title: Intraoperative comparison of knee laxity between anterior cruciate ligament-reconstructed knee and contralateral stable knee using navigation system.
abstract: OBJECTIVE
  The objective of this study was to compare knee laxity between anterior cruciate ligament (ACL)-reconstructed knees and contralateral stable knees by use of intraoperative navigation.
  
  
  METHODS
  Five patients with ipsilateral ACL-deficient knees with contralateral stable knees without any ligament injuries were included in this study. Anteroposterior (AP) knee laxity during anterior drawer force applied manually and range of tibial rotation and AP knee laxity during internal and external rotational torque applied manually in both the ACL-deficient knee and the contralateral stable knee were measured by use of a navigation system from 15 degrees to 90 degrees of knee flexion. After the temporary fixation of the posterolateral bundle, anteromedial bundle (AMB), or double-bundle (DB) reconstruction, knee laxity was measured again and compared with that of the stable knee.
  
  
  RESULTS
  The mean laxities for PLB reconstruction were significantly greater than those of the contralateral stable knee at more than 75 degrees of knee flexion (P < .05). The mean laxities for AMB or DB reconstruction were not significantly different from those of the contralateral stable knee at all knee flexion angles. Those for AMB reconstruction were within +1.6 mm and those for DB reconstruction were within -2.0 mm of those of the contralateral stable knee. The mean rotations for all reconstructions were significantly less than those of the contralateral stable knee at less than 30 degrees of knee flexion (P < .05).
  
  
  CONCLUSIONS
  DB and AMB reconstructions could restore knee laxity closer to the level of the contralateral stable knee. Because normal knee laxity is different in each individual, evaluation of contralateral stable knee laxity during ACL reconstruction surgery would be helpful for restoration to the level of the specific preinjury knee laxity.
  
  
  METHODS
  Level IV, therapeutic case series.
authors.affiliation: Department of Orthopaedic Surgery, Hirosaki University School of Medicine, Japan. kazu3miura@aol.com
authors.forename: Kazutomo
authors.initials: K
authors.lastname: Miura
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Ishibashi
authors.forename: Eiichi
authors.initials: E
authors.lastname: Tsuda
authors.forename: Akira
authors.initials: A
authors.lastname: Fukuda
authors.forename: Harehiko
authors.initials: H
authors.lastname: Tsukada
authors.forename: Satoshi
authors.initials: S
authors.lastname: Toh
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D001182:Arthroscopy; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007593:Joint Instability / Q000601:surgery*; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009038:Motion; D011184:Postoperative Period; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D013710:Tendons / Q000637:transplantation; D019415:Torque; D055815:Young Adult