title: The Bare Area of the Proximal Ulna: An Anatomic Study With Relevance to Chevron Osteotomy.
abstract: OBJECTIVE
  A chevron osteotomy of the ulna is widely used to obtain intra-articular access to the elbow in the treatment of type C distal humerus fractures. The trochlear notch of the proximal ulna is divided into 2 articular parts by the "bare area." Ideally, the olecranon osteotomy should be centered on the bare area to minimize damage to the joint cartilage. The goals of this study were to describe the anatomy of the bare area and design an ideal chevron-shaped osteotomy.
  
  
  METHODS
  We dissected 38 cadaver elbows and measured the width of the bare area, the distance between the tip of the triceps insertion and the area on the olecranon cortex corresponding to the bare area. We then designed a chevron osteotomy to stay within the bare area and measured the distance from the tip of the triceps insertion to the osteotomy apex as well as the angle of the osteotomy plane and the angle of the chevron cuts.
  
  
  RESULTS
  The bare area existed in all 38 cadavers. The mean longitudinal and transverse widths were 4.0 mm (range, 1.0-8.6 mm) and 19.0 mm (range, 16.9-23.8 mm), respectively. The mean distance between the tip of the triceps insertion and the area on the olecranon cortex corresponding to the bare area was 19.0 mm (range, 16.0-23.0 mm). The mean transverse and longitudinal widths of the cortical notch were 3.0 mm (range, 1.6-4.5 mm) and 8.0 mm (range, 6.5-14.8 mm), respectively. The mean distance between the tip of the triceps insertion and the osteotomy apex was 22.0 mm (range, 18.0-24.0 mm) and the mean angle between the osteotomy surface and the vertical plane corresponding to the tangent plane was 20° (range, 10° to 25°). The mean angle of the V shape was 140° (range, 130° to 150°).
  
  
  CONCLUSIONS
  Using the narrowest edge lacking cartilage (lateral or medial side) as a point of reference to locate the bare area, the designed chevron osteotomy entered the joint in the bare area in most specimens and decreased associated damage to the joint cartilage.
  
  
  CONCLUSIONS
  This study describes the anatomy of the bare area and the design of the ideal chevron-shaped osteotomy to treat type C distal humerus fractures.
authors.affiliation: Department of Orthopaedics, Shanghai Pudong Hospital, Shanghai Fudan University Pudong Medical Center, Shanghai, China.
authors.forename: Rongguang
authors.initials: R
authors.lastname: Ao
authors.affiliation: Department of Orthopaedics, Shanghai Pudong Hospital, Shanghai Fudan University Pudong Medical Center, Shanghai, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedics, Shanghai Pudong Hospital, Shanghai Fudan University Pudong Medical Center, Shanghai, China.
authors.forename: Dejian
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Orthopaedics, Shanghai Pudong Hospital, Shanghai Fudan University Pudong Medical Center, Shanghai, China.
authors.forename: Fancheng
authors.initials: F
authors.lastname: Chen
authors.affiliation: Department of Orthopaedics, Shanghai Pudong Hospital, Shanghai Fudan University Pudong Medical Center, Shanghai, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Orthopaedics, Shanghai Pudong Hospital, Shanghai Fudan University Pudong Medical Center, Shanghai, China. Electronic address: doctorybq@163.com.
authors.forename: Baoqing
authors.initials: B
authors.lastname: Yu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D004551:Elbow Joint / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D006810:Humeral Fractures / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D014457:Ulna / Q000473:pathology* / Q000601:surgery*
keywords: Proximal ulna; chevron osteotomy; distal humerus fracture