THEMATIC ISSUE
A Framework for Recording Recurrences, Reinjuries, and
Exacerbations in Injury Surveillance
Colin W. Fuller, PhD,* Roald Bahr, MD, PhD,† Randall W. Dick, MSc,‡
and Willem H. Meeuwisse, MD, PhD§
Abstract: A previous injury can increase the risk of sustaining
a similar injury by up to an order of magnitude. To understand the
role of previous injury as a risk factor, it is necessary to consider,
among other issues, the clinical status of the first (index) injury at the
time of the subsequent (recurrent) injury: currently, the inconsistent
use of descriptive terms for recurrent injuries makes this extremely
difficult. Although recent consensus statements on injury definitions
based on return-to-play criteria have provided a consistent methodology for recording and reporting index and recurrent injuries, these
statements do not differentiate between the types of recurrent injuries
that can occur. This paper presents a recording and reporting
framework that subcategorizes recurrent injuries into reinjuries and
exacerbations on the basis of whether a player was fully recovered
from the preceding index injury, with the state of fully recovered
determined by medical opinion. A reinjury is a repeat episode of
a fully recovered index injury and an exacerbation is a worsening in
the state of a nonrecovered index injury. With this more detailed
framework, researchers will be able to investigate risk factors for
reinjuries and exacerbations separately, and they will be able to
investigate how well players have been rehabilitated before returning
to full training and match play.
(Clin J Sport Med 2007;17:197–200)
INTRODUCTION
A previous injury can increase the risk of sustaining
a similar injury by up to an order of magnitude.1–5 To
understand the role of previous injury as a risk factor, it is
necessary to consider a range of intrinsic and extrinsic risk
factors,6–8 including the nature and clinical status of the first
(index) injury at the time of the subsequent (recurrent) injury.
For example, the issue of whether the index injury was an
acute injury with a sudden onset or an overuse injury with
a gradual onset, and the state of rehabilitation of the index
Submitted for publication December 5, 2006; accepted February 5, 2007.
From the *Centre for Sports Medicine, University of Nottingham,
Nottingham, UK (C.W.F.); †Oslo Sports Trauma Research Center,
Norwegian School of Sport Sciences, Oslo, Norway (R.B.); ‡National
Collegiate Athletic Association, Indianapolis, Indiana (R.W.D.); and
§Sports Injury Prevention Research Centre, University of Calgary,
Calgary, Canada (W.H.M.).
Reprints: Dr. Colin W. Fuller, PhD, Centre for Sports Medicine, University of
Nottingham, Nottingham, NG7 2UH, United Kingdom (e-mail: colin.
fuller@nottingham.ac.uk).
Copyright Ó 2007 by Lippincott Williams & Wilkins
Clin J Sport Med Volume 17, Number 3, May 2007
injury at the time the player returned to full training/match
play, may affect the likelihood of a recurrent injury occurring.
At the present time, this level of information is not routinely
collected in injury-surveillance studies; if it is collected, the
information is not recorded consistently from study to study.
Variations in reporting arise through the inconsistent use of
terms, such as acute, traumatic, overuse, chronic, persistent,
recurrent, reinjury, exacerbation, macrotrauma, and microtrauma. In addition, these terms mix descriptions of injury
occurrence, pathology, and/or causation. Recent consensus
statements on injury definitions in football9 and rugby union10
that are based on return-to-play criteria have presented
researchers with a consistent methodology for recording and
reporting index and recurrent injuries. However, although the
statements9,10 provide clear criteria for defining recurrent
injuries, the criteria do not include the rehabilitation status of
the index injury. The aim of this paper is to develop a recording
and reporting framework that subcategorizes recurrent injuries
in terms of the clinical status of the index injury at the time of
the recurrence.
RECURRENT INJURIES
There are many scenarios in which players may sustain
repeat episodes of injury. In injury-surveillance studies, it is
essential to provide clear criteria that define when a player is
injured and when the player has recovered from injury, because
this improves intra- and interstudy consistency. Confirming
when a player has achieved complete recovery from an injury
is, however, a complex decision, based on objective and
subjective indicators such as the achievement of specified
clinical and functional rehabilitation objectives.11 The consensus statements9,10 on injury definitions and data-collection
procedures define injury as any physical complaint (caused by
a transfer of energy that exceeded the body’s ability to
maintain its structural and/or functional integrity) sustained by
a player during a match or training, irrespective of the need for
medical attention or time loss from sports activities. An injury
that results in a player receiving medical attention is referred to
as a medical-attention injury, and an injury that results in
a player being unable to take a full part in future training or
match play is referred to as a time-loss injury. The statements
define recurrent injury as an injury of the same type and at the
same site as an index injury, occurring after a player’s return to
full participation from the index injury. Injury severity is
defined as the number of days that have elapsed from the date
of injury to the date of the player’s return to full participation in
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Fuller et al
team training, and the player’s availability for match selection.
These statements provide pragmatic, nonclinical criteria to
define the closure of an index injury and to identify the point in
time at which further injuries of the same type at the same site
should be recorded as recurrent injuries. By adopting simple,
objective, return-to-play criteria to define the closure of an
injury, the clinical opinion required to determine when an
injury has fully recovered is removed; this is particularly
important for studies where a medical opinion is not
available—a situation that often occurs when working with
youth and amateur teams.
At all levels of sport, players may return to full
participation before an injury has completely recovered. A
common scenario is for players to compete in a match when
they are only able to undertake limited team training in the
days before and after the match. In this case, a second episode
of injury of the same type at the same site during the match
could be viewed as a continuation of the index injury, thus not
constituting a new injury. In injury-surveillance studies,
recurrent injuries sustained in these circumstances are recorded
in the same way as recurrent injuries sustained by players
returning to full participation after full recovery. It could be
argued, however, that even a continuation of an injury should
be recorded as a recurrent injury, because the extended period
Clin J Sport Med Volume 17, Number 3, May 2007
of time loss experienced by the player may not have occurred if
the player had continued rehabilitation of the index injury to
the point of full recovery before returning to full participation.
In terms of understanding the underlying causes of recurrent
injuries, the two scenarios are clearly quite different and,
therefore, in studies of recurrent injury risk factors, the two
cases should be recorded and interpreted differently.
Scenarios in which recurrent injuries may occur are
summarized in the decision framework presented in Figure 1.
In this framework, an injury is described by the definitions
presented in the consensus statements,9,10 and a recordable
injury is an injury that results in time loss from training or
match play. The first subdivision of recordable injuries is made
on the basis of whether the injury is a new (index) or recurrent
injury, depending on whether the player had returned to full
participation as defined in the consensus statements.9,10
Recurrent injuries are further subdivided on the basis of
whether the player was fully recovered from the preceding
index injury on the basis of medical opinion: reinjury is
a repeat episode of a fully recovered index injury, and
exacerbation is a worsening in the state of a nonrecovered
index injury, such that the player misses further training and/or
match play. Although this framework is presented in the
context of time-loss injuries, it is equally appropriate for use
FIGURE 1. Framework for recording time-loss recurrent injuries. N, number of injuries; D, total days lost from training and match
play as a consequence of N injuries; I, index; R, recurrent.
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Clin J Sport Med Volume 17, Number 3, May 2007
with medical-attention injuries,9,10 in which case the question
in the decision framework, ‘‘Did injury cause time loss from
training/match play?’’ should be replaced by, ‘‘Did the injury
require medical attention?’’
The decision framework is consistent with the definitions presented in both injury consensus statements,9,10 so
adoption of this framework still provides fixed points for
interstudy comparisons of index and recurrent injuries. The
appropriate calculations for making these comparisons are
presented in Table 1. The framework also provides a consistent
terminology for subcategorizing recurrent injuries, enabling
researchers to choose, depending on the specific aims of their
research studies and on the availability of medical opinion,
whether to subdivide recurrent injuries into reinjuries and
exacerbations. The greater the level of subdivision adopted in
a study, the greater the level of information available to the
researchers investigating the causes of recurrent injuries.
REPORTING RECURRENT INJURIES
If an exacerbation were treated simply as a worsening in
the state of an index injury that was not fully recovered, it
could be argued that exacerbations should not be recorded as
new injuries. In this case, the time loss associated with the
exacerbation should be added to the original time loss recorded
for the index injury. Two cases, which differentiate between
the ways in which reinjuries and exacerbations would be
recorded using the two criteria, illustrate this point (Table 2):
Case A: A rugby player sustained a hamstring muscle
strain, which required 18 days of rehabilitation before the
player was able to return to full team training and match play.
Ten weeks later, the player strained the same hamstring muscle
and required a further 27 days of rehabilitation before being
able to return to full team training and match play. In this case,
the recurrence should be subcategorized as a reinjury because
the player was deemed fully recovered from the index injury.
As noted in Table 2, both regimens would record two distinct
injuries—the first being an index injury with a time loss of
18 days, and the second being a reinjury with a time loss of
27 days—because the player had completely recovered from
the index injury before being injured again.
Case B: A footballer developed groin pain, which
resulted in 5 days of absence from team training; at this time,
the pain had diminished sufficiently to allow the player to
compete in a match. During the match, the player experienced
a worsening of the pain and was substituted; as a consequence,
the player was unable to train or play for a further 21 days. In
this case, the recurrence should be subcategorized as an
exacerbation because the player had not completely recovered
Recurrent Injuries
from the index injury. As noted in Table 2, using the return-toplay criteria, two injuries would be recorded: an index injury
resulting in 5 days of absence, and an exacerbation resulting in
21 days of absence. However, using the fully recovered criteria,
only one injury (index) would be recorded, resulting in 26 (5 +
21) days of absence, because the player had not completely
recovered from the index injury.
Adopting the fully recovered regimen would result in
studies reporting fewer recurrent injuries, because the number
of recurrent injuries would exclude exacerbations and would
equate solely to the number of reinjuries. In addition, the
severity of index injuries would be higher because the total
days lost for index injuries would increase to the sum of the
original number of days lost (from the index injuries) and
the number of days lost from the exacerbations, although the
number of index injuries would remain unchanged. An
argument against this approach is that it exaggerates the
severity of index injuries and reflects the consequences of the
return-to-play decisions rather than providing a true reflection
of the inherent severities of index injuries. Recording exacerbations as separate injuries and assigning the number of days
lost to these specific injuries quantifies the risk associated with
return-to-play decisions before players are fully recovered. An
advantage of the framework presented here is that it provides
a reference point for researchers to clearly define their injuryreporting methodology, which will improve consistency in
studies of recurrent injuries.
In practical terms, trying to implement a fully recovered
requirement into the definition of injury is difficult, because
medical staff are unlikely to make a decision about the clinical
state of a player’s injury before each exposure to training and
match play. Decisions made after an injury may be unreliable
and subject to affiliation bias, because the decision would
almost certainly be made by the person involved in the player’s
rehabilitation. If medical staff identified that a player was not
fully recovered from an index injury when they were returned
to play, and the player subsequently sustained a recurrence,
this could create an ethical dilemma and a potentially litigious
situation for the medical staff. Without a clear exit point from
an injury, it is not apparent how players would progress from
the state of returned to play but not fully recovered to returned
to play and fully recovered. It is beyond the scope of this paper
to delineate these issues, because there are many factors that
influence the clinical decisions surrounding medical clearance
for an injured player’s return to play. Adopting pragmatic
return-to-play criteria for recovery from injury circumvents
most practical problems and provides a consistent exit point
from injury; if a player is training or competing, he or she must
de facto be recovered, at least functionally.
TABLE 1. Comparison of the Number and Severity of Index Injuries, Recurrences, Reinjuries, and Exacerbations Reported Using
Return-to-play and Fully Recovered Criteria for Closing an Injury (see Figure 1 for Identification of Abbreviations for the Number of
Injuries [N] and Total Days Lost [D])
Index Injuries
Criteria for Closing Injury Number
Return to play
Fully recovered
NI
NI
Severity
Recurrent Injuries
Number
Severity
DI/NI
NR (ie, NRi + NRx) DR/NR (ie, {DRi + DRx}/{NRi + NRx})
(DI + DRx)/NI NR (ie, NRi)
DR/NR (ie, DRi/NRi)
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Reinjuries
Exacerbations
Number Severity Number Severity
NRi
NRi
DRi/NRi
DRi/NRi
NRx
0
DRx/NRx
N/A
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Fuller et al
TABLE 2. Examples, Based on the Two Cases Outlined in the Text, Illustrating the Reporting of the Number and Severity of Index
Injuries, Recurrent Injuries, Reinjuries, and Exacerbations, Using the Return-to-play and Fully Recovered Criteria
Index Injuries
Recording Regimen
Case A
Return to play
Fully recovered
Case B
Return to play
Fully recovered
All
Return to play
Fully recovered
Number
Severity
Recurrent Injuries
Exacerbations
Severity
Number
Severity
Number
Severity
1
1
18
18
1
1
27
27
1
1
27
27
0
N/A
—
N/A
1
1
5
26
1
0
21
—
0
0
—
—
1
N/A
21
N/A
2
2
11.5
22
2
1
24
27
1
1
27
27
1
N/A
21
N/A
CONCLUSION
The proposal presented here can be applied in any sport
where the injury consensus statements for football and rugby
are applicable. It is anticipated that in most injury-surveillance
studies, the basic categories of index and recurrent injuries
would be recorded and reported using return-to-play criteria,
as shown in the first stage of Figure 1 and as described in the
consensus statements for football9 and rugby union.10
However, in studies focusing on issues of recurrent injury
causation and return-to-play decisions, more detailed information would be required. In these studies, it is envisaged that
the subcategories of reinjuries and exacerbations would be
recorded and reported separately, provided appropriate
medical opinion was available, as shown in the second stage
of Figure 1. With this more detailed analysis framework,
researchers would be able to investigate risk factors for
reinjuries and exacerbations separately, and they would be able
to investigate how well players had been rehabilitated before
returning to full training and match play.
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