title: The effect of axial rotation of the anterior resection plane in patellofemoral arthroplasty.
abstract: BACKGROUND
  Patellofemoral arthroplasty (PFA) has a small but definite place in replacement surgery of the knee, especially in young patients. The main surgical considerations in PFA are the patient's anatomy, the type of prosthesis and the surgical technique. The surgical technique and PFA success rely heavily on the anterior resection. In this study we investigate the effect of axial rotation of the anterior resection plane.
  
  
  METHODS
  We tested the outcome of PFA fit based on resection footprint measurements, axial and coronal groove angles, and lateral trochlear inclination (LTI) angle in a virtual PFA model. The range of anterior resection plane axial rotations was from five degree internal to five degree external with an increment of one degree.
  
  
  RESULTS
  Axial rotation of anterior resection plane changes the resection footprint dimension, which leads to coronal rotation of the femoral component. External rotation of the resection plane results in valgus rotation of the trochlear groove and decreased LTI after PFA and the opposite was observed for internal rotation.
  
  
  CONCLUSIONS
  Our study showed that by changing the axial rotation of the anterior cut, the coronal groove of the prosthesis can be altered to lie more closely with the native groove line without compromising the prosthesis-cartilage transition.
authors.affiliation: Department of Mechanical and Mechatronic Engineering, Stellenbosch University, Private Bag X1, Matieland 7600, South Africa. Electronic address: kyjincho@gmail.com.
authors.forename: K J
authors.initials: KJ
authors.lastname: Cho
authors.affiliation: Department of Orthopaedics, Stellenbosch University, Private Bag X1, Matieland 7600, South Africa. Electronic address: pieter@orthoclinic.co.za.
authors.forename: P J
authors.initials: PJ
authors.lastname: Erasmus
authors.affiliation: Department of Mechanical and Mechatronic Engineering, Stellenbosch University, Private Bag X1, Matieland 7600, South Africa. Electronic address: cobusmul@sun.ac.za.
authors.forename: J H
authors.initials: JH
authors.lastname: Müller
mesh_terms: D000328:Adult; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007720:Knee Prosthesis; D008279:Magnetic Resonance Imaging; D057071:Patellofemoral Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D012399:Rotation
keywords: Alignment of femoral component; Anterior resection plane rotation; Axial rotation; Femoral component positioning; Patellofemoral arthroplasty; Trochlear groove alignment