Real vs sham meniscus surgery - an review of the Sihvonen paper

A recent article in The New England Journal of Medicine (http://www.nejm.org/doi/pdf/10.1056/NEJMoa1305189 ) has grabbed headlines for stating that surgery for partial meniscal tears is no better than ‘sham’, or placebo surgery.  This follows the results of two previous studies stating that surgery for osteoarthritis of the knee is no more effective than sham surgery  (http://www.prairietrailphysio.ca/assets/Kirkley-et-al-2008.pdf and http://faculty.fortlewis.edu/burke_b/Criticalthinking/Readings/Moseley%20et%20al%20-%20placebo%20surgery.pdf for those interested).   Often the headlines reported in popular press (newspapers, magazines) simply copy the abstract of the article without delving further into whether the study was actually a high quality study, and as such, it’s results can be taken on board without as many concerns.

So, with that, let’s look into the article a bit further with some explanation along the way.

 

160 patients were ultimately included in the trial. All of these had degenerative, medial meniscal tears. A word on meniscal tears – there are generally two types – acute and degenerative. If you think of the meniscus as having, say, 1000 fibres, an acute tear would involve tearing perhaps 200 or 300 fibres in one, acute instance. Bang! You certainly know something has gone wrong when this happens.

A degenerative tear, using the same analogy, would involve tearing 5 or 10 fibres on repeated occasions over a long time period – perhaps many years – until you tear enough to get some symptoms.

Acute tears were excluded from this study.  Clinically, these are often the type of meniscal tears that are associated with ‘mechanical’ symptoms – catching, locking or giving way of the knee – and generally appear to do well with surgery. 

Also excluded in this study were people with knee osteoarthritis – ‘wear and tear’ of the smooth surface of the knee joint.  Finally – people with lateral (outside) meniscus tears were excluded – generally these type of tears are less common but also result in greater problems when compared to medial meniscal tears.

The age of the patients enrolled in the study, varied from 35 to 65 years old, with an average of 52. This is worth bearing in mind if you see a 30 year old football player in the clinic with this condition in the future!  These people had knee pain for at least 3 months, but with an average of 10 months and some up to 4 years or more!

The surgery – a very common one really – involved trimming the degenerative fibres of the meniscus back to a ‘stable margin’ i.e. back to normal healthy meniscus. The sham surgery involved making the traditional cuts or portals to access the knee but no actual surgical procedure beyond this.

We know from previous research that removing the meniscus isn’t a great thing if it can be helped – it fast tracks wear and tear in the knee – however it is sometimes necessary – particularly in those knees I’ve described with mechanical symptoms.

Both sham and ‘real’ surgical groups were given the same rehabilitation program after surgery – an extraordinarily basic program which is quite generic and very basic and I think underplays the role of appropriate rehabilitation in knee surgery – but now is not the time or place to discuss that!

So how were the results of the sham/’real’ surgery measured? The researchers used 4 tools:

·        Pain after exercise

·        A ‘Lysholm’ knee score and a ‘WOMET’ knee score – both on a scale where 0 represents severe symptoms and 100 reflects no symptoms.

·        Another generic quality of life questionnaire (15D).

Anyway – as reported – the results between groups were largely similar.

But onto the limitations of the study:

·        Meniscal tears can occur at the front, middle, or rear of the meniscus. Tears at the rear (‘posterior horn’) are more common, and these tears have pressure but on them in activities involving flexing the knee with weight on it, like squatting deeply.  Other tears have a lot of load put through them when pivoting on the knee, for example changing direction while running

·        The paper didn’t discuss what sports, or occupations those undertaking the surgery were involved in. A better way to present the results would to have been to compare the results in highly active vs highly sedentary groups.   The advice given to patients is going to be different if one works as a landscaper and has to squat all day, compared to someone who has a desk based job and walks as their main fitness activity.   The results of this paper can’t be generalized to both groups.

So, what is the take away message? Certainly if a mid 50’s patient comes to see you next week with a 1 year history of medial knee pain, AND clinical examination (and maybe MRI) confirms a degenerative medial meniscal tear, AND their knee is otherwise quite healthy, AND they have no mechanical symptoms, AND they aren’t playing a high impact or running based sport, AND their occupation doesn’t involve a lot of squatting or similar – well yes they will probably do better with advice (weight management, activity modification, strengthening etc) than surgery

However this can’t be said for a soccer player with an acute meniscal tear, a lateral meniscal tear, or a landscaper or builder, or quite a lot of people under 35 and probably under 50 really!  More research is needed to prove that these groups won’t benefit significantly from meniscus surgery and I would be surprised if this research appears!  A careful opinion from an experienced practitioner still carries a lot of weight when making decisions regarding surgery or conservative management.  Treat each knee individually taken into account the patient's age, sport, occupation, general health and goals.