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Annals of Sports Medicine and Research

Elevated Pre-Season BESS Scores Not-Predictive of Development of Lower Extremity Injuries in Division 1 Football Players and a Prophylactic Ankle Program did not Reduce Risk

Research Article | Open Access Volume 8 | Issue 2 |

  • 1. Department of Family Medicine/Human Performance Center, Department of Orthopaedics University of North Carolina Chapel Hill, USA
  • 2. UNC School of Medicine, USA
  • 3. UNC-Chapel Hill, Division of Gastroenterology and Hepatology, USA
  • 4. Duke University Team Physician, Duke University Student Health, Duke Department of Family Medicine and Community Health, USA
  • 5. UNC-Chapel Hill Department of family medicine, USA
  • 6. University of Notre Dame, USA
  • 7. Ashville Orthopaedic Associates, UNC Asheville Team Physician, USA
  • 8. Primary Care Specialists Inc, USA
  • 9. Clinic Athletic Trainer, Novant Health, USA
  • 10. Department of Sports Medicine, University of North Carolina Chapel Hill and North Carolina Central University Athletics
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Corresponding Authors
Lauren Porras, Department of Family Medicine/Human Performance Center, Department of Orthopedics University of North Carolina Chapel Hill, United States.
Context

BESS scores have been shown to be reflective of balance deficits that can cause LE injury or concussions. There is no current literature that addresses whether these scores are predictive of injury.

Objective: To find if a preseason BESS scores of 15 or greater is predictive of the development of LE injury or concussion and whether a prophylactic ankle rehabilitation program lowers this risk.

Design: Prospective Cohort Study

Setting: Sport Setting

Patients or Other Participants: The North Carolina Central University football team from 2014 – 2016, and 2018.

Interventions: A prophylactic ankle rehabilitation HEP was performed twice daily during the 2016 and 2018 seasons.

Main Outcome Measures: Athlete preseason BESS scores and injury data from the season was analyzed using a multiple logistic regression. Those athletes with a BESS score of x≥15 underwent prophylactic ankle rehabilitation and the injury results were compared to see if there was a reduction in risk.

Results: Elevated Bess scores (x≥15) proved to be non-predictive of LE Injury or concussion in both the control seasons (p = .55, p = .81) or the intervention seasons (p = .90, p = .69), nor did the ankle rehabilitation reduce the injury risk (p = .52, p = .71). A previous concussion did increase the risk of LE injury in the control seasons (p = .03).

Conclusion: An athlete’s BESS score proved to be non-predictive of LE injury or concussion and the prophylactic ankle program did not reduce the risk of either. Suffering a previous concussion did show an increase in risk to subsequent LE injury.

Keywords

BESS Test , Concussion , Lower Extremity Injury

Citation

Porras L, Lawson B, Barrett CM, Bowen Johnston KJ, Dotson A, Higginson C, et al. (2021) Elevated Pre-Season BESS Scores Not-Predictive of Development of Lower Extremity Injuries in Division 1 Football Players and a Prophylactic Ankle Program did not Reduce Risk. Ann Sports Med Res 8(2): 1177.

KEYPOINTS

•    An elevated BESS score is nonpredictive of future LE injury or concussion.
•    Previous concussions do increase an athlete’s risk of subsequent LE injuries.
•    Although an elevated BESS score demonstrates increased ankle instability, prophylactic ankle rehabilitation does not
diminish an athlete’s risk to future LE injury or concussion.

The Balance Error Scoring System (BESS) is a clinical tool originally developed for concussion assessment of athletes suffering from mild head injury and to aid in deciding whether they should return to play. The BESS is a reliable test to evaluate static postural stability and is used regularly by clinicians. It is currently used for in-season assessment of concussion in athletes at North Carolina Central University, as well as many other Division I athletic programs. At NCCU, pre-season BESS scores are collected on most football players at their pre-season physicals. These baseline scores are used for comparison when evaluating the athlete after a head injury.

The BESS can be useful as an outcome measure beyond its original role in head injury [1]. Studies have shown that those with ankle instability perform worse on the BESS. Docherty et al [2] reported in a 2006 study of sixty Division I athletes, thirty with functional ankle instability and thirty controls, those with ankle instability scored more errors than controls and, therefore, had higher total BESS scores. This study showed that deficits in postural control resulting from functional ankle instability are reflected in the BESS score. In addition, Smith & Bell [3] showed in a 2013 study that patients with prior ACL reconstruction have poorer postural control than healthy controls, reflected in higher BESS scores.

Thus, BESS scores reflect balance deficits that can be attributed to lower extremity instability. However, there are no studies in the literature that address whether BESS can be used as a tool to predict if athletes with higher pre-season scores are more likely to develop lower extremity injuries during the season. We hypothesize that football players with preseason BESS scores greater than 15 will be more likely to develop lower extremity (LE) injuries during the season.

BESS has been used as an outcome measure in assessing balance improvements after neuromuscular training. In a study of high school female basketball players who underwent a neuromuscular training program, trained subjects had a significant decrease in BESS scores compared to controls [4]. We will take our retrospective review one step further to examine data from the season in which a prophylactic ankle strengthening program was implemented at NCCU in the 2016 and 2018 season to determine if this program diminished the risk of lower extremity injuries in those athletes with elevated scores.

METHODS

Study Design

We performed a retrospective review of football athletes’ BESS scores and medical records for the 2014- 2016 seasons at NC Central University while also gathering the data for the 2018 season. A summary can be seen in Table 1. Our primary outcome of interest was LE injury with a secondary outcome of interest in the type of injury, duration of injury, if the injury was season ending, and if the athlete suffered an in-season concussion. We also reviewed potential cofounders: previous LE injury, previous 

Table 1: Participant Demographic & BESS Scores (N).

    Control Intervention        
Variable Total 2014+15 2016+18 2014 2015 2016 2018
N 310 182 128 86 96 98 30
Bess score            
Mean (± SD) 9.6 (± 7.9) 6.8 (± 8.1) 13.5 (± 5.7) 7.5 (± 8.8) 6.2 (± 7.3) 13.2 (± 5.6) 14.2 (± 6.1)
Range 0 - 37 0 - 37 0 - 28 0 - 37 0 - 37 0 - 28 3 - 27
n ≥ 15 85 31 54 18 13 39 15
Grade              
Freshman 64 35 29 23 12 18 11
Sophomore 36 19 17 6 13 12 5
Junior 36 22 14 8 14 12 2
Senior 20 13 7 6 7 7 0
Redshirt freshman 33 16 17 5 11 9 8
Redshirt sophomore 40 29 11 21 8 8 3
Redshirt junior 46 34 12 13 21 11 1
Redshirt senior 30 10 20 1 9 20 0
Position              
Offense 150 88 62 42 46 47 15
Defense 138 80 58 34 46 45 13
Special teams 14 8 6 5 3 4 2
Injury history            
Previous LE injury 130 110 20 51 59 4 16
Previous LE surgery 104 37 67 19 18 61 6
Previous concussion 95 69 26 34 35 19 7

LE surgery, previous concussion, offensive/defensive/special teams player, and year in school. BESS scores were measured and recorded for new players (freshman and transfers) their first year and every two years for current players. The scores were taken in the preseason by Athletic Trainers and Athletic Training Students using a standard BESS test. The BESS test consists of athletes holding three stances (single-leg, double-leg, and tandem) on both a firm and a foam surface. Athletes hold the stance for 20 seconds with their eyes closed and hands on their hips. The total number of errors between the three stances comprises the individual’s BESS score.

Those athletes in 2016 and 2018 with a BESS score of 15 or higher were provided a prophylactic ankle rehabilitation program (Table 2). The ankle rehabilitation was provided as a home exercise program with instructions to perform the exercises twice daily for the entirety of the season. We did not monitor whether the athletes were compliant.

We chose 15 as a cutoff point due to data from Valovich et al’s [4] study. In Table 2 of the study, the two control groups had an average BESS score of 13.7 and 14.2. Respectively, and a standard deviation of 1 [4]. Thus we thought that setting the BESS at 15 would consistently be above the standard deviation of the mean.

Participants

We chose football athletes of the NC Central University Division I football team from the 2014-2016, and 2018 seasons. For the secondary analysis,the previous athleteswith a preseason BESS score of 15 or higher in the 2016 and 2018 seasons were used.

Analysis

We performed the primary and the secondary analysis through the UNC Odum Institute for Research in Social Science using SAS Enterprise Guide Software. For the primary analysis we used a multivariate logistic regression model to determine if elevated BESS scores of 15 or higher in the 2014-2016 and 2018 seasons were predictive of suffering a LE injury or concussion during the season. This was done by individual year and combined groups: the control seasons of 2014 and 2015 and the intervention seasons of 2016 and 2018. We performed a chi square goodness of fit test for the secondary analysis to observe the effectiveness of the prophylactic ankle rehabilitation on lowering the risk of LE injury or concussion. The results were reviewed on an intent-to-treat basis.

RESULTS

In the primary analysis, there were 121 reported lower extremity injuries out of 310 entries for all four seasons.  The majority of the injuries were ankle (36%) and knee (30%) injuries. Injuries lasted on average 4.3 weeks (± 6.4) and with an average of 5.25 season ending injuries per year. For all four years combined, Redshirt Juniors were found to be injured the most (19.0%) while Seniors were the least injured (7.4%). There were a total of 24 sports related concussions during the four seasons with an athlete taking on average 3.2 weeks (± 4.1) to return to play for the 2014, 2015, and 2018 seasons. Of the 5 concussions in the 2016 season, no athletes returned to competition. A breakdown of the injuries and concussion by category can be seen in Table 3 and Table 4.

Table 2: Prophylactic Ankle Rehab HEP.

No. Exercise Reps/Sets/ Hold time Description
1 Ankle Circles 10 reps / 2 sets While seated, move your ankle in a circular pattern one direction for several repetitions and then reverse the direction
2 Ankle ABC's 2 sets While seated, write out the alphabet in the air with your big toe while moving your ankle
3 Gastrocnemius/Soleus Stretch 3 sets/ 15 sec Keep back leg straight and heel on the floor, lean into the wall until a stretch is felt in the calf. Then perform on the opposite leg. After all sets are done, repeat the exercise with the back leg slightly bent at the knee.
4 Half On/Half Off Towel Stretch 3 sets/ 30 sec. Place a folded towel a few feet away from a wall. Stand with the involved foot half on/half off the inside edge of the towel. Perform the gastrocnemius stretch in exercise 3. Repeat with your foot on the outside edge of the towel
5 One Leg Standing Eyes Open/Eyes Closed 3 sets/ 1 min With your eyes open, stand on one leg and hold that position for as long as you can. If you do not need outside assistance to maintain balance within 10 seconds, progress to one leg standing with your eyes closed.
6 Posterior Leg Reach 15 reps / 2 sets Start by standing on one leg. Reach back with the other leg as you reach forward with the hand on that same side. Return to the starting position.
7 Anterior Reach 15 reps / 2 sets Start by standing on one leg. Reach forward with the opposite foot, bending the knee you are standing on. Return to the starting position and repeat.
8 Lateral Reach 15 reps / 2 sets Start by standing one leg. Reach out to the side with your opposite leg, bending the knee of the stance leg. Return to start position and repeat.
9 Adduction Reach 15 reps / 2 sets Start by standing on one leg. Reach across your body with the opposite leg, slightly bending the stance leg. Return to starting position
10 One Leg Standing, Pillow, Eyes Open/Closed 3 sets / 1 min With your eyes open, stand with one leg on a standard pillow and maintain balance as long as you can. If you do not need outside assistance within 10 seconds, progress to standing with your eyes closed.
11 4 Square Single Leg Jump Forward 2 reps / 10 sets Create four, connected, squares on the ground using tape. On one leg, jump from one square to another maintaining knee alignment and balance. Switch legs between sets. Be sure to jump in all 6 directions.

Table 3: In-Season LE Injury (N).

    Control Intervention      
Variable Total 2014+2015 2016+2018 2014 2015 2016 2018
N 121 68 53 34 34 34 19
Grade              
Freshman 20 8 12 5 3 5 7
Sophomore 15 6 9 2 4 6 3
Junior 14 10 4 4 6 2 2
Senior 9 7 2 4 3 2 -
Redshirt freshman 16 8 8 4 4 4 4
Redshirt sophomore 11 7 4 6 1 1 3
Redshirt junior 23 18 5 8 10 5 0
Redshirt senior 13 4 9 1 3 9 -
Position              
Offense 70 38 32 18 20 20 12
Defense 48 28 20 15 13 14 6
Special teams 3 2 1 1 1 0 1
Injury history            
Previous LE injury 81 48 33 24 24 22 11
Previous LE surgery 31 18 13 11 7 9 4
Previous concussion 51 35 16 20 15 12 4

Table 4: In-Season Concussions (N).

    Control Intervention      
Variable Total 2014+2015 2016+2018 2014 2015 2016 2018
N 24 17 7 9 8 5 2
Grade              
Freshman 5 4 1 4 0 0 1
Sophomore 3 3 0 0 3 0 0
Junior 4 3 1 1 2 1 0
Senior 0 0 0 0 0 0 -
Redshirt freshman 1 1 0 0 1 0 0
Redshirt sophomore 5 4 1 3 1 0 1
Redshirt junior 1 1 0 1 0 0 0
Redshirt senior 1 1 4 0 1 4 -
Position              
Offense 12 7 5 4 3 3 2
Defense 12 10 2 5 5 2 0
Special teams 0 0 0 0 0 0 0
Special teams            
Previous LE injury 12 7 5 3 4 4 1
Previous LE surgery 4 3 1 1 2 1 0
Previous concussion 10 8 2 5 3 2 0

BESS scores in both the control seasons (2014 and 2015) and the intervention seasons (2016 and 2018) proved to be non-significant in predicting LE injury (p = .55 and p = .90 by multivariate logistic regression). Additionally, there was not a significant difference of injury when the total control and intervention results were compared against each other (p = .59 by multivariate logistic regression). A summary of the breakdown by individual and combined years can be seen in Table 5. Players with a previous concussion were found to be at a significantly higher risk of LE injury in both the control seasons and 2014 season (p = .03 and p = .02 by multivariate logistic regression). Players had a 35% (95% Confidence Interval [CI] = 22.3%, 51.0%) and 33% (CI = 14.7%, 57.5%) chance of LE injury in the controlled and 2014 season’s models respectively. In the intervention seasons, player position was found to be significant (p =.04 by multivariate logistic regression) with offense having a 55% (CI = 32.6%, 75.1%) chance of being injured vs defense with a 38% (CI = 24.6%, 53.8%) chance within the model. Individual positions were only gathered for the 2014 -2016 seasons but offensive linemen were found to be the most injured (n = 21 total injuries), followed by defensive backs (n = 19), defensive linemen (n = 16), wide receivers (n = 12), running backs (n = 11), and tight ends (n = 10). All other variables proved to be nonsignificant in predicting LE injuries.

BESS scores were also not significant in predicting concussions for players in both the control and intervention 

Table 5: Variable Effect on LE Injury during Season, (P).

  Control Intervention        
Variable 2014+15 2016+18 2014 2015 2016 2018
BESS score .55 .90 .91 .26 .74 .65
Grade .14 .87 .12 .39 .33 .82
Position (off, def, st) .49 .04 .56 .15 .08 .12
Previous LE injury .48 .92 .70 .45 .89 .70
Previous LE surgery .55 .38 .33 .71 .33 .59
Previous concussion .03 .76 .02 .48 .50 .82

Table 6: Variable Effect on Concussions during Season (P)

  Control Intervention        
Variable 2014+15 2016+18 2014 2015 2016 2018
BESS score .41 .29 .21 .82 .30 .97
Grade .29 .03 .64 .31 .05 .91
Position (off, def, st) .49 .12 .91 .43 .34 -
Previous LE injury .04 .41 .06 .32 .51 .97
Previous LE surgery .50 .30 .97 .30 .48 -
Previous concussion .08 .36 .06 .56 .59 -

seasons (p = .81 and p = .69 by multivariate logistic regression) and there was not a significant difference when compared against each other (p =.18). For the control seasons, a player without a previous LE injury was at a significantly higher risk of injury (p = .04 by multivariate logistic regression). These athletes had a 16% (CI 4.7%, 40.9%) chance of injury while athletes who had a previous LE injury had a 4% (CI = 1.4%, 12.4%) chance within the model. This was not carried over to the intervention seasons. In the intervention seasons a player’s grade was found to be significant of concussions (p = .03 by multivariate logistic regression). The highest risk was in Redshirted Seniors at 22% (CI = 3.2%, 71.5%) as opposed to Freshman with the least risk at 1% (CI = 0.2%, 12.0%) within the model. All other variables were found to not be significant and are shown in Table 6. As there were only two in-season concussions in the 2018, some of the categories were excluded.

A summary of the results for the prophylactic ankle rehabilitation program can be found in Table 7. The ankle rehabilitation program in 2016 and 2018 was found to not be significant (p = 0.52 by Chi square analysis) in lowering the LE injury rate for those athletes with a BESS score of 15 or above when compared to the control years. Similarly, the ankle rehabilitation program did not significantly decrease the risk of concussions in the intervention seasons when compared to the control seasons (p = 0.71 by Chi square analysis). Of the 24 total concussions in the study, only 7 occurred to players with a BESS score of 15 or above, 3 in the control years and 4 in the intervention years preventing analysis.

DISCUSSION

Concussions and LE injuries are a major risk for varsity NCAA football players. Between the 2009, 2010, and 2011 seasons there was an average of 20.45 LE injuries per 1000 exposures [5]. This climbed to 23.55 LE injuries per 1000 in the 2012, 2013, and 2014 seasons [5] Similarly, sports related concussion rates in football rose 34% in the same time frame, with an annual national average of 3417 concussions a year [5,6] This accounts for over a third of all NCAA sports related concussions [6]. Thus, any easily identifiable preseason risk factor, such as a BESS score, that could be screened for and treated prophylactically should improve a player’s chances of staying injury free.

The BESS test is a commonly administered baseline tool used to gather data for concussions and assess an athlete’s balance and stability [1]. It has been shown that athletes with joint instability receive higher BESS scores [2,3]. Additionally, football players with balance deficits, and thus higher BESS scores, are at an increased risk of LE injury [7] Despite this, preseason BESS scores proved to be non-significant in their ability to predict whether an athlete would suffer an in season injury or not. Furthermore, although the BESS test has been proven to be helpful in the assessment of concussions, it did not prove to be predictive of them.

This study did find that athletes with a previous concussion were significantly more at risk in suffering a LE injury, supporting similar results in previous studies. These previous studies showed athletes suffered injuries in a variety of time, sports, and competitive settings following a concussion [7-12]. The odds of injury for previously concussed players ranged from 1.6 [11] to 3.39 [12] times greater than non-previously concussed players. Our study strengthens the current literature that concussions raise the risk of a subsequent LE musculoskeletal injury, as opposed to just head injuries.

Offensive players were found to be at a higher risk of LE injury than defensive players, with offensive lineman sustaining the most injuries out of all the positions. This mirrors the results previous studies on football positional injury rates. In Badgeley et al, [13]. High school offensive linemen were found to suffer the most injuries. Similarly, in a review of the NFL, Kluczynski et al [14] found offensive linemen to lead the league in knee injuries and in the top three positions to suffer ankle injuries. These injuries can be attributed to current blocking techniques, targeting of knees and ankles, and increased player-to-player contact [13,15].

Table 7: LE injuries of athletes with a BESS score x≥15 in 2014+15 vs 2016+2018.

  2014 + 15, (N) 2016 + 18, (N)  
Variable Healthy Injured Healthy Injured p
Total          
BESS score x≥15 20 11 31 23 .52
Injury by grade          
Freshman 5 0 12 3 .33
Sophomore 4 0 3 4 .06
Junior 1 1 5 0 .09
Senior 2 2 2 0 .22
Redshirt freshman 1 2 2 5 .88
Redshirt sophomore 4 1 3 2 .49
Redshirt junior 3 4 1 3 .55
Redshirt senior 0 4 3 6 .49
Injury by position          
Offense 11 8 15 14 .67
Defense 7 3 14 9 .61
Special teams 0 0 2 0 n/a
Injury with history of concussion        
No previous concussion 11 2 23 12 .20
No previous concussion 9 9 8 11 .63
Injury with history of LE injury        
No previous LE injury 14 6 15 13 .25
Previous LE injury 6 5 16 10 .69
Injury with history of LE surgery        
No previous surgery 19 7 28 17 .35
Previous surgery 1 4 3 6 .59

Previous LE injury and a player’s grade proved to be significant risk factors for concussions within the study. Both of the results can be attributed to practice and playing time. Athletes who had suffered a previous LE injury were at a greater chance of missing practice/playing time due to the injury versus those athletes that had stayed healthy. Thus, the injured players had a decreased time of exposure to the risk of a concussion. Similarly, seniors who had previously been redshirted were more likely to practice/play than other grades, increasing their exposure risk, while freshmen had the least chance of practice and playing time, decreasing their risk.

In the second part of the study, we chose to see whether those athletes who had a BESS score of 15 or above and underwent a prophylactic ankle rehabilitation program had a significant decrease in risk of a concussion or a LE injury as compared to the two control years. The ankle rehabilitation proved to be ineffective in changing a player’s risk of LE injury or concussion with the results all coming back non-significant. As can be seen in Table 7, several of the variables had under 5 participants which can disrupt the results. Similarly, there were 24 concussions during all 4 seasons of the study, of which only 7 qualified for the secondary analysis. Due to this, almost all the variables had less than 5 participants in each category making the results unreliable.

Our study had several imitations. First, the pre-season BESS scores were taken by different athletic trainers and athletic training students which subjects the scores to interrater reliability. Interrater reliability of administering the BESS test ranges with an overall ICC of 0.57, [16] and the individual sections of the test ranging from 0.44 to 0.96 [16-18] Meanwhile intratester reliability of the BESS test is 0.74 overall, with individual sections ranging from 0.50 to 0.99 [16-18]. For perspective, some studies have suggested that ICCs below 0.75 have poor/moderate reliability while those above 0.75 have good reliability.16 A second limitation is that the ankle rehabilitation program was aHEP. We did notfollow whether or notthe athletes performed the program twice a day, every day, as instructed. This adds to the study’s limitations since we analyzed the ankle rehabilitation program on an intent-to-treat basis, with every athlete considered to be compliant. Finally,there might have been other unnoted variables that could have affected the injury rates, some examples being: changes in coaching practices and styles, strength and conditioning changes, and quality of equipment or opposing teams.

Though we used a BESS score of 15 as a differentiation point in our study analysis, this may not have been the most appropriate cutoff point to use. Post-hoc linear analysis found that risk may have increased using a cutoff BESS score as low as 9 for LE injury and 3 for concussions. This indicates that there may be more of an effect from the screening and the prophylactic ankle rehabilitation if a lower BESS score is used as a cutoff.

While the BESS test is a common and easily administered test that can set a baseline on an athlete’s LE instability, it did not prove to be predictive of LE injury or concussions. Furthermore, the prophylactic ankle rehabilitation program did not prove to be effective in lowering the risk of LE injuries or concussions. Our study did find that those players with previous concussions were at a higher risk of LE injury, strengthening the argument that concussions raise the risk of subsequent overall injury. Future studies may continue the investigation into objective measures that are predictive of concussion and injury. Additionally, future studies may look back at the prophylactic ankle program with monitored compliance as opposed to a HEP.

ACKNOWLEDGMENT

We would like to thank Chris Wiesen, of the UNC Odum Institute for Research in Social Science, for his help in the data analysis.

REFERENCES

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2. Docherty CL, Valovich McLeod TC, Shultz SJ. Postural Control Deficits in Participants with Functional Ankle Instability as Measured by the Balance Error Scoring System. Clin J Sport Med. 2006; 16: 203-208.

3. Smith MD, Bell DR. Negative Effects on Postural Control After Anterior Cruciate Ligament Reconstruction as Measured by the Balance Error Scoring System. J Sport Rehabil. 2013; 22: 224-228.

4. Valovich McLeod TC, Armstrong T, Miller M, Sauers JL. Balance Improvements in Female High School Basketball Players after a 6-Week Neuromuscular Training Program. J Sport Rehabil. 2009; 18: 465-481.

5. Westermann RW, Kerr ZY, Wehr P, Amendola A. Increasing Lower Extremity Injury Rates Across the 2009-2010 to 2014-2015 Seasons of National Collegiate Athletic Association Football. Am J Sports Med. 2016; 44: 3230-3236.

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9. Brooks MA, Peterson K, Biese K, Sanfilippo J, Heiderscheit BC, Bell DR. Concussion Increases Odds of Sustaining a Lower Extremity MusculoskeletalInjury After Return to Play Among Collegiate Athletes. Am J Sports Med. 2016; 44: 742-747.

10.  Nordström A, Nordström P, Ekstrand J. Sports-related concussion increases the risk of subsequent injury by about 50% in elite male football players. Br J Sports Med. 2014; 48: 1447-1450.

11.  Gilbert FC, Burdette GT, Joyner AB, Llewellyn TA, Buckley TA. Association between Concussion and Lower Extremity Injuries in Collegiate Athletes. Sports Health. 2016; 8: 561-567.

12.  Herman DC, Jones D, Harrison A, Moser M, Tillman S, Farmer K, et al. Concussion May Increase the Risk of Subsequent Lower Extremity Musculoskeletal Injury in Collegiate Athletes. Sports Med. 2017; 47: 1003-1010.

13.  Badgeley MA, McIlvain NM, Yard EE, Fields SK, Comstock RD. Epidemiology of 10,000 high school football injuries: patterns of injury by position played. J Phys Act Health. 2013; 10: 160-169.

14.  Kluczynski MA, Kelly WH, Lashomb WM, Bisson LJ. A Systematic Review of the Orthopaedic Literature Involving National Football League Players. Orthop J Sports Med. 2019; 7: 2325967119864356.

15.  Bradley J, Honkamp NJ, Jost P, West R, Norwig J, Kaplan LD. Incidence and variance of knee injuries in elite college football players. Am J Orthop (Belle Mead NJ). 2008; 37: 310-314.

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Received : 16 Jan 2021
Accepted : 15 Mar 2021
Published : 21 Mar 2021
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JSM Tropical Medicine and Research
ISSN : 2578-3165
Launched : 2016
JSM Head and Face Medicine
ISSN : 2578-3793
Launched : 2016
JSM Cardiothoracic Surgery
ISSN : 2573-1297
Launched : 2016
JSM Bone and Joint Diseases
ISSN : 2578-3351
Launched : 2017
JSM Bioavailability and Bioequivalence
ISSN : 2641-7812
Launched : 2017
JSM Atherosclerosis
ISSN : 2573-1270
Launched : 2016
Journal of Genitourinary Disorders
ISSN : 2641-7790
Launched : 2017
Journal of Fractures and Sprains
ISSN : 2578-3831
Launched : 2016
Journal of Autism and Epilepsy
ISSN : 2641-7774
Launched : 2016
Annals of Marine Biology and Research
ISSN : 2573-105X
Launched : 2014
JSM Health Education & Primary Health Care
ISSN : 2578-3777
Launched : 2016
JSM Communication Disorders
ISSN : 2578-3807
Launched : 2016
Annals of Musculoskeletal Disorders
ISSN : 2578-3599
Launched : 2016
Annals of Virology and Research
ISSN : 2573-1122
Launched : 2014
JSM Renal Medicine
ISSN : 2573-1637
Launched : 2016
Journal of Muscle Health
ISSN : 2578-3823
Launched : 2016
JSM Genetics and Genomics
ISSN : 2334-1823
Launched : 2013
JSM Anxiety and Depression
ISSN : 2475-9139
Launched : 2016
Clinical Journal of Heart Diseases
ISSN : 2641-7766
Launched : 2016
Annals of Medicinal Chemistry and Research
ISSN : 2378-9336
Launched : 2014
JSM Pain and Management
ISSN : 2578-3378
Launched : 2016
JSM Women's Health
ISSN : 2578-3696
Launched : 2016
Clinical Research in HIV or AIDS
ISSN : 2374-0094
Launched : 2013
Journal of Endocrinology, Diabetes and Obesity
ISSN : 2333-6692
Launched : 2013
Journal of Substance Abuse and Alcoholism
ISSN : 2373-9363
Launched : 2013
JSM Neurosurgery and Spine
ISSN : 2373-9479
Launched : 2013
Journal of Liver and Clinical Research
ISSN : 2379-0830
Launched : 2014
Journal of Drug Design and Research
ISSN : 2379-089X
Launched : 2014
JSM Clinical Oncology and Research
ISSN : 2373-938X
Launched : 2013
JSM Bioinformatics, Genomics and Proteomics
ISSN : 2576-1102
Launched : 2014
JSM Chemistry
ISSN : 2334-1831
Launched : 2013
Journal of Trauma and Care
ISSN : 2573-1246
Launched : 2014
JSM Surgical Oncology and Research
ISSN : 2578-3688
Launched : 2016
Annals of Food Processing and Preservation
ISSN : 2573-1033
Launched : 2016
Journal of Radiology and Radiation Therapy
ISSN : 2333-7095
Launched : 2013
JSM Physical Medicine and Rehabilitation
ISSN : 2578-3572
Launched : 2016
Annals of Clinical Pathology
ISSN : 2373-9282
Launched : 2013
Annals of Cardiovascular Diseases
ISSN : 2641-7731
Launched : 2016
Journal of Behavior
ISSN : 2576-0076
Launched : 2016
Annals of Clinical and Experimental Metabolism
ISSN : 2572-2492
Launched : 2016
Clinical Research in Infectious Diseases
ISSN : 2379-0636
Launched : 2013
JSM Microbiology
ISSN : 2333-6455
Launched : 2013
Journal of Urology and Research
ISSN : 2379-951X
Launched : 2014
Journal of Family Medicine and Community Health
ISSN : 2379-0547
Launched : 2013
Annals of Pregnancy and Care
ISSN : 2578-336X
Launched : 2017
JSM Cell and Developmental Biology
ISSN : 2379-061X
Launched : 2013
Annals of Aquaculture and Research
ISSN : 2379-0881
Launched : 2014
Clinical Research in Pulmonology
ISSN : 2333-6625
Launched : 2013
Journal of Immunology and Clinical Research
ISSN : 2333-6714
Launched : 2013
Annals of Forensic Research and Analysis
ISSN : 2378-9476
Launched : 2014
JSM Biochemistry and Molecular Biology
ISSN : 2333-7109
Launched : 2013
Annals of Breast Cancer Research
ISSN : 2641-7685
Launched : 2016
Annals of Gerontology and Geriatric Research
ISSN : 2378-9409
Launched : 2014
Journal of Sleep Medicine and Disorders
ISSN : 2379-0822
Launched : 2014
JSM Burns and Trauma
ISSN : 2475-9406
Launched : 2016
Chemical Engineering and Process Techniques
ISSN : 2333-6633
Launched : 2013
Annals of Clinical Cytology and Pathology
ISSN : 2475-9430
Launched : 2014
JSM Allergy and Asthma
ISSN : 2573-1254
Launched : 2016
Journal of Neurological Disorders and Stroke
ISSN : 2334-2307
Launched : 2013
JSM Sexual Medicine
ISSN : 2578-3718
Launched : 2016
Annals of Vascular Medicine and Research
ISSN : 2378-9344
Launched : 2014
JSM Biotechnology and Biomedical Engineering
ISSN : 2333-7117
Launched : 2013
Journal of Hematology and Transfusion
ISSN : 2333-6684
Launched : 2013
JSM Environmental Science and Ecology
ISSN : 2333-7141
Launched : 2013
Journal of Cardiology and Clinical Research
ISSN : 2333-6676
Launched : 2013
JSM Nanotechnology and Nanomedicine
ISSN : 2334-1815
Launched : 2013
Journal of Ear, Nose and Throat Disorders
ISSN : 2475-9473
Launched : 2016
JSM Ophthalmology
ISSN : 2333-6447
Launched : 2013
Journal of Pharmacology and Clinical Toxicology
ISSN : 2333-7079
Launched : 2013
Annals of Psychiatry and Mental Health
ISSN : 2374-0124
Launched : 2013
Medical Journal of Obstetrics and Gynecology
ISSN : 2333-6439
Launched : 2013
Annals of Pediatrics and Child Health
ISSN : 2373-9312
Launched : 2013
JSM Clinical Pharmaceutics
ISSN : 2379-9498
Launched : 2014
JSM Foot and Ankle
ISSN : 2475-9112
Launched : 2016
JSM Alzheimer's Disease and Related Dementia
ISSN : 2378-9565
Launched : 2014
Journal of Addiction Medicine and Therapy
ISSN : 2333-665X
Launched : 2013
Journal of Veterinary Medicine and Research
ISSN : 2378-931X
Launched : 2013
Annals of Public Health and Research
ISSN : 2378-9328
Launched : 2014
Annals of Orthopedics and Rheumatology
ISSN : 2373-9290
Launched : 2013
Journal of Clinical Nephrology and Research
ISSN : 2379-0652
Launched : 2014
Annals of Community Medicine and Practice
ISSN : 2475-9465
Launched : 2014
Annals of Biometrics and Biostatistics
ISSN : 2374-0116
Launched : 2013
JSM Clinical Case Reports
ISSN : 2373-9819
Launched : 2013
Journal of Cancer Biology and Research
ISSN : 2373-9436
Launched : 2013
Journal of Surgery and Transplantation Science
ISSN : 2379-0911
Launched : 2013
Journal of Dermatology and Clinical Research
ISSN : 2373-9371
Launched : 2013
JSM Gastroenterology and Hepatology
ISSN : 2373-9487
Launched : 2013
TEST Journal of Dentistry
ISSN : 1234-5678
Launched : 2014
Annals of Nursing and Practice
ISSN : 2379-9501
Launched : 2014
JSM Dentistry
ISSN : 2333-7133
Launched : 2013
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