title: The effect of medial opening wedge proximal tibial osteotomy on patellofemoral contact.
abstract: BACKGROUND
  It has been suggested that patellofemoral contact pressures and contact forces may be altered secondary to an opening wedge high tibial osteotomy, yet few data are available that quantify the effect of varying degrees of medial opening wedge osteotomy on the patellofemoral joint contact characteristics.
  
  
  OBJECTIVE
  Opening wedge medial proximal tibial osteotomy will increase patellofemoral contact force and pressure.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Nine human cadaver knees were used. Pressure-sensitive film was placed in the suprapatellar pouch, leaving the patellar tendon and medial and lateral retinacula intact. The quadriceps tendon was attached to a materials testing machine along the axis of the femur, whereby a pulley mechanism generated 950 N of force. Patellofemoral contact characteristics were measured with pressure-sensitive film at 30°, 60°, 90°, and 120° of flexion for the native knee and after subsequent 10-mm and 15-mm medial opening wedge proximal tibial osteotomies. The film was analyzed with imaging software.
  
  
  RESULTS
  There was a statistically significant increase (P < .05) in mean contact pressure at 30° and 120° between the 10-mm osteotomy and native knee and across all flexion angles between the 15-mm osteotomy and native knee. Furthermore, a significant difference was seen in peak pressures when native knees were compared with 10-mm and 15-mm opening wedge osteotomies at all flexion angles.
  
  
  CONCLUSIONS
  There was a significant increase in patellofemoral pressures at varying degrees of knee flexion after medial opening wedge proximal tibial osteotomies of only 10 mm; a larger osteotomy resulted in a greater increase.
  
  
  CONCLUSIONS
  When performing a medial opening wedge proximal tibial osteotomy, the surgeon should consider the negative effects of increased patellofemoral peak pressure.
authors.affiliation: Orthopaedic Biomechanics Laboratory, Long Beach VA Healthcare System, Long Beach, California, USA.
authors.forename: Pooya
authors.initials: P
authors.lastname: Javidan
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Adamson
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Miller
authors.forename: Pierre
authors.initials: P
authors.lastname: Durand
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Dawson
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Pink
authors.forename: Thay Q
authors.initials: TQ
authors.lastname: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010027:Osteotomy; D057071:Patellofemoral Joint / Q000502:physiology / Q000601:surgery*; D013977:Tibia / Q000502:physiology / Q000601:surgery*