title: Does patient sex affect the anatomic relationships between the sternoclavicular joint and posterior vascular structures?
abstract: BACKGROUND
  Despite increased concern for injury during surgical reconstruction of the sternoclavicular joint, to our knowledge there are few studies detailing the vascular relationships adjacent to the joint.
  
  
  OBJECTIVE
  We investigated sex differences in the following relationships for sternoclavicular joint reconstruction: (1) safe distance from the posterior surface of the medial clavicle's medial and lateral segments to the major vessels, (2) length of the first costal cartilage and safe distance from the first rib to the internal mammary artery, (3) minimum distance medial to the sternoclavicular joint for optimal hole placement, and (4) safe distance from the manubrium to the great vessels.
  
  
  METHODS
  Fifty normal postcontrast CT scans of the chest were reviewed. Means, standard deviations, and 95% CI were calculated for each aforementioned measurement. A t-test was used to determine if a sex difference exists (p≤0.05).
  
  
  RESULTS
  At the medial end of the clavicle, the safe distance from the medial segment (first 10 mm) to the major vessels was greater in males than in females (3.5 mm versus 2.4 mm, respectively; 95% CI, 3 mm-4 mm versus 1.7 mm-3 mm, respectively; p=0.014). For the lateral segment (next 10 mm), the distance also was safer in males than in females (3.3 mm versus 1.7 mm, respectively; 95% CI, 2.7 mm-4 mm versus 1.1 mm-2.3 mm, respectively; p<0.001). The mean length of the first costal cartilage also was greater in males (35.8 mm versus 30.1 mm, respectively; 95% CI, 33.8 mm-37.8 mm versus 28.5 mm-31.9 mm, respectively; p<0.001); the distance from the first costochondral joint to the internal mammary artery was safer in males than in females (19.1 mm versus 15.4 mm, respectively; 95% CI, 16.5 mm-21.8 mm versus 13 mm-17.9 mm, respectively; p=0.05). The minimum distance to avoid inadvertent penetration of the sternoclavicular joint was greater in males than in females (16 mm versus 12.3 mm, respectively; 95% CI, 14.6 mm-17.5 mm versus 11 mm-13.6 mm, respectively; p<0.001). The distance to vessels after penetration of the manubrium was not different between males and females (5.6 mm versus 3.9, respectively; 95% CI, 4.4 mm-6.8 mm versus 2.6 mm-5.2 mm, respectively; p=0.06).
  
  
  CONCLUSIONS
  This study makes apparent the intimate relationships between vessels and the musculoskeletal structures associated with sternoclavicular reconstruction. Based on our findings, we recommend considering the sex of the patient, using caution when drilling, and protecting essential structures posterior to the joint.
authors.affiliation: Department of Orthopaedic Surgery, San Francisco Orthopaedic Residency Program, St. Mary's Medical Center, San Francisco, CA, USA.
authors.forename: Jarrad A
authors.initials: JA
authors.lastname: Merriman
authors.forename: Diego
authors.initials: D
authors.lastname: Villacis
authors.forename: Brian
authors.initials: B
authors.lastname: Wu
authors.forename: Dakshesh
authors.initials: D
authors.lastname: Patel
authors.forename: Anthony
authors.initials: A
authors.lastname: Yi
authors.forename: George F Rick
authors.initials: GF
authors.lastname: Hatch
mesh_terms: D000328:Adult; D001808:Blood Vessels / Q000033:anatomy & histology*; D066186:Costal Cartilage / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008323:Mammary Arteries / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods; D013902:Radiography, Thoracic; D012016:Reference Values; D012189:Retrospective Studies; D012727:Sex Characteristics; D013247:Sternoclavicular Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
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