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· DOS Abstracts
Is the use of oral contraceptives associated with
operatively treated anterior cruciate ligament injury?
A case-control study from the Danish Registry of
Knee Ligament Reconstruction
Lene Rahr-Wagner, Theis Thillemann, Frank Menhert, Alma Pedersen,
Martin Lind
department of ortopaedic surgery, Aalborg University Hospital; department
of clinical epidemiology, Aarhus University Hospital; department of ortopaedic
surgery, sports medicine, Aarhus University Hospital
Background:
The incidence of anterior cruciate ligament (ACL) injuries is 2-9
times higher in women than in men. Additionally, in vitro studies have demon-
strated that ACL is an estrogen target tissue, and some studies have therefore
suggested a protective association between oral contraceptives (OC) and the
likelihood of sustaining ACL injury.
Purpose / Aim of Study:
The aim was to test the hypothesis of a protective
association between OC use and the likelihood of sustaining operatively treated
ACL injury.
Materials and Methods:
The study population included 4,497 female cases
with an operatively treated ACL injury registered in the Danish Registry of Knee
Ligament Reconstruction for the 2005-2011 period and 8,858 age-matched
controls with no ACL injury. The study evaluated exposure to OC use at the time
of ACL injury and in the five previous years (ever user) or no OC use (never
user). Ever users were further classified as either new users, long-term users
or recent users. Finally, a dose-response analysis of OC use was performed. We
used conditional logistic regression to calculate the relative risk (RR) with a 95%
confidence interval (CI) of sustaining operatively treated ACL injury according
to OC use.
Findings / Results:
The adjusted RR associating OC with ACL injury was 0.82
(95% CI: 0.75 to 0.90) between ever users and never users. Furthermore, we
found a decreased relative risk (RR) of sustaining ACL injury of 0.80 (95% CI:
0.74 to 0.91) in long-term users and 0.81 (95% CI: 0.72 to 0.89) in recent us-
ers. Additionally, we found a trend towards a dose-response association. Using
OC for more than four years did not seem to alter the likelihood of sustaining
operatively treated ACL injury.
Conclusions:
This indicates a protective association between OC use and the
likelihood of sustaining operatively treated ACL injury.
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