title: Objective measurement devices to assess static rotational knee laxity: focus on the Rotameter.
abstract: OBJECTIVE
  The present article summarizes the development of a simple, objective, and non-invasive measurement device for tibiofemoral rotation to assess static rotational knee laxity.
  
  
  RESULTS
  The device is based on the dial test with the patient lying prone and the knee flexed to 30°. From measurements of 30 healthy participants, the device achieved high inter- and intra-observer reliability and showed a high correlation of the measured results with the contralateral knees of the participants. Measurements of the device were also performed in a human cadaver study and revealed highly correlated results when compared to the simultaneous measurements of a knee navigation system, which was used as an invasive standard method to assess tibial rotation. In human cadaver specimens, it was shown that a simulated tear of the posterolateral bundle as well as a complete ACL tear led to a significant increase in isolated tibiofemoral rotation compared to the intact ACL. A retrospective case series investigated the clinical results as well as knee laxity measurements after ACL surgery in vivo. Rotational, as well as anteroposterior (AP), knee laxity was objectively assessed in 52 patients at a mean postoperative follow-up of 27 months by comparing the measured results with the results of the contralateral unaffected knee in each patient. The clinical results were comparable to the results reported in the literature. Moreover, rotational laxity was successfully restored after ACL reconstruction, whereas AP laxity showed significant differences compared to the contralateral knees although they were defined as clinically successful according to the IKDC classification.
  
  
  CONCLUSIONS
  A non-invasive and objective knee rotational measurement device has been developed, which offers good potential for objective quality control in knee ligament injuries and their treatment.
  
  
  METHODS
  Review article, Level IV.
authors.affiliation: Department of Orthopedic Surgery, Saarland University, Kirrberger Str., 66421 Homburg (Saar), Germany. olaf.lorbach@gmx.de
authors.forename: Olaf
authors.initials: O
authors.lastname: Lorbach
authors.forename: Matthias
authors.initials: M
authors.lastname: Brockmeyer
authors.forename: Matthias
authors.initials: M
authors.lastname: Kieb
authors.forename: Tina
authors.initials: T
authors.lastname: Zerbe
authors.forename: Dietrich
authors.initials: D
authors.lastname: Pape
authors.forename: Romain
authors.initials: R
authors.lastname: Seil
mesh_terms: D000293:Adolescent; D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000009:adverse effects / Q000379:methods*; D053587:Arthrometry, Articular / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D004867:Equipment Design; D005260:Female; D005269:Femur / Q000502:physiology; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D007718:Knee Injuries / Q000175:diagnosis / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012399:Rotation; D013977:Tibia / Q000502:physiology; D055815:Young Adult