Arthroscopic debridement of the knee for osteoarthritis: Is it ever indicated?

Despite its ineffectiveness in many, it may have benefits for a group of select patients.

Issue: August 2009

ByStephen M. Howell, MD

Stephen M. Howell, MD
Stephen M. Howell

The topic of performing arthroscopic debridement of the knee as a treatment for osteoarthritis has been a sensitive one for several years now, particularly since the paper by J. Bruce Moseley, MD, and colleagues appeared in The New England Journal of Medicine in July 2002. In the report of their control trial, the researchers stated that “the outcomes after arthroscopic lavage or arthroscopic debridement were no better than those after a placebo procedure.”

Despite the fact that many patients said they felt better after having undergone arthroscopy, the researchers could not conclusively explain how the procedure achieved that result. They began to suspect the procedure offers a placebo effect.

Just last year, Alexandra Kirkley, MD, and her colleagues in Canada arrived at the same conclusion. In their paper, which also appeared in The New England Journal of Medicine (NEJM), they reported that patients demonstrated similar outcomes at 2 years whether they underwent arthroscopic surgery for osteoarthritis (OA) of the knee or optimized physical and medical therapy with NSAIDs.

Arthroscopic debridement for symptomatic OA is not recommended for patients with radiographic joint space narrowing. Any degree of joint space narrowing on weight-bearing AP and 45° knee flexion views is a contraindication for arthroscopic debridement.

Images: Howell SM

The findings of these two studies have served as the basis for the American Academy of Orthopaedic Surgeons’ (AAOS) clinical practice guidelines, which were released in December. In their practice guidelines, the AAOS affirmed that arthroscopy was no more effective than physical therapy and NSAID medication for patients with OA of the knee, and they recommended against performing arthroscopy with debridement or lavage in patients who have a primary diagnosis of symptomatic knee OA. This statement is particularly true when a patient has mild to severe joint space narrowing, according to the guidelines.

Scoping the knee

While I certainly agree with that statement and I believe that it is best to attempt nonsurgical approaches to managing a patient’s knee OA first, there are a few caveats regarding the use of arthroscopic debridement for knee OA. According to the AAOS’ recommendations, arthroscopic partial meniscectomy and loose body removal are indicated when the primary symptoms are locking from a meniscus tear or mobile loose body.

Symptomatic loose bodies occur four or five times a year in my patients, but you have to be careful that these loose bodies are indeed “loose” or moving around the knee. Loose bodies discovered on knee radiographs in subjects without clear locking symptoms are more often incidental findings, and because they adhere to the joint capsule or are loculated in a baker’s cyst, they do not need to be removed. Patients should understand that they don’t have to have them out just because they appear on the radiograph.

Sometimes a patient will present with persistent stiffness from a chronic effusion due to a focal cartilage delamination that is often detected in MRI and not on radiograph. Removal of the loose cartilage and thermal fusion of the edges of the focal defect but not the base has alleviated the chronic effusion and stiffness in some patients.

Focal cartilage delamination
A patient with chronic effusions and stiffness from a full-thickness, focal cartilage delamination without joint space narrowing on weight-bearing radiographs may benefit from removal of cartilage flaps and thermal fusion of the edges of the crater and/or microfracture.

An MRI shows a knee with chronic effusion, joint space narrowing due to loss of femoral and tibial articular cartilage (white arrow), and a torn meniscus (black arrow). The MRI is the best way to diagnose avascular necrosis.

An intraoperative photograph of the knee depicted in the MRI shows the extensive articular cartilage loss on the medial femoral condyle. Arthroscopic debridement is not indicated when there is extensive, non-focal cartilage loss.

“Anvil osteophytes”

Sometimes you see extension lost as a result of an “anvil osteophyte.” The anvil osteophyte is seen on the lateral radiographic view. If the patient complains of a limp from loss of extension, then removal of the osteophyte may help. Again, you have to be careful about promising improvement in extension in these cases.

Anterior anvil osteophyte (outlined in black) can block knee extension when the radiograph shows a normal radius of curvature of the femoral condyle and no more than a small posterior femoral osteophyte. Arthroscopic resection of the anvil osteophyte can improve knee extension in these selected patients.

Look carefully for erosion of the condyle with an irregular radius of curvature of the femoral condyle, as well as for posterior femoral osteophytes, both of which may block extension even after removal of the anvil osteophyte. If you remove the anvil osteophyte in a knee with these two conditions, the knee probably will not regain complete extension.

It is true that you can get a sense of satisfaction from using arthroscopic debridement to help these patients. Their extension will improve. It won’t be perfect right away because the capsules contracted, but if you wait, their extension will come back as long as there is no severe arthritis.

It’s also important to remember that rehabilitation plays an important role even with patients who undergo arthroscopy. A good rehabilitation program can assist in providing symptomatic relief.

Reflecting on the guidelines

Ultimately, the NEJM articles serve as the foundation for the recent AAOS guidelines on treating OA of the knee, and you can bet that the “gatekeepers,” including our primary care colleagues and Medicare officials, have read them. Performing arthroscopic surgery for knees with primary OA symptoms when there is any radiographic or MRI evidence of joint space narrowing offers no additional benefit beyond physical therapy and the use of NSAIDs.

My view is that if there is joint space narrowing, you have to look for other sources of discomfort to justify scoping the knee, such as locking from a large meniscal fragment or a loose body or an extension loss from an anterior anvil osteophyte.

Most patients with symptomatic OA are older and have other comorbidities that increase the risk of complications from arthroscopic surgery. As a result, you have to be careful how you diagnose these patients, and be especially careful if you decide to use arthroscopy. If you scope one of these patients and they have a complication or don’t improve, you will feel terrible. Arthroscopy in symptomatic OA should only be done for the right reasons.

Extension loss from an anterior anvil osteophtye is shown at the time of arthroscopic debridement.

For more information:

Stephen M. Howell, MD, is an adjunct professor of mechanical engineering at the University of California, Davis. He is also an editorial board member of The Journal of Knee Surgery. He can be reached at Timberlake Professional Building, 8100 Timberlake Way, Ste. F, Sacramento, CA 95823; 916-689-7370; e-mail: sebhowell@mac.com.

References:

AAOS Work Group. Treatment of osteoarthritis of the knee (non-arthroplasty): Full guidelines. Dec. 6, 2008.

Kirkley A, Birmingham TB, Litchfield RB, et al. A randomized trial of arthroscopic surgery for osteoarthritis of the knee. New Eng J Med. 2008;359:1097-1107.

Moseley JB, O’Malley K, Petersen NJ, et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. New Eng J Med. 2002;347:81-88.