title: A classification method for neurogenic heterotopic ossification of the hip.
abstract: BACKGROUND
  Existing classifications for heterotopic ossification (HO) do not include all HO types; nor do they consider the anatomy of the involved joint or the neurological injury. Therefore, we performed this study to propose and evaluate a classification according to the location of neurogenic HO and the neurological injury.
  
  
  METHODS
  We studied the files of 24 patients/33 hips with brain or spinal cord injury and neurogenic HO of the hip treated with excision, indomethacin, and radiation therapy. We classified patients according to the Brooker classification scheme as well as ours. Four types of neurogenic HO were distinguished according to the anatomical location of HO: type 1, anterior; type 2, posterior; type 3, anteromedial; type 4, circumferential. Subtypes of each type were added based on the neurological injury: a, spinal cord; b, brain injury. Mean follow-up was 2.5 years (1-8 years).
  
  
  RESULTS
  The Brooker classification scheme was misleading-all hips were class III or IV, corresponding to ankylosis, even though only 14 hips had ankylosis. On the other hand, our classification was straightforward and easy to assign in all cases. It corresponded better to the location of the heterotopic bone, and allowed for preoperative planning of the appropriate surgical approach and evaluation of the prognosis; recurrence of neurogenic HO was significantly higher in patients with brain injury (subtype b), while blood loss was higher for patients with anteromedial (type 3) and circumferential (type 4) neurogenic HO.
  
  
  CONCLUSIONS
  Our proposed classification may improve the management and evaluation of the prognosis for patients with neurogenic HO.
authors.affiliation: Department of Orthopaedics, Orthopaedic Oncology Service, Istituto Ortopedico Rizzoli, University of Bologna, Via Di Barbiano 1/10, 40136, Bologna, Italy.
authors.forename: Andreas F
authors.initials: AF
authors.lastname: Mavrogenis
authors.forename: Giovanni
authors.initials: G
authors.lastname: Guerra
authors.forename: Eric Lodwijk
authors.initials: EL
authors.lastname: Staals
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Bianchi
authors.forename: Pietro
authors.initials: P
authors.lastname: Ruggieri
mesh_terms: D000293:Adolescent; D000328:Adult; D001930:Brain Injuries / Q000150:complications*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006615:Hip / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000145:classification* / Q000175:diagnosis / Q000209:etiology; D011379:Prognosis; D012189:Retrospective Studies; D013119:Spinal Cord Injuries / Q000150:complications*; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult