Increasing rates of anterior cruciate ligament
reconstruction in young Australians, 2000e2015
, Christopher Vertullo
, Jane E Grayson
The known Rupture of the anterior cruciate ligament (ACL) is
a common and devastating injury that is largely preventable by
neuromuscular agility training.
The new The incidence of ACL reconstructions in Australia is
the highest in the world, and is increasing. At greatest risk are
men aged 20e24 years and women aged 15e19 years, but
incidence is increasing most rapidly among 5e14-year-old
children. The incidence of revision ACL is increasing more
rapidly than that of primary ACL reconstructions.
The implications These ﬁndings justify establishing a national
ACL injury prevention program and an ACL reconstruction
registry to improve outcomes for active young Australians.
Rupture of the anterior cruciate ligament (ACL) is a com-
mon and debilitating injury that typically results from a
non-contact event in which a previously healthy indi-
vidual changes direction at speed while playing a multi-
directional sport. ACL ruptures were once thought to be
uncommon in the skeletally immature,
but recent evidence
suggests that the global burden of ACL injury falls increasingly
on adolescents and young adults.
The short term consequences
of ACL rupture include the inability to participate in sport,
reconstructive surgery, and prolonged rehabilitation.
In the long
term, regardless of whether or not an ACL reconstruction is
performed, almost all individuals who tear an ACL are at
increased risk of osteoarthritis and disability,
and this risk is
substantially increased by concurrent meniscal injury.
Descriptive analyses of population-based data indicate that the
incidence of ACL reconstruction in Australia is among the highest
in the world.
Recent analyses of data in Victorian injury data-
bases have found increasing rates of sport-related hospitalisations
and lower limb injuries in older children and young adults,
is uncertain whether this trend applies to the entire country, is
conﬁned to younger people, or is sex-speciﬁc.
Several studies have found that neuromuscular agility and pro-
prioceptive training programs are effective as preventive measures,
averting 50e80% of ACL injuries.
Sports injuries, particularly
ACL injuries, are emerging as an internationally recognised public
health problem, making it vital that the demographic features
associated with an increased risk of ACL injury are characterised.
The aim of our study was to investigate the incidence and
demographic features of ACL reconstructions in Australia, by
age and sex, and to determine whether the incidence of ACL
reconstructions has changed during the past 15 years.
Longitudinal data for ACL reconstructions were extracted from the
National Hospital Morbidity Database (NHMD) of the Australian
Institute of Health and Welfare (AIHW) (http://www.aihw.gov.
au/hospitals-data/procedures-data-cubes). The NHMD com-
prises conﬁdential electronic record summaries for episodes of care
provided by state and territory health authorities, including data
from public and private hospitals, as well as from private surgical
centres. The database affords national coverage of information on
inpatient hospital treatments, with a negligible proportion of
missing data (0.004% of cases per year).
The database collects
information on the type of procedure (according to the Interna-
tional Statistical Classiﬁcation of Diseases and Related Health
Problems, 10th revision, Australian modiﬁcation [ICD-10-AM]
and the third to eighth editions of the Australian Classiﬁcation of
Health Interventions [ACHI]
), year of procedure, sex and age
group of patient, and whether the procedure required day or
Patients who underwent a primary knee reconstruction during the
period 1 July 2000 e30 June 2015 were identiﬁed by ICD-10-AM
block number 1522 (with ICD-10-AM procedure codes 49539-00,
49539-01, 49542-00, 49542-01). AIHW procedure numbers included
both isolated cruciate reconstruction and cruciate reconstruction
with concurrent meniscal injury. Revision knee reconstructions
Objectives: To investigate the incidence and demographic
features of anterior cruciate ligament (ACL) reconstructions in
Australia by age and sex, and to determine whether the
incidence has changed during the past 15 years.
Design and setting: Descriptive epidemiological analysis of
longitudinal data on ACL reconstructions (July 2000 eJune
2015) in the National Hospital Morbidity Database.
Main outcome measures: Population ACL reconstruction rates,
by age group and sex.
Results: 197 557 primary ACL reconstructions were performed
during the study period; the annual incidence increased by
43% (from 54.0 to 77.4 per 100 000 population), and by
74% among those under 25 years of age (from 52.6 to 91.4 per
100 000 population). In males, the peak incidence in 2014e15
was for 20e24-year-olds (283 per 100 000 population); for
females, it was for 15e19-year-olds (164 per 100 000 population).
Annual growth in incidence was greatest in the 5e14-year-old age
group (boys, 7.7%; girls, 8.8%). Direct hospital costs of ACL
reconstruction surgery in 2014e15 were estimated to be
$142 million. The annual incidence of revision ACL reconstructions
increased from 2.49 (2000e01) to 5.65 per 100 000 population
(2014e15), or by 5.6% per year; revisions as a proportion of
all ACL reconstruction increased from 4.4% to 6.8%.
Conclusions: The increasing incidence of ACL reconstructions in
young Australians over 15 years is worrying. The individuals at
greatest risk are men aged 20e24 years and women aged
15e19 years; the rate of reconstruction is increasing most rapidly
among those aged 5e14 years. Revision rates are increasing
more rapidly than those of primary reconstructions.
Knee Research Australia, Gold Coast, QLD.
Grifﬁth University, Gold Coast, QLD.
Gold Coast Orthopaedic Research and Education Alliance, Grifﬁth University, Gold Coast, QLD.
University of Sydney, Sydney, NSW. d.zbrojkiewicz@grifﬁth.edu.au jdoi: 10.5694/mja17.00974 jSee Editorial, p. 341 jPublished online 23/04/2018
Podcast with Christopher Vertullo available at https://www.mja.com.au/podcasts
MJA 208 (8) j7 May 2018
were identiﬁed by ICD-10-AM block number 1524 with the ICD
procedure code 49551-00.
ACL incidence rates were expressed as number per 100 000 pop-
ulation for each year of the study, based on Australian Bureau of
Statistics population ﬁgures.
Trends in population-adjusted numbers of procedures were ana-
lysed in SPSS Statistics 23 (IBM). P< 0.05 was deemed statistically
The base data for this investigation were de-identiﬁed data
publicly available from the AIHW. Our investigation was
therefore granted exemption from formal ethics review by the
Grifﬁth University Human Research Ethics Committee.
During 2000e2015, 197 557 primary ACL reconstructions were
performed in Australia: 134 695 (68.2%) in males and 62 862
(31.8%) in females. The annual number of primary ACL re-
constructions increased from 9662 in 2000e01 to 16 990 in 2014e15;
the overall incidence of ACL reconstructions increased by
43% during this period, from 54.0 to 77.4 per 100 000 population.
The rate in males increased from 73.3 to 101.6 per 100 000, in fe-
males from 35.0 to 53.4 per 100 000 population (average annual
growth rates of 2.2% and 2.9% respectively) (Box 1).
Throughout the study period, the rates were higher for males than
for females in all 5-year age groups. In males, the peak incidence in
2014e15 was for the 20e24-year-old group (283 per 100 000 pop-
ulation), but rates were also high for 15e19-year-olds (241 per
100 000) and 25e29-year-olds (232 per 100 000). In females, the
peak incidence was for the 15e19-year-old group (164 per 100 000
population) (Box 2,Box 3).
Annual growth in the incidence of ACL reconstruction was highest
for the 5e14-year-old age group (7.7% for males, 8.8% for females);
the rates for 15e19-year-olds were 4.4% (males) and 5.0% per year
(females). The growth rates were also large for older age groups:
5.3% (males) and 4.2% annually (females) for people aged 45e49
years, and 6.0% (males) and 4.8% per year (females) for those aged
50e54 years (Box 4).
During the 15-year period analysed, the annual incidence of ACL
reconstruction in people under 25 years of age grew by a total of
73.8% (3.8% per year); the incidence for those aged 25 or more
increased by 28.4% (1.7% per year) (Box 5). The incidence in females
under 25 grew by a total of 90.6% (4.4% per year), in males under 25
by 69.3% (3.7% per year) (Box 6). Incidence rates for 2015e16 to
2024e25 were forecast by assuming that trends over the past 15
years will be maintained. On this basis, overall growth in incidence
for the period 2000e01 to 2024e25 will be greatest for females
under 25 (239%, or 8.5% per year); the projected total growth for
males under 25 is 119% (5.4% per year), and for all people over 25 it
is 48.7% (2.7% per year) (Box 6).
Estimated costs of anterior cruciate ligament surgery
According to the 2017 variance report of the Royal Australasian
College of Surgeons and Medibank, the average direct hospital and
surgery cost per ACL reconstruction was $8364.
direct costs of primary ACL reconstruction surgery in 2014e15
were $142 million. This ﬁgure does not include the rehabilitation,
disease burden, and societal costs associated with the injury.
1 Incidence of primary anterior cruciate ligament
reconstruction in Australia, 2000e2015, by sex
2 Incidence of primary anterior cruciate ligament
reconstruction in males, 2000e2015, by age group
3 Incidence of primary anterior cruciate ligament
reconstruction in females, 2000e2015, by age group
MJA 208 (8) j7 May 2018
Revision anterior cruciate ligament surgery
A total of 12 878 revision ACL reconstructions were reported
during 2000e01 to 2014e15; 9588 (74.5%) were for males and 3290
(25.5%) for females. The annual number increased from 477 in
2000e01 and to 1328 in 2014e15; the annual incidence increased by
127%, from 2.49 to 5.65 per 100 000 population, or by 5.6% per year.
The incidence in males increased from 3.62 to 8.35 per 100 000
population (5.7% per year), in females from 1.37 to 2.98 per 100 000
population (5.3% per year) (Box 7). Revision ACL reconstructions
as a proportion of all reconstructions increased from 4.4% in
2000e01 to 6.8% in 2014e15.
During 2000e2015, the incidence of ACL reconstruction surgery
increased in Australia in all age groups; the overall incidence was
greatest among 15e24-year-olds. Consistent with other recent
the rate of growth in incidence was greatest among
Our calculated primary ACL reconstruction incidence of
77.4 per 100 000 population is the highest population-
adjusted rate in the world; lower rates in comparable
Organisation for Economic Cooperation and Develop-
ment (OECD) nations include those for the United States
(52), New Zealand (37), Denmark (38), Norway (34), and
Sweden (32 per 100 000 population).
We identiﬁed age and sex differences in the incidence of
ACL reconstruction surgery, with the peak incidence in
males being for a slightly older age group and
73% higher than the peak incidence in females. This is
consistent with studies that have reported higher rates
of ACL reconstruction in males,
being two to ten times more likely to rupture their ACL
when participating in high risk sports such as basketball
It is conceivable that the higher incidence
in males reﬂects greater participation in sports such as
Australian rules football, in which pivoting, jumping
and rapid deceleration increase the risk of ACL injury.
That the peak incidence for females is in a younger age
group is consistent with their higher rates of sports
participation during early adolescence, declining when they reach
ACL rupture imposes a considerable health burden on a young and
active population. We identiﬁed an annual incidence growth in its
incidence for Australians under 25 of 3.8%, compared with 1.7% for
those over 25. Moreover, growth in reconstruction incidence was
most rapid for boys (7.7%) and girls (8.8%) aged 5e14 years,
although it should be noted that the base ACL reconstruction
incidence in this age group was low. The increased incidence in
children is nevertheless of particular concern, as ACL injury in this
age group was previously rare. The burden of future degenerative
disease falls most heavily on our youngest patients.
The rising incidence of ACL reconstruction during 2000e2015 can
be attributed to several factors, including increasing medical and
public awareness of the procedure, diagnostic improvements, the
availability of magnetic resonance imaging, and increased access to
About 72% of ACL reconstructions in
Australia are sport-related; the sports most frequently involved are
Australian rules football, rugby union, rugby league, netball,
basketball, soccer, and skiing.
The rise of ACL injury in young
people has been attributed to earlier specialisation by younger
5 Incidence of primary anterior cruciate ligament
reconstruction in Australia, 2000e2015, by
broad age group
4 Annual growth in the incidence of primary anterior
cruciate ligament reconstruction, 2000e2015, by sex and
6 Incidence of primary anterior cruciate ligament reconstruction in
Australia, 2000e2015, by sex and broad age group
MJA 208 (8) j7 May 2018
athletes, longer sporting seasons, more intense training, higher
levels of competition,
and a lack of free play.
The costs of ACL injury can be divided into direct and indirect
costs. We estimated the direct hospital costs for ACL re-
constructions were $142 million in 2014e15, a substantial cost to
the health care system that is growing with the incidence of ACL
injuries. Despite the considerable direct hospital costs, ACL
reconstruction surgery is signiﬁcantly more cost-effective than
rehabilitation alone in both the short and long term, with patients
experiencing greater improvements in quality-adjusted life-years
at a lower cost.
An American group calculated the average life-
time costs to society per ACL rupture to be $US88 938 with reha-
bilitation only and $US38 121 with ACL reconstruction.
people, delaying ACL reconstruction surgery or opting for non-
operative management is associated with signiﬁcantly poorer
outcomes in both the short and long terms.
Nevertheless, prevention is much more cost-effective than either
ACL reconstruction or rehabilitation. Establishing a national ACL
injury prevention program has been reported as a cost-effective
strategy for improving sporting health outcomes for young Aus-
tralians, with low barriers to implementation.
In addition to
reducing health care costs, prevention programs allow athletes to
avoid the consequences of injury, including reduced functional
capacity because of pain, chronic knee instability,
and time away
from work or education.
In the longer term, the future compli-
cations of osteoarthritis
can lead to loss of productivity, fewer
employment opportunities, reduced social interaction, and lower
quality of life.
The link between ACL injury and knee replacement later in life is
The incidence of knee replacements in Australia
is high compared with other OECD nations, and it is expected to
continue to increase.
An estimated annual loss of $9.4 billion in
GDP has been attributed to early retirement caused by arthritis in
The incidence of revision ACL reconstruction surgery increased
across the study period by an average 5.6% per year, and the
proportion of reconstructions that were revision reconstructions
rose from 4.4% to 6.8%. While graft position, tunnel placement,
younger age, and early return to sport are established risk factors
for ACL graft failure,
further investigations are warranted, and
the need to carefully document emerging trends, risk factors and
the effects of interventions would justify the establishment of a
national ACL reconstruction registry.
As we analysed national electronic records summaries for episodes
of care, our investigation had some limitations. Firstly, AIHW
procedural data cubes did not allow differentiation between ACL
and posterior cruciate ligament (PCL) reconstructions. While iso-
lated PCL injuries requiring reconstruction are uncommon (fewer
than 1% of all knee injuries seen in the clinic),
the risk of osteo-
arthritis after PCL reconstruction is similar to that for ACL recon-
struction. Secondly, the AIHW data did now allow analysis of
reconstruction rates by state and territory, limiting our analysis to
the national scale. Additionally, as with any database study, cod-
ing errors are possible. Accurate direct hospital costs per ACL
reconstruction were unavailable for 2014e15, and the estimated
costs for this year were calculated using 2017 costing data. The
validity of comparing ACL reconstruction rates in different coun-
tries is limited by the availability of data on the incidence of ACL
injuries and reconstruction, which are related but distinct phe-
nomena. While the rate of ACL reconstruction may be an indirect
measure of that of ACL injury, many ACL injuries are either not
diagnosed or do not lead to surgical reconstruction.
This Australian population-level data analysis found a worrying
increase in the incidence of ACL reconstructions in young Aus-
tralians during 2000e2015. Most such reconstructions could be
averted by neuromuscular agility training and other preventive
measures. The individuals at greatest risk are men aged 20e24
years and women aged 15e19 years; the rate of reconstruction is
increasing most rapidly among boys and girls aged 5e14 years.
Moreover, rates of revision reconstruction are increasing more
rapidly than the rate of primary ACL reconstructions. The
increasing incidence of ACL injury in Australia is an emerging
public health problem with potentially detrimental long term
health outcomes, especially for young people.
Competing interests: No relevant disclosures.
Received 5 Oct 2017, accepted 12 Dec 2017. n
ª2018 AMPCo Pty Ltd. Produced with Elsevier B.V. All rights reserved.
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