Sports Medicine Research: In the Lab & In the Field: Degenerative Changes in the Knee Joint Are Present in Elite American Football Players (Sports Med Res)


Wednesday, January 25, 2017

Degenerative Changes in the Knee Joint Are Present in Elite American Football Players

Knee osteoarthritis is associated with previous meniscus and anterior cruciate ligament surgery among elite college American football athletes.

Smith MV, Nepple JJ, Wright RW, Matava MJ, and Brophy RH. Sports Health. 2016. [Epub Ahead of Print].

Take Home Message: One in 4 American Football players at the NFL Combine with a history of knee surgery have knee osteoarthritis despite being only 20 to 26 years of age.

A football player is at high risk for a knee injury, which may have long-term implications (for example, osteoarthritis). Knee osteoarthritis is particularly concerning because it can be a chronic and disabling disorder. Unfortunately, we know very little about osteoarthritis among young elite American football players. Therefore, Smith and colleagues completed a retrospective cohort study to assess the relationship between previous knee injury, body mass index and player position on knee osteoarthritis. The authors reviewed records from 594 players (704 knees, 20 to 26 years of age) who attended the NFL Combine between 2005 and 2009. These players needed magnetic resonance (MR) imaging because of a history of knee injury/surgery or knee symptoms. This group was ~36% of all players attending the NFL Combine during this 5-year period. The authors defined osteoarthritis as moderate or severe nonfocal articular cartilage loss on MR images or joint space narrowing on x-ray. Overall, 423 of 704 included knees had a history of surgery. Osteoarthritis was present in 104 of the 704 (~15%) knees. A player with history of surgery was more likely to have osteoarthritis than someone without a history of surgery (23% versus 4%). The frequency of osteoarthritis was particularly high for those with a history of a partial meniscectomy (27%) or an anterior cruciate ligament reconstruction (24%), but less so for those with a history of a meniscal repair (11%). Player body mass index was associated with knee osteoarthritis but player position was not related to osteoarthritis.

The current study presents the next step in better understanding the development of long-term consequences in the knee following athletic participation with a history of knee surgery. It is important to note that all the players had a history of knee injury/surgery or had knee symptoms. This means that we are unable to determine the prevalence of knee osteoarthritis among all the players at the NFL Combine. Regardless, this study highlights that a player with a history of knee surgery is more likely to have knee osteoarthritis even though they are only 20 to 26 years of age. While the presence of structural changes is no guarantee that the player currently has knee symptoms it does increase the chances that they have or will develop knee symptoms. This could have a dramatic effect on an athlete’s playing career and quality of life after football. The current study was limited because the authors did not assess the severity of knee symptoms. Understanding the severity of knee symptoms would help clinicians identify what, if any impact a history of surgery may have on athletic performance, daily function, and quality of life. Furthermore, there was little detail provided to understand how these athletes were treated; such as, type of graft, type of rehabilitation following surgery, and return to play criteria. These are all factors that could affect the development of knee osteoarthritis. Despite these limitations, the current findings should inform clinicians that they need to be aware that these athletes are at increased risk for osteoarthritis, equitably council their athletes on the long-term consequences of injury/surgery, and seek to implement best clinical practices to prevent joint damage.

Questions for Discussion: What other factors would you be interested in future research evaluating in this population? Do you think these findings are generalizable to other populations?

Written by: Kyle Harris
Reviewed by:  Jeffrey Driban

Related Posts:
ACL Injury May Increase the Likelihood of Knee Osteoarthritis

Smith MV, Nepple JJ, Wright RW, Matava MJ, & Brophy RH (2016). Knee Osteoarthritis Is Associated With Previous Meniscus and Anterior Cruciate Ligament Surgery Among Elite College American Football Athletes. Sports health PMID: 27940573


Ryan Duffy said...

The findings of the study are interesting, but unfortunately unsurprising. I would be interested to see if future research finds any disparities in prevalence between race. We know that certain races have higher rates of certain diseases, such as arthritis, so I wonder if these disparities are still present in this population. I think these findings are generalizable to other populations. Regardless of whether or not you’re a high level athlete, knee surgery (ACL-R, meniscus repair, etc.) will increase your chances of developing knee OA later in life. I think the same can be said for obese individuals/those with high BMI’s. Researchers and clinicians have a good understanding of factors that may contribute to knee OA later in life, but the demands of high level athletes make it difficult to control or prevent these factors.

Kyle Harris said...


Thanks for the great comment. I agree with your query about the affect of race. I think that in general the entire study was very exploratory in nature and really sets up a number of different, more targeted studies. I think that some very interesting trends would begin to develop of future studies collect more demographic data as well as more stringently define the threshold for the presence of OA. In many studies looking at OA development, the scale used and the threshold for determining OA is critical in the significance of the studies findings. Ultimately though, the added factor of these participants being elite athletes does give this study another layer of complexity. Thanks again for the great thought!


Nicholas Erdman said...

The findings of this study are not surprising in that I expected the rate of OA to be higher for those who had ACL-R or partial menisectomy. These findings fit the building body of literature that shows surgical intervention within the knee joint capsule leads to increased risk of OA. Although intercapsular, a meniscus repair should salvage the original articular tissue and lead to better long-term results regarding OA.

Looking forward, how do these findings change clinical practice for sports medicine professionals in the elite collegiate football setting?

I speculate that extrinsic factors are likely to overshadow the findings of this study. An elite collegiate football player that believes he has a chance at a career in the NFL may be more willing to take the risk of future disability given the reward of improved income. Given that the average NFL career is 3.3 years, these findings may be of significant value to all elite collegiate football players before determining a plan of action following a knee injury. Overall, it is the duty of the sports medicine team to present the risks and rewards of all treatment options. Given the findings of this article, increased risk of OA should now be seriously considered when determining a plan of action following a knee injury in elite collegiate football players.

Kyle said...


Excellent comment! As I was finishing up this post I too was struck by how unsurprising these finding were and yet struck by the fact that this group has yet to be looked at. First let me say, that I am not a clinician who works with elite collegiate football so I too am interested in the perspective of those who do. I would imagine that this data is most valuable as a clinical education tool, where clinicians can try to help their athletes gain some perspective. I would also hope that this study sparks some follow ups as well. I would be very interested in seeing more medical history on these patients such as history of knee injury dating back into high school. I think a follow-up such as this would even further bolster this growing body of knowledge.

To your other point about the meniscus repair, much of the data does support the overall concept that the less disruption of the meniscus the better long-term health of the knee. There is some very interesting biochemical data as well that suggests that the injury itself triggers a biochemical cascade in the joint where cartilage turnover rates change and do not return completely to their preinjury levels. With this change in cartilage turnover, it makes the protective function of the meniscus even more important.

Again, thank you for the excellent comment. I really hope to see some insight from those who work with these athletes. I am especially interested in getting some perspective surrounding your comment regarding extrinsic factors.

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