title: Patellar inversion: 180 degree rotation of the patella around its vertical axis within the intercondylar notch.
abstract: BACKGROUND
  Dislocation of the patella can occur around its vertical as well as horizontal axis. However, near 180 degree rotation of the patella around its vertical axis within the intercondylar notch without its complete dislocation has never been previously reported to the best of our knowledge. We report one such neglected case along with its management.
  
  
  METHODS
  The patient underwent open reduction and de-rotation of patella with repair of the medial and lateral patellar retinacula. The orientation of the patellar tendon intra-operatively was used as a guide for the reduction manoeuvre required.
  
  
  RESULTS
  The patient had a good functional result at more than one year of follow-up.
  
  
  CONCLUSIONS
  A skyline view of the knee in symptomatic patients with normal AP and lateral radiographs of the knee can be useful in diagnosing a rare intra-articular dislocation of the patella around its vertical axis. Neglected cases of such injuries can be easily treated with open reduction with the orientation of the patellar tendon guiding the manoeuvre to de-rotate the patella. Careful repair of lateral and medial retinacula in such cases is important in preventing future patellar instability.
authors.affiliation: Department of Orthopaedics, Woodend Hospital, Aberdeen, Scotland, UK. Electronic address: samarthmittal@gmail.com.
authors.forename: Samarth
authors.initials: S
authors.lastname: Mittal
authors.affiliation: Department of Orthopaedics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Arkesh
authors.initials: A
authors.lastname: M
authors.affiliation: Department of Orthopaedics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Vivek
authors.initials: V
authors.lastname: Shankar
authors.affiliation: Department of Orthopaedics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Swapnil
authors.initials: S
authors.lastname: Singh
authors.affiliation: Department of Orthopaedics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Sharma
authors.affiliation: Department of Orthopaedics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Ravi
authors.initials: R
authors.lastname: Mittal
mesh_terms: D000328:Adult; D006801:Humans; D007718:Knee Injuries / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D031222:Patellar Dislocation / Q000000981:diagnostic imaging* / Q000209:etiology / Q000601:surgery*; D011859:Radiography
keywords: Patellar dislocation; Patellar flipping; Patellar inversion