title: Joint capsule attachment to the coronoid process of the ulna: an anatomic study with implications regarding the type 1 fractures of the coronoid process of the O'Driscoll classification.
abstract: BACKGROUND
  The attachment of the anterior joint capsule on the ulnar coronoid process is not yet completely understood. The purpose of this study was to clarify the anatomic relationship between the anterior capsule of the elbow joint and the tip of the coronoid process.
  
  
  METHODS
  Seventeen embalmed elbows were used for this anatomic study. The anterior capsule of the elbow joint was reflected, and the attachment of the capsule on the coronoid process was exposed. The attachment of the joint capsule on the coronoid process was macroscopically and histologically observed, its relationship to the coronoid tip was assessed, and the length of the attachment of the joint capsule was measured.
  
  
  RESULTS
  The length of the capsule attachment at the radial side of the coronoid (11.9 mm) was greater than that at the ulnar side (6.1 mm). The bone thickness on the coronoid tip from the proximal edge of the joint capsule attachment was 1.9 mm; together, the cartilage and bone thickness was 4.7 mm. At the radial side of the coronoid, the thickness of the joint capsule at the proximal aspect of the attachment of 2 samples was 0.6 mm and 0.3 mm, and that at the tip of the coronoid was 2.6 mm and 1.7 mm, respectively.
  
  
  CONCLUSIONS
  The anterior capsule of the elbow joint had a substantial attachment on the radial side of the coronoid process. The subtype 2 tip fractures of the O'Driscoll classification included the joint capsule attachment, joint cartilage, and subchondral bone.
authors.affiliation: Department of Orthopaedic and Spinal Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Shimura
authors.affiliation: Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. Electronic address: nimura.orj@tmd.ac.jp.
authors.forename: Akimoto
authors.initials: A
authors.lastname: Nimura
authors.affiliation: Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Hisayo
authors.initials: H
authors.lastname: Nasu
authors.affiliation: Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Fujishiro
authors.affiliation: Department of Orthopaedic Surgery, Okayama Saiseikai General Hospital, Okayama, Japan.
authors.forename: Junya
authors.initials: J
authors.lastname: Imatani
authors.affiliation: Department of Orthopaedic and Spinal Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Okawa
authors.affiliation: Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Akita
mesh_terms: D000368:Aged; D002102:Cadaver; D002358:Cartilage, Articular / Q000033:anatomy & histology; D004551:Elbow Joint / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D017746:Joint Capsule / Q000033:anatomy & histology*; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D014457:Ulna / Q000033:anatomy & histology*; D014458:Ulna Fractures / Q000145:classification
keywords: Anatomy; O'Driscoll classification; brachialis muscle; coronoid process; elbow; joint capsule; joint cartilage; subchondral bone