Sunday, June 02, 2013

Ambiguous empirical factors

OK, it's one thing to lack data or significant studies on point (I gather there isn't much out there) regarding my assertion, in my forthcoming international tax book, that the U.S. rules create high deadweight loss relative to the revenue being raised.  Everyone appears to agree with this anyway.

It's another matter entirely to have tough personal choices depend on probabilistic estimates that would require better empirical data than one has.  (Even apart from the challenging task of assigning welfare weights to the key aspects of various alternative scenarios.)

So yes, as a consumer though not producer of empirical literature, I would like to have better information than I have regarding the merits of alternative courses of action with regard to the torn, and hence now effectively non-existent, anterior cruciate ligament (ACL) in my right knee.

ACL is an odd injury.  If you're a sports fan, you read about Derrick Rose, Iman Shumpert, Mariano Rivera, etcetera, tearing their ACLs, having corrective surgery, and taking nine months to a year or longer before they are back in action - but generally, with full restoration of prior function.  But one thing I've learned already about my month-old injury is how startlingly high-functioning, for some but not other purposes, one can be without an ACL.  The swelling is mostly gone and I'm doing rehab. But at this point I can easily walk 5-10 miles, handle stairs but not irregular climbing, am working back towards my pre-injury capacity on elliptical machines, and pretty much never feel significant pain.  On the other hand, I can't run, feel significant instability in the knee, and if I tried any activity such as basketball or tennis I would likely be carted off on a stretcher within the first 5 minutes.  The real danger is knee buckling (I've had two major instances since the injury) that can involve tearing cartilage, increased likelihood of arthritis down the road, etc.

So should I have the surgery?  I've met with three surgeons, and the one I thought best (e.g., for being the most evidence-based of them) said that, even putting tennis entirely to one side, it would be "very reasonable" to have the surgery.  Part of the reason it's no more than that is age.  Restorative surgery (using either one's own ligament scrapings or, ahem, a cadaver) is considered entirely standard for people under age 40, but once you get beyond that it's a closer call (and at one time SOP said not to do it).

Arguably, if I do the surgery, I'll be playing tennis for 20 to 30 more years, albeit shifting at some point to doubles.  But I have a history as an injury magnet.  Imagine doing all the work to restore my knee and then having something else go out.

Closer at hand, there's the issue of my risk of developing arthritis.  A weakened knee that keeps buckling and suffering additional cartilage tears is  truly a prime candidate for debilitating arthritis, which can only at best be managed, not cured.  But the evidence isn't clear regarding how much I actually help myself with the surgery, which can itself promote onset if it doesn't go entirely well.  Or take the question of whether I should expect further buckling incidents if it isn't fixed, and how likely these are to involve significant cartilage tearing.  (At the moment, my kneecap has some damage but the menisci apparently are fine.)  Very hard to gauge.  Even with more and better data, the particularities of my case would undermine relying on it.

Such studies as there are often prove frustratingly unclear about where the odds lie, as to questions ranging from the whether to the when to the how.  And one problem is that there are multiple groups that need to be disaggregated.  E.g., younger vs older, professional versus recreational athletes, people who are more cautious and diligent versus those who are less so, people who follow different recovery timetables, people who are in better vs. worse shape when they go in and thus might face different probabilities of facing serious atrophy & rehab problems with associated muscles (such as the quadriceps).

Anyway, I've picked my surgeon, assuming I do it, and answered a couple of the how questions.  The big remaining question is when - although this includes the "if" question, since one time I could do it is never.  As I am going to Israel for two weeks this Friday, and as I love the summer and don't want to ruin it for myself entirely, the "sooner" option right now probably means the end of July, so I will be sufficiently recovered to teach my first fall semester class (even if I'm still on crutches) at the end of August.

"Later" means early December, right after my last class.  That's a much better time of year for me to deal with the rehab, in multiple dimensions.  But it would mean that I got started on recovery 4 months later, and it would be unwise if I spent the interim making things worse such as through incremental cartilage tears.  On the other hand if I spent it getting into really great shape, the recovery might go faster.  Plus if I go that long and have more function restored than I am currently expecting (e.g., suppose I can actually run again, at least in a straight line), then the "if" question becomes harder again.

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