Purpose: Anterior cruciate ligament (ACL) reconstruction is commonly performed in athletes, with
the goal of return to sports activities. Unfortunately, this operation may fail, and the rates of either
reinjuring an ACL-reconstructed knee or sustaining an ACL rupture to the contralateral knee range
from 3% to 49%. One problem that exists is a lack of information and consensus regarding the
appropriate criteria for releasing patients to unrestricted sports activities postoperatively. The purpose
of this study was to determine the published criteria used to allow athletes to return to unrestricted
sports activities after ACL reconstruction. Methods: A systematic search was performed to identify
the factors investigators used to determine when return to athletics was allowed after primary ACL
reconstruction. Inclusion criteria were English language, publication within the last 10 years, clinical
trial, all adult patients, primary ACL reconstruction, original research investigation, and minimum 12
months’ follow-up. Results: Of 716 studies identified, 264 met the inclusion criteria. Of these, 105
(40%) failed to provide any criteria for return to sports after ACL reconstruction. In 84 studies (32%)
the amount of time postoperatively was the only criterion provided. In 40 studies (15%) the amount
of time along with subjective criteria were given. Only 35 studies (13%) noted objective criteria
required for return to athletics. These criteria included muscle strength or thigh circumference (28
studies), general knee examination (15 studies), single-leg hop tests (10 studies), Lachman rating (1
study), and validated questionnaires (1 study). Conclusions: The results of this systematic review
show noteworthy problems and a lack of objective assessment before release to unrestricted sports
activities. General recommendations are made for quantification of muscle strength, stability,
neuromuscular control, and function in patients who desire to return to athletics after ACL reconstruction,
with acknowledgment of the need for continued research in this area. Level of Evidence:
Level IV, systematic review of Level I to IV studies.