■ sports medicine update
Section Editor: Darren L. Johnson, MD
Outcomes of Cervical and Lumbar Disk
Herniations in Major League Baseball Pitchers
David W. Roberts, MD; Gilbert J. Roc, MD; Wellington K. Hsu, MD
Abstract: The effects of disk herniations on the career and performance outcomes of Major League Baseball (MLB) pitchers are unknown. The purpose of this study is to determine the
outcomes after a cervical or lumbar disk herniation for MLB
pitchers. Forty MLB pitchers from 1984 to 2009 with a cervical
disk herniation or lumbar disk herniation were identified using
a previously established protocol. Cervical disk herniation was
identified in 11 pitchers, 8 of which were treated operatively.
The majority of pitchers with cervical disk herniation (8/11)
returned to play at an average of 11.6 months. Lumbar disk herniation was identified in 29 pitchers, 20 of which were treated
operatively. All pitchers with lumbar disk herniation (29/29)
returned to play at an average of 7.3 months after diagnosis.
C
ompared to other Major
League Baseball (MLB)
players, pitchers are disproportionately represented on
the disabled list, accounting
for 57% of disabled list days.1
A significant number of these
injuries involve the spine,1
and prevalent among these are
lumbar and cervical disk her-
niations. A study of college
athletes found baseball players
to be at the highest risk of lumbar disk degeneration compared
to other groups of athletes, at a
rate ⬎3 times that of nonathlete
controls.2 Baseball players are
known to develop lumbar disk
herniations, comprising 13% to
35% of reported cases in studies
Drs Roberts and Hsu are from the Department of Orthopedic Surgery,
Northwestern University Feinberg School of Medicine, Chicago, Illinois; and
Dr Roc is from University of Toledo Medical School, Toledo, Ohio.
Drs Roberts, Roc, and Hsu have no relevant financial relationships to
disclose.
Correspondence should be addressed to: David W. Roberts, MD, 676 N
St Clair, Ste 1350, Chicago, IL 60611 ([email protected]).
doi: 10.3928/01477447-20110627-23
602
of elite athletes.3,4 However, the
effects of lumbar disk herniation treatment on performance
after treatment are unknown.
Although cervical disk herniations have also been diagnosed
in professional athletes,5 no data
exist that can guide expectations after treatment, especially
for pitchers.
The outcomes for pitchers with disk herniations in the
cervical or lumbar spine merit
specific consideration, as the
pitching motion is one of the
most demanding high-speed
torsional activities in sports.
Studies with dynamic electromyography have shown that
professional pitchers generate
high torsional forces across
the trunk and spine6 that are
known to produce annular tears
and disk herniations.4 Returning to the normal function of
pitching after a disk herniation
therefore represents a distinct
challenge relative even to other
elite level athletic endeavors.
Despite published reports suggesting a favorable prognosis of
disk herniations in among elite
athletes,7-9 there remains a common public misconception that
these injuries may signal the
end of a player’s career, especially if treated with surgery.
Because existing studies of
disk herniations in elite athletes
have only reported outcomes
collectively,2-4,10-17 further study
is required to aid the decisionmaking process for unique positions such as that of the elitelevel pitcher. The purpose of
this study is to investigate the
outcomes after treatment of cervical and lumbar disk herniation
in professional MLB pitchers.
MATERIALS AND METHODS
Inclusion and Exclusion Criteria
Using a previously established protocol,7-9,18-20 a clinical database of MLB players
with the diagnosis of cervical
or lumbar disk herniation was
compiled through newspaper
archives, team injury reports,
player profiles, and press releases. All data sources were
obtained from the public record.
Inclusion criteria were athletes
with primary position as a
pitcher, reported “disk herniation” or “herniated disk” in the
cervical or lumbar spine, active
status on an MLB team at the
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Cover Story
Cover illustration © Scott Holladay
AUGUST 2011 | Volume 34 • Number 8
603
■ sports medicine update
Table 1
Table 2
Patient Demographics
Diagnosis and Treatment
Diagnosis
Mean⫾SD
Cervical Disk
Herniation
Lumbar Disk
Herniation
11
29
Age at diagnosis, y
30.7⫾3.7
31.4⫾4.9
.69
MLB experience, y
5.2⫾3.1
7.5⫾5.2
.18
BMI
25.9⫾1.2
25.5⫾2.5
.66
No.
P Value
Abbreviations: BMI, body mass index; MLB, Major League
Baseball; SD, standard deviation.
time of injury, and a treatment
plan confirmed from at least 2
different sources. Surgical treatment of cervical disk herniation
was defined as either a 1-level
anterior cervical diskectomy
and fusion or cervical disk replacement. For lumbar disk
herniation, only players who
underwent a lumbar diskectomy with or without laminotomy
were included for data analysis.
Players with indeterminate or
conflicting medical information, diagnoses of cervical or
lumbar “strain” or “degenerated
disk,” and who are not pitchers
were excluded.
Outcome Measures
For each player, demographic information such as age,
MLB debut date, height, weight,
and position was recorded from
public MLB data sources. Body
mass index (BMI) was calculated as weight (kg) divided by the
square of height (m). The date
of injury, type of treatment, and
date of surgery (if applicable)
were recorded and confirmed
from at least 2 independent
published sources. Data for the
last game played and date of re-
604
turn-to-play (if applicable) were
recorded from aforementioned
sources.
Successful
return-to-play
was defined as being on the active roster of an MLB team for
at least 1 season after treatment.
Time to return-to-play was calculated as the length of time
between the last game played
before injury and the first game
played after treatment at the
MLB level (minor league games
were excluded). Major League
Baseball experience at time of
injury was calculated as the
time between the MLB debut
date and date of injury, and the
number of games played prior
to injury. The number of games
played after injury was recorded,
up to the end of the 2009 season
for current players.
Performance-based
outcomes were compiled from
game statistics from public MLB
data sources for earned run average, innings pitched, and walks
plus hits per innings pitched for
all seasons before injury, and
all seasons after return-to-play.
Earned run average is defined
as the average number of earned
runs allowed by a pitcher per 9
Treatment
No.
ACDF
7
CDR
1
Cervical disk herniation
(n⫽11)
Lumbar disk herniation
(n⫽29)
%
73
None
3
27
Microdiskectomy
20
69
None
9
31
Abbreviations: ACDF, anterior cervical diskectomy and fusion;
CDR, cervical disk replacement.
innings pitched; a lower number
indicates better performance.
Walks plus hits per innings
pitched is defined as the average
number of allowed walks plus
hits per innings pitched; a lower
number indicates better performance. These pitching statistics
have been previously reported
in the literature to assess performance after orthopedic procedures in MLB pitchers.21 If data
for a complete season were unavailable prior to injury (eg, if a
player was injured in his rookie
year), the player was excluded
from pre- and post-injury performance comparison. Comparisons were made between
per-season averages for all complete seasons for each pitcher’s
career pre- and post-treatment.
Data from incomplete seasons
(eg, if a player was injured midseason or returned to play midseason) were excluded to avoid
measurement bias in calculating
per-season averages.
Categorical data was analyzed with Fisher’s exact test.
Continuous variables for each
cohort were analyzed with a
2-tailed Student t test for normally distributed data. Statisti-
cal significance was accepted as
P⬍.05. A multivariate linear regression analysis was performed
to control for independent variables such as age at diagnosis,
BMI, and MLB experience.
RESULTS
Forty MLB pitchers diagnosed with cervical disk herniation and lumbar disk herniation
from 1984 to 2009 met the inclusion criteria. Eleven pitchers
were identified with cervical
disk herniation, and 29 pitchers
with lumbar disk herniation. Demographic data including age,
BMI, and MLB experience was
similar for pitchers with cervical
disk herniation and lumbar disk
herniation (P⬎.05) (Table 1).
A similar percentage of pitchers with cervical disk herniation
(73%) and lumbar disk herniation (69%) were treated surgically (P⫽1.00). In the cervical
disk herniation cohort, 7 pitchers underwent anterior cervical
diskectomy and fusion and 1
pitcher underwent cervical disk
replacement. Those with lumbar
disk herniation all underwent
microdiskectomy and/or laminotomy (Table 2).
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■ sports medicine update
Return-to-Play and Career
Length
The majority of pitchers
with cervical disk herniation
successfully returned to play
(8/11; 73%) at an average time
of 11.6 months after diagnosis. Pitchers with cervical disk
herniation treated with surgery
returned to play at a higher rate
(7/8; 88%) than those treated
without surgery (1/3; 33%), but
the difference was not statistically significant with the numbers available (P⫽.15) (Table
3). Average career length prior
to treatment for cervical disk
herniation was 160 games over
5.1 years, and average career
length after treatment was 63
games over 3.7 years (Figure 1).
Subgroup analysis by treatment
type showed no significant differences in age or post-treatment career length (Table 4).
All pitchers with lumbar
disk herniation successfully
returned to play after treatment
(29/29; 100%). The average
time to return-to-play for pitchers with lumbar disk herniation was 7.3 months. Subgroup
comparison based on type of
treatment showed no difference
in time to return-to-play rates
(Table 3). For pitchers with
lumbar disk herniation, career
length prior to treatment was
282 games over a 7.5-year period, and average career length
after treatment was 121 games
over 5.1 years (Figure 2). Subgroup analysis for pitchers with
lumbar disk herniation showed
that those who underwent surgery were older and more experienced compared to those who
had nonoperative treatment
(P⬍.03) (Table 4). However,
there was no significant differ-
Table 3
Return-to-Play Rates
Diagnosis
Treatment
No.
Cervical disk herniation
No.
Returned
%
Time to
Return, mo
All
11
8
73
11.6⫾9.9
Surgery
8
7
88
13.1⫾9.6
Nonoperative
3
1
33
P⫽.15a
Lumbar disk herniation
All
29
29
100
7.3⫾4.2
Surgery
20
20
100
8.0⫾3.6
Nonoperative
9
9
100
5.7⫾5.2
P⫽1.00
a
1.0
N/A
a
P⫽.17b
Fisher’s exact test.
Unpaired 2-tailed Student t test.
b
ence in post-treatment career
length for pitchers with lumbar
disk herniation treated with or
without surgery (Table 4).
Performance-based Outcomes
Pitchers with cervical disk
herniation had significantly
fewer average innings pitched
per season after treatment
(41.7⫾43.1) compared to before
treatment (68.5⫾44.7) (P⫽.04).
With the limited numbers available, there were no significant
differences in per season averages for earned run average before and after treatment or walks
plus hits per innings pitched
(Tables 5, 6; Figure 3). For those
treated operatively, no significant differences were noted in
performance-based outcomes
pre- and postoperately. Statistical comparisons were not possible for the nonoperative group
due to limited numbers available
(Table 6).
Pitchers with lumbar disk
herniation demonstrated significantly fewer innings pitched
per season after treatment
AUGUST 2011 | Volume 34 • Number 8
1
Figure 1: Career length after treatment for cervical disk herniation.
(92.5⫾61.1) compared to before treatment (116.3⫾66.9)
(P⫽.03). However, there was
no significant difference in
per-season earned run average
after treatment (5.34⫾4.38)
compared to before treatment
(3.85⫾0.85) (P⫽.08), or walks
plus hits per innings pitched
before and after treatment
(1.35⫾0.18 vs 1.47⫾0.37)
(P⫽.11) (Table 7; Figure 4).
Pitchers with lumbar disk
herniation treated surgically
demonstrated significantly fewer innings pitched per season
(89.3⫾54.6 vs 121.4⫾66.2;
P⫽.02) and significantly increased walks plus hits per innings pitched (1.52⫾0.38 vs
1.31⫾0.15; P⫽.02) after treatment compared to before treatment. There was no significant
difference in earned run average after treatment (5.83⫾5.05)
compared to before treatment
(3.84⫾0.69) (P⫽.10). However, for pitchers treated nonoperatively, there were no significant differences in per-season
earned run average, innings
pitched, or walks plus hits per
605
■ sports medicine update
Table 4
Career Length
Pre-Treatmenta
Diagnosis
Cervical disk
herniation
Treatment
Age, y
No. Games
No. Months
No. Games
No. Months
All
30.7
160⫾105
62⫾38
63⫾107
44⫾48
Surgery
30.6
168⫾114
67⫾44
50⫾84
28⫾35
Nonoperative
31.0
139⫾92
50⫾18
100⫾173
72⫾69
.89
.71
.56
.52
.18
All
31.4
282⫾227
90⫾62
121⫾110
61⫾46
Surgery
32.9
343⫾238
109⫾62
131⫾109
56⫾36
Nonoperative
28.1
148⫾127
48⫾42
99⫾116
73⫾65
.01
.03
.01
.48
.38
P valueb
Lumbar disk
herniation
Post-Treatmenta
P valueb
a
Mean⫾standard deviation.
Unpaired 2-tailed Student t test.
b
innings pitched before and after treatment with the numbers
available (Table 8) (P⬎.05).
DISCUSSION
2
Figure 2: Career length after treatment for lumbar disk herniation.
Table 5
Performance-based Outcomes
for Cervical Disk Herniation
Mean⫾SD
Pre-treatment
(n⫽11)
Post-treatment
(n⫽8)
P Valuea
ERA
4.06⫾1.23
8.32⫾6.74
.15
IP
68.5⫾44.7
41.7⫾43.1
.04
WHIP
1.46⫾0.12
1.98⫾0.87
.17
Abbreviations: ERA, earned run average; IP, innings pitched; SD,
standard deviation; WHIP, walks plus hits per innings pitched.
a
Paired 2-tailed Student t test.
606
The clinical outcomes after
treatment for disk herniation of
the cervical and lumbar spine in
the general population are favorable.22-30 However, elite athletes
have different concerns from the
lay public regarding post-treatment outcomes. Success rates
derived from traditional clinical
questionnaires such as the visual
analog scale, Oswestry Disability Index, and Neck Disability
Index may not apply to professional athletes, who are primarily concerned with return-to-play
and maintenance of high-level
athletic performance.
Furthermore, given the repetitive high stress torsional demands of pitching,6 successful
return to baseline function for
elite pitchers would seem more
difficult than the general population. It is not surprising that
there is a perception among me-
dia reporters, MLB players, and
team managers that the longevity and performance of a pitcher
who has undergone surgery of
the spine may be compromised.
Misconceptions about these injuries may put players and treating physicians in a challenging
situation when faced with decisions regarding treatment.
Data from this study suggest that successful treatment
of cervical disk herniation and
lumbar disk herniation in MLB
pitchers leads to higher returnto-play rates, longer careers,
and better performance-based
outcomes than we expected.
The majority of pitchers
with cervical disk herniation
(73%) returned to play at an
average of 11.6 months after
diagnosis and subsequently
had substantial careers, pitching in 63 games over 3.7 years.
Performance statistics for those
returning to play were similar to
baseline, regardless of the type
of treatment, except that those
returning pitched fewer innings
per season, which suggests that
cervical disk herniation in MLB
pitchers has a favorable prognosis, even if treated surgically. To
our knowledge, this is the first
report of a professional athlete
who underwent a cervical total
disk arthroplasty and successfully returned to play. These
data are favorable compared to
a similar study of cervical disk
herniation in National Football
League (NFL) athletes, in which
60% of those with cervical disk
herniation returned to play for
an average of 2.2 years,31 and
to reported return-to-work rates
for anterior cervical diskectomy
and fusion and cervical disk
replacement in a worker’s com-
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■ sports medicine update
Table 6
Performance-based Outcomes
for Cervical Disk Herniation by Treatment
Mean⫾SD
Treatment
Pre-treatment
Post-treatment
8
7
P Valuea
Surgery
No.
ERA
4.21⫾0.87
8.95⫾7.02
.14
IP
64.3⫾30.7
32.9⫾38.1
.09
WHIP
1.43⫾0.12
2.07⫾0.91
.14
Nonoperative
No.
3
1
ERA
3.66⫾2.13
3.92
N/A
IP
79.6⫾80.3
102.6
N/A
WHIP
1.54⫾0.09
1.38
N/A
Abbreviations: ERA, earned run average; IP, innings pitched; SD,
standard deviation; WHIP, walks plus hits per innings pitched.
a
Paired 2-tailed Student t test.
3
Figure 3: Performance-based outcomes for cervical disk herniation. Abbreviations: ERA, earned run average; IP, innings pitched; SD, standard deviation; tx,
treatment; WHIP, walks plus hits per innings pitched.
Table 7
Performance-Based Outcomes
for Lumbar Disk Herniation
Mean⫾SD
Pre-treatment
(n⫽29)
Post-treatment
(n⫽29)
P Valuea
ERA
3.85⫾0.85
5.34⫾4.38
.08
IP
116.3⫾66.9
92.5⫾61.1
.03
WHIP
1.35⫾0.18
1.47⫾0.37
.11
Abbreviations: ERA, earned run average; IP, innings pitched; SD,
standard deviation; WHIP, walks plus hits per innings pitched.
a
Paired 2-tailed Student t test.
pensation population (53% and
63%, respectively).32
All pitchers with lumbar
disk herniation (100%) returned to play at an average of
7.3 months after diagnosis, for
an average of 121 games over
5.1 years. For the entire lumbar
disk herniation cohort, regardless of treatment, those players returning to play pitched
fewer innings per season, but
also had similar statistical
performance before and after
treatment. However, for the operative group, performance as
AUGUST 2011 | Volume 34 • Number 8
4
Figure 4: Performance-based outcomes for lumbar disk herniation. Abbreviations: ERA, earned run average; IP, innings pitched; SD, standard deviation; tx,
treatment; WHIP, walks plus hits per innings pitched.
607
■ sports medicine update
Table 8
Performance-based Outcomes
for Lumbar Disk Herniation by Treatment
Mean⫾SD
Treatment
Pre-treatment
Post-treatment
20
20
P Valuea
Surgery
No.
ERA
3.84⫾0.69
5.83⫾5.05
.10
IP
121.4⫾66.2
89.3⫾54.6
.02
WHIP
1.31⫾0.15
1.52⫾0.38
.02
Nonoperative
No.
9
9
ERA
3.86⫾1.18
4.25⫾2.17
.54
IP
104.7⫾71.1
99.4⫾76.9
.75
WHIP
1.45⫾0.20
1.37⫾0.36
.60
Abbreviations: ERA, earned run average; IP, innings pitched; SD,
standard deviation; WHIP, walks plus hits per innings pitched.
a
Paired 2-tailed Student t test.
measured by walks plus hits per
innings pitched significantly
worsened after return-to-play,
although earned run average
was not different than baseline.
The reasons for this finding
are unclear. Because potential
confounders such as age and
MLB experience can affect
performance, the difference in
age between groups was likely
a contributing factor. Furthermore, disease severity or associated neurologic deficits, both of
which were not controlled for in
this study, could have affected
the results. Finally, because of
the inherent limitations of the
methodology of this study, with
the numbers available, this finding could have been a result of
mere chance. These data are
favorable compared to a similar
study of lumbar disk herniation
in NFL linemen, in which 70%
of those with lumbar disk herniation returned to play for an
608
average of 2.2 years,8 and to reported return-to-work rates for
laborers (53%)33 and data from
the Spine Patient Outcomes Research Trial (76%).25
Further study is required to
assess the impact of repetitive
torque-producing actions on the
long-term health of the lumbar
spine. While some authors have
stated that sports with repetitive
throwing motions leads to increased incidence of degenerative disk disease,2,34-36 this has
not been proven in a controlled
trial. It remains a possibility
that the morbidity of surgical
treatment may somehow impair
the ability of the lumbar spine
to handle the repetitive torsional
demands of pitching,6 but a prospective trial would be required
to support this claim.
The literature reporting the
clinical outcomes of spinal disorders in elite athletes is limited, and even more so when
considering outcomes specific
to a particular position such as
pitching. Return-to-play has
been shown to be ⬎90% after
single-level microdiskectomy
in 14 elite college athletes, but
the cohort did not include baseball players.15 Mochida et al3
studied 30 elite athletes undergoing percutaneous nucleotomy for lumbar disk herniation
and showed worse outcomes in
athletes compared to nonathlete
controls, with a success rate of
only 57% at 2-year follow-up.
However, the study included
only 4 baseball players, and the
positions of the players were
not indicated. Watkins et al16 reported 60 Olympic and professional athletes who underwent
lumbar microdiskectomy, with
88% returning to their chosen sport in an average of 5.2
months postoperatively. In this
cohort, 19 of the 21 athletes who
were baseball players returned
to sport (90.5%) at a mean time
of 5.3 months, although the
positions of the players were
not indicated. Currently only 1
study in the literature addresses
cervical disk herniation in elite
athletes,37 as most of the existing literature on cervical spine
injuries in athletes focuses on
catastrophic injuries such as
spinal cord injury.38-42 Of note,
in our study, none of the pitchers with cervical disk herniation
suffered a spinal cord injury after returning to play, regardless
of the method of treatment.
There are recognizable
limitations to this study. First,
diagnosis information and
type of treatment were obtained from the public record,
which creates a possibility of
reporting errors, inaccurate
classification of diagnosis, and
selection bias. Because clinical or radiographic data was
not available, it is impossible
to determine the individual
characteristics of each cervical disk herniation or lumbar
disk herniation that may affect outcome. Finally, confounding variables, such as a
typical performance decline
over the course of a player’s
career, concomitant unrelated
injuries, or external factors
such as management decisions
affecting assignments, may
also have affected data in this
study.
Despite these limitations, at
the present time, more detailed
data for these types of injuries in
this specific population are not
available in the literature, and,
furthermore, current professional league injury reports do
not account for these outcome
measures. Thus, this study design represents the best available method to address these
important questions. We believe
that accurate reporting of injuries and clinical outcomes in
professional league injury databases would improve the ability
of treating physicians to more
accurately counsel specialized
players with these types of injuries.
CONCLUSION
The data in this study suggest that treatment for cervical
disk herniation or lumbar disk
herniation in MLB pitchers can
lead to high rates of return-toplay and stable elite-level performance after treatment. Both
cervical disk herniation and
lumbar disk herniation can be
treated surgically, with favor-
ORTHOPEDICS | ORTHOSuperSite.com
■ sports medicine update
able prognosis for return-toplay, career longevity, and performance-based outcomes.
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