Monday, October 7, 2013

Meniscal tears in arthritic knees: refer to physical therapy first

- Jennifer Middleton, MD, MPH

Meniscal injuries in arthritic knees challenge me. While some patients are more than willing to start with physical therapy (PT), some like the idea of a "quick" surgical fix over the perceived drudgery of a course of PT.  I struggle, too, at times, trying to judge who and when to refer to orthopedics, knowing full well that the patients I refer are likely to end up undergoing arthroscopy.

Kirkley et al showed in 2008 that arthroscopy for osteoarthritis makes no difference in pain or mobility scores. The AFP By Topic on Arthritis and Joint Pain includes this 2011 AFP article on knee osteoarthritis treatment that goes into more detail regarding the lack of evidence showing benefit following knee arthroscopy.  The jury is still out regarding whether surgery is necessary for meniscal tears even in patients without arthritis; a 2000 Cochrane review found insufficient evidence to conclude that surgery or PT is superior to the other.  Until recently, though, no one had specifically studied if arthroscopy benefits adults with osteoarthritis who suffer a meniscal tear.

A study published this past spring in the New England Journal of Medicine, which American Family Physician will be reviewing in its upcoming issue, may give us an answer.  The authors found no difference in pain and mobility after 6 and 12 months among patients who had had arthoscopic surgery followed by PT versus patients who only had PT.  In this trial, researchers randomized adults with painful meniscal tears (verified by MRI) who also had radiologic evidence of osteoarthritis to either surgery followed by PT or just PT alone. (Interestingly, patients did not have to have had symptomatic osteoarthritis prior to their meniscal tear; the appearance of arthritic changes on MRI alone got them enrolled in the study.)  The researchers then followed participants with previously validated pain and knee function questionnaires 6 and 12 months after their therapy or surgery. They found no statistically significant difference in these scores between groups.

Although the authors state that they conducted an intention-to-treat analysis in the article's abstract, in the methods section they qualify this as having been a "modified intention-to-treat approach in which patients who did not withdraw from the study were evaluated in the group to which they were randomly assigned."  Participants in the PT arm did have the opportunity to cross over to the surgical arm if they failed therapy, and 51 of the participants initially assigned to the PT group did so.  The authors appropriately included these patients in their intention-to-treat analysis but chose not to include the participants who dropped out before the 12 month follow-up.

31 of the study's inital 351 participants dropped out, and not including them in the statistical analysis could have skewed the results.  It's possible, for example, that the patients who dropped out of the PT arm went somewhere else for surgery and did better than they otherwise would have.  I applaud the authors for their transparency regarding this decision but remain unsure why they chose not to include the drop-outs in their final analysis.

That small misgiving aside, their findings still make intuitive sense given what we already know about knee arthroscopy.  This study's findings will make me more likely to refer patients with suspected meniscal tears to physical therapy first, even if they already have osteoarthritis.

Will this study change your management of meniscal tears in your older adults with known or suspected knee arthritis?



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