title: Early Cocking Phase Mechanics and Upper Extremity Surgery Risk in Starting Professional Baseball Pitchers.
abstract: BACKGROUND
  Early cocking phase pitching mechanics may affect risk of upper extremity injury requiring surgery in professional baseball players.
  
  
  OBJECTIVE
  To assess the occurrence of inverted-W arm positioning and early trunk rotation in Major League Baseball (MLB) pitchers and to determine whether this throwing position is associated with upper extremity injury requiring surgery.
  
  
  METHODS
  Cross-sectional study; Level of evidence, 3.
  
  
  METHODS
  For 250 MLB pitchers in the 2010 season, 15 to 20 pitches from the start and end of an outing were reviewed using slow-motion game video for presence of an inverted-W position and early trunk rotation. Previous or current incidence of upper extremity injury requiring surgery for each player was determined using the MLB injury database, minor league injury records, available collegiate data, and publicly available online injury databases. Upper extremity surgery associated with an injury was considered to result from pitching.
  
  
  RESULTS
  Consensus between investigators was achieved for 99% of players for inverted-W positioning (248 players) and in 97% of players for early trunk rotation (243 players) for videos reviewed independently. Rate of surgery with and without inverted-W position was 28 of 93 (30%) and 42 of 155 (27%), respectively. Rate of surgery with and without early trunk rotation was 37 of 111 (33%) and 30 of 132 (23%), respectively. Using a Cox proportional hazards model for risk analysis using the measured number of innings pitched at time of surgery as an approximate index of exposure and adjusting for age and fastball speed at time of surgery, early trunk rotation was associated with significantly increased risk of shoulder and/or elbow surgery with hazard ratio estimate of 1.69 (95% CI, 1.02-2.80). Presence of the inverted-W position was not associated with significantly increased risk (hazard ratio, 1.30; 95% CI, 0.79-2.14).
  
  
  CONCLUSIONS
  The inverted-W throwing position was not associated with significantly greater risk of upper extremity injury requiring surgery in MLB pitchers. Early trunk rotation was associated with significantly elevated risk of injury requiring surgery.
authors.affiliation: Department of Orthopaedic Surgery, MedStar Washington Hospital Center, Washington, DC, USA.
authors.forename: Wiemi A
authors.initials: WA
authors.lastname: Douoguih
authors.affiliation: MedStar Georgetown University Hospital, Washington, DC, USA.
authors.forename: Donald L
authors.initials: DL
authors.lastname: Dolce
authors.affiliation: MedStar Sports Medicine Research Center, MedStar Health Research Institute, Baltimore, Maryland, USA.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Lincoln
keywords: Major League Baseball; baseball; elbow; pitching; pitching mechanics; shoulder