In Reply

We thank the authors for their interest in our article (1) and we are happy to comment on the points put forward for discussion.

In our article, we have already mentioned the problem of selection bias in prospectively randomized studies. This problem of course strongly applies—as correctly indicated by Dr. Müller-Rath—to the Sihvonen study (2). We were unable to find a specific “as treated” analysis in the appendix of Katz et al. (3). The crossover rate of 35%, however, reveals that a proportion of patients do not benefit from conservative treatment. The clinical scores for these patients improved only following arthroscopic surgery.

We believe it is more important to again point out that the information in the appendix shows that arthroscopic meniscus surgery is also effective for higher grade stages of osteoarthritis (Kellgren–Lawrance Grade 3).

Overall, we agree with our colleague Dr. Müller-Rath that the available data only superficially show the equivalence of both therapies (operative versus non-operative).

Critical analysis of the scientific data shows that arthroscopic partial meniscectomy still has a role in the treatment of meniscal lesions.

We also thank Dr Sauerland for agreeing with our statements. The studies published to date show that arthroscopic partial meniscectomy can be beneficial. However, the evidence regarding the subset of patients who benefited from this intervention is not as clear as indicated in the comment. Locking symptoms were unfortunately not predictive for the success of operative treatment.

The only indication that patients with locking symptoms benefit from a surgical procedure is actually found in the work of Herrlin et al. (4), as clinical experience shows that flap tears provoke significant locking symptoms.

It seems entirely plausible to us to conclude that arthroscopy is beneficial based on the crossover of study patients (of up to 35%) from conservative treatment to arthroscopically resective surgery. Indeed, the clinical scores for these patients improved after surgery.

We agree with the Sauerland group, however, that it is important to keep in mind the strong placebo effects of surgery. This applies in fact also to a sham operation. Therefore, future studies should if possible not incorporate sham operations into the comparison group.

When faced with a lack of success, the threshold for undergoing a second surgery is much higher than that for switching from a non-operative therapy to surgery.

In summary, a critical analysis of prospective randomized studies supports the conclusion that arthroscopic partial meniscectomy still plays an important role. This is true for knee joints with and without signs of arthrosis.