The most common symptom that an orthopaedic surgeon treats is pain, while simple in concept it turns out to be surprisingly difficult to pin down the cause. The picture is a bed of nails, CC by Ormando Madoery

Degenerative meniscal tears in the knee are a truly elusive problem for orthopaedic surgeons. As I have previously posted, degenerative meniscal tears are a common MRI finding in the healthy population above 40 years of age, and fail to correlate with actual knee symptoms, such as pain. As a surgeon it is tempting to try surgery for these injuries, but there is an increasing pile of evidence against this. This post is a comment on the most recent evidence, a NEJM study by Katz et al.

It is important to understand the difference between a degenerative meniscal tears and a traumatic one: the first can occur spontaneously or may “appear” after a minor trauma, like stepping of a bus (low load), while the second one usually is sport related where the femur grinds & twists around the tibia with the meniscus caught in between (high load). Many argue that early stages of osteoarthritis manifest as degenerative meniscal tears, Englund et al’s excellent Nature article is an interesting review of the menisci.

Katz et al. posed in their study a very simple question: will the patients get better with surgery, or should we just go with physiotherapy? They performed a multicenter study where they included patients above 45 years of age, MRI-verified medial meniscal tear, and symptoms that had not subsided within a month. After the inclusion patients were randomized to arthroscopic surgery or physiotherapy. Outcomes were patient reported scores measured at 3, 6 & 12 months after randomization.

They included 351 patients, 330 were available for analyses, and the results did not differ between the groups. The improvement for the scores (WOMAC, KOOS & SF-36) were slightly better early on but not significant.

A few things caught my eye:

• The most problematic part of this study is the generalization; only one in four eligible participated. It is a pity that they didn’t follow those that declined study participation with some kind of metric. If the difference between the groups was minimal, then perhaps the results would be applicable to those as well.
• There was also a considerable cross-over to surgery, where almost every third patient opted for surgery in the physiotherapy arm. Most alarming was the difference in cross-over rates between centers 0-60 %. This indicates that the information differs between centers and it would be interesting to see a regression performed to see how much impact different centers have on their patient’s outcomes. While the intention to treat analysis was used it is important to remember that this is a study reporting negative findings and this cross-over will probably attenuate any difference between the groups, thus limiting the power.
• They also included rather advanced osteoarthritis, about ¼ belonged to Kellgren-Lawrence grade 3 (≥ 50 % joint space narrowing). While interesting, I personally don’t believe that any meniscal intervention matters at this stage. Doing a subgroup analysis on those without osteoarthritis on plain X-rays would therefore be of interest.
• There was no attempt to blind patients to the two treatment arms. This has been done previously with sham surgery and perhaps this would have limited the cross-over rates. Furthermore it would be interesting to see if those with actual surgery would have opted for secondary surgery.

My own thoughts

I try to refer my patients as much as possible to the physiotherapist. While I try to explain to them why, I often feel that they don’t quite believe me, especially if they know someone who has done the surgery. Furthermore, some patients are willing to take the chance as they feel that they can’t wait for the physiotherapy effect to kick in. Explaining to this group the risk of rare adverse events is very tough. While Katz et al’s excellent study was a good read; I unfortunately doubt that it will change patient behavior. It is also difficult from a study like this to conclude that carefully selected individuals would not benefit from surgery.

J. N. Katz, R. H. Brophy, C. E. Chaisson, L. de Chaves, B. J. Cole, D. L. Dahm, L. A. Donnell-Fink, A. Guermazi, A. K. Haas, M. H. Jones, B. A. Levy, L. A. Mandl, S. D. Martin, R. G. Marx, A. Miniaci, M. J. Matava, J. Palmisano, E. K. Reinke, B. E. Richardson, B. N. Rome, C. E. Safran-Norton, D. J. Skoniecki, D. H. Solomon, M. V. Smith, K. P. Spindler, M. J. Stuart, J. Wright, R. W. Wright, och E. Losina, ”Surgery versus Physical Therapy for a Meniscal Tear and Osteoarthritis”, New England Journal of Medicine, vol 368, num 18, ss 1675–1684, 2013.

M. Englund, F. W. Roemer, D. Hayashi, M. D. Crema, and A. Guermazi, “Meniscus pathology, osteoarthritis and the treatment controversy,” Nat Rev Rheumatol, vol. 8, no. 7, pp. 412–419, Jul. 2012.