Psychological Patient-reported Outcomes Cannot Predict a Second Anterior Cruciate Ligament Injury in Patients who Return to Sports after an Anterior Cruciate Ligament Reconstruction.

Only 64 patients had a second ACL injury, so the study may not have had enough cases to reliably test the questionnaires. The authors said 33 patients in each group would be needed to detect a useful questionnaire cut-off, and that the population was heterogeneous enough that even that might not be enough. The study used one cut-off per questionnaire, but the authors noted that both high and low psychological scores might be risk factors, so a single threshold may be conceptually wrong. Some patients returned to their pre-injury activity level as early as four months after reconstruction, and it is unclear how this affected results. The average age was 24.8 years, while the ACL-RSI has been reported to be more sensitive in patients aged 20 years or younger, so age-specific cut-offs were not tested. Not every questionnaire had data for all 641 patients; the analysed numbers were 382, 627, and 630 depending on the scale.

The authors declared no conflict of interest.

Do not conclude that a patient who passes an ACL-RSI, KOOS, or K-SES 18 cut-off is protected from a second ACL injury. The cut-offs did not separate patients who had a second injury from those who did not, and symmetrical quadriceps strength did not improve prediction.