title: Retrograde lag screw placement in anterior acetabular column with regard to the anterior pelvic plane and midsagittal plane -- virtual mapping of 260 three-dimensional hemipelvises for quantitative anatomic analysis.
abstract: Percutaneous screw placement can be used for minimally invasive treatment of none or minimally displaced fractures of the anterior column. The complex pelvic geometry can pose a major challenge even for experienced surgeons. The present study examined the preformed bone stock of the anterior column in 260 hemipelvises (130 male and 130 female). Screws were virtually implanted using iPlan(®) CMF (BrainLAB AG, Feldkirchen, Germany); the maximal implant length and the maximal implant diameter were assessed. The study showed, that 6.5mm can generally be used in men; in women however individual planning is essential in regard to the maximal implant diameter since we found that in 15.4% of women, screws with a diameter less than 6.5mm were necessary. The virtual analysis of the preformed bone stock corridor of the anterior column showed two constrictions of crucial clinical importance. These can be found after 18% and 55% (men) respectively 16% and 55% (women) measured from the entry point along the axis of the implant. The entry point of the retrograde anterior column screw in our collective was located lateral of tuberculum pubicum at the level of the superior-medial margin of foramen obturatum. In female patients, the entry point was located significantly more lateral of symphysis and closer to the cranial margin of ramus superior ossis pubis. The mean angle between the screw trajectory and the anterior pelvic plane in sagittal section was 31.6 ± 5.5°, the mean angle between the screw trajectory and the midsagittal plane in axial section was 55.9 ± 4.6° and the mean angle between the screw trajectory and the midsagittal plane in coronal section was 42.1 ± 3.9° with no significant deviation between both sexes. The individual angles formed by the screw trajectory and the anterior pelvic and midsagittal plane are independent from anthropometric parameters sex, age, body length and weight. Therefore, they can be used for orientation in lag screw placement keeping in mind that the entry point differs in both sexes.
authors: BG Trauma Centre, Eberhard Karls University of Tuebingen, Schnarrenbergstraße 95, 72076 Tuebingen, Germany.
authors: Bjoern Gunnar
authors: BG
authors: Ochs
authors: BG Trauma Centre, Eberhard Karls University of Tuebingen, Schnarrenbergstraße 95, 72076 Tuebingen, Germany.
authors: Fabian Maria
authors: FM
authors: Stuby
authors: BG Trauma Centre, Eberhard Karls University of Tuebingen, Schnarrenbergstraße 95, 72076 Tuebingen, Germany.
authors: Atesch
authors: A
authors: Ateschrang
authors: BG Trauma Centre, Eberhard Karls University of Tuebingen, Schnarrenbergstraße 95, 72076 Tuebingen, Germany.
authors: Ulrich
authors: U
authors: Stoeckle
authors: BG Trauma Centre, Eberhard Karls University of Tuebingen, Schnarrenbergstraße 95, 72076 Tuebingen, Germany. Electronic address: cgonser@bgu-tuebingen.de.
authors: Christoph Emanuel
authors: CE
authors: Gonser
mesh_terms: D000077:Acetabulum / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D049628:Body Size; D001863:Bone Screws; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods; D006620:Hip Fractures / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D012737:Sex Factors; D025321:Surgery, Computer-Assisted / Q000295:instrumentation; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods
keywords: Acetabular fracture; Anterior column; Anterior pelvic plane; Intraoperative navigation; Lag screw; Midsagittal plane; Preformed bone stock