title: Morphometry of the sacrum and its implication on trans-sacral corridors using a computed tomography data-based three-dimensional statistical model.
abstract: Trans-sacral implants are increasingly used to treat fractures of the sacrum, especially for osteoporosis-associated fragility fractures. However, the complex and highly variable sacral anatomy limits their use. It is still not clear which morphologic characteristics are critical to determine the availability and dimensions of trans-sacral corridors.
  
  
  
  This study aims to assess sacral anatomy and its influence on trans-sacral corridors.
  
  
  
  This study used a computed tomography (CT)-based three-dimensional (3D) statistical size and shape model of the sacrum with multiple morphometric measurements.
  
  
  
  A 3D statistical model was computed using clinical CT data of 92 intact pelvises (mean age 61.5 years). Multiple measurements of the sacrum and the trans-sacral corridors were taken. Descriptive statistics and linear regression were calculated. Shape and size were analyzed using principal component analysis.
  
  
  
  The limiting craniocaudal diameter of the trans-sacral corridor was 13.1 mm (±5 mm) in S1 and 13.8 mm (±2.4 mm) in S2. In S1, the craniocaudal diameter correlated with larger sacral curvature (SC), pelvic incidence (PI), and cranially located auricular surfaces. The presence of an accessory articulation with L5 was associated with a larger trans-sacral corridor S1. In contrast, the craniocaudal diameter of the S2 corridor correlated with more caudally situated auricular surfaces and lower PI. The sacral shape, as demonstrated by the statistical model, was highly variable, which affected the size and availability of trans-sacral corridor S1. Important determinants of trans-sacral corridor S1 were the craniocaudal position of the auricular surfaces and the shape of the sacral ala, which were influenced by SC, sacral height, and PI.
  
  
  
  The human sacrum is highly variable in size and shape. The dimensions of trans-sacral corridors depend on the sacral shape and specific morphologic characteristics. Understanding of morphologic variants helps with preoperative assessments of the trans-sacral corridors. When planning to use trans-sacral implants, because of variable sacral anatomy and dimensions of the trans-sacral corridors, thorough preoperative planning is mandatory.
authors.affiliation: AO Research Institute Davos, Davos, Switzerland; Department of Orthopaedics and Traumatology, University Medical Center Mainz, Mainz, Germany. Electronic address: wagner.daniel@gmx.ch.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wagner
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Kamer
authors.affiliation: Department of Orthopedics and Joint Reconstructive Surgery, Toyama Municipal Hospital, Toyama, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sawaguchi
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Robert Geoff
authors.initials: RG
authors.lastname: Richards
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Hansrudi
authors.initials: H
authors.lastname: Noser
authors.affiliation: Department of Orthopaedics and Traumatology, University Medical Center Mainz, Mainz, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Hofmann
authors.affiliation: Department of Orthopaedics and Traumatology, University Medical Center Mainz, Mainz, Germany.
authors.forename: Pol M
authors.initials: PM
authors.lastname: Rommens
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010388:Pelvis / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012445:Sacrococcygeal Region / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012447:Sacrum / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: Anatomy; Fracture; Iliosacral screw; Sacrum; Statistical model; Trans-sacral