title: Assessment of knee laxity using a robotic testing device: a comparison to the manual clinical knee examination.
abstract: OBJECTIVE
  The purpose of this study was to collect knee laxity data using a robotic testing device. The data collected were then compared to the results obtained from manual clinical examination.
  
  
  METHODS
  Two human cadavers were studied. A medial collateral ligament (MCL) tear was simulated in the left knee of cadaver 1, and a posterolateral corner (PLC) injury was simulated in the right knee of cadaver 2. Contralateral knees were left intact. Five blinded examiners carried out manual clinical examination on the knees. Laxity grades and a diagnosis were recorded. Using a robotic knee device which can measure knee laxity in three planes of motion: anterior-posterior, internal-external tibia rotation, and varus-valgus, quantitative data were obtained to document tibial motion relative to the femur.
  
  
  RESULTS
  One of the five examiners correctly diagnosed the MCL injury. Robotic testing showed a 1.7° larger valgus angle, 3° greater tibial internal rotation, and lower endpoint stiffness (11.1 vs. 24.6 Nm/°) in the MCL-injured knee during varus-valgus testing when compared to the intact knee and 4.9 mm greater medial tibial translation during rotational testing. Two of the five examiners correctly diagnosed the PLC injury, while the other examiners diagnosed an MCL tear. The PLC-injured knee demonstrated 4.1 mm more lateral tibial translation and 2.2 mm more posterior tibial translation during varus-valgus testing when compared to the intact knee.
  
  
  CONCLUSIONS
  The robotic testing device was able to provide objective numerical data that reflected differences between the injured knees and the uninjured knees in both cadavers. The examiners that performed the manual clinical examination on the cadaver knees proved to be poor at diagnosing the injuries. Robotic testing could act as an adjunct to the manual clinical examination by supplying numbers that could improve diagnosis of knee injury.
  
  
  METHODS
  Level II.
authors.affiliation: University Orthopaedic Clinic, Decatur, GA, USA.
authors.forename: T P
authors.initials: TP
authors.lastname: Branch
authors.affiliation: ArthroMetrix, LLC, Atlanta, GA, USA. stinton@gmail.com.
authors.forename: S K
authors.initials: SK
authors.lastname: Stinton
authors.affiliation: ATOS Klinik, Heidelberg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Siebold
authors.affiliation: Suburban Orthopaedics, Bartlett, IL, USA.
authors.forename: H I
authors.initials: HI
authors.lastname: Freedberg
authors.affiliation: Lexington Clinic, Lexington, KY, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Jacobs
authors.affiliation: Department of Orthopaedics, Emory University School of Medicine, Atlanta, GA, USA.
authors.forename: W C
authors.initials: WC
authors.lastname: Hutton
mesh_terms: D001696:Biomechanical Phenomena; D002102:Cadaver; D005269:Femur; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000503:physiopathology; D007717:Knee; D007718:Knee Injuries / Q000175:diagnosis* / Q000503:physiopathology; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000293:injuries / Q000503:physiopathology*; D010808:Physical Examination; D012371:Robotics / Q000295:instrumentation*; D012399:Rotation; D013977:Tibia
keywords: Clinical knee examination; Knee injury; Knee laxity; Ligament injury; Medial collateral ligament; Posterolateral corner; Robotic knee testing