title: Rolimeter measurements are suitable as substitutes to stress radiographs in the evaluation of posterior knee laxity.
abstract: OBJECTIVE
  The quantification of posterior knee laxity is crucial in the evaluation of injuries to the posterior cruciate ligament (PCL) as it has important implications to the treatment for these injuries. The objective of this study was to compare the test results of stress radiography and instrumented drawer testing (Rolimeter) for the assessment of posterior knee laxity in patients with PCL injury.
  
  
  METHODS
  In 45 patients with an injury to the PCL, lateral radiographs of both knees were obtained under anterior and posterior tibial load (150 N) using a standardized approach. Patients with injury of the ACL to either knee were excluded from the study. During the same clinic visit, an instrumented measurement of anterior-posterior knee laxity was performed at 90° of knee flexion by an experienced examiner using the Rolimeter device. The mean side-to-side differences (SSD) of both (radiographic and instrumented) measurements were compared to each other, and the correlation was calculated using the Pearson coefficient.
  
  
  RESULTS
  The SSD (affected/healthy side) of posterior translation determined from the radiographs was 8.2 ± 3.2 mm, and the SSD of the instrumented measurement testing was 7.6 ± 3.2 mm. The mean difference between radiographic and Rolimeter test results was 1.8 ± 1.5 mm. The Pearson's correlation coefficient revealed a good correlation between both measurements of 0.74.
  
  
  CONCLUSIONS
  It may be suggested by the results of this study that under the absence of an ACL injury and a fixed posterior drawer sign, the Rolimeter is a suitable tool to assess the posterior laxity of the knee in the clinical setting. Its advantages are the absence of radiation to the patient, its availability, and the low cost. Therefore, the Rolimeter device may serve as a valuable alternative to stress radiography in the evaluation of PCL-injured patients.
  
  
  METHODS
  II.
authors.affiliation: Department of Trauma and Orthopaedic Surgery, Clinic for Sports Traumatology, Cologne-Merheim Medical Center, University of Witten-Herdecke, Ostmerheimer Str. 200, 51109, Cologne, Germany, jhoeher@t-online.de.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Höher
authors.forename: Ralph
authors.initials: R
authors.lastname: Akoto
authors.forename: Philip
authors.initials: P
authors.lastname: Helm
authors.forename: Sven
authors.initials: S
authors.lastname: Shafizadeh
authors.forename: Bertil
authors.initials: B
authors.lastname: Bouillon
authors.forename: Maurice
authors.initials: M
authors.lastname: Balke
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D007718:Knee Injuries / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D016119:Posterior Cruciate Ligament / Q000293:injuries*; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D013314:Stress, Mechanical