Quadriceps Strength Influences Patient Function More Than Single Leg Forward Hop During Late-Stage ACL Rehabilitation.

This was a cross-sectional study, so it shows association, not that quadriceps strength caused better IKDC scores. The sample was small, with 48 participants, and may not represent all people recovering from ACL reconstruction. Participants were young, relatively healthy athletes with unilateral ACL reconstruction and minimal other knee injuries, so results may not apply to older patients, non-athletes, or more complex knee injuries. Rehabilitation, surgical technique, and graft type were not controlled, and pre-surgery baseline measures were not available. Actual return to sport status was not monitored, so it is unknown whether test results were used in decisions or whether participants returned to sport. Quadriceps strength explained 39% of IKDC variance, and the rest was unexplained. The study used established thresholds, but some thresholds may not fully account for sex, age, or sport differences.

The research was supported by the National Institute of General Medical Sciences of the National Institutes of Health. No other conflicts of interest are stated in the supplied text.

Do not assume that a normal single-leg forward hop means adequate quadriceps strength. In this study, hop symmetry averaged 92.7% while quadriceps symmetry averaged 85.5%, and hop measures did not add prediction beyond quadriceps strength. This was also a cross-sectional association study, not proof that strength testing changes outcomes.