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Knee Arthroscopy

Meniscal Tears :: Cartilage Defects :: Microfracture :: Osteochondral Autograft Transplant
Cartilage Cell Technique :: ACL Ligament :: Anesthesia for Knee Arthroscopy

Meniscal Tears

As mentioned on the Knees page, the meniscal cartilage is between the two layers of articular cartilage. When healthy, this cartilage is very rubbery and helps to cushion the knee. In young athletes, this cartilage may be torn by an injury to the knee. Because the cartilage is pie-shaped with a very thin edge, many tears occur in this thin portion. This area has no direct blood supply, and therefore, has no ability to heal. It is usually necessary to remove the torn and damaged portions of this cartilage. Occasionally, the cartilage will tear in the thicker portion where there is blood supply, and when this occurs, the cartilage can be sewn back together through a very small incision.

In older patients, meniscal tears are often termed "degenerative." As a person ages, the meniscal cartilage may become more fragile and easily torn, and sometimes very minor trauma may cause a tear. It is very important to use good medical judgment as to when to perform arthroscopy in instances of degenerative tear. If the degree of arthritis in the knee is severe, arthroscopy will not improve the function of the joint and, in some cases, may make it worse.

If, however, the weight bearing x-ray (an x-ray taken with the patient's full weight standing on the knee) shows maintenance of the space between the bones, then removal of the damaged cartilage usually will provide reasonable relief. However, it must be remembered that this is not a young, healthy knee, but rather a degenerative knee. Thus, recovery may be slow, and it may be expected that the arthritis will progress with time, ultimately leading to the need for a joint replacement.

See sample /images See sample /images

The above picture (link) shows three degrees of cartilage damage of the knee. The first is a small crack or fissure in the cartilage. The second shows signs of wear and tear arthritis and the third is advanced with exposed bone. Though the arthroscope, mild damage is easily fixed, the moderate arthritis can be improved but not "cured" while the advanced arthritis may worsen with an arthroscopic procedure.

 

Cartilage Defects

Damage to areas of the articular cartilage may occur in young or older patients. There may be damage to the cartilage itself or to the cartilage and underlying bone. In some cases, using small shavers or specialized radio-frequency probes, it is possible to smooth these damaged areas (see image at right). However, if the damage goes down to the bone, or if the bone itself is damaged, more extensive procedures may be required, including Microfracture, OAT's procedure, or cell culture.

In small defects, it is possible to use a small instrument which punctures the bone in the area of the defect. This allows fresh blood from the femur to enter the defect. The fresh blood contains cells called "precursors" or "multipotential" cells capable of producing new cartilage. This is a moderately effective technique.

Cartilage Defects

Modern tiny shavers and "radiofrequency" devices can be used to smooth rough and damaged areas. Lasers are not commonly used any longer due to risks.

 

Microfracture

In small defects, it is possible to use a small insturument which punctures the bone in the area of the defect. This allows fresh blood from the femur to enter the defect. The fresh blood contains cells called "precursors" or "multipotential" cells capable of producing new cartilage. This is a moderately effective technique.

A small drill or "pick" is used to place holes in the bone where cartilage should be. This allows cells from the bone marrow to enter the area and become cartilage manufacturing cells.

 

Osteochondral Autograft Transplant

In more severe or larger defects, a specialized drill is used to place holes in the defective area. Another specialized drill called a "trephine" is used to remove plugs of cartilage and bone from an area of the knee where it is not needed.

The first image demonstrates where "plugs" of bone and cartilage are harvested from a non-essential area of the knee for transplant to the weight bearing, damaged area. The second image shows the device used with the arthroscope to implant the plugs. The final image is an arthroscopic picture taken months after the transplant, showing the cartilage alive and well.

These plugs are then placed into the holes drilled in the defect. The bone of the plugs heals to the bone of the femur, and the cap of cartilage on each of these plugs heals to one another. This is like using plugs of grass on a new lawn. As each plug takes hold and grows, the grass expands to fill out the grass in between. This technique is good for moderately sized cartilage defects and has the advantage of being done through very small incisions all in one surgical procedure.

 

Cartilage Cell (Carticel) Technique

In this technique, when the surgeon identifies the cartilage defects, he or she harvests cartilage from an area of the knee where it is not needed. The cells are then sent to Boston where a special cartilage cell growth technique is used. About six weeks later, the patient goes back to surgery, and a modest size incision is made into the knee directly over the defect. A second incision is made over the tibia (shin bone). The tissue which covers the tibia is called the periosteum. A small piece is harvested and then placed over the defect in the knee. Tiny stitches are used to attach this periosteum over the defect, and a biologic glue is also used to seal it. The concentrated, cultured cartilage cells are then injected under the periosteum and into the defect. Over the next several months, the cartilage cells grow and fill in the defect.

Dr. Clyburn likes to think of this as "seeding the lawn." Like the grass analogy, the cartilage grows evenly across the defect, but it takes a long time. Also, like the "seeded" lawn, it is important that the patient not walk on the defect until it is completely healed.

Cartilage Cell Technique

This image shows the steps of the Carticel technique. An arthroscopic procedure is done to harvest a small amount of the patient's healthy cartilage. Step 2, the cells are grown in culture. Step 3, about 6 weeks later a small incision is made in the knee and the damaged area of cartilage is removed. Step 4, at the same surgery, another small incision is made over the tibia (shin bone) and the periosteum (a layer of tissue over the bone is taken and sewn over the defect in the cartilage. Finally, the cartilage cell culture which is rich with new cells is injected under the periosteum and into the defect

 

ACL Ligament

ACL LigamentThe ACL ligament, which runs from the front of the knee to the upper back of the knee, is very important for stability and function. It is also commonly injured and may tear alone or in conjunction with cartilage damage. This ligament has been repaired for over 30 years, but for about the last 20 years, most are done with what is called "arthroscopic-aided technique." Unfortunately, it is not possible to simply sew the torn ligament back together. All ligament repair is in fact a reconstruction.

When to Repair It

In some cases of older individuals, ACL repair is not recommended. For most active patients, repair is necessary. Because it is actually a reconstruction, it is not urgent to have the surgery. In fact, multiple studies have shown that patients who have repair done immediately after the time of injury, develop stiffness and generally have poorer results. It is recommended that the injured patient attend physical therapy to restore movement and strength as well as reduce swelling before surgery is done.

What Repair to Have

There are many different reconstructions of the ACL. The tissue used to perform the repair may come from the patient or from tissue banks.

ACL Ligament

The first image is of the normal Anterior Cruciate Ligament (ACL). The second shows the basic steps in ACL Reconstruction. This procedure is done through the arthroscope with very small incisions.

Your Own Tissue

The most common tendon material used in reconstruction of the ACL comes from the hamstrings or from the patella ligament (the ligament which attaches the patella, or kneecap, to the tibia, the shin bone).

Hamstrings

The hamstrings are easily harvested through a small incision, but individually are not strong enough for the ACL repair. They, therefore, must be folded over on themselves and sewn together. In addition, some athletes (especially jumpers) feel the loss of their hamstrings may limit their abilities. The hamstrings have more elasticity (or stretch ability) than other tendons. Thus, the knee repaired with the hamstrings may have a tendency to be slightly loose. Dr. Clyburn does not routinely use the hamstrings.

Patella Tendon

This is often called "BTB" or "bone tendon bone" because a strip of the patella ligament (which is the middle third) is harvested along with a segment of bone from the patella and from the tibia. It is then transferred into the knee where it is secured exactly where the original tendon existed. The bone is then secured with screws. This is the repair Dr. Clyburn chose for himself in 1989. The disadvantage to this procedure is that it requires a moderate incision to harvest the graft, and tenderness or pain from the site of the harvest is not uncommon. The advantage is that it is a very strong repair.

Tissue Bank Tendons

There are a number of different tendons available for ACL reconstruction from the tissue bone. Dr. Clyburn has chosen to use the patella ligament, or bone tendon bone, because of his familiarity with the technique and the excellent strength of the material. It is performed exactly as the usual BTB technique except that the patient does not have the disadvantage of pain about the donor site (the area where the graft has been taken). This is the technique he chose when his son suffered an ACL tear a couple of years ago. The disadvantage is a very slight risk of infection from the graft. Reputable graft sources use extreme caution in harvesting human tissue and test them extensively. Despite this, there have been extremely rare and isolated cases of disease transmission.

 

Anesthesia for Knee Arthroscopy

It is possible to do knee arthroscopy under spinal anesthesia, regional anesthesia, or even local anesthesia. However, in routine cases, Dr. Clyburn recommends a general anesthetic. Most arthroscopic candidates are young and healthy, and most of the surgeries are very brief. Thus, the risks of general anesthesia are low.

Most patients wake up very quickly and are able to go home almost immediately after surgery. With spinal or general anesthesia, it may take 30 minutes or more to perform the anesthetic, and it may not wear off for a number of hours after surgery. Patients cannot leave the hospital until the anesthetic has worn off.

For more involved surgery like ACL reconstruction, Dr. Clyburn often uses a "single shot" spinal. This is done with a long acting agent placed into the spinal canal. This allows the patient to go home, but yet the pain relief of the spinal continues for up to 24 hours.

Another technique is a pain pump. The pump may be placed directly in the knee or may be placed by the anesthesiologist into the epidural area of the spine. With this technique, the patient pushes a button which injects small amounts of medication through the pump. The patient simply pulls the tiny tube out when the medication runs out. Dr. Clyburn often injects moderately large amounts of anesthetic agents directly into the tissues about the joint, and this too is a very effective technique.

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