title: Physiological sagittal plane patellar kinematics during dynamic deep knee flexion.
abstract: OBJECTIVE
  Lateral radiographic views can be easily taken and have reveal considerable information about the patella. The purpose of this study was to obtain sagittal plane patellar kinematics data through the entire range of knee flexion under weight-bearing conditions.
  
  
  METHODS
  Patellar flexion angles relative to the femur and tibia and anterior-posterior and proximal-distal translations of the patella relative to the femur and tibia were measured from 0 to 165° knee flexion in nine healthy knees using dynamic radiographic images.
  
  
  RESULTS
  The patella flexed relative to the femur and tibia by two thirds times and one third times the knee flexion angle, respectively. The patella translated in an arc relative to the femur and tibia as the knee flexed. In early flexion, the superior and centroid points translated anteriorly and then the patella translated posteriorly relative to the femur. All three points of the patella translated posteriorly relative to the tibia during a full range of flexion. An average of four and three millimetres proximal patellar translation relative to the tibia was demonstrated from 0 to 20° and 140 to 160° knee flexion, respectively.
  
  
  CONCLUSIONS
  Physiological sagittal plane patellar kinematics, including patellar flexion angles and translations relative to the femur and tibia, showed generally similar patterns for each subject. Measurements of dynamic radiographic images under weight-bearing activities may enhance the opportunity to identify patellar pathological conditions.
authors.affiliation: Department of Mechanical & Aerospace Engineering, University of Florida, Gainesville, FL, USA. hamachan@ortho.med.kyushu-u.ac.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hamai
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Dunbar
authors.forename: Taka-aki
authors.initials: TA
authors.lastname: Moro-oka
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Miura
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
authors.forename: Scott A
authors.initials: SA
authors.lastname: Banks
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005269:Femur / Q000000981:diagnostic imaging / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D008297:Male; D010329:Patella / Q000000981:diagnostic imaging / Q000502:physiology*; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D013977:Tibia / Q000000981:diagnostic imaging / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology