limb as they can tolerate. However this procedure is somewhat less desirable than a repair as early arthritis in the knee may occur after removal of portions of the meniscus.
After a trimming the patient is usually cleared for return to contact sports within three weeks allowing time for the small incisions to heal.
For those who have undergone meniscal repair crutches are required for six weeks and longer if inadequate quadriceps strength is noted at that time.
Crutches are used for comfort for those who have had a trimming of the meniscus. The crutches may be discarded when the patient desires.
Patients do not ordinarily need any convalescent stay after arthroscopic treatment of meniscal tears.
Range of motion therapy modalities (ice ultrasound) quadriceps and hamstring strengthening and proprioceptive or balance training may all be useful to a patient’s rehabilitation after surgery.
Some surgeons recommend full unrestricted weight bearing after meniscal repair but others believe such a program unnecessarily puts the meniscal repair at risk of failure i.e. re-tearing of the stitched meniscus. Patients should discuss the rehabilitation options for their particular condition and treatment with their surgeon.
Return to sports before three weeks for patients who have undergone a trimming of the meniscus may result in breaking open of the small wounds or portal sites through which the arthroscopic surgery was performed.
Rehabilitation for arthroscopic treatment of meniscal tears can certainly be done at home as long as some instruction has been given either preoperatively or early postoperatively regarding the desired rehabilitation program.
For those who have undergone a meniscal repair the return to activity may require a period of time for retraining beyond the six month point before prior levels of competition may be achieved.
Most patients do well after trimming of a torn meniscus with clearance for return to sports in approximately three weeks.
Early arthritis may occur despite apparently successful treatment of a meniscal tear. This condition may result in pain with activities and intermittent swelling of the knee.
Aggressive early return to activities after a meniscal repair may lead to re-tearing of the meniscus.
Therapy after arthroscopic treatment of meniscal tears usually continues until the prior activity level has been satisfactorily achieved.
For those who have undergone meniscal repair crutches are required for six weeks limiting return to ordinary daily activities.
For patients who have had their tear trimmed and not repaired return to normal activities of daily living may occur within one to two weeks.
There should be no long-term limitations from arthroscopic treatment of meniscal tear.
For those who have undergone a meniscal repair a more regular and perhaps twice-weekly program of therapy visits may optimize strength and capacity for early return to activity. The costs of these programs would depend on a patient’s particular insurance benefits.
For those who have undergone a trimming of a meniscus therapy would consist of a few intermittent appointments to confirm restoration of motion and strength of the knee.
The five most important facts about arthroscopic treatment of meniscal tears are: