LETTERS TO THE EDITOR
I thank Dr. Kweon and colleagues for their thoughtful critique of the recent editorial in Clinical Orthopaedics and Related Research® about orthopaedic surgeons’ responsibilities vis-à-vis football players and chronic traumatic encephalopathy (CTE) . As I noted in response  to an earlier letter  on this same editorial, though we typically do not reply to letters to the editor about editorials in CORR®, I am doing so here because of the importance of the topic, and the broad traction it seems to be getting not just in the scientific press but also the lay media [2, 5].
I was drawn to Dr. Kweon’s analogy about whether orthopaedic surgeons should avoid parties where alcohol is served because of the risk of intoxicated driving that could follow such events. While reasoning by analogy is one accepted approach in logic, it may not be the best one here, for reasons one can trace back to Aristotelian argument and perhaps earlier . There just are too many dissimilarities between the analogy and the facts of the case before us. My coauthors and I purposefully avoided reasoning by analogy in the editorial, though it was tempting. We first discussed an analogy involving gladiators: Those being entertained (the fans) and those making the most money (the owners, the league) are not the ones taking the existential risks. We then considered hypothetical blood sports. Imagine that the only way some new sport—let’s say full-contact sword fighting—could go on were to be if a vascular surgeon was on standby. Would we prefer that the vascular surgeon stick around, or would we rather that (s)he identify the new spectacle as beyond the pale, and not endorse it with his or her professional presence?
All three analogies—the driving analogy offered by Kweon and colleagues, as well as the two I’ve offered here—are colorful, and they generate emotional reactions. But all three miss far too much nuance to offer any probative value. If I were at a party where someone had imbibed to excess, I certainly would do what I could to keep him or her from getting in the car. Not everyone at a party “where alcohol is served” is at risk, but everyone on the football field is. I’m sure the authors of the letter can find similar soft spots in my two analogies.
Rather than analogy, I propose instead that we consider the best evidence as we decide how to act.
Here is what we know:
- Compelling evidence links concussions with the development of CTE; though late to the party, even the National Football League now acknowledges this both with words  and, more recently, with a billion-dollar settlement on the topic .
- The link between football, concussions, and CTE appears dose-dependent [13, 14]; many if not all of Hill’s criteria for causation  are met as we connect football with CTE.
- The study in JAMA  along with an analysis of the denominator in the New York Times  together suggest that CTE occurs with despairing frequency in professional football players.
- Many football players with CTE have life-changing or life-ending problems later in life .
And this is what we may reasonably infer:
- It may not just be concussions but subconcussive blows, so-called “repetitive head impacts” that matter here .
Alongside what, for now, is but pure speculation:
- The idea that rule changes in football or sideline coverage as suggested by Drs. Kweon and colleagues will reduce the number or severity of either concussions or subconcussive blows, and that those rule changes or sideline coverage will somehow protect players.
What troubles me the most is that proving or disproving that bit of speculation will involve running a life-threatening experiment on another generation of young men. Since Dr. Kweon’s group covers the University of Washington Huskies football team, I am certain that the lay-media coverage of the latest CTE-related tragic football story there did not escape their notice . I hope never to read another report like that of Huskies’ ex-defensive back, Darin Harris, and I know Dr. Kweon’s group feels likewise.
It’s clear that well-meaning people can differ here—in fact, well-meaning people already have. Some of the topics raised by Drs. Kweon and colleagues, including whether it is important or even essential for orthopaedic surgeons to be on the sidelines to care for bone and joint injuries (apart from concussions) were also raised by Dr. Scott Rodeo and his partners from the Hospital for Special Surgery in an earlier letter to the editor in CORR  and my responses to those points likewise have been published , and so I will refrain from covering that material again here.
Although we do not completely agree, I remain grateful to Drs. Kweon and colleagues for the opportunity to continue this critically important dialogue on behalf of the athletes we treat, and I thank them for taking the time and care to write such a thoughtful letter.
6. Hill AB. The environment and disease: Association or causation? Proc R Soc Med. 1965;58:295–300.
8. Leopold SS. Reply to the letter to the editor: Editorial: Do orthopaedic surgeons belong on the sidelines at American football games? Clin Orthop Relat Res. [Published online ahead of print October 12, 2017]. DOI: .
9. Leopold SS, Dobbs MB, Gebhardt MC, Gioe TJ, Rimnac CM, Wongworawat MD. Editorial: Do orthopaedic surgeons belong on the sidelines at American football games? Clin Orthop Relat Res. [Published online ahead of print September 5, 2017]. DOI: .
10. Mez J, Daneshvar DH, Kiernan PT, Abdolmohammadi B, Alvarez VE, Huber BR, Alosco ML, Solomon TM, Nowinski CJ, McHale L, Cormier KA, Kubilus CA, Martin BM, Murphy L, Baugh CM, Montenigro PH, Chaisson CE, Tripodis Y, Kowall NW, Weuve J, McClean MD, Cantu RC, Goldstein LE, Katz DI, Stern RA, Stein TD, McKee AC. Clinicopathological evaluation of chronic traumatic encephalopathy in players of American football. JAMA. 2017;318:360–370.
11. Montenigro PH, Alosco ML, Martin BM, Daneshvar DH, Mez J, Chaisson CE, Nowinski CJ, Au R, McKee AC, Cantu RC, McClean MD, Stern RA, Tripodis Y. Cumulative head impact exposure predicts later-life depression, apathy, executive dysfunction, and cognitive impairment in former high school and college football players. J Neurotrauma. 2017;34:328–340.
12. Rodeo SA, Taylor SA, Kinderknecht JJ, Warren RF. Letter to the editor: Editorial: Do orthopaedic surgeons belong on the sidelines at American football games? Clin Orthop Relat Res. [Published online ahead of print October 12, 2017]. .
13. Stamm JM, Bourlas AP, Baugh CM, Fritts NG, Daneshvar DH, Martin BM, McClean MD, Tripodis Y, Stern RA. Age of first exposure to football and later-life cognitive impairment in former NFL players. Neurology. 2015;84:1114–1120
14. Teasdale TW, Frøsig AJ, Engberg AW. Adult cognitive ability and educational level in relation to concussions in childhood and adolescence: A population study of young men. Brain Inj. 2014;28:1721–1725.