The American Journal of Sports
Medicine
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Predictive Value of Prior Injury on Career in Professional American Football Is Affected by Player
Position
Robert H. Brophy, Stephen Lyman, Eric L. Chehab, Ronnie P. Barnes, Scott A. Rodeo and Russell F. Warren
Am J Sports Med 2009 37: 768 originally published online February 19, 2009
DOI: 10.1177/0363546508329542
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Predictive
Article TitleValue of Prior Injury on Career in
Professional
Article Subtitle American Football Is Affected
by
AuthorPlayer Position
Affiliation
Robert H. Brophy,* MD, Stephen Lyman, PhD, Eric L. Chehab, MD, Ronnie P. Barnes,
Scott A. Rodeo, MD, and Russell F. Warren, MD
From
the Hospital
for covers
Special
The abstract
goes here and
two Surgery,
columns. New York, New York
The abstract goes here and covers two columns.
The abstract goes here and covers two columns.
Background: The National Football League holds an annual combine where individual teams evaluate college football players
The abstract goes here and covers two columns.
likely to be drafted for physical skills, review players’ medical history and imaging studies, and perform a physical examination.
Purpose: The purpose of this study was to test the effect of specific diagnoses and surgical procedures on the likelihood of playing
KEYlength
WORDS
list of key
words
goes
and
of career
in the
league
byhere
position.
Study Design: Cohort study; Level of evidence, 3.
Methods: A database for all players reviewed at the annual National Football League Combine by the medical staff of 1 National
Football League team from 1987 to 2000 was created, including each player’s orthopaedic rating, diagnoses, surgical procedures, number of games played, and number of seasons played in the National Football League. Athletes were grouped by
position as follows: offensive backfield, offensive receiver, offensive line, quarterback, tight end, defensive line, defensive secondary, linebacker, and kicker. The percentage of athletes who played in the National Football League was calculated by position
for each specific diagnosis and surgery.
Results: The effect of injury on the likelihood of playing in the league varied by position. Anterior cruciate ligament injury significantly lowered the likelihood of playing in the league for defensive linemen (P = .03) and linebackers (P = .04). Meniscal injury
significantly reduced the probability of playing (P < .05) and length of career (P = .002) for athletes in the defensive secondary.
Shoulder instability had a significant effect on playing in the league for offensive (P = .03) and defensive linemen (P = .02), and
shortened the length of career for defensive linemen (P = .016). Spondylolisthesis did not significantly reduce the chance of playing in the league for any position, while a history of spondylolysis had a significant effect for running backs (P = .01). Miscellaneous
injuries (eg. acromioclavicular joint, knee medial collateral ligament, carpal fractures) had isolated position-specific effects.
Conclusion: The significant injuries and diagnoses appear congruent with the position-specific demands placed on the athletes.
This information is useful to physicians and athletic trainers caring for college football athletes as well as those assessing these
athletes at the National Football League Combine.
Keywords: college football; National Football League (NFL); combine; anterior cruciate ligament (ACL); shoulder; meniscus
The database includes each player’s position, collegiate
division, diagnoses, and surgical procedures. A previous
study based on this database reported the prevalence and
trends of musculoskeletal disorders in this population.1
The most common diagnoses varied by position, but the
most common procedures were similar across different
positions in this cohort.
A follow-up study combined this database with career
statistics from Elias Sports Bureau (New York, New York)
on each athlete in the NFL to demonstrate that the orthopaedic rating system predicts the likelihood of playing in
the league and the length of career in terms of games
played in the league.2 Among all participants at the combine, athletes with a history of shoulder instability, meniscal injury, and anterior cruciate ligament (ACL) injury, as
The National Football League (NFL) holds an annual combine, organized and operated by National Football Scouting
Inc, where individual teams evaluate college football players who are likely to be drafted. As part of the process, the
teams review the players’ medical history and imaging
studies and perform a physical examination. A database
for all players reviewed at the annual combine by the
medical staff of 1 NFL team from 1987-2000 was created.
Presented at the interim meeting of the AOSSM, San Francisco,
California, March 2001.
*Address
Brophy,
MD,1,14532
Address correspondence
correspondencetotoRobert
AuthorH.1,
Address
City, South
State,Outer
Zip,
Forty
Drive, Chesterfield, MO 63017 (e-mail: brophyr@wudosis.wustl.edu).
Affiliation.
No
conflict
of interest
Anypotential
author’s notes
could
also go declared.
here.
The
The American
American Journal
Journal of
of Sports
Sports Medicine,
Medicine, Vol.
Vol. 37,
33, No.
No. 4X
DOI:
DOI: 10.1177/0363546508329542
10.1177/1073858403253460
©
© 2009
2005 American
American Orthopaedic
Orthopaedic Society
Society for
for Sports
Sports Medicine
Medicine
768
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Predictive Value of Prior Injury on Football Career Affected by Position 769
Vol. 37, No. 4, 2009
TABLE 1
Summary of the Athletes at the National Football League Combine by Position, 1987-2000
Position
Offensive backfield
Offensive receiver
Offensive line
Tight end
Quarterback
Defensive line
Defensive secondary
Linebacker
Kicker
Average Length of Career
Number at Combine
Number
Played in League
Percentage
Who Played
Games
Seasons
713
692
870
277
322
929
546
494
161
402
372
471
168
143
612
328
308
41
56.4
53.8
54.1
60.7
44.4
65.9
60.1
62.4
25.5
61.9 ± 48.3
60.8 ± 51.4
73.4 ± 54.6
71.5 ± 50.4
52.4 ± 58.7
72.6 ± 53.5
68.1 ± 51.4
70.7 ± 53.7
99.1 ± 74.2
5.5 ± 3.3
5.5 ± 3.4
6.7 ± 3.4
6.2 ± 3.4
7.3 ± 4.4
6.2 ± 3.5
5.7 ± 3.4
6.0 ± 3.5
7.7 ± 5.2
well as individuals who had undergone ACL reconstruction, were less likely to play in the league than athletes
without these diagnoses or surgery.2
Given the varied demands placed on athletes depending
on the position they play, the effect of diagnoses and surgical procedures on future success in the NFL likely depends
on position. For example, a recent study demonstrated that
player position does influence the type of shoulder injury
seen among elite collegiate football athletes.8 The purpose
of this study was to test the hypothesis that the effect of
specific diagnoses and procedures on the likelihood of playing in the league and length of career in the league varies
by position.
we tested whether an increasing number of diagnoses or
procedures made it less likely for athletes who played a
particular position to play in the league. Survival analysis
using Cox regression was performed to determine whether
ACL injury/reconstruction, meniscal injury, and shoulder
instability/stabilization affected length of career in the
NFL by position. All models were adjusted for draft position, which was considered a surrogate for talent/skill—a
presumptive predictor of career length independent of
injury history. A P value of < .05 was considered statistically significant. All analyses were performed using SAS
for Windows (SAS Institute, Cary, North Carolina).
RESULTS
METHODS
A database for all players reviewed at the annual combine
by the medical staff of 1 NFL team from 1987 to 2000 was
created from the records of the team’s head physician,
including each player’s position, collegiate division, diagnoses, and surgical procedures.1 We then linked this database
to a proprietary data set purchased from Elias Sports
Bureau, the official statistician of the NFL, containing the
round drafted, number of seasons, and number of regular
season games played in the NFL for each athlete who first
played in the league from 1987 to 2001.2
Athletes were grouped by position: offensive backfield,
offensive receiver, offensive line, quarterback, tight end,
defensive line, defensive secondary, linebacker, and kicker.
The overall number of athletes at the combine, and the number and percentage who played at least 1 game in the NFL,
were calculated for each position. For each position, the percentage of all athletes with a history of a particular diagnosis/
surgery who played in the league was compared with the
percentage of all athletes without that diagnosis/surgery
who played in the league. Finally, the average length of
career in the NFL was calculated for each position.
Chi-square tests were calculated to compare the frequency of athletes in a particular position with a given
diagnosis or procedure playing in the league to the frequency of all other athletes in that position without that
diagnosis or procedure playing in the league. In addition,
Overall, 56% (2845 of 5004) of the players at the combine
played at least 1 game in the NFL. The overall number of
athletes at the combine, the number and percentage who
played at least 1 game in the NFL, and the mean length of
career in games and years for each position are shown in
Table 1.
The effect of ACL injury and reconstruction by position
on the percentage of athletes playing in the league is
shown in Table 2. Athletes with a history of ACL reconstruction were included in both groups; athletes with a
history of an ACL injury but no history of reconstruction
had a severe ACL sprain or a chronic injury that had been
treated nonoperatively. A history of ACL injury resulted in
a significantly lower percentage of defensive linemen (54%
[37 of 69] vs 67% [575 of 860]; P = .03) and linebackers
(48% [21 of 44] vs 64% [277 of 450]; P = .04) playing professional football. Anterior cruciate ligament reconstruction
resulted in a significantly smaller percentage of linebackers (46% [15 of 33] vs 64% [293 of 461]; P = .04), offensive
linemen (40% [18 of 45] vs 55% [453 of 825]; P = .05), and
defensive linemen (54% [29 of 54] vs 67% [583 of 875]; P =
.05) playing professional football. Anterior cruciate ligament injury (P = .002) and ACL reconstruction (P = .003)
resulted in a significantly shorter playing career for offensive linemen (Figure 1), but did not affect length of career
for any other positions. Based on the hazard ratio, offensive linemen with a history of ACL injury were 2.0 times
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770 Brophy et al
The American Journal of Sports Medicine
TABLE 2
Effect of ACL Injury and ACL Reconstruction by Positiona
History of ACL Injury
Position
Present, %
Offensive backfield
Offensive receiver
Offensive line
Tight end
Quarterback
Defensive line
Defensive secondary
Linebacker
Kicker
49
48
43
47
50
54
50
48
33
History of ACL Reconstruction
Not Present, %
(34/69)
(21/44)
(26/61)f
(8/17)
(9/18)
(37/69)b
(17/34)
(21/44)c
(3/9)
57
54
55
62
44
67
61
64
25
(368/644)
(351/648)
(445/809)f
(160/260)
(134/304)
(575/860)b
(311/512)
(287/450)c
(38/152)
Present, %
46
49
40
57
47
54
41
46
25
(24/52)
(18/37)
(18/45)d
(8/14)
(7/15)
(29/54)e
(9/22)f
(15/33)c
(2/8)
Not Present, %
57 (378/661)
54 (354/655)
55 (453/825)d
61 (160/263)
44 (136/307)
67 (583/875)e
61 (319/524)f
64 (293/461)c
26 (39/153)
a
Athletes with a history of anterior cruciate ligament (ACL) reconstruction were included in both groups; athletes with a history of an
ACL injury but no history of reconstruction usually had a severe ACL sprain or a chronic injury that had been treated nonoperatively.
b
P = .03.
c
P = .04.
d
P = .05.
e
P = .05.
f
P = .06.
Figure 1. Survival analysis of offensive linemen in the National Football League.
more likely to have a shorter career than those without a
history of ACL injury, while those with a history of ACL
reconstruction were 2.2 times more likely to have a short
career than those without.
The effect of meniscal injury by position on the likelihood of playing in the NFL is shown in Table 3. The only
position with a statistically significant difference was the
secondary (48% [29/60] vs 62% [299/486]; P = .049). All
other positions except running backs faced a nonsignificant reduction in the percentage of athletes playing professional football if they had a history of meniscal injury.
Among running backs, 60% of athletes with a history of
meniscal injury played at least 1 game in the NFL,
whereas 56% of athletes without a history of previous
meniscal injury played at least 1 game in the NFL.
Meniscal injury shortened the length of career for players
in the defensive secondary (P = .002) (Figure 2). Athletes in
the secondary with a meniscal injury were 2.0 times more
likely to have a shorter career than those without a history
of meniscal injury.
Shoulder instability reduced the percentage of offensive
(43.9% [43/98] vs 55.4% [428/772]; P = .03) and defensive
(54.3% [44/81] vs 67.0% [568/848]; P = .02) linemen playing
in the NFL (Table 4). Shoulder stabilization did not significantly decrease the percentage of athletes playing in
the league for any position, although there was a trend
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Predictive Value of Prior Injury on Football Career Affected by Position 771
Vol. 37, No. 4, 2009
TABLE 3
Effect of Meniscal Injury by Positiona
Position
Offensive backfield
Offensive receiver
Offensive line
Tight end
Quarterback
Defensive line
Defensive secondaryb
Linebacker
Kicker
Meniscal Injury
No Meniscal Injury
Played in NFL, %
Played in NFL, %
60
47
47
58
38
59
48
51
25
(48/80)
(34/73)
(54/114)
(18/31)
(12/32)
(70/118)
(29/60)
(24/47)
(3/12)
56
55
55
61
45
67
62
64
26
(354/633)
(338/619)
(417/756)
(150/246)
(131/290)
(542/811)
(299/486)
(284/447)
(38/149)
a
NFL, National Football League.
P = .049.
b
among defensive linemen (53.7% [22/41] vs 66.4% [590/888];
P = .09). Shoulder instability and shoulder stabilization
reduced the length of career for receivers (P = .044 and
.014, respectively) and defensive linemen (P = .016 and
.044, respectively) (Figures 3 and 4). For receivers, shoulder instability and shoulder stabilization increased the
likelihood of a shorter career by a factor of 1.5 and 1.6,
respectively. For defensive linemen, the effect was 1.7
(shoulder instability) and 2.4 (shoulder stabilization).
A history of spondylolysis reduced the percentage of running backs playing in the league (18.2% [2/11] vs 57%
[400/702]; P = .01). There was a trend toward fewer receivers
playing in the league with a history of spondylolysis (28.6%
[4/14] vs 54.3% [368/678]; P = .06). Spondylolisthesis did not
significantly reduce percentage of athletes playing in the
NFL for any position. Among offensive linemen, 18 of 24
athletes (75%) with spondylolisthesis played in the league,
which was significantly higher than the percentage of offensive linemen without spondylolisthesis who played at least
1 game in the NFL (53.6%) (P = .04). Other significant findings are summarized in Table 5.
An increased number of surgical procedures in offensive
and defensive linemen significantly decreased the percentage of athletes playing in the league. In other positions, an
increasing number of procedures did not have a significant
effect.
DISCUSSION
Figure 2. Survival analysis of defensive secondary in the
National Football League.
The effect of specific diagnoses and procedures on the NFL
career of college American football athletes does vary by
position. Defensive linemen who participated in the NFL
Combine had the greatest probability of playing at least
1 game in the league, while quarterbacks and kickers had
the lowest probability of playing professional football. In
terms of seasons in the league, athletes at speed positions
such as running backs, receivers, and the defensive secondary had the shortest careers, while quarterbacks and kickers lasted the most seasons in the league. However,
quarterbacks had the shortest career length of all positions
TABLE 4
Effect of Shoulder Instability and Shoulder Stabilization by Positiona
Position
Offensive backfield
Offensive receiver
Offensive line
Tight end
Quarterback
Defensive line
Defensive secondary
Linebacker
Kickers
Shoulder Instability
No Shoulder Instability
Shoulder Stabilization
No Shoulder Stabilization
Played in NFL, %
Played in NFL, %
Played in NFL, %
Played in NFL, %
54
49
44
58
48
54
53
63
27
(28/52)
(18/37)
(43/98)b
(18/31)
(13/27)
(44/81)c
(27/51)
(35/56)
(3/11)
57
54
54
61
44
67
61
62
25
(374/661)
(354/655)
(428/672)b
(150/246)
(130/295)
(568/848)c
(301/495)
(273/438)
(38/150)
54
67
48
62
50
54
48
63
40
(14/26)
(8/12)
(20/42)
(8/13)
(8/16)
(22/41)d
(12/25)
(19/30)
(2/5)
a
56
54
55
61
44
66
61
62
25
(388/687)
(364/680)
(451/728)
(160/264)
(135/306)
(590/888)d
(316/521)
(289/464)
(39/156)
Some athletes with a history of shoulder instability did not have a history of shoulder stabilization. NFL, National Football League.
P = .03.
c
P = .02.
d
P = .09.
b
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772 Brophy et al
The American Journal of Sports Medicine
Figure 3. Survival analysis of wide receivers in the National Football League.
Figure 4. Survival analysis of defensive linemen in the National Football League.
in terms of games played while kickers had the longest
career in games played. The apparent discrepancy in the
quarterback data probably reflects the need for backup quarterbacks, who may be in the league for several seasons but
see relatively little playing time.
Clearly one of the most significant injuries to a collegiate
football player is a rupture of the ACL. From 1987 to 2001,
ACL reconstruction was the third most common procedure
among participants at the combine, behind meniscectomy
and knee arthroscopy (not otherwise specified), and ACL
injury was among the top 15 diagnoses at the combine.1 In
our previous study including all participants at the combine, ACL injury and ACL reconstruction significantly
reduced the percentage of athletes playing in the NFL.2 By
position, ACL injury significantly reduced the percentage
of defensive linemen and linebackers playing in the league,
and showed a strong negative trend for offensive linemen.
Anterior cruciate ligament reconstruction resulted in a
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Predictive Value of Prior Injury on Football Career Affected by Position 773
Vol. 37, No. 4, 2009
TABLE 5
Other Diagnoses/Procedures by Position That Decrease the Probability of Playing in the NFLa
Position
Offensive backfield
Offensive receiver
Offensive line
Tight end
Quarterback
Defensive line
Defensive secondary
Linebacker
Kicker
Diagnosis/Procedure
Played
Did Not Play
Spondylolysis
Spondylolysis
Carpal fractures
Rotator cuff repair
Knee articular cartilage surgery
LCL (knee)
MCL (knee)
Forearm fracture
Rotator cuff injury
na
AC joint injury
na
2
4
5
0
0
0
16
1
10
na
27
na
9
10
13
4
4
3
36
10
13
na
27
na
Total
11
14
18
4
4
3
52
11
23
na
54
na
Percentage Played in League
18
29
28
0
0
0
31
9
44
vs
vs
vs
vs
vs
vs
vs
vs
vs
57 (P
54 (P
55 (P
54 (P
54 (P
61 (P
47 (P
46 (P
67 (P
na
50 vs 64 (P
na
=
=
=
=
=
=
=
=
=
.01)
.06)
.02)
.04)
.04)
.06)
.03)
.03)
.02)
= .05)
a
NFL, National Football League; LCL, lateral collateral ligament; MCL, medial collateral ligament; AC, acromioclavicular; na, not available.
lower percentage of linebackers playing professional football and a strong trend toward less success for offensive
and defensive linemen, as well as athletes in the defensive
secondary. Although not always statistically significant,
ACL injury and ACL reconstruction resulted in a smaller
percentage of athletes playing in the league in all other
positions except for quarterbacks and kickers. Approximately
half the quarterbacks with an ACL injury and a little over
25% of kickers with ACL injuries played in the league.
Neither of these rates was significantly different from the
overall rate of success for noninjured athletes in those
positions.
A recent study by Carey et al3 examined the effect of
ACL injury on running backs and wide receivers already
playing in the NFL. Almost 80% of these athletes returned
to play and the performance of those who did play was
reduced by a third. Although our previous study suggested
that the treatment of ACL injury has improved over time,1
ACL injury reduces the chances of making the transition
from collegiate football player to the professional level,2
particularly for linemen and linebackers. However, the
magnitude of the difference in terms of the percentage of
athletes who play in the NFL is smaller than might be
expected for other positions. Among kickers and quarterbacks, for example, athletes with a history of ACL injury
had the same percentage or higher of going on to play in
the league as athletes without such an injury, suggesting
that treatment for these injuries can be very effective.
Length of career was significantly affected by ACL injury
and reconstruction only among offensive linemen. Combined
with the reduced likelihood of playing in the league for
offensive linemen, it appears that injury to the ACL may be
particularly challenging for these athletes. Future research
should study the specific effects of ACL injury and reconstruction on offensive linemen and what influences their
ability to continue playing football after such an injury.
Meniscal injury has been shown to reduce the likelihood
of playing in the NFL for all participants at the combine.2
Although meniscal injury only had a significant negative
effect for athletes in the defensive secondary, meniscal
injury did reduce the percentage of athletes playing in the
league in all positions except running backs. This is particularly relevant because meniscal injury was the sixth most
common diagnosis and meniscectomy was the most common
procedure among all athletes at the combine.1 The effect of
meniscal injury on athletes in the secondary is particularly
important as it reduces their likelihood of playing in the
league and their longevity if they make it to the NFL. The
running and cutting demands on these athletes may make
them particularly sensitive to the effects of meniscal injury,
and this presents another area of opportunity for future
research. It is very interesting that meniscal injury did not
decrease the percentage of running backs playing in the
NFL. In this sizable cohort of 80 running backs with a history of meniscal injury, 48 of them played at least 1 game of
professional football. Furthermore, meniscal injury did not
reduce their longevity in the league.
The other injury that was shown to have a negative
effect on playing in the NFL for all combine participants
was shoulder instability.2 Shoulder instability was the
ninth most common diagnosis at the NFL combine and
shoulder stabilization was the fourth most common procedure.1 A recent MRI study found that football players are
15 times more likely to have a posterior labral tear than
non-football players.4 Shoulder instability reduces the percentage of both offensive and defensive linemen who play
in the NFL and reduces the length of career for defensive
linemen who play in the league. Although rotator cuff
injury is less common than shoulder instability among
these athletes, rotator cuff injury lowered the percentage
of defensive linemen who played professional football and
rotator cuff surgery did the same for offensive linemen. A
recent study showed that 50% of elite college football athletes have a history of shoulder injury and a third have a
history of shoulder surgery.8 While injuries were more
common in quarterbacks and defensive backs, surgery was
more common in linebackers and linemen. Anterior instability reconstruction made up 48% of those surgeries; posterior instability surgery and rotator cuff surgery each
made up another 10%. Linemen were more likely to have
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774 Brophy et al
The American Journal of Sports Medicine
posterior instability and rotator cuff injuries, making up
71% and 41% of these injuries, respectively. Of note, rotator cuff injuries accounted for 25% of all offensive linemen
shoulder injuries in that study. Another study reporting on
full-thickness rotator cuff injuries in professional football
players reported that offensive linemen were most commonly affected, with 22 of 51 tears occurring in offensive
linemen.5 In conjunction with our results, it is clear that
shoulder injury can be damaging to the career prospects of
a collegiate football lineman.
The findings in the spine are contrary to the perception
of spondylolisthesis as an unfavorable finding in elite athletes.21 In a survey of NFL team physicians, 64% believed
that the presence of spondylolisthesis implies a poor prognosis and 96% downgraded the rating of players with
known spondylolisthesis before the NFL draft.19 In our
study, spondylolisthesis did not reduce the percentage of
athletes playing in the league, even among linemen. At the
combine, most of these injuries are probably chronic and
asymptomatic. Because athletes with a symptomatic spondylolysis/spondylolisthesis are unlikely to be invited to the
combine, our findings are not necessarily applicable to all
collegiate linemen. In contrast to spondylolisthesis, spondyloysis did have a negative effect on running backs and
approached significance in receivers. Previous studies suggested that spondylolysis was not a significant finding in
collegiate football athletes.10,18 However, our study suggests that spondylolysis is a more significant finding in
skilled position players than spondylolisthesis in linemen
at the combine.
The fact that no offensive linemen played in the league
after knee articular cartilage surgery is of clinical interest.
Among all participants at the combine over this study
period, 22 athletes had a history of knee articular cartilage
surgery and only 10 of them played at least 1 game in the
league. Cartilage lesions can be a difficult problem to treat in
any cohort and they are particularly challenging in elite
athletes facing the demands of the NFL. Steadman et al20
reported on the results of microfracture for full-thickness
chondral lesions in NFL players. They reported that 19 of 25
players (76%) returned to play the following season, while 9
of 25 (36%) continued to play at average follow-up of 4.5
years (range, 2-13 years). Fourteen of the 25 players were
linemen, although this study did not report results by position. A prior study that reported on high-impact athletics
after microfracture found that only 3 of 9 football players
returned to their sport after this surgery.12 This may be
related to player size, as a higher body mass index (BMI),
specifically a BMI >30, has been shown to be associated with
worse outcomes after microfracture.11 This is particularly
relevant for linemen, who had the highest BMI in a recent
study of 1 NFL team (offensive line BMI, 37.1 ± 1.9; defensive line BMI, 34.6 ± 1.4).9 New treatments are becoming
available, and although there are some reports of using these
techniques in athletes,6,7,13 no results specific to American
football are available to date. Cartilage lesions remain a difficult clinical problem, particularly in high-demand, highperformance athletes such as those in the NFL.
Other injuries appear to have position-specific effects
that are consistent with the demands of the position. The
negative effect of forearm fractures on quarterbacks is not
surprising. Carpal fractures may make it difficult for offensive linemen to block. The most common fracture in the
wrist among athletes is the scaphoid,16 and previous studies have described both conservative14,16,17 and surgical14,15,16
treatment. We reviewed our data to see if surgery had any
effect on outcome. A total of 6 offensive linemen had surgical treatment of their carpal fractures and only 1 (17%)
played in the league. Twelve offensive linemen had carpal
fractures that were treated nonoperatively and 4 of them
(33%) played in the league. With the small numbers in this
cohort, the difference was not significant. Furthermore, this
small retrospective group does not control for injury severity and more severe injuries may have been more likely to
be treated with surgery.
The significant effect of a knee medial collateral ligament (MCL) injury on quarterbacks is surprising. We
hypothesized that this relatively benign injury reduced the
probability of quarterbacks playing in the NFL because it
was associated with more significant combined knee ligamentous injury. However, the data did not support this
theory. A history of combined ACL-MCL injury was present
in only 3 of the 36 quarterbacks at the combine with an
MCL injury who did not play in the NFL. By comparison,
4 of the 16 quarterbacks with an MCL injury who did play
in the NFL also had an ACL injury. Further investigation
is warranted to identify how these injuries may be detrimental to the quarterback athlete.
Although this study uses retrospectively collected data
from the combine, given the high stakes at risk, the assessment process at the combine is likely both thorough and
accurate. To play at least 1 regular season game in the
NFL, the athlete has to be functioning at a level at which
an NFL coaching staff believes the individual is able to
withstand the rigors of professional football competition.
Differentiating athletes based on playing 1 game in the
NFL is a limitation, although any threshold will be arbitrary and subject to criticism. A higher threshold requiring
more games in the league could be more sensitive to other
factors, such as athletic talent, relative opportunity based
on roster depth, and new injuries incurred in the NFL. By
analyzing the length of career as well, we also assessed
whether these injuries affect the durability of these athletes. Injuries that reduced the likelihood of playing in the
league for athletes in a particular position often reduced
the length of career for the same cohort.
Analyzing the data by position obviously reduces the
power of our study by reducing the sample size. This may
have been particularly relevant in the positions with fewer
subjects, such as kickers (161), tight ends (275), and quarterbacks (322). However, our database is perhaps the largest
collection of comprehensive data available on this population of elite athletes. Despite the limitations, the findings in
this study provide new information on how certain injuries
may affect collegiate football athletes in different positions.
Comparing all athletes with a specific diagnosis/procedure
to all other athletes without that specific diagnosis/procedure
is a significant limitation as it does not take into account
the effect of other diagnoses and/or procedures. However,
with the large number of athletes in this database, it is
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Vol. 37, No. 4, 2009
Predictive Value of Prior Injury on Football Career Affected by Position 775
reasonable to assume that the distribution of the other
diagnoses and procedures does not bias the results of the
comparison. On the other hand, limiting the study population
to athletes with a history of only 1 particular diagnosis or
surgery, for example, would further limit the power of the
study and probably introduce a different, and perhaps more
significant, source of bias.
Although the study does not adjust for differences by
position in the number of athletes at the combine or the
number of spots on the field and roster, all comparisons are
intraposition, not interposition, so these differences should
not alter the analysis. Another limitation is the lack of
specific information about each diagnosis; for example,
meniscal injury includes both medial and lateral meniscus
pathology. Shoulder instability includes anterior and posterior injuries, and we do not know whether shoulder stabilization was open or arthroscopic. Finally, the findings in
this study only apply to athletes invited to the combine.
This analysis does not account for the effect of injuries on
the likelihood to be invited to the combine. Therefore, the
findings cannot necessarily be extrapolated to the average
collegiate football athlete.
College football players should be advised of how specific
injuries influence the percentage of athletes who play
professional football based on position and their durability
in the league. The data reported herein should not be
accepted as an absolute predictor for the probability of success or failure, but rather as a general guide on how past
injuries may influence the potential for a professional football career. The effect of these injuries does depend on the
position that the athlete plays, and the significant injuries
and diagnoses appear congruent with the position-specific
demands placed on the athletes. This information is useful
to physicians and athletic trainers caring for and advising
aspiring professional football athletes as well as those
assessing these athletes at the NFL Combine.
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