title: Smartphone versus knee ligament arthrometer when size does not matter.
abstract: OBJECTIVE
  The use of available mechanical methods to measure anterior tibial translation (ATT) in anterior cruciate ligament (ACL)-deficient knees are limited by size and costs. This study evaluated the performance of a portable device based on a downloadable electronic smartphone application to measure ATT in ACL-deficient knees.
  
  
  METHODS
  A specific smartphone application (SmartJoint) was developed for this purpose. Two independent observers nonsequentially measured the amount of ATT during execution of a maximum manual Lachman test in 35 patients with an ACL-deficient knee using KT 1000 and SmartJoint on both involved and uninvolved knees. As each examiner performed the test three times on each knee, a total of 840 measurements were collected. Statistical analysis compared intertest, interobserver and intra-observer reliability using the interclass correlation coefficient (ICC). An ICC > 0.75 indicates excellent reproducibility among measurements.
  
  
  RESULTS
  Mean amount of ATT on uninvolved knees was 6.1 mm [standard deviation (SD = 2)] with the KT 1000 and 6.4 mm (SD = 2) with SmartJoint. Mean side-to-side difference was 8.1 mm. (SD = 4) with KT 1000 and 8.3 mm (SD = 3) with SmartJoint. Intertest reliability between the two methods yielded an ICC 0.797 [95 % confidence interval (CI) 0.717-0.857] for the uninvolved knee and of 0.987 (CI 0.981-0.991) for the involved knee. Interobserver ICC for SmartJoint and KT 1000 was 0.957 (CI 0.927-0.976) for the uninvolved knee and 0.992 (CI 0.986-0.996) for the involved knee and 0.973 (CI 0.954-0.985) for the uninvolved knee and 0.989 (CI 0.981-0.994) for involved knee, respectively.
  
  
  CONCLUSIONS
  The performance of SmartJoint is comparable and highly correlated with measurements obtained from KT 1000. SmartJoint may provide a truly portable, noninvasive, accurate, reliable, inexpensive and widely accessible method to characterize ATT in ACL-deficient knee.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ferretti
authors.affiliation: Orthopaedic Unit and "Kirk Kilgour" Sports Injury Centre S. Andrea Hospital, University of Rome, Via Grottarossa 1035, Rome (RM), Sapienza, Italy.
authors.forename: Ferretti
authors.initials: F
authors.lastname: Andrea
authors.forename: Luigi
authors.initials: L
authors.lastname: Valeo
authors.forename: Valeo
authors.initials: V
authors.lastname: Luigi
authors.forename: Daniele
authors.initials: D
authors.lastname: Mazza
authors.forename: Mazza
authors.initials: M
authors.lastname: Daniele
authors.forename: Luca
authors.initials: L
authors.lastname: Muliere
authors.forename: Muliere
authors.initials: M
authors.lastname: Luca
authors.forename: Paolo
authors.initials: P
authors.lastname: Iorio
authors.forename: Iorio
authors.initials: I
authors.lastname: Paolo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Giovannetti
authors.forename: Giovannetti
authors.initials: G
authors.lastname: Giovanni
authors.forename: Fabio
authors.initials: F
authors.lastname: Conteduca
authors.forename: Conteduca
authors.initials: C
authors.lastname: Fabio
authors.forename: Raffaele
authors.initials: R
authors.lastname: Iorio
authors.forename: Iorio
authors.initials: I
authors.lastname: Raffaele
mesh_terms: D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction; D053587:Arthrometry, Articular / Q000295:instrumentation*; D040421:Cell Phone; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000601:surgery; D007718:Knee Injuries / Q000175:diagnosis* / Q000601:surgery; D007719:Knee Joint / Q000601:surgery; D063731:Mobile Applications; D010808:Physical Examination; D013977:Tibia