title: Variations in kinematics and function following patellar stabilization including tibial tuberosity realignment.
abstract: OBJECTIVE
  The current study was performed to characterize the influence of patellar stabilization procedures on patellofemoral and tibiofemoral dynamic motion.
  
  
  METHODS
  Six knees were evaluated pre-operatively and 1 year or longer following stabilization via tibial tuberosity realignment, with simultaneous medial patellofemoral ligament reconstruction performed for five knees. Knees were imaged during extension against gravity using a dynamic CT scanner. Models representing each knee at several positions of extension were reconstructed from the images. Local coordinate systems were created within one femur, patella and tibia for each knee, with shape matching of the bones used to transfer the coordinate axes to the other models. The patellar lateral shift and tilt and tibial external rotation were quantified based on the reference axes and interpolated to flexion angles from 5° to 40°. Pre-operative and post-operative data were compared with the paired t tests.
  
  
  RESULTS
  Surgical realignment significantly decreased the average patellar lateral shift and tilt at low flexion angles. At 5°, surgical realignment decreased the average lateral shift from 15.5 (6.3) to 8.5 (4.7) mm and decreased the average lateral tilt from 20.8 (9.4)° to 13.8 (6.4)°. The changes were statistically significant (p<0.05) at 5° and 10° of flexion, as well as 20° for lateral shift. The average tibial external rotation also increased significantly at 30° and 40° following surgery.
  
  
  CONCLUSIONS
  Patellar stabilization including a component of tuberosity realignment reduces patellar lateral shift and tilt at low flexion angles, but the long-term influence of increased tibial external rotation on tibiofemoral function is currently unknown.
  
  
  METHODS
  Prospective comparative study, Level II.
authors: Department of Orthopaedic Surgery, Akron General Medical Center, Akron, OH, USA, john.elias@akrongeneral.org.
authors: John J
authors: JJ
authors: Elias
authors: John A
authors: JA
authors: Carrino
authors: Archana
authors: A
authors: Saranathan
authors: Loredana M
authors: LM
authors: Guseila
authors: Miho J
authors: MJ
authors: Tanaka
authors: Andrew J
authors: AJ
authors: Cosgarea
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D010329:Patella / Q000503:physiopathology*; D011446:Prospective Studies; D016059:Range of Motion, Articular; D012399:Rotation; D013977:Tibia / Q000503:physiopathology* / Q000601:surgery; D055815:Young Adult