Arthroscopy Of The Knee

What Is Arthroscopy of the Knee?

Arthroscopy is a minimally invasive surgical procedure that allows an orthopedic surgeon to see and operate inside a joint using a device called an arthroscope. The arthroscope is inserted through very small incisions in the skin.

An arthroscope is a pen-shaped instrument to which a tiny video camera and light source is attached.

  • Lenses inside the arthroscope magnify images from inside a joint up to 30 times their normal size.
  • These images are transmitted to a TV monitor, giving the orthopedic surgeon an exceptionally clear view of the inside of a joint.
  • From this view, the surgeon can then operate inside the joint using small instruments inserted through separate tiny incisions.

Joint surgery has improved greatly since the arthroscope was introduced. Surgery is less traumatic, healing is faster, scarring is reduced, and recovery is quicker. Only a number of tiny scars remain to show that surgery was ever done.

Facts about arthroscopy of the knee:

  • More than 1.5 million knee arthroscopies are performed in the U.S. each year.
  • In the U.S., more than 11.2 million visits are made to physicians’ offices because of a knee problem.
  • Arthroscopy is one of the most common orthopedic procedures in the U.S.
  • Millions of people have recovered and returned to work following a knee injury much sooner thanks to arthroscopy.
  • Modern or contemporary arthroscopy of the knee was first performed in the late 1960s.

Understanding The Knee

The knee is a hinged joint made up of three bones held firmly together by ligaments that stabilize the joint.

The bones that meet at the knee are the upper leg bone (the femur), the lower leg bone (the tibia) and the knee cap (the patella). The bones inside the joint are lined by a smooth protective layer called articular cartilage, which allows the bones to glide smoothly upon each other. In arthritis, this smooth lining becomes damaged.


Ligaments are dense structures of connective tissue that fasten bone to bone and stabilize the knee.

Inside the knee joint are two major ligaments.

  • The anterior cruciate ligament (ACL)
  • The posterior cruciate ligament (PCL)

These cross in the center of the knee (that’s why they’re called cruciate ligaments) and control the backward and forward motion of the knee. The ACL is frequently injured in severe twisting injuries of the knee.

Two other major ligaments are actually located outside the knee joint, on the outer and inner side of the leg. They act to stabilize the knee’s sideways motion. The ligament on the inner side of the knee is called the medial collateral ligament or MCL (medial means inner side). The ligament on the outer side of the knee is the lateral collateral ligament or LCL (lateral means outer side).

The patellar ligament (the ligament of the knee cap) connects the lower part of the patella to the upper part of the tibia, specifically to the bony prominence one can feel on the lower leg bone (the tibia). The central one-third of this ligament is the most commonly used graft source in reconstructing a torn ACL.


The meniscus is a half moon-shaped structure placed between the weight-bearing bone ends in the knee. There are two menisci in each knee, one on the inner side called the “medial meniscus” and one on the outer side called the lateral meniscus.”

The two menisci act as shock absorbers within the knee and also help spread the weight load.

The meniscus is a type of cartilage, though it is different than the cartilage that lines the bones.

The menisci may be torn during twisting movements of the knee.

What’s Wrong With My Knee?

Arthroscopy is able to deal effectively with a number of problems in the knee joint, including:

  • Meniscal injury
  • Ligament injury
  • Loose bodies within the knee
  • Chondromalacia of the patella
  • Osteoarthritis

You will most likely have an MRI (magnetic resonance imaging) scan, which clearly will show the problem affecting your knee.


Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to create detailed images of the body’s soft tissue structures, such as ligaments, tendons, and cartilage, which do not appear on an x-ray image of the same part of the body. A computer converts signals from the MRI scan into frontal, lateral, and cross-sectional images.

In an MRI of the knee, many separate images are produced, each one representing a ‘slice’ of the knee (like very thin slices of bread but a lot thinner). Each slice is a cross section image of a different section of the knee. The clarity of the images allows the radiologist and orthopedic surgeon to easily see any problems in the knee.

For more information about MRI, go to MRI.

Meniscal Injury

These are the most common knee injuries. The menisci are two pads of fibrocartilage on either side of the knee that act as cushions or shock absorbers. They also help distribute the weight load inside the knee.

  • The meniscus on the inner side of the knee is called the medial meniscus (medial means ‘inner’).
  • The meniscus on the outer side of the knee is called the lateral meniscus (lateral means ‘outer’).

Most tears of the meniscus result from a sudden twisting movement of the knee, as often occurs in sports injuries. As the knee bends and twists, the meniscus may be pinched between the bones. This is often accompanied by a “popping” sensation. The knee is likely to swell a few hours after the injury.

The tear may occur along the inner edge of the meniscus, or, less commonly, along the outer edge. There may be just a small torn “flap” of the meniscus, or a longer so-called “bucket-handle” tear, which is a tear along the length of the meniscus. Such a tear may cause the knee joint to “lock,” meaning that the leg cannot be straightened.

The menisci may be also become damaged and torn as part of normal wear and tear within the knee joint as we age.

All types of meniscal tears can be treated by arthroscopy. Because the inner part of the meniscus has no blood supply, a tear along the inner part will not heal. Treatment, therefore, involves trimming away the torn piece of the meniscus. This is done with miniature motorized instruments inserted through a tiny incision on the side of the knee.

Meniscal injuries along the outer edge of the knee may be repaired rather than removed because the blood supply to this part of the meniscus is better, giving an improved chance of healing.

Ligament Injury

Ligaments are strong bands of tissue that fasten the bone ends together and stabilize the joint.

There are two ligaments inside the knee that can be reconstructed with the assistance of the arthroscope:

  • The “anterior cruciate ligament” (ACL).
  • The “posterior cruciate ligament” (PCL), which is less frequently injured.

The cruciate ligaments restrict both the forward and backward motion of the knee and its rotation. They may be torn by sudden twisting motions of the knee beyond its normal range.

Not all cruciate ligament injuries need to be reconstructed; it depends on your age, level of activity, type of activity, and what you expect from your knee. A frank discussion with your doctor will help both of you determine whether surgery would be beneficial.

  • If you enjoy active sports, it would be appropriate to have surgery.
  • If you have a sedentary-type job and are not active in your leisure time, you may not require surgery.

Unfortunately, a simple repair by suturing the torn ligament together again is not effective. A successful repair involves completely replacing the torn ligament. There are a number of ways to accomplish this, depending on the preference of the surgeon.

  1. Ligament reconstruction is most commonly performed utilizing the patella tendon graft. The orthopedic surgeon takes the central strip of the patella tendon and roots this through the knee through tunnels drilled in the tibia and femur. This creates a new ligament to replace the torn one.
  2. More and more surgeons are now using the hamstring tendons from the back of the knee. The surgeon folds over these tendons four times into a strong, thick band and passes it through the knee. The advantage of this technique is that the patella tendon is left intact. There does not appear to be any damage caused to the hamstring muscles. Results using this technique are extremely good.

    Both of these methods require an extra skin incision (about 2 inches in length) to harvest the tendons to be used.

  3. Some surgeons prefer to use a donor ligament from a recently deceased person. Most commonly, the Achilles tendon is used. The advantage of this method is that the patella tendon and hamstrings are left intact. The disadvantage is the exceptionally small risk of disease transmission.

For more information about ACL Tears, go to ACL Tears.

Loose Bodies Within The Knee

A traumatic incident to the knee can cause a fragment of cartilage, or a fragment of bone attached to cartilage, to come loose and float around the joint. This condition may result from “osteochondritis dissecans” (OCD).

Depending on the size of the fragment and whether it is still attached, the orthopedic surgeon may decide to reattach it or remove it entirely. The surgeon can perform either using the arthroscope.

A number of arthritic conditions may also cause loose bodies inside the knee.

Chondromalacia Of The Patella

This is a condition in which the cartilage surface lining the kneecap softens, sometimes to the point where the articular surface cracks, giving it an irregular surface. This may lead to discomfort felt in the front of the knee, particularly when going up and down steps.

If the problem does not respond to medication or physical therapy, some surgeons elect to smooth the rough areas of the kneecap using arthroscopic surgery.


As we get older, our joints, including the knee, may suffer from wear and tear that can cause pain and discomfort. If medication can’t control the discomfort, your surgeon may use arthroscopy to shave and smooth the roughened surfaces of the bone and trim any damage to the meniscus.

Clearing out the debris often helps reduce the pain of arthritis for a period of time. This is a significantly less traumatic procedure than a total knee replacement, which may ultimately be required if the pain and discomfort from osteoarthritis becomes severe.

For more information about osteoarthritis, go to Osteoarthritis.

Arthroscopy of the Knee: How Is The Procedure Done?

Arthroscopic surgery is generally done on an outpatient basis, allowing you to go home a few hours after surgery. However, following ACL reconstruction, you may stay in the hospital an extra day.

Preparing for arthroscopy

The operation

Preparing For Arthroscopy

Depending on your age, certain preoperative tests will be arranged, such as blood tests, urine tests, chest x-ray, and EKG.

  • For an ACL reconstruction, leg measurements may be taken to order a knee brace. Your rehabilitation program will be discussed in detail with you.
  • You may meet the anesthesiologist, who may offer you a choice of anesthesia:
    • If you choose a general anesthetic, you will be asleep during the procedure.
    • If you choose an epidural, an injection is given into the back that numbs the lower half of the body. This wears off a couple of hours after surgery.
    • If you chose a local anesthetic, you will receive injections of a local painkiller in the knee and surrounding areas.

    If you have an epidural or local anesthesia, you can often watch the whole operation on the television monitor as seen through the arthroscope.

Need To Know:

  • If you take aspirin, anti-inflammatory drugs, or blood thinners, you should stop taking them one week before surgery to minimize bleeding. Discuss this with your doctor. Also, beware of certain homeopathic supplements that may interact with anesthetic agents.
  • You should not eat or drink anything (even water) for eight hours before surgery. This usually means not eating or drinking anything after midnight the night before surgery.
  • If you would normally be taking medication during the hours before surgery, talk to your doctor.

Need To Know:

What to tell your doctor

Be sure to tell your doctor:

  • If you are allergic to iodine, penicillin, or any other drugs
  • What medications you take
  • About your past medical history
  • If you have ever had deep vein thrombosis or other blood clotting abnormalities

    For more information about deep vein thrombosis, go to Deep Vein Thrombosis.

Also tell your doctor if you develop any of these symptoms prior to surgery:

  • Fever or chills
  • Irritation of the eyes, ears, throat or gums
  • Sniffling or sore throat
  • Boils or inflamed skin abrasions and cuts

The Operation

After the chosen anesthetic has been administered, the leg is thoroughly cleaned, usually with an iodine-based solution. A tourniquet may be placed around the thigh.

A tiny incision is made on the outer side of the knee about level with the lower end of the knee cap. The arthroscope is then gently introduced into the knee, so the surgeon can see the inside of the knee on the TV monitor.

Another small incision is then made on the inner side of the knee to allow the surgeon to insert specialized instruments.

  • If the meniscus is torn: the torn flap or segment is carefully trimmed away, leaving a smooth edge. However, if the tear is on the outer side of the meniscus, where the blood supply is better, it is possible to repair the tear using specialized sutures.
  • If the anterior cruciate ligament is completely torn: an additional two-inch incision will be required to remove either the patella tendon or hamstring tendon to create a new cruciate ligament. Tunnels are drilled in the tibia and femur through which the new ligament is passed. The ligament is then anchored firmly to the bone, usually with screws at either end.

    For more information about ACL tears, go to ACL Tears.

  • If a loose body is found, treatment may vary. If it is truly loose and floating around the joint, it can be easily removed. If it is still partially attached, it can be gently pushed back into place and held with a specialized screw.
  • If the problem is arthritis or chondromalacia, the roughened surface may be smoothed with power instruments. The surgeon will also remove any bits of bone or cartilage floating in the joint.

Recovering After Arthroscopy

  • You will usually have recovered enough to be driven home a few hours after the surgery.
  • You may or may not be allowed to put weight on your knee immediately after surgery, depending on what was done to your knee. A physical therapist will help you get mobile with crutches before going home.
  • Expect some swelling and discomfort in the knee for a few days. You will be given a prescription for pain medication and an anti-inflammatory drug to deal with the swelling.

Need To Know:

Tips to help your recovery

  • Elevate your leg on a couple of pillows to reduce swelling.
  • Ice the knee periodically for about 10 – 15 minutes at a time during the first week. Do not apply the ice directly to the knee, but wrap the ice in a waterproof pack, which you can then wrap in a towel and place on your knee.
  • Take the medications prescribed by your doctor.
  • Move your ankles up and down. This simple exercise, called “ankle pumps,” is important for preventing possible blood clots in the leg.
  • Use crutches if you have been told to keep weight off the knee.
  • Do the exercises you have been told to do in order to quickly regain the strength in your leg.
  • Gradually increase your walking as instructed by your orthopedic surgeon or physical therapist.
  • If you have been fitted with a brace, be sure to wear it.

Caring For The Incision

Sutures may or may not have been used to close the wounds. Your doctor will instruct you when you may remove the bandage, usually within a day or two (depending on the procedure), leaving smaller dressings over the actual incisions.

Your doctor will let you know how long to wait before you can get your knee wet, but in general, do not get your knee wet until the sutures are removed. You will need to cover the leg with a large plastic bag when bathing, to keep the incision dry for the first week to 10 days.

Need To Know:

When to contact your doctor

There are very few complications that occur after arthroscopy, but you should be aware of the possibility of postoperative problems. Contact your doctor if:

  • There is increasing pain and swelling in the knee
  • The knee becomes increasingly red
  • Fluid or pus oozes from a wound
  • You have a fever above 101°
  • You have pain and tenderness in the calf muscle (this may suggest a clot in the veins)
  • You have chest pain (this may suggest a blood clot in the lung).

Physical Therapy And Leg-Strengthening Exercises

As your leg strengthens in the days after surgery, you will begin formal physical therapy using specialized equipment and working under the supervision of a physical therapist. The aim is to improve the strength of the muscles as well as the range of motion of the knee by working the muscles against varying degrees of resistance.

It is important to strengthen the thigh muscles following knee surgery. Particular emphasis is placed on the quadriceps and hamstring muscles as well as the inner and outer thigh muscles. The following exercises are useful in the days after surgery:

Heel slide:

While lying on your back, bend your knee as you slowly slide the heel of your operated leg up toward your buttock. Slide as far back as you can and hold for five seconds. Slide back to the starting position and repeat again.

Knee press:

While lying on your back on the floor, try pressing the back of your knee flat against the floor. Hold for 10 seconds and release. Repeat regularly.

Straight leg raising:

This is an excellent set of exercises that can strengthen all the muscles of the upper leg. There are four different straight-leg exercises to strengthen the four sides of the upper leg.

  • Quads strengthening – While lying on your back, lift your leg straight up to about 12 inches. Hold for 10 seconds and slowly lower. Repeat.
  • Hamstring strengthening – While lying on your stomach, raise your leg backward about 12 inches. Hold for 10 seconds and slowly lower. Repeat.
  • Abductor strengthening – While lying on your side, raise the operated leg 12-18 inches. Hold for 10 seconds. Slowly lower. Repeat.
  • Abductor strengthening – This time lie on the operated side. Rest the good leg on a support about two feet off the ground. Lift the operated leg up to the elevated leg. Hold for 10 seconds and then slowly lower. Repeat.

The same exercises should be done on the healthy leg as well.

Arthroscopy Of The Knee: How Long Until Full Recovery?

Recovery time will depend on the procedure performed.

  • If a partially torn meniscus was removed – You should be back to full activities within four to six weeks.
  • If a partially torn meniscus was repaired – You should expect four to six months until full recovery.
  • If you had an ACL reconstruction – You should commit to an aggressive rehabilitation program and expect full recovery in six to nine months (but you can be back at a desk job within a week or two).
  • If you had loose bodies removed – Recovery may take two to four weeks.
  • If you had a loose body repaired – Recovery is usually six to eight weeks.
  • If you had chondromalacia or arthritis – You should expect a couple of weeks to recover.

You will be encouraged to undertake a moderate exercise routine well before your knee is fully recovered. Generally, you will be discouraged from activities that place excess weight or stress on the knee until full recovery. Non-weight-bearing aerobic exercises, like cycling and swimming, are strongly encouraged during the recovery period. Pool exercises are very helpful.

After Arthroscopy: When To Return To Work?

Return to work will depend on your job and the procedure that was done. Generally:

  • If you have a desk job, you could return to work within one week. Try to keep your foot elevated initially to prevent swelling. Get up for a short walk at least every hour for the first few weeks.
  • If you stand most of the day but do not lift heavy objects, you’ll probably be ready to return to work within four to six weeks.
  • If your job requires climbing or lifting heavier objects, recovery time will depend on the procedure. You may need to wait two to four months before returning to work and initially avoid lifting objects that weigh more than 10 lbs.

Frequently Asked Questions: Arthroscopy Of The Knee

Here are some frequently asked questions related to arthroscopy of the knee.

Q: What types of knee problems can arthroscopy help?

A: Arthroscopy may help relieve problems of persistent pain, catching, or swelling in your knee due to meniscal tears, cruciate ligament injuries or loose bodies in the knee.

Q: Why is my knee prone to injury?

A: There are many soft tissue components to the knee, making it vulnerable for various types of injuries. The knee is the largest joint in the body, and one of the most easily injured.

Q: What’s the advantage to having local instead of general anesthesia?

A: While the risk of problems with any type of anesthesia is small, there are fewer risks associated with local anesthesia than with general. In addition, local anesthesia is less expensive than general, and recovery in most cases is quicker.

Q: My doctor told me I’ve injured my cruciate ligament. Does this mean I have to have surgery?

A: Not all cruciate ligament injuries need to be reconstructed. You need to discuss with your doctor your lifestyle and level of activity. If you have a sedentary-type job and are not active in your leisure time, you may not require surgery.

Q: Do knee injuries from playing sports happen only to professional athletes?

A: Unfortunately, knee injuries during sports can happen to anyone. A casual game of soccer can turn into a painful and debilitating injury for someone whose body is unprepared for athletics. Knee injuries can happen during an impromptu volleyball game at your company picnic, when your are heading out to the ski slopes on your first free weekend in a while, or even while playing a game of catch with your children.

Q: How much physical therapy will I need after the ACL reconstruction?

A: One of the main priorities after ACL reconstruction is to regain the knee range of motion. This along with establishing a good strengthening program is usually best done two to three times per week for the first four to six weeks. Because many insurance policies will not cover this many visits to the therapist, an independent home program may need to be instructed earlier. Compliance in performing the exercises in and out of the clinic is the key.

Q: I like to snow and water ski. Can I still do these activities after ACL reconstruction?

A: Unless the surgeon advises otherwise, most people return to enjoying both of these sports with the use of a brace. However, remember every individual injury is different. Following the recommendations of the surgeon is of utmost importance.

Putting It All Together: Arthroscopy Of The Knee

Here is a summary of the important facts and information related to arthroscopy of the knee.

  • Arthroscopy is a surgical procedure that allows an orthopedic surgeon to see and operate inside a joint using a device called an arthroscope. The arthroscope is inserted through small incisions in the skin and has a tiny camera at the end.
  • Arthroscopy is able to deal effectively with a number of problems in the knee joint, including meniscal injury, ligament injury, loose bodies within the knee, chondromalacia of the patella, and osteoarthritis.
  • In most cases, arthroscopic surgery is done on an outpatient basis, allowing you to go home a few hours after surgery.
  • After surgery, you may need to use crutches for some time to avoid putting weight on the knee.
  • Appropriate exercises can help strengthen your knee and speed your recovery.

Glossary: Arthroscopy Of The Knee

Here are definitions of medical terms related to arthroscopy of the knee.

Menisci: cresent-shaped piece of tissue found in the knee joint.

Ligament: fiborus bands that hold bones together in the joint region.

Knee Joint: the juncture of the point of the femur and tibia.

Additional Sources Of Information: Arthroscopy Of The Knee

Here are some reliable sources that can provide more information on arthroscopy of the knee.

  • Extensive information for consumers on knee injuries and arthroscopic procedures is available at the Web site of the American Academy of Orthopedic Surgeons,

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