title: Visual-palpatory versus fluoroscopic intraoperative determination of the femoral entry point in medial patellofemoral ligament reconstruction.
abstract: OBJECTIVE
  Malpositioning of the femoral entry point in reconstruction of the medial patellofemoral ligament (MPFL) can lead to abnormal and painful patellar kinematics and loss of flexion. Determination of this point is usually performed by palpation of anatomic landmarks. Accuracy of this method has not yet been investigated. The hypotheses were: 1. palpatory method is not as accurate as fluoroscopically guided method using established radiological criteria; 2. accuracy correlates with surgical experience.
  
  
  METHODS
  Three surgeons of varying experience defined the femoral entry point for the MPFL by palpation in ten cadaveric legs. The blinded procedures were repeated three times, and subjective difficulty of the determination was recorded. Results were documented by fluoroscopy on a true lateral radiograph. The accuracy was assessed using established radiological criteria. Surgical experience was correlated with the results, and confounding or interacting variables were assessed.
  
  
  RESULTS
  Mean deviation from the correct zone for the femoral entry point was 3.5 mm (range 0-18 mm). Twenty-nine percent of all palpatory determinations were inside the correct zone, 47 % were within 5 mm distance from the correct zone, and 23 % were further than 5 mm apart from the correct zone ("outliers"). No significant difference was found between surgeons of varying experience. No correlation was observed between subjective difficulty of the procedure and accuracy of determination.
  
  
  CONCLUSIONS
  The validity of the isolated palpatory determination of the femoral entry point in MPFL reconstruction seems to be insufficient, regardless of surgical experience. Derived from this study, fluoroscopic guidance is used in our clinic by default.
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Balgrist, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland. rherschel@bluewin.ch.
authors.forename: R
authors.initials: R
authors.lastname: Herschel
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Balgrist, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Hasler
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Balgrist, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland.
authors.forename: P M
authors.initials: PM
authors.lastname: Tscholl
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Balgrist, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland.
authors.forename: S F
authors.initials: SF
authors.lastname: Fucentese
mesh_terms: D001696:Biomechanical Phenomena; D002983:Clinical Competence; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery*; D005471:Fluoroscopy; D006801:Humans; D008023:Ligaments, Articular / Q000601:surgery*; D008297:Male; D010173:Palpation; D057071:Patellofemoral Joint / Q000502:physiology / Q000601:surgery*; D016059:Range of Motion, Articular
keywords: Accuracy; Femoral entry point; MPFL; Reconstruction