Measurement of varus–valgus and internal–external rotational knee laxities in vivo—Part II: relationship with anterior–posterior and general joint laxity in males and females

Abstract We examined sex differences in general joint laxity (GJL), and anterior–posterior displacement (ANT–POST), varus–valgus rotation (VR–VL), and internal–external rotation (INT–EXT) knee laxities, and determined whether greater ANT and GJL predicted greater VR–VL and INT–EXT. Twenty subjects were measured for GJL, and scored on a scale of 0–9. ANT and POST were measured using a standard knee arthrometer at 133 N. VR–VL and INT–EXT were measured using a custom joint laxity testing device, defined as the angular displacements (deg) of the tibia relative to the femur produced by 0–10 Nm of varus–valgus torques, and 0–5 Nm of internal–external torques, respectively. INT–EXT were measured during both non‐weight‐bearing (NWB) and weight‐bearing (WB = 40% body weight) conditions while VR–VL were measured NWB. All laxity measures were greater for females compared to males except for POST. ANT and GJL positively predicted 62.5% of the variance in VR–VL and 41.8% of the variance in WB INT–EXT. ANT was the sole predictor of INT–EXT in NWB, explaining 42.3% of the variance. These findings suggest that subjects who score higher on clinical measures of GJL and ANT are also likely to have greater VR–VL and INT–EXT knee laxities. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:989–996, 2007