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Common Knee Surgery Appears to Have Little Benefit

Health Letter article, February 2014

A well-designed study recently published in the New England Journal of Medicine (NEJM) showed that a very commonly used arthroscopic surgery to repair tears in meniscal cartilage of the knees offered no more benefit than a fake surgical procedure performed for the purposes of the study.[1] These results add to a growing body of evidence indicating that many U.S. patients are unnecessarily undergoing knee surgery for torn cartilage. Eliminating such unneeded surgery would help patients avoid medical risks and save valuable health care dollars.

What is meniscal cartilage?

Meniscal cartilage is a C-shaped, rubbery disc that acts as a shock absorbing cushion in the knee joint between the lower end of the femur (thigh bone) and the upper end of the tibia (shin bone), as shown here:

Image: Alila Medical Media/Shutterstock.com

The medial meniscus is located at the inner edge of the knee joint and the lateral meniscus at the outer edge. Meniscal cartilage keeps the knee stable by balancing a person’s weight across the knee.

Tears in the medial or lateral meniscus can occur with sudden turning or twisting of the knee — particularly if the foot is planted while the knee is bent — and with heavy lifting. Tears also can occur as people get older, a result of long-term wear and tear on the joint (degenerative meniscal tears). A torn meniscus can cause pain and sometimes interfere with normal motion of the knee joint (for example, patients may experience a locked knee joint that will not bend). However, most people middle age and older who are incidentally found to have tears in the meniscal cartilage do not experience any such pain or difficulty moving.[2]

Arthroscopic knee surgery: An overview

Arthroscopic knee surgery is one of the most frequently performed orthopedic procedures in the U.S.[3] The procedure,[4] which is nearly always an outpatient procedure, involves inserting a fiber optic scope and surgical instruments into the knee joint space through small incisions, as shown here:


Image: piotrwzk/Shutterstock.com

Knee arthroscopy is used to remove loose bone or cartilage fragments, mend tears in meniscal cartilage, and repair ligaments, among other things.

In 2006, the most recent year for which national statistics are available, approximately 985,000 arthroscopic knee surgeries were performed in the outpatient setting in the U.S., representing about half of all orthopedic procedures.[5] The table below lists the top five reasons for which patients underwent such surgery in 2006.

Five Most Frequent Diagnoses for Patients Who Had Knee Arthroscopy in 2006[6]

Diagnosis Number of Surgeries Percentage of Surgeries
Tear of medial meniscus cartilage 362,387 37
Chondromalacia of the patella (damage to cartilage under the knee cap) 127,534 13
Tear of the lateral meniscus cartilage 103,527 11
Sprain or strain of cruciate knee ligament 83,039 8
Osteoarthritis of the knee 56,532 6

The first and third most frequent reasons for arthroscopic knee surgery were for the repair of medial and lateral meniscal cartilage tears.

Among adults age 50 and older in the general population who have meniscal tears, about two-thirds have tears only in the medial meniscus, one-fourth only in the lateral meniscus and 10 percent in both.[7]

Over the past two decades, the number of patients undergoing arthroscopic surgery for treatment of osteoarthritis (also known as degenerative joint disease) of the knees has decreased substantially.[8],[9] This decline occurred after controlled clinical trials demonstrated that such arthroscopic surgery was not effective for treating osteoarthritis of the knee.

In contrast, during approximately the same time period, the number of arthroscopic knee surgeries to repair tears of the medial and lateral meniscal cartilage has been gradually increasing, with a nearly 25 percent increase from 1996 to 2006.[10] The expansion in the use of knee arthroscopy for repair meniscal tears occurred despite the lack of controlled clinical trials assessing whether this procedure provides clinical benefit. The data from the new NEJM study strongly indicates that for many people with meniscal tears, arthroscopic surgery is no better than conservative, nonsurgical treatment.

NEJM study design

The study took place at five orthopedic clinics in Finland between December 2007 and January 2013 and was published on Dec. 26, 2013.[11] The researchers used a randomized, controlled, double-blinded study design — the gold standard for conducting clinical trials.

Patients enrolled in the study met the following criteria:[12]

  • Age 35 to 65;
  • Knee pain for more than three months that had not improved with conservative treatment; and
  • A tear of the medial meniscus, seen on an MRI scan before surgery and confirmed during knee arthroscopy before randomization.

Patients who had knee pain immediately following trauma or evidence of osteoarthritis of the knee were excluded.[13] The researchers believed that the subjects selected for this study — individuals with a degenerative tear of the medial meniscus and no osteoarthritis — would be a patient group most likely to benefit from arthroscopic surgical repair of such tears.[14]

If a patient was confirmed to have a medial meniscal tear (and no other knee joint pathology) during arthroscopy, he or she was randomly assigned to immediately undergo either repair of the meniscal tear or a sham (fake) procedure.[15] A research nurse who was present in the operating room at the time of arthroscopy opened an envelope containing the patient’s random group assignment and relayed this information to the surgeon. The patient was not informed of the study group assignment.

Patients assigned to the surgical treatment group underwent a standard arthroscopic procedure to repair the meniscal tear.[16] Patients in the sham-surgery group underwent a simulated repair procedure. To mimic the sensations and sounds of a true arthroscopic repair procedure, the surgeons asked operating room staff for surgical instruments used to repair meniscal tears, manipulated the knee as if the repair was being performed, and inserted instruments that would be used for such repairs, but nothing was done to repair the torn meniscus. The patient also remained in the operating room for the usual length of time needed to repair a torn medial meniscus.[17]

Following the arthroscopy procedure, patients in both groups received standard walking aids, instructions for graduated exercise programs and directions to use over-the-counter pain relievers as needed.[18]

To assess the effectiveness of real versus sham surgery, patients’ knee symptoms were assessed at baseline before arthroscopy and at two, six and 12 months after surgery.[19] At each time point, patients rated their knee pain following exercise on a scale ranging from 0 to 10. They also completed two standardized questionnaires used to rate the severity of multiple knee symptoms combined (such as pain, mobility problems, swelling and emotional impact of symptoms) on scales ranging from 0 to 100 (with 0 indicating the most severe symptoms and 100 representing the absence of symptoms).

The study was double-blinded, meaning neither the patients nor the research staff evaluating the patients knew the patients’ study group assignment. The use of the sham procedure, combined with double-blinding, minimized the possibility of bias, as well as the possibility that any difference between the two groups would be due to a placebo effect in those who underwent actual repair of the medial meniscus.

NEJM study findings

Of the 146 patients randomized in the study, 70 underwent arthroscopic repair of their meniscal tears, and 76 underwent the sham procedure.[20] The patients had an average age of 52 years and 61 percent were men.[21]

There was marked improvement in knee pain ratings and overall knee symptoms from baseline to 12 months in both study groups.[22] Furthermore, there were no statistically significant differences in the change from baseline to 12 months in any of these outcome measures.[23] There also were no significant differences between the two groups with respect to patient satisfaction with their treatment, the number of patients who needed additional knee surgery or the number of serious adverse events. (One patient in the real surgery group developed a serious knee infection four months after surgery.)[24]

Conclusions and study implications

The results of this newest NEJM study add to a growing body of evidence indicating that arthroscopic knee surgery is not beneficial for the most common knee conditions afflicting people who are middle age or older. For example, two well-designed randomized controlled trials, which also used sham surgery control groups, demonstrated that arthroscopic knee surgery was no more effective in treating osteoarthritis of the knee than physical therapy and other conservative nonsurgical management.[25],[26]

The NEJM study clearly demonstrates that arthroscopic repair of degenerative medial meniscal tears offers no significant benefit for most patients. These results are consistent with the findings of three other randomized controlled trials evaluating arthroscopic surgery for repair of meniscal tears — both in patients with and those without osteoarthritis of the knee — that were published in 2013.[27],[28],[29] Hopefully, as was the case for trends in arthroscopic surgery for treatment of osteoarthritis of the knee, these results will lead to a significant decrease in the number of arthroscopic surgeries for the repair of meniscal tears.

Conservative management with walking aids, graduated exercise programs and over-the-counter analgesics as needed should be sufficient for most patients with symptomatic degenerative medial meniscal tears. Patients should not consider arthroscopic surgery for such tears unless they have failed to improve after a prolonged trial of conservative nonsurgical management.

References

[1] Sjhvonen R, Paavola M, Malmivaara A, et al. Arthroscopic partial meniscectomy versus sham surgery for a degenerative meniscal tear. N Engl J Med. 2013;396(26):2515-2524.

[2] Englund M, Guermazi A, Gale D, et al. Incidental meniscal findings on knee MRI in middle-aged and elderly persons. N Engl J Med. 1008;358(11):1108-1115.

[3] Kim S, Bosque J, Meehan JP, et al. Increase in outpatient knee arthroscopy in the United States: A comparison of national surveys of ambulatory surgery, 1996 and 2006. J Bone Joint Surg Am. 2011;93(11):994-1000.

[4] Ibid.

[5] Ibid.

[6] Ibid.

[7] Englund M, Guermazi A, Gale D, et al. Incidental meniscal findings on knee MRI in middle-aged and elderly persons. N Engl J Med. 1008;358(11):1108-1115.

[8] Kim S, Bosque J, Meehan JP, et al. Increase in outpatient knee arthroscopy in the United States: A comparison of national surveys of ambulatory surgery, 1996 and 2006. J Bone Joint Surg Am. 2011;93(11):994-1000.

[9] Holmes R, Moschetti W, Martin B, et al. Effect of evidence and changes in reimbursement on the rate of arthroscopy of osteoarthritis. Am J Sports Med. 2013;41(5):1039-1043.

[10] Kim S, Bosque J, Meehan JP, et al. Increase in outpatient knee arthroscopy in the United States: A comparison of national surveys of ambulatory surgery, 1996 and 2006. J Bone Joint Surg Am. 2011;93(11):994-1000.

[11] Sjhvonen R, Paavola M, Malmivaara A, et al. Arthroscopic partial meniscectomy versus sham surgery for a degenerative meniscal tear. N Engl J Med. 2013;396(26):2515-2524.

[12] Ibid.

[13] Ibid.

[14] Ibid.

[15] Ibid.

[16] Ibid.

[17] Ibid.

[18] Ibid.

[19] Ibid.

[20] Ibid.

[21] Ibid.

[22] Ibid.

[23] Ibid.

[24] Ibid.

[25] Moseley JB, O’Malley K, Petersen NJ, et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med. 2002;347(2):81-88.

[26] Kirkley A, Birmingham TB, Litchfield RB, et al. A randomized trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med. 2008;359(11):1097-1107.

[27] Katz JN, Brophy RH, Chaisson CE, et al. Surgery versus physical therapy for a meniscal tear and osteoarthritis. N Engl J Med. 2013;368(18):1675-1684.

[28] Herrlin SV, Wange PO, Lapidus G, et al. Is arthroscopic surgery beneficial in treating non-traumatic, degenerative medial meniscal tears? A five year follow-up. Knee Surg Sports Traumatol Arthrosc. 2013:21(2):358-364.

[29] Yim JH, Seon JK, Song EK, et al. A comparative study of meniscectomy and non-operative treatment for degenerative horizontal tears of the medial meniscus. Am J Sports Med. 2013;41(7):1565-1570.

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