title: Painful knee prosthesis: CT scan to assess patellar angle and implant malrotation.
abstract: BACKGROUND
  According to literature, the incidence of pain in knee prostheses is on the increase. In the last decade Authors have focused attention on rotational alignment of the prosthetic components. The aim of this study is to evaluate the efficiency of a new angle, which we define as patellar angle, in order to achieve early diagnosis of malrotation.
  
  
  METHODS
  We set up a retrospective observational study recruiting 100 subjects who had undergone total knee prosthesis. 50 subjects suffered from knee anterior pain and 50 without any symptoms. Through CAT scan and VITREA software®, we were able to study the rotation of prosthetic components. We defined a new angle, which links the tibial component and the patella margins. The angles were measured by two different orthopaedic surgeons blinded to the study.
  
  
  RESULTS
  The patella angle ranged from 10 to 28°, with an average value of 23.2° in the control group; in the study group the angle ranged from 26 to 34°, with an average value of 29.9°.
  
  
  CONCLUSIONS
  Our data supported the reproducibility and efficacy of new angular value. It would represent a new method to detect tibial rotational malalignment.
  
  
  METHODS
  IV.
authors.affiliation: Orthopaedics Unit, Department of Basic Medical Science, Neuroscience and Sensory Organs, Faculty of Medicine and Surgery, University of Bari, General Hospital, Bari, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Spinarelli
authors.affiliation: Orthopaedics Unit, Department of Basic Medical Science, Neuroscience and Sensory Organs, Faculty of Medicine and Surgery, University of Bari, General Hospital, Bari, Italy.
authors.forename: Vito
authors.initials: V
authors.lastname: Pesce
authors.affiliation: Unit of Radiology Faculty of Medicine and Surgery, University of Bari, General Hospital, Bari, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Campagna
authors.affiliation: Orthopaedics Unit, Department of Basic Medical Science, Neuroscience and Sensory Organs, Faculty of Medicine and Surgery, University of Bari, General Hospital, Bari, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Maccagnano
authors.affiliation: Orthopaedics Unit, Department of Basic Medical Science, Neuroscience and Sensory Organs, Faculty of Medicine and Surgery, University of Bari, General Hospital, Bari, Italy.
authors.forename: Biagio
authors.initials: B
authors.lastname: Moretti
keywords: axial view; tibial apophysis; tibial plate