title: Three-dimensional virtual simulation and evaluation of the femoroacetabular impingement based on "black bone" MRA.
abstract: BACKGROUND
  Femoroacetabular impingement (FAI) is a recognised cause of secondary osteoarthritis of the hip. Several imaging methods have been used to analyse the pathologic signs. Because of the lack of precise pre- and intraoperative overview and the difficulty locating osseous pathologies, arthroscopic and minimal invasive treatment is still challenging, even for trained surgeons. This paper describes a procedure that is based on magnetic resonance arthrography (MRA) and is used to virtually verify the range of motion (ROM) of the hip. It enables the evaluation of FAI and the preoperative simulation of adequate surgical manoeuvres.
  
  
  METHODS
  Each MRI was completed on a 3.0 T system using a flexible transmit/receive surface body coil with the patient in the supine position. An axial three-dimensional (3D) gradient-echo (VIBE, volume interpolated breathhold examination) sequence was performed. For the generation of 3D bone models, semiautomatic segmentation of the MRA data was accomplished using Amira(®) visualisation software version 5.2. The self-developed software "HipProject", written in C++, computes the maximal ROM of the hip. The virtual colliding regions were visualised for verification and simulation of osseous trimming.
  
  
  RESULTS
  In addition, for necessary information about damage to the cartilage and labrum, "black bone" MRA was used to generate extremely precise 3D reconstructions of the hip joint to automatically calculate the preoperative osseous ROM. Furthermore, the acetabular and femoral locations of the impingement zone were individually visualised and quantified.
  
  
  CONCLUSIONS
  The described procedure is a useful tool for the preoperative investigation of impinging hips. It enables appropriate planning of required surgical interventions.
authors.affiliation: Department of Orthopedic Surgery, Martin Luther University Halle-Wittenberg, Ernst-Grube-Str. 40, 06120, Halle (Saale), Germany, florian.radetzki@gmx.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Radetzki
authors.forename: B
authors.initials: B
authors.lastname: Saul
authors.forename: A
authors.initials: A
authors.lastname: Hagel
authors.forename: T
authors.initials: T
authors.lastname: Mendel
authors.forename: T
authors.initials: T
authors.lastname: Döring
authors.forename: K S
authors.initials: KS
authors.lastname: Delank
authors.forename: D
authors.initials: D
authors.lastname: Wohlrab
authors.forename: D
authors.initials: D
authors.lastname: Stoevesandt
mesh_terms: D000328:Adult; D003287:Contrast Media; D057925:Femoracetabular Impingement / Q000175:diagnosis*; D006621:Hip Joint / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology; D012984:Software; D014584:User-Computer Interface
chemical_list: D003287:Contrast Media