The Utility of Limb
Symmetry Indices in Return-to-Sport Assessment in Patients With Bilateral
Anterior Cruciate Ligament Reconstruction

C, Schmitt LC, Thomas S, Hewett TE, and Paterno MV. Am J Sports Med. 2016. [Epub Ahead of Print].

Take Home Message: Limb symmetry indices may not be sufficient
to identify strength and performance deficits,
particularly in patients who have a history of bilateral anterior cruciate ligament (ACL) reconstruction.

Clinicians commonly
use limb symmetry indices to determine if a patient who sustained an ACL
rupture is able to return to play. However, it is unclear if these indices are
useful when an athlete has a history of bilateral ACL ruptures because both
limbs may have strength deficits. Therefore, Zwolski and colleagues completed a
cross-sectional study of 45 female athletes to evaluate limb symmetry indices among
patients who had sustained bilateral or unilateral ACL ruptures. The authors
recruited 15 patients with a unilateral ACL rupture, 15 patients with bilateral
ACL ruptures, and 15 athletes with no history of ACL injury. These patients
were all matched on age, sex and sport participation. The 30 female athletes
with an ACL tear enrolled in the study when they were cleared for return to
sport. All athletes performed 3 hop tests (single-leg hop for distance,
triple-hop for distance, and triple-crossover hop for distance). The authors
randomized the order of limbs being tested. Quadriceps strength was also
assessed using 3 maximum contraction trials using a Biodex machine. Overall the
authors found that both ACL groups had performance deficits and impaired
limb symmetry indices with the single-leg hop for distance test compared with
the healthy participants. However, the limb symmetry indices for the other two
hop tests and quadriceps strength assessment were only different between the unilateral
ACL group and control participants but not the ACL group with a history of
bilateral tears. Despite the poor performance of limb symmetry indices among
those with a history of bilateral ACL injuries it is noteworthy that the
authors detected differences between left and right limbs with the triple-hop
for distance and quadriceps strength tests.

The data presented in
this study is concerning to clinicians who rely on limb symmetry indices to
make return-to-play decisions. Patients who had a history of bilateral ACL reconstructions
were less likely to show deficits than patients with a unilateral reconstruction.
This may be attributed to the lack of a control limb in the bilateral ACL reconstruction
group. This should also raise concern about using symmetry indices when
patients have other contralateral injuries that may impair their performance.
For example, what if a patient has chronic ankle instability? The other
concerning finding from this study is that patients who were cleared to return
to sport still had strength and performance deficits. We recently reported on a study where patients who failed to meet functional
criteria for return-to-sport or who had a lower hamstring:quadriceps ratio were
at greater risk for an ACL graft rupture. Hence, we need to ensure that our patients
return to activity with the strength and performance they need to succeed but
we also need to be cautious about how we define an acceptable level of
performance. As these tests continue to be evaluated, clinicians can continue
to use limb symmetry indices to aid in making return to play decisions, but
should be increasingly cautious if the patient in question has a history of
bilateral ACL reconstruction.

for Discussion
: Do you use limb symmetry indices to assess a patient’s capability of
being return to play? If so, how you think this data might affect your decision
making process now?

Written by: Kyle Harris
Reviewed by:  Jeffrey Driban

Related Posts:

Zwolski, C., Schmitt, L., Thomas, S., Hewett, T., & Paterno, M. (2016). The Utility of Limb Symmetry Indices in Return-to-Sport Assessment in Patients With Bilateral Anterior Cruciate Ligament Reconstruction The American Journal of Sports Medicine, 44 (8), 2030-2038 DOI: 10.1177/0363546516645084