title: Anatomic Alignment and Integrity of the Sustentaculum Tali in Intra-Articular Calcaneal Fractures: Is the Sustentaculum Tali Truly Constant?
abstract: BACKGROUND
  In an intra-articular calcaneal fracture, the sustentaculum tali is generally thought to remain tightly bound to the talus by the interosseous talocalcaneal ligaments, spring ligament, and deltoid ligament, providing a "constant" fragment that remains anatomically aligned. The extensile lateral approach is commonly used for reduction based on this assumption, but because it provides only limited access to the medial aspect of the calcaneus, indirect fracture reduction is required to restore an anatomic relationship of these fragments to the sustentacular fragment. The purpose of this study was to determine the prevalence and displacement of sustentacular fractures in patients with an intra-articular calcaneal fracture, and thus determine whether the sustentacular fragment can be accurately considered as constant and can be consistently relied on to maintain anatomic alignment.
  
  
  METHODS
  All patients with an intra-articular calcaneal fracture who presented to two level-I trauma centers from 2006 to 2012 were included in the study if computed tomography scanning was performed. The presence or absence of a sustentacular fracture was documented, along with the displacement and the comminution of any such fracture and the subluxation or dislocation of the sustentaculum tali.
  
  
  RESULTS
  Sustentacular fractures were present in ninety-four (44.3%) of the 212 patients who met the inclusion criteria. Seventy-two (76.6%) of the sustentacular fractures were nondisplaced, eleven (11.7%) were displaced, and ten (10.6%) were comminuted. The articulation between the sustentaculum tali and the talus was anatomically aligned in 166 (78.3%) of the calcaneal fractures, subluxated in forty-three (20.3%), and dislocated in two (0.9%).
  
  
  CONCLUSIONS
  This study provides a detailed description of the frequency of sustentacular fractures, the displacement of such fractures, and articular subluxation or dislocation associated with intra-articular calcaneal fractures. Fixation by means of a lateral approach may be compromised when the sustentaculum tali is fractured or subluxated. A medial approach or combined medial and lateral approaches may be considered in such circumstances. Special attention should be paid to the integrity and alignment of the sustentacular fragment prior to surgical fixation.
  
  
  METHODS
  Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114. E-mail address for I.L. Gitajn: igitajn@partners.org.
authors.forename: Ida Leah
authors.initials: IL
authors.lastname: Gitajn
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114. E-mail address for I.L. Gitajn: igitajn@partners.org.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Abousayed
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114. E-mail address for I.L. Gitajn: igitajn@partners.org.
authors.forename: Rull James
authors.initials: RJ
authors.lastname: Toussaint
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114. E-mail address for I.L. Gitajn: igitajn@partners.org.
authors.forename: Beverlie
authors.initials: B
authors.lastname: Ting
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114. E-mail address for I.L. Gitajn: igitajn@partners.org.
authors.forename: Jenny
authors.initials: J
authors.lastname: Jin
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114. E-mail address for I.L. Gitajn: igitajn@partners.org.
authors.forename: John Y
authors.initials: JY
authors.lastname: Kwon
mesh_terms: D000328:Adult; D064386:Ankle Fractures / Q000145:classification* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002111:Calcaneus / Q000000981:diagnostic imaging / Q000293:injuries*; D005260:Female; D006801:Humans; D057072:Intra-Articular Fractures / Q000145:classification* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008023:Ligaments, Articular / Q000000981:diagnostic imaging / Q000293:injuries; D008297:Male; D012042:Registries; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014193:Trauma Centers