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Review
A Systematic Review of the Orthopaedic
Literature Involving National Football
League Players
Melissa A. Kluczynski,* MS, William H. Kelly,* MS, William M. Lashomb,* BS,
and Leslie J. Bisson,*
†
MD
Investigation performed at the University at Buffalo, The State University of New York at Buffalo,
Buffalo, New York, USA
Background: Orthopaedic injuries of National Football League (NFL) players can have a deleterious effect on their health, with
minimal to no high-level evidence on the management of these injuries.
Purpose: To summarize all data published between January 1980 and March 2018 on orthopaedic injuries experienced by NFL
candidates and professional players in the NFL.
Study Design: Systematic review; Level of evidence, 4.
Methods: A literature search of studies examining orthopaedic injuries in the NFL was performed through the PubMed, Embase,
and CINAHL databases. The review included studies of orthopaedic injuries in college football recruits attending the NFL Combine
as well as professional NFL players. Excluded were studies of nonorthopaedic injuries, such as concussions, traumatic brain injury,
facial injuries, and vascular injuries, as well as case reports.
Results: A total of 147 articles met the inclusion criteria and were divided into 11 topics based on anatomic site: general (16%),
spine (13%), shoulder (13%), elbow (3%), hand and wrist (3%), trunk (0.7%), hip and pelvis (7%), thigh (3%), knee (24%), ankle
(5%), and foot (12%). Of these studies, 74% were of level 4 evidence. Most studies obtained data from the NFL Combine database
(26%), by searching the internet (24%), and via the NFL Injury Surveillance System (22%). Studies using internet search methods to
identify injuries consistently found fewer participants than studies using the NFL Injury Surveillance System.
Conclusion: This systematic review provides National Collegiate Athletic Association and NFL team physicians with a single
source of the most current literature regarding orthopaedic injuries in NFL players. Most research was published on knee, spine,
shoulder, and foot injuries and consisted of level 4 evidence. A substantial portion of the published literature was based on data
obtained from internet searches and may not accurately represent the NFL population.
Keywords: orthopaedic; musculoskeletal; injury; football; Combine; National Football League
American football enjoys broad participation, and injuries
commonly occur.
1,4,101
Football is also associated with the
most catastrophic injuries and fatalities among sportsin the
United States.
1
The National Football League (NFL) and
fantasy football are extremely popular, and information
about player’s injuries can often be found in the public
domain. This makes it possible to create databases from
publicly available information and publish studies using
these databases. Additionally, the anecdotal observations
of NFL team physicians suggest that the injuries experi-
enced by NFL players experience are unique in comparison
with those of the general US population. One goal of medi-
cine should be to base treatment on the highest levels of
evidence. Injuries can have a deleterious effect on a football
player’s health and career, and there is no high-level evi-
dence to guide the management of injuries sustained by
NFL players.
88
The primary objective of this systematic
review was to summarize all data published on orthopae-
dic injuries among college-level NFL recruits and profes-
sional players in the NFL. The secondary objective was to
characterize the literature based on anatomic site, level of
evidence, and source of data from which the study was
based. Finally, when possible, we sought to compare the
†
Address correspondence to Leslie J. Bisson, MD, UBMD Ortho-
paedics and Sports Medicine, Erie County Medical Center, 462 Grider St,
Buffalo, NY 14215, USA (email: ljbisson@buffalo.edu).
*Department of Orthopaedics, Jacobs School of Medicine and
Biomedical Science, University at Buffalo, Buffalo, New York, USA.
One or more of the authors has declared the following potential con-
flict of interest or source of funding: This study was funded by the Ralph C.
Wilson, Jr, Foundation. L.J.B. has received funding for education from
Arthrex, royalties from Zimmer Biomet, and hospitality payments from
Prodigy Surgical Distribution.
The Orthopaedic Journal of Sports Medicine, 7(8), 2325967119864356
DOI: 10.1177/2325967119864356
ªThe Author(s) 2019
1
This open-access article is published and distributed under the Creative Commons Attribution - NonCommercial - No Derivatives License (http://creativecommons.org/
licenses/by-nc-nd/4.0/), which permits the noncommercial use, distribution, and reproduction of the article in any medium, provided the original author and source are
credited. You may not alter, transform, or build upon this article without the permission of the Author(s). For article reuse guidelines, please visit SAGE’s website at
http://www.sagepub.com/journals-permissions.
results among the different sources of data, including the
NFL Injury Surveillance System (NFLISS), team and
medical records, and internet-based sources.
METHODS
PubMed, Embase, and CINAHL were searched from Janu-
ary 1, 1980, to March 31, 2018, to identify all studies of
orthopaedic injuries in professional football players. Search
terms were “National Football League” in combination with
“combine” or “football.” We included studies of orthopaedic
injuries in college football recruits attending the NFL Com-
bine as well as those to professional NFL players. Excluded
were case reports and studies of nonorthopaedic injuries,
including concussions, traumatic brain injury, facial inju-
ries, and vascular injuries. Two authors (W.H.K., W.M.L.)
independently conducted the literature search and com-
pared their findings. The articles were divided into 11 cate-
gories corresponding with the anatomic site of injury:
general, spine, shoulder, elbow, hand and wrist, trunk, hip
and pelvis, thigh, knee, ankle, and foot. Level of evidence,
source of data, and type of injury were extracted from each
article. Finally, when possible, we compared studies on over-
lapping topics that used various data sources, including the
NFLISS, team or surgeon medical records, and the internet.
RESULTS
The PRISMA (Preferred Reporting Items for Systematic
Reviews and Meta-Analyses) flowchart of the searchstrategy
is presented in Figure 1. We identified 855 articles through
our literature search,of which 147 articlespublished between
1980 and 2018 met the inclusion criteria. Figure 2 illustrates
the number of included articles by type of orthopaedic injury.
Most articles examined knee (24%), spine (13%), shoulder
(13%), and foot (12%) injuries. Of the studies reviewed, 74%
were of level 4 evidence (Figure 3). No level 1 studies met the
inclusion criteria. As shown in Table 1, most studies obtained
data from the NFL Combine database (26%), the internet
(24%), and the NFLISS (22%). The results of the included
articles are summarized and grouped according to anatomic
location.
General Information
Several studies investigated the football field and environ-
mental conditions and their effect on injury. The studies
consistently found higher rates of lower extremity injury
on artificial surfaces in comparison with natural
turf,
46,107,108
although 1 study from 1989 to 1998 found lower
rates of anterior cruciate ligament (ACL) tears on AstroTurf
in cold weather.
102
Lawrence et al
71
found that game-day
temperature below 50was a risk factor for concussions and
ankle injuries.
Medical grading systems can predict future availability
and performance in NFL Scouting Combine players and
should incorporate the player’s position and history of
injury, with shoulder instability, meniscal injury, ACL
tear, and other lower extremity injuries having well-
documented decreased performance and availability
effects.
4,10,11,15,79,111
The most common site of injury was the knee, followed by
hamstring strains and contusions.
35,72
Injuries were more
common in the first 2 weeks of training camp and during
games
35
and occurred most commonly in defensive players,
particularly defensive backs, although other positions had
unique injury patterns. These included acromioclavicular
Records idenfied through database
searching
(PubMed, n = 521
Embase, n = 730
CINAHL, n = 28
Total, n = 1,279)
Records idenfied by
searching reference lists
(n = 41)
Records screened aer duplicates removed
(n = 855)
Full-text arcles assessed
for eligibility
(n = 214)
Full-text arcles included
(n = 147)
Records excluded based
on tle and abstract
(n = 641)
Full-text arcles excluded (n = 67)
Case reports (n = 12)
Nonmusculoskeletal (n = 55)
Figure 1. PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) flowchart.
2Kluczynski et al The Orthopaedic Journal of Sports Medicine
(AC) joint separations in quarterbacks, forearm fractures in
defensive backs, and lower extremity strains in kick-
ers.
17,49,61,72
Corticosteroid injections for muscle strains
as well as certain ligament sprains, such as the AC joint
or ankle syndesmosis, have been shown to be safe as well as
effective in allowing earlier return to play (RTP).
29,30,75,85
Finally, several studies documented increased arthritis and
whole-person impairment in former NFL players, with the
cervical and lumbar spine being highly affected.
27,42,97
Spinal Injuries
Spine injuries accounted for 7%of NFL injuries, were about
10 times more common in games than in practices, were
most common in the cervical spine, and most commonly
occurred in offensive linemen or defensive players who
were blocking or tackling.
43,82
Cervical Spine. The space available for the spinal cord on
cervical magnetic resonance imaging (MRI) was decreased
in heavy-contact NFL positions and was associated with
chronic stingers when the space available for the spinal cord
was <5mm.
109,110
Cervical pathology negatively affected the
number of games played in the NFL but did not affect player
performance.
50,122
Players with cervical disc herniation may
safely RTP, but RTP decreased to approximately 70%in
those requiring anterior cervical discectomy and fusion
(ACDF).
80,93
Adjacent segment degeneration occurred in
10%of players undergoing ACDF, while those treated with
foraminotomy had an RTP rate of 92%and returned earlier
than those with ACDF but had a 50%reoperation rate.
80
Lumbar Spine. Hyperconcavity of the lumbar spine was
commonly found on radiographs but had no evident conse-
quences.
106
The lumbar spine was the most common site of
Figure 2. Percentage of articles by type of orthopaedic injury. Injury categories are not mutually exclusive.
Figure 3. Number of articles by level of evidence and type
of orthopaedic injury. No level 1 or 2 articles were found.
The Orthopaedic Journal of Sports Medicine Orthopaedic Injuries in NFL Players 3
disc herniation, especially L5/S1, and lumbar herniations
were most common in offensive linemen.
44
Lumber condi-
tions, including disc herniation or spondylolisthesis, com-
monly led to team physicians’ downgrading draft prospects;
but there were conflicting data regarding player longevity
and no evident effect on performance in those players
drafted into the NFL.
78,121,123,127
Treatment of lumbar disc
herniations with epidural injections allowed RTP in 90%of
NFL players with few practices or games missed, but it was
less successful in the setting of weakness on examination or
disc sequestration on MRI.
68
When surgery was indicated
for lumbar disc herniation, NFL data and internet-based
studies showed that RTP was approximately 75%to 80%
but with 15%of players requiring revision decompres-
sion.
51,52,118,141
Performance was preserved in those
returning to play. Lumbar transverse process fractures
occurred, rarely involved viscera, and typically took 3 to
4 weeks before RTP.
138
Trunk Injuries
Chondral rib fractures were common and typically diag-
nosed by computed tomography and/or MRI. Sixty percent
of team physicians used an anesthetic block for pain man-
agement acutely, and 40%used a block to allow for RTP.
Shoulder Injuries
A history of shoulder injury, particularly AC separation
and instability, was found in 50%of NFL prospects, and
the most common shoulder surgery was for anterior insta-
bility.
39,58
Compared with players without shoulder inju-
ries, those with a history of shoulder injury were more
likely to go undrafted, and they played and started in
fewer games.
39
AC Joint. Most AC injuries occurred in games rather
than practices, were low grade, and rarely required sur-
gery, with quarterbacks missing more time than other
players (17 vs 10 days).
61,77
Rotator Cuff. Preexisting rotator cuff tears were rare in
NFL prospects but, when present, they decreased the ath-
letes’ likelihood of being drafted and were associated with
lower availability and performance in those who were
drafted.
41
Rotator cuff injuries included contusions and
tears, and contusions led to minimal time lost and were
treated with rehabilitation and occasionally with injec-
tion.
25
Of players with rotator cuff injuries, 11%ultimately
required surgery. Rotator cuff tears occurred most com-
monlyinoffensivelinemenandlinebackers,with90%
being treated with surgery and 90%of those surgically
treated returning to play at a mean of 5 months.
38
Residual
shoulder pain after rotator cuff repair was common.
Fractures. Clavicle fractures were successfully treated
nonoperatively and operatively, with both methods allow-
ing RTP in 95%of players; however, surgical treatment led
to earlier healing and RTP.
55,94
Some athletes had
decreased availability and/or performance after a clavicle
fracture, including offensive skill players (quarterbacks,
wide receivers [WRs], and running backs [RBs]).
55,56
Shoulder Instability. Shoulder instability decreased the
likelihood of NFL Combine prospects being drafted as well
as reduced career longevity.
14
Nonoperative treatment of
instability had recurrence rates from 40%to 55%but
allowed players to RTP in 1 week for subluxation and 3
weeks for dislocation, while players undergoing surgery
had 80%to 90%RTP rates but took nearly 9 months before
RTP, with a recurrence rate that ranged from 13%to
26%.
74,100,145
Latarjet surgery history was rare in NFL
Combine players but, when present, decreased the likeli-
hood of being drafted and was commonly associated with
hardware complications and glenohumeral osteoarthritis,
TABLE 1
Number of Articles by Source of Data and Type of Injury
a
Source of Data
Type of
Injury
NFL
Combine
Database
NFL Injury
Surveillance
System
Internet-Based
Search of Publicly
Available Data
Data From
a Single
Team
Medical
Records of
Players
Survey of Team
Physicians or Athletic
Trainers or Players
Med Sports
Systems Limited
Database
Data Collected
by Athletic
Trainers
Trunk 0 0 0 0 1 1 0 0
Elbow 0 4 0 0 0 0 0 0
Hand/Wrist 0 2 1 1 0 1 0 0
Hip/Pelvis 3 3 2 0 2 0 0 0
Thigh 1 2 0 2 0 0 0 0
Ankle 1 2 0 3 1 2 0 0
Foot 6 0 10 4 1 2 0 0
General
Injuries
54 3 52 4 0 2
Shoulder 6 5 3 2 5 1 0 0
Spine 7 3 6 2 1 1 1 0
Knee 9 8 11 5 1 6 0 0
Total 38 33 36 24 14 18 1 2
a
Data are not mutually exclusive. NFL, National Football League.
4Kluczynski et al The Orthopaedic Journal of Sports Medicine
with 1 of 2 studies showing a negative effect of Latarjet
surgery on NFL participation.
66,73
Other. SLAP (superior labral anterior-posterior) tears
were rare in NFL Combine participants (3%)but,when
present, decreased future player availability. When NFL
Combine participants underwent labral repair, 32%had
recurrent tearing and/or degenerative joint disease on MRI,
but this did not affect availability in their first NFL sea-
son.
65
In NFL players, SLAP tears were most common in
offensive linemen and were typically treated nonopera-
tively (60%).
23
Nonoperative treatment led to RTP after a
mean of 21 days versus 4 to 5 months with surgery. Pector-
alis major injuries were rare in NFL players (1 injury per
season for the entire league) and occurred most often in
games (90%) and during tackling (50%) rather than with
weight lifting, with RTP after surgery taking 4 months on
average.
136
Elbow and Forearm Injuries
Most NFL elbow injuries were sprains (77%)ordisloca-
tions (18%) and included hyperextension (56%)ormedial
collateral ligament (MCL) injuries (20%).
63
They most
commonly occurred in offensive and defensive linemen.
21
Elbow MCL sprains were usually treated nonoperatively,
andplayersmissedupto1game.Tricepstearsoften
occurred in linemen, with one-third having prodromal
symptoms and 25%having a prior steroid injection. Nearly
half of partial triceps tears eventually required surgery,
and athletes commonly returned to play following repair of
partial and complete tears, although they may miss the
remainder of the season and possibly the season after sur-
gery.
37,81
Forearm injuries were most commonly fractures
and involved defensive backs.
21
Hand and Wrist Injuries
Mall et al
83
reported that the overall incidence of hand
injuries in NFL players over 10 years (1996-2005) was
10.6 per 1000 athletic exposures, with 50%of injuries
involving the fingers, 30%hand, and 20%first ray. Also
according to Mall et al,
83
metacarpal fractures (17%)and
peripheral interphalangeal dislocations (17%), especially
of the ulnar 2 digits, were the most common types of inju-
ries, with the most common activity being tackling and the
most common positions being linemen (hand) and WRs
and defensive secondary (fingers). Thumb ligament inju-
ries have been a topic of study, and researchers have found
that ulnar collateral ligament injuries are often treated
surgically, with RTP in 4 to 5 weeks and no decline in
performance; 25%of ulnar collateral ligament injuries
also involve the radial collateral ligament and should be
treated surgically (which can safely be delayed until the
end of the season).
133,143
Lunate or perilunate dislocations were described in
10 NFL players, with hyperextension being the most fre-
quent mechanism of injury.
112
Closed or open reduction
with percutaneous pinning allowed for successful RTP after
a minimum of 4 weeks.
Hip and Pelvis Injuries
Feeley et al
36
found that 3%of all NFL injuries involved the
hip and were primarily muscle strains (36.3%). Defensive
backs and WRs had the most hip injuries, and offensive
linemen missed the most time (mean, 18.3 days). Blocking
was the most common mechanism of hip injury, and contu-
sions were due to contact while strains were usually non-
contact injuries. Proximal rectus femoris avulsion was
successfully treated nonoperatively, but time to RTP varied
from 3 to 10 weeks.
40
Adductor longus ruptures were usu-
ally treated nonoperatively, with RTP at a mean of 6 weeks,
but surgery was indicated in approximately 25%of cases
and RTP took 12 weeks.
120
In NFL Combine attendees, a history of core muscle sur-
gery did not significantly affect an athlete’s draft status or
future NFL performance.
64
In NFL players, an internet-
based study found that 95%of players undergoing surgery
for a core muscle injury were able to RTP, with no decrease
in statistical performance but a slightly shorter career
(approximately 6 months shorter on average) and 2 fewer
games played per season in comparison with controls.
53
Imaging studies of NFL Combine attendees and retired
NFL players noted a high incidence of impingement find-
ings, including labral tears (89%), chondral lesions (98%),
and ligamentum teres tears (81%) in athletes with symp-
toms.
28,95
An increased alpha angle seemed to be the best
imaging study predictor of pain.
70
Persistent symptoms of
adductor and rectus strain that did not resolve despite
therapy were described as the “sports hip triad” and
should raise suspicion of a labral tear.
36
Finally, when hip
surgery was indicated, impingement surgery and labral
repair both showed an RTP rate of approximately 85%
to 90%,
100,108
although the odds of RTP were about 6 times
less in lineman compared to other positions.
92,98
Thigh Injuries
A case-control study found that isokinetic parameters mea-
sured at the NFL Combine were not associated with ham-
string injuries that occurred within the player’s first
season.
147
Hamstring injuries primarily occurred 4 times
as often during the preseason as in the regular season,
happened primarily during practices (53%), were noncon-
tact (82%), and resulted in a mean 13 days lost among NFL
players.
32
Forty-one percent of hamstring injuries were minor
(<7dayslost),41%moderate (1-3 weeks lost), and 18%major
(>21 days lost), and most hamstring injuries occurred in
defensive backs (23%), WRs (21%), and special teams players
(13%). Corticosteroid injection for hamstring straincan safely
speed RTP without leading to recurrence, while platelet-rich
plasma has not been effec tive.
75,114
Finally,repair of proximal
hamstring avulsions can restore strength, but only 5 of 10
NFL players who underwent early repair were able to play
in more than 1 NFL game after surgery.
86
Knee Injuries
General. Among NFL Combine attendees, approxi-
mately 50%had a history of knee injury, most commonly
The Orthopaedic Journal of Sports Medicine Orthopaedic Injuries in NFL Players 5
MCL (40.8%), meniscal (26.3%), or ACL (19%).
8
Linemen
and tight ends had the highest incidence of knee injury
(57%-68%), and knee surgery was most common in RBs and
linebackers (35%).
Anterior Cruciate Ligament. Two percent of all injuries
reported to the NFLISS between 1994 and 1998 involved the
ACL.
9
Most noncontact ACL tears from 1989 to 1993
occurred during games (47.5%), on natural grass (65.6%),
and on a dry surface (93.4%).
125
A video analysis found that
the majority of ACL tears (72%) in NFL athletes involved a
noncontact mechanism, with the lower extremity exhibiting
significant valgus of the knee, particularly during lateral
movement.
57
The incidence of ACL injuries was the highest
for speed players (6.3%-10%), including WRs, tight ends,
linebackers, fullbacks, and halfbacks, and players experienc-
ing reinjury were more likely to injure the same knee versus
the contralateral knee (12.3%vs 7.3%,P<.05).
26
A study of NFL Combine participants found that a 30
reduction of hip internal rotation was associated with
increased odds of ACL tears in the ipsilateral (odds ratio,
4.06) and contralateral (odds ratio, 5.29) sides.
5
In a sepa-
rate imaging study of combine athletes, ACL reconstruc-
tions with more posterior tibial tunnels and grafts with
less sagittal obliquity had increased translation on Lach-
man examination.
84
Finally, Keller et al
60
studied players
at the 2010 through 2014 NFL Combines and found no
differences in measures of speed, jumping, agility, and
quickness in players with a history of ACL reconstruction
versus controls; in addition, they found that isolated ACL
reconstruction in combine participants did not shorten
their future NFL career.
13
Survey studies of NFL team physicians regarding man-
agement of ACL injuries found that 80%to 90%preferred
patellar tendon autograft via a single-bundle technique,
most recommended at least 6 months until RTP, and most
did not routinely recommend a brace.
9,33,88
RTP after ACL reconstruction ranged from 60%to 90%,
varied by position, and was highest in quarterbacks, but
longevity was found to be diminished.
24,31,34,113,128,146
RTP
was lower in less experienced and/or less highly skilled
players, had a significant negative financial impact on
future earnings, and was also associated with diminished
performance following RTP in all positions except
quarterbacks.
20,31,34,126,128
Okoroha et al
99
found that if the ACL graft failed, 79%of
24 NFL players who underwent revision ACL reconstruc-
tion returned to play at a mean of 12.6 months, with expe-
rience and skill associated with successful RTP and no
effect on career longevity.
Collateral Ligaments. Two studies documented success-
ful nonoperative treatment of isolated collateral ligament
injuries up to grade 3, reporting faster RTP with lower-
grade injuries and injuries managed nonoperatively.
19,129
MRI was helpful in predicting time lost following injury.
129
Articular Cartilage. Full-thickness cartilage lesions
were common in NFL prospects, being found in 40%to
60%of players at the NFL Combine who underwent knee
MRI.
47,96
Most isolated cartilage lesions were in the patel-
lofemoral compartment, and full-thickness cartilage lesions
were more common in a compartment of the knee that
underwent prior arthroscopic partial meniscectomy (APM),
particularly laterally. In NFL Combine players with knee
osteoarthritis based on plain radiographs or MRI, 27%had
a history of APM, 24%ACL reconstruction, and 11%menis-
cal repair.
132
History of knee surgery and body mass index
30 kg/m
2
were associated with knee osteoarthritis. When
players experienced articular cartilage injuries in the NFL,
roughly 50%occurred during games, 50%involved linemen,
50%involved the medial femoral condyle, and 50%required
eventual surgery.
16
RTP was longer for operative versus
nonoperative management (124 vs 36 days). Finally,
according to a survey of team physicians regarding the
management of chondral lesions, microfracture was
favored the most (43%), followed by debridement (31%) and
nonoperative treatment (13%).
16
Several studies focused on treatment of articular carti-
lage injuries in NFL players, with chondroplasty with or
without microfracture rates of 70%to 75%and with predic-
tors of return rates being absence of microfracture and
more presurgical games per season played.
119,124,134
Finally, Tabacco et al
135
studied 31 NFL players with knee
osteoarthritis treated with autologous stem cell therapy
and found that all players were satisfied with their treat-
ment and that RTP occurred at a mean of 2.4 months.
Meniscus. Lateral meniscectomy resulted in 60%RTP in
NFL players by 8 to 9 months after surgery, with more
skilled and experienced players successfully returning and
speed players less likely to return.
2
Isolated APM resulted
in fewer games played and a shortened career.
13
Concomitant Injuries. One study of multiligament knee
injuries identified through the NFLISS database (2000-
2016) found RTP rates of 70%after combined ACL-MCL
injuries, 55%RTP after ACL and posterior cruciate liga-
ment and/or lateral collateral ligament injuries, and 50%
RTP after frank knee dislocations.
3
Other. Tejwani et al
137
identified 24 players from a sin-
gle NFL team (1993-2006) with Morel-Lavallee lesions, of
which only 2 players missed 1 game each and all players
were treated successfully with compression/cryotherapy/
physical therapy (52%) or aspiration (48%). However, 20%
of players required repeated aspirations, and 10%needed
doxycycline sclerodesis when 3 aspirations failed to resolve
the fluid collections. Quadriceps injuries most commonly
occurred in defensive linemen and had only a 50%RTP
rate, with return more successful in more talented players.
7
In contrast, patellar tendon ruptures had an approximately
80%RTP rate, with return again favoring more talented
players.
6
Finally, a radiographic study of patellofemoral
congruence in 132 athletes at the 2011 NFL Combine found
incongruence in 10%, with an association of higher body
mass index with patellofemoral incongruence but no asso-
ciation with quadriceps-to-hamstring strength ratios.
18
Ankle Injuries
A history of ankle (and foot) injuries, particularly lateral
sprains, was very common in NFL Combine participants
(>70%), particularly in special teams players, WRs, and
offensive linemen.
59
Syndesmotic injuries were a topic of
several studies in the NFL; they often occurred in special
6Kluczynski et al The Orthopaedic Journal of Sports Medicine
teams players and offensive linemen, with the mean num-
ber of days missed being just over 2 weeks when all grades
were combined.
59,103
Steroid injection of stable syndesmosis
sprains led to early RTP by approximately 10 days, while
higher-grade injuries with positive squeeze test were asso-
ciated with longer RTP times.
85,130
In a survey of NFL trai-
ners in 1997, most used ice, electrical muscle stimulation, a
cast and/or brace, and nonsteroidal anti-inflammatory
drugs during the acute phase of the injury; proprioceptive
training, ultrasound, and taping were the most common
follow-up modalities. Recovery time was thought to be
reduced by immobilization, corticosteroid injection, ice, and
exercise.
29
Isolated fibular fractures were found to require surgery in
50%of cases and allowed for faster RTP when isolated, but
when treated with surgery, even isolated fractures required
a mean of 10 weeks to RTP.
144
In NFL athletes requiring
ankle fracture fixation, superficial deltoid complex avulsion
was a distinct injury that should be recognized, and these
players might benefit from primary open repair.
48
Finally, calf injuries have been studied in NFL players,
and 75%were isolated to the gastrocnemius, 15%to the
soleus, and 10%to both muscles.
142
The mean time to RTP
for calf injuries was 17 days, and 3 players required sur-
gery. Larger fascial defects and the presence of fluid collec-
tion on MRI were associated with longer RTP.
Foot Injuries
Lisfranc Injuries. Kent et al
62
reviewed 16 videos of tar-
sometatarsal injuries and found that these injuries typi-
cally occurred when a player was engaged with another
player and when a combination of axial loading of a
plantarflexed foot, external rotation, and pronation or supi-
nation occurred. Lisfranc sprains in NFL Combine partici-
pants were shown to negatively affect draft position and
player availability, particularly when >2-mm residual dis-
placement is present, while internet data of Lisfranc
sprains in NFL players showed >90%RTP at a median of
11 months with no effect on performance or career
length.
90,91
Type 1 and 2 injuries were treated nonopera-
tively, with RTP within 1 week for grade 1 and at 5 weeks
for grade 2, while grade 3 injuries required surgery but
allowed eventual RTP.
104
Achilles Tendon Ruptures. Several studies investigated
Achilles tendon ruptures in NFL athletes, including data
from the NFLISS, the internet, and individual surgeon
studies. There were similar results based on all these data
sets, with RTP occurring in 66%to 72%of players and var-
ious performance metrics being decreased for 2 to 3 years
following repair.
45,54,67,89,105,139
Fractures. Multiple studies investigated fifth metatarsal
fracturesin NFL Combine participants and NFL players. The
incidence of this injury was approximately 2%in NFL Com-
bine participants and was higher in athletes with long,
straight, narrow fifth metatarsals and an adducted forefoot;
7%to 12%had nonunions after surgery versus 20%without
surgery.
22,69,76,116,140
There was a nonsignificant association
with player availability in 1 study
22
and no association in
another,
140
as well as a negative effect on performance.
131
Successful completion of at least 1 college season after sur-
gery for fifth metatarsal fracture decreased the likelihood of
reinjury.
117
Operative treatment was successful at maximiz-
ing RTP when it employed (1) a protocol of fixation with a
Jones-specific intramedullary screw and iliac crest bone mar-
row aspirate with demineralized bone matrix injected at the
fracture site, (2) noninvasive bone stimulators, (3) use of cus-
tomized orthoses, and (4) an aggressive patient-specific reha-
bilitation protocol; however, 12%developed nonunion and
required revision surgery when returning during the same
season (at a mean of 9 weeks).
69
Other. One study found that age, playing on artificial
surface, and decreased ankle dorsiflexion were risk factors
for turf toe in NFL players,
115
while another study found
that players with a history of turf toe had decreased first
metatarsophalangeal dorsiflexion and higher peak hallucal
pressures but no difference in peak first metatarsophalan-
geal pressures.
12
Comparison of Overlapping Findings
From the NFLISS vs Medical Records
vs Internet-Based Studies
Cervical Disc Herniation. Hsu
50
sought to describe out-
comes of cervical disc herniation in NFL athletes and, using
the internet, was able to identify 99 players with cervical
disc herniations over 30 seasons (1979-2008), or 3.3 cases
per year. In contrast, Gray et al
44
used NFLISS data and
found 61 cervical herniations over 12 seasons (2000-2012),
or 5.1 cases per year. No studies of cervical disc herniation
utilized team medical record data. Although many remote
cases were likely missed by Hsu using an internet search
and despite the fact that the number of teams in the NFL
has increased since 1979, the disparity between the
2 sources of data suggests that the medical information
on NFL players available via the internet is likely
incomplete.
Lumbar Disc Herniation. Two studies contained over-
lapping data regarding lumbar disc herniation.
44,141
Weis-
troffer and Hsu
141
used internet search methods to identify
lumbar disc herniations in NFL linemen and found 66 cases
from 1982 to 2009 (approximately 2.4 cases per year). In
contrast, Gray et al
44
used NFLISS data to identify lumbar
disc herniations and found 83 cases in linemen from 2000 to
2012 (6.9 cases per year).
44
This suggests that a large num-
ber of cases are missed with information from the public
domain and introduces bias into the internet-based study.
No studies of lumbar disc herniation utilized team medical
record data.
Achilles Tendon Repair. Five studies collected internet-
based data and found 31 to 172 ruptures in NFL players;
however, there was much variation in the period for data
extraction (2-58 years).
45,54,67,105,1 39
Two of these studies
reported RTP rate, which ranged from 66%to 72%and was
similar to a study by McCullough et al,
89
who found that 78%
returned to play after mini-open repair according to medical
record data from a single surgeon’s practice.
54,105
No studies
on Achilles tendon ruptures utilized data from the NFLISS.
The Orthopaedic Journal of Sports Medicine Orthopaedic Injuries in NFL Players 7
ACL Injuries. Multiple studies used the internet or
NFLISS to identify ACL tears in certain NFL populations,
affording an opportunity to determine the ability of an inter-
net search to capture a given player population.
9,20,24,26,3 1,57
Three studies provided data regarding the number of RBs
and WRs experiencing ACL tears over a defined period.
9,20,26
Using the NFLISS, Bradley et al
9
searched the years 1994 to
1998 (5 seasons) and found 39 ACL tears among RBs and
WRs, while Dodson et al
26
found 57 ACL tears in RBs and
WRs from 2010 to 2013 (4 seasons). In contrast, Cary et al
20
found 33 ACL tears in these positions using the internet for
the 5 seasons from 1998 to 2002.
In another set of studies focusing on a different position,
Cinque et al
24
used the internet to identify ACL tears in
linemen and, over the 6 seasons from 2010 to 2015, found 38
ACL tears. In comparison, Bradley et al
9
found 57 ACL
tears in these positions in their study using the NFLISS
over 5 seasons, and Dodson et al
26
found 56 tears over 4
seasons, also using the NFLISS. Finally, in 2 studies using
the internet to identify all NFL ACL tears over the same
period, Eisenstein et al
31
found 92 cases in the 2013 and
2014 seasons, while Johnston et al
57
found 108 ACL tears
during those same 2 seasons.
Taken together, these findings imply that (1) an internet
search is likely to miss eligible participants; (2) higher-
profile players, such as RBs and WRs, may be more easily
identified via an internet search; (3) internet searches to
identify ACL tears at lower-profile positions, such as line-
men, may miss a significant number of cases with a risk of
spurious findings; and (4) differences in internet search
methods may lead to many eligible cases being missed.
No studies on ACL injuries extracted data from medical
records.
DISCUSSION
This systematic review provides a comprehensive summary
of the orthopaedic literature involving NFL players. Most
studies examined knee, spine, and shoulder injuries in NFL
players, and the majority of articles were level 4 evidence.
The most common sources of data were the NFL Combine
database, internet, and NFLISS.
Orthopaedic injuries in NFL players occurred more often
during games than practices and led to decreased perfor-
mance.
4,35
Injuries to the trunk were rare, with only 1 chon-
dral rib fracture reported per year.
87
Spine injuries
accounted for 7%of all injuries in NFL players.
82
Preexisting
cervical spine conditions resulted in fewer games played but
were not associated with diminished performance.
122
Cervi-
cal pathology failing nonoperative management was often
treated with ACDF or foraminotomy, depending on the
pathoanatomy and symptom complex. About 70%of players
returned to play after ACDF; however, later adjacent seg-
ment degeneration occurred in 10%of players.
93
The RTP
rate after foraminotomy (92%) was higher than that after
ACDF, although 50%of players required another opera-
tion.
80
Players with a history of lumbar spine conditions
were less likely to be drafted, but when they were drafted,
their career longevity and performance were not affected.
123
Shoulder injuries were fairly common in football players,
with about 50%of recruits at the NFL Combine reporting a
history of shoulder injury. Shoulder injuries occurred most
often during passing plays and as a result of direct
trauma.
58
AC separation and anterior instability were the
most common types of shoulder injuries, and the rate of
RTP was as high as 90%after shoulder surgery (rotator cuff
repair and surgery for clavicle fractures and shoulder insta-
bility).
38,55,61,145
Most hand injuries were fractures and dis-
locations; elbow and wrist injuries were primarily
ligamentous; and forearm injuries were fractures.
21,83
Hip injuries accounted for only 3%of all injuries in NFL
players and were mainly muscle strains.
36
Most NFL
players returned to play within 1 to 2 weeks of treatment
for thigh injuries, but only 50%returned following complete
proximal hamstring avulsion and quadriceps inju-
ries.
7,32,75,86
About 50%of players at the NFL Combine
reported a history of knee injury, primarily MCL, meniscal,
and ACL injuries.
8
Team physicians preferred patellar ten-
don autograft for ACL reconstruction.
9,33,88
About 60%of
players returned to play after ACL reconstruction, and per-
formance seemed to diminish after surgery.
60,128
About
40%to 60%of players at the NFL Combine had full-
thickness cartilage lesions on MRI, and 46%of NFL players
with articular cartilage injuries required surgery and took
longer to RTP than those treated nonoperatively.
16,96
About 70%of players at the NFL Combine had a history
of ankle injuries, with lateral and syndesmotic sprains,
metatarsophalangeal dislocations, and fibular fractures
being the most common.
59
Sixty eight percent of players
returned to play following Achilles tendon rupture.
105
Type
1 (undisplaced) and type 2 (2 mm or less of widening vs the
opposite side on weightbearing bilateral radiographs) Lis-
franc injuries were treated nonoperatively, with RTP
within 1 week for grade 1 and at 5 weeks for grade 2, while
grade 3 (3 mm of widening) required surgery (open reduc-
tion internal fixation without fusion, with optional removal
of hardware at approximately 4-6 months) but allowed for
eventual RTP.
104
Care must also be taken to recognize
proximal Lisfranc variants with any degree of widening
between the medial and middle cuneiform, and these were
commonly treated with internal fixation.
One strength of this study is that it is the first systematic
review, to our knowledge, that has examined the range of
orthopaedic injuries in NFL players. This systematic review
provides National Collegiate Athletic Association (NCAA)
and NFL team physicians with the most up-to-date infor-
mation regarding the frequency and outcomes of orthopae-
dic injuries in professional football players. There are
several limitations of this systematic review. Very few stud-
ies have been published for certain types of orthopaedic
injuries in NFL players, such as trunk injuries. This may
be due to the rarity of these types of injuries. The majority of
studies provided lower-quality evidence (level 3 or 4); how-
ever, this seems appropriate, as all of the included studies
examined descriptive data pertaining to injuries in NFL
players. Multiple studies in this review collected their data
by performing an internet-based search of publicly available
data (eg, injury reports, player profiles, press releases).
Data collected in this fashion were not standardized and
8Kluczynski et al The Orthopaedic Journal of Sports Medicine
may produce unreliable estimates. Also, publically available
data are very limited and do not provide access to detailed
medical records and demographics of the players. We found
that 17%of studies collected data from a single team only;
therefore, the results of these studies may not be generaliz-
able to all NFL players. We also found that 10%of studies
conducted a survey of team physicians and/or athletic trai-
ners. Survey data are subject to recall bias (ie, information
is misremembered) and nonresponse (ie, all questions are
not completed or all respondents do not complete the
survey).
In conclusion, this systematic review provides the NCAA
and NFL team physicians with a single source of the most
current literature regarding orthopedic injuries in NFL
players.
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