A more correct interpretation

A systematic review and meta-analysis of arthroscopic surgery for degenerative tears of the meniscus was recently published on cmaj.ca.1 We commend the authors for their timely work summarizing the available scientific evidence.

The authors evaluated “the efficacy of arthroscopic meniscal débridement in comparison with nonoperative or sham treatments.” This is correct for the study comparing arthroscopic surgery to sham surgery,2 the study comparing arthroscopic surgery to steroid injection3 and the study comparing arthroscopic surgery to medical exercise therapy.4 However, this aim is incorrectly stated for the studies by Herrlin and colleagues,5 Katz and colleagues,6 and Yim and colleagues,7 where exercise was a component of treatment provided to both groups. These three latter studies together comprise the majority of patients, 522 out of 805, included in this meta-analysis, and they studied the additional effect of a combination of arthroscopic surgery and exercise in comparison with exercise alone. Thus, a comparison of the effects from arthroscopic surgery alone to exercise alone is not possible.

A more correct interpretation of the results from the meta-analysis would therefore be, “there is moderate evidence to suggest that there is no additional benefit of arthroscopic meniscal débridement for degenerative meniscal tears compared to exercise, and no benefit in comparison with sham surgery or injection therapy.”