Measurement of varus-valgus and internal-external rotational knee laxities in vivo--Part I: assessment of measurement reliability and bilateral asymmetry

J Orthop Res. 2007 Aug;25(8):981-8. doi: 10.1002/jor.20397.


We examined the capabilities of the Vermont Knee Laxity Device (VKLD) in measuring varus (VR)-valgus (VL) and internal (INT)-external (EXT) rotational laxities by quantifying measurement consistency and absolute measurement error (N = 10). Based on the expected measurement error, we then examined side-to-side differences (N = 20). For all measures, the knee was flexed 20 degrees , the thigh securely fixed, and counterweights applied to the thigh and shank to create an initial zero shear and compressive load across the tibiofemoral joint. A 10-Nm torque was applied to the knee for VL and VR during non-weight-bearing, and a 5-Nm torque was applied for INT and EXT during non-weight-bearing and weight-bearing conditions. Position sensors measured angular displacements (deg). Except for INT during weight bearing, measurement consistency was good to excellent (range, 0.68-0.96), with absolute measurement errors generally less than 2 degrees for VR-VL and 3-4 degrees for INT-EXT. Although side-to-side differences were observed, they did not exceed absolute measurement errors. The VKLD yields reliable measures of VR-VL and INT-EXT laxities, with sufficient measurement precision to yield clinically relevant differences.

Publication types

  • Validation Study

MeSH terms

  • Adult
  • Biomechanical Phenomena / instrumentation
  • Female
  • Humans
  • Joint Instability / diagnosis
  • Knee Joint / physiology*
  • Male
  • Movement / physiology*
  • Reproducibility of Results
  • Rotation