Establishing good data when fame precludes randomisation

American football is a high-contact sport, as evidenced by Gronkowski’s 2012 Superbowl

Rob Gronkowski, the New England Patriots’ famed tight-end, suffered his third disc herniation in seven years last November, bringing his participation in the 2016 American football season to an early end. Gronkowski is expected to be out of play for at least eight weeks, after undergoing a lumbar discectomy in early December. Gronkowski’s history of injuries—including ankle, forearm, chest and knee complaints—is not unusual in the high-contact sport. Author of numerous papers focusing on return-to-play following orthopaedic surgery, Wellington Hsu (Chicago, USA)’s work has focused on the optimal management of sports-related injuries,1 working with large league injury databases2 and the outcomes associated with particular orthopaedic injuries and surgeries.3,4 He speaks to Spinal News International about the best methods to study athletes too famous for randomisation.

What is Rob Gronkowski’s place in American football?

Rob Gronkowski is a “tight-end” for the New England Patriots. This means is he needs to catch passes, as well as block large defensive lineman. The position is a jack-of-all-trades.

Gronkowski is widely considered the best tight-end in American football, and I believe he is probably one of the top five most valuable players to his team in any given season. He has revolutionised the way the position is played because of his combination of size and speed. He is around six foot six inches tall, and is pushing 270 pounds. He is much larger than your average tight-end on the field.

What is the nature of his November 2016 injury?

The precise cause of Gronkowski’s back injury is somewhat unclear, because he was nursing some other injuries at the time including a chest injury.

During one of the plays when he was sprinting, it looked like he could not make a full dive for a pass. He likely hurt his back on that particular play.

In the past, he has had two disc surgeries in his back. On that play, the reports are that he suffered another lumbar disc herniation which led to his third surgery. Each time after surgery so far he has been able to come back to the field and play very well.

Gronkowski has also had a history of other injuries, too—most significantly a forearm injury that prevented him from playing for about six months.

What kind of surgery was performed for his injury?

He had a disc fragment that came out of its normal spot—pushing on the nerve roots in the spinal canal—so a lumbar discectomy was performed that relieved pressure on the nerve root.

To my knowledge he has now had three discectomies; two of them were done at the same level, and one at a separate level.

Wellington Hsu

American football is a high-contact sport. What injuries are most commonly seen?

The most common injury by far in American football is a muscular strain. This can be caused by contact—if you are hit in a certain way—but also by just running and then turning in a way your body is not prepared for.

These injuries usually resolve within about a week or so. They are the most benign since they do not usually lead to any long-term problems, and they quickly resolve.

How can athletes prevent these kinds of injuries?

The best way to prevent back injuries in general—not only for professional athletes—is to keep a very strong core muscle base. There are certain core muscle routines that I believe that everybody should be doing, no matter whether you play professional football, or if you sit at a desk. They can prevent muscle injuries from arising, and they can help prevent disc injuries from occurring as well.

How does this kind of consistent activity affect athletes in the long run?

It is true that the more activity you have, there is a risk of having more arthritis at the segment that you have surgery at. In my opinion, the sports that have greatest risk for this are those that require a lot of twisting and turning, such as baseball and cricket.

There are some nuances on how a professional athlete is treated surgically—but, by and large, the outcomes from this type of injury and surgery are much better than previously thought before we started studying it on a scientific basis.

Our research group at Northwestern University (Chicago, USA) has published a number of different studies on athlete performance after discectomies. The previous dogma was that if you were a professional athlete, this kind of surgery would significantly decrease the length of your career or affect your performance on the field.

On the contrary, our studies have certainly demonstrated this not to be the case. Return-to-play rates can be very high and an athlete’s performance on the field after a successful surgery can be just as good as it was before regardless of sport played.

What is the most interesting thing about working with athletes?

By and large my practice is comprised of patients of all age groups, all physical demands, and with different types of spinal injuries. The most interesting part of working with high-level athletes is the question: should we be treating them any differently from the general population?

What kinds of treatments would you consider appropriate for athletes in comparison to the general population?

For example, as it applies to the low back, we try to avoid fusion procedures because of the potential effects on on-field performance. On the flip side though, for the neck, a fusion may lead to a better outcome than a motion-preserving procedure.

There are very few American football players that could get back to work after a lumbar fusion is performed, but if an athlete undergoes a discectomy, there is over an 80% chance that they will return to play.

If you try to compare that to, for example, an older individual who is under community ambulatory care where mobilisation and treatment goals are different, we may choose to treat more aggressively to optimise outcome.

Your work has focused on the impact of orthopaedic surgeries on athletes. What are the greatest challenges in this area?

When we talked about treating these athletes historically, this has been broadly anecdotal. If we had this conversation, say, 10–15 years ago, all of my opinions would have been based on expert opinion and individual conversations. This is not scientific, and not how we should base our decisions for this group.

The type of clinical study that we strive for in the general population involves prospectively randomising patients into groups and following their outcomes over a two-year period of time. In the professional athlete population, this study design is unreasonable and untenable because of the high profile nature of these players. Our research has focused on using concepts of “big data” to make meaningful conclusions for these athletes and the physicians who treat them. By accumulating a large sample size for our studies, we have much stronger data than what has been previously published.

We are now able to compare outcomes after different types of surgeries such as knee ligament reconstruction, shoulder surgery, and a neck fusion. We can also provide guidelines as to how long the recovery period is, and how we should manage rehabilitation after surgery.

How does the National Football League (NFL) track player injuries?

The NFL’s Injury Surveillance System is a very well-known database that captures injuries that occur among NFL players, as well as some surgical treatment.

The problem with this database is that players are de-identified for obvious privacy reasons. It would thus be impossible to discover what the outcomes were for a specific player after a particular surgery, as we are able to do with our studies.

The only way to predict how somebody like Rob Gronkowski would do after surgery would be to identify players who have had similar injuries, and to track their outcomes in terms of physical performance and such. My research group has been able to do that, which, in my opinion, offers greater potential than that of a de-identified injury database.

Do you think Gronkowski will be back on the field for 2017?

Given everything we have discussed, I do believe that Gronkowski will be back playing at a high level for this year’s season. He has a number of positive predictors for success including his age, talent level, and game experience. If he follows the path of other similar players who have had revision surgery, he has a very good prognosis.

Wellington Hsu is Clifford C Raisbeck, MD, professor of Orthopaedic Surgery at Northwestern University Feinberg School of Medicine, Chicago, USA


  1. HT Mai and WK Hsu. Operative Techniques in Orthopaedics, September 2015; 25: 3
  2. HT Mai et al. Am J Sports Med. 2016; 44: 9
  3. SV Minhas et al. Am J Sports Med 2016; 44: 4
  4. RW Cook and WK Hsu. Clinics in Sport Medicine 2016; 35: 4


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