Level 1: Likely reliable evidence

Arthroscopic surgeries for patients with established knee osteoarthritis are becoming less common due to a lack of clinical evidence supporting their use.

A Cochrane review found that arthroscopic surgery is ineffective for unselected patients with knee osteoarthritis, based partly on the findings of a randomized trial showing no significant improvement in pain or function scores with either arthroscopic debridement or arthroscopic lavage compared with placebo surgery.1,2

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Another randomized trial subsequently showed that the addition of arthroscopic surgery to physical and medical therapies did not improve function or pain scores in individuals who had moderate-to-severe knee osteoarthritis.3

More recently, a randomized trial in patients with meniscal tear and knee osteoarthritis showed that arthroscopic partial meniscectomy plus physical therapy did not improve symptoms more than physical therapy alone.4

However, the implications for patients without clearly established knee osteoarthritis have remained unclear. A recent randomized trial comparing meniscectomy to strengthening exercises in patients presenting with degenerative medial meniscus tear and no clear evidence of osteoarthritis (Kellgren-Lawrence grade 0-1) found no significant between-group differences in function, pain, or patient satisfaction scores.5

Now, a randomized trial compares arthroscopic partial meniscectomy to sham surgery in patients with medial meniscus tear without knee osteoarthritis.6

A total of 146 patients aged 35 years to 65 years with symptomatic degenerative medial meniscus tear without knee osteoarthritis were randomized to arthroscopic partial meniscectomy vs. sham surgery and followed for 12 months. Postoperative care, including walking aids and instructions for graduated exercises, was identical for both groups, and all patients were instructed to take OTC analgesics as required.

Symptoms were assessed using the Lysholm and Western Ontario Meniscal Evaluation Tool (WOMET) scores, which both range from 0 to 100; higher scores indicate less severe symptoms. Knee pain was assessed after exercise using a numeric rating scale with a range of 0 to 10, with higher scores indicating greater pain severity.

Both groups had a significant improvement from baseline in symptom and knee pain scores, but there were no significant between-group differences for these outcomes at 12 months. The mean improvement in the Lysholm score was 21.7 points with arthroscopic partial meniscectomy vs. 23.3 points with sham surgery, with a difference of 11.5 points considered clinically meaningful.

Similarly, the mean improvement in the WOMET score was 24.6 points with partial meniscectomy vs. 27.1 points with sham surgery, with a difference of 15.5 points considered clinically meaningful. The mean improvement in knee pain was 3.1 points with partial meniscectomy vs. 3.3 points with sham surgery, with a difference of 2 points considered clinically meaningful.

There were also no significant differences in the rate of subsequent knee surgery, patient-reported satisfaction, patient-reported improvement, or serious adverse events.

Recent clinical evidence from randomized trials has consistently shown a lack of efficacy of arthroscopic surgeries for patients with knee osteoarthritis, including patients with meniscus tears.

This trial extends those findings to patients with meniscus tears but without established knee osteoarthritis, showing no significant difference in symptom or pain scores between patients receiving arthroscopic partial meniscectomy and those receiving sham surgery.

It should be noted that the Lysholm and WOMET scores used in this trial for symptom assessment are primarily focused on basic activities of daily living, and may not adequately describe high-level function as may be required for strenuous work or sports.

Alan Ehrlich, MD, is a deputy editor for DynaMed, Ipswich, Mass., and assistant clinical professor in Family Medicine, University of Massachusetts Medical School in Worcester.

DynaMed is a database that provides evidence-based infor­­mation on more than 3,000 clinical topics and is updated daily through systematic surveillance covering more than 500 journals. The most important evidence identified is summarized here.


  1. Laupattarakasem W et al. Cochrane Database Syst Rev. 2008; doi:10.1002/14651858.CD005118.pub2.
  2. Moseley JB et al. N Engl J Med. 2002;347:81-88.
  3. Kirkley A et al. N Engl J Med. 2008; 359:1097-1107.
  4. Katz JN et al. N Engl J Med. 2013;368:1675-1684.
  5. Yim J et al. Am J Sports Med. 2013;41(7):1565-1570.
  6. Sihvonen R et al. N Engl J Med 2013;369:2515-2524.