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 (KOS-ADL) 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 knee-laxity values predicted KOS-ADL and KOS-SAS scores within each sex.

Results: Women had higher magnitudes of anterior, posterior (POST(LAX)), varus (VAR(LAX)), valgus (VAL(LAX)), and internal-rotation laxity than men and trended toward greater external rotation (ER(LAX)) laxity. Greater POST(LAX), less VAL(LAX), and greater VAR(LAX) was associated with lower KOS-ADL scores (KOS-ADL = -4.8 [POST(LAX)], + 3.3 [VAL(LAX)] - 2.2 [VAR(LAX)] + 100.4, R2 = 0.74, P < .001) and greater POST(LAX) and less VAL(LAX) was associated with lower KOS-SAS scores (KOS-SAS = -8.2 [POST(LAX)], + 3.6 [VAL(LAX)] + 96.4, R2 = 0.67, P < .001) in women. In men, greater POST(LAX) and less ER(LAX) was associated with lower KOS-SAS scores (KOS-ADL = -4.7 [POST(LAX)], + 0.9 [ER(LAX)] + 96.4, R2 = 0.49, P < .001).

Conclusions: The combination of POST(LAX) with less relative VAL(LAX) (women) or less relative ER(LAX) (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.