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Measurement of varus–valgus and internal–external rotational knee laxities in vivo—part i: assessment of measurement reliability and bilateral asymmetry
Author(s) -
Shultz Sandra J.,
Shimokochi Yohei,
Nguyen AnhDung,
Schmitz Randy J.,
Beyn Bruce D.,
Perrin David H.
Publication year - 2007
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.20397
Subject(s) - valgus , orthodontics , consistency (knowledge bases) , knee joint , torque , accuracy and precision , reliability (semiconductor) , observational error , mathematics , medicine , physics , surgery , statistics , geometry , thermodynamics , power (physics) , quantum mechanics
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°, 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° for VR–VL and 3–4° 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. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:981–988, 2007