Multiplanar knee laxity and perceived function during activities of daily living and sport

Context: Greater knee-joint laxity may lead to a higher risk of knee injury, yet it is unknown whether results of self-reported outcome measures are associated with distinct knee-laxity profiles. Objective: To identify the extent to which multiplanar knee laxity is associated with patient-reported outcomes of knee function in healthy individuals during activities of daily living and sport. Design: Descriptive laboratory study. Setting: University research laboratory. Patients or Other Participants: Forty healthy individuals (20 men, 20 women; age = 18-31 years). Main Outcome Measure(s): All participants were given the Knee Outcome Survey Activities of Daily Living Scale (KOSADL) and Sports Activities Scale (KOS-SAS) and subsequently measured for knee laxity in the sagittal, frontal, and transverse planes. Separate backward stepwise regression analyses were performed to determine the extent to which multiplanar kneelaxity values predicted KOS-ADL and KOS-SAS scores within each sex. Results: Women had higher magnitudes of anterior, posterior (POSTLAX), varus (VARLAX), valgus (VALLAX), and internalrotation laxity than men and trended toward greater external rotation (ERLAX) laxity. Greater POSTLAX, less VALLAX, and greater VARLAX was associated with lower KOS-ADL scores (KOS-ADL =-4.8 [POSTLAX], + 3.3 [VALLAX]-2.2 [VARLAX] + 100.4, R2 = 0.74, P <.001) and greater POSTLAX and less VALLAX was associated with lower KOS-SAS scores (KOS-SAS =-8.2 [POSTLAX],+3.6 [VALLAX]+96.4, R2=0.67, P <.001) in women. In men, greater POSTLAX and less ERLAX was associated with lower KOS-SAS scores (KOS-ADL =-4.7 [POSTLAX], + 0.9 [ERLAX] + 96.4, R2 = 0.49, P <.001). Conclusions: The combination of POSTLAX with less relative VALLAX (women) or less relative ERLAX (men) was a strong predictor of KOS scores, suggesting that a self-reported outcome measure may be beneficial as part of a preparticipation screening battery to identify those with perceived functional deficits associated with their knee laxity.