title: Optimal Elbow Angle for Sonographic Visualization of the Ulnar Collateral Ligament.
abstract: OBJECTIVE
  To formally examine the sonographic appearance of the elbow ulnar collateral ligament (UCL) at 30° versus 70° of elbow flexion in asymptomatic baseball pitchers.
  
  
  METHODS
  A prospective, cross-sectional design.
  
  
  METHODS
  Sports medicine clinic in a tertiary academic medical center.
  
  
  METHODS
  Thirty asymptomatic adolescent baseball pitchers 13-18 years of age (mean 15.8 years), with at least 3 years of continuous pitching experience and no significant history of elbow pain or injury.
  
  
  METHODS
  Static sonographic images of the bilateral UCLs were obtained at 30° and 70° of elbow flexion by a single experienced examiner. Images were anonymized and randomized into a slide set. Three clinicians with different levels of ultrasound experience reviewed the static 30° and 70° images for each elbow and chose their preferred image based on UCL conspicuity. The clinicians reviewed a re-randomized slide set 1 week later. A different study co-investigator measured UCL cross-sectional area (CSA) on all images using ultrasound machine electronic calipers.
  
  
  METHODS
  Preference for the sonographic conspicuity of the UCL at 30° versus 70° of elbow flexion, and UCL CSA at 30° versus 70° of flexion.
  
  
  RESULTS
  Each clinician demonstrated a significant preference for UCL images obtained at 70° of flexion when compared to those obtained at 30° (80.3% overall preference for 70°, P < .001). There was no statistically significant effect of clinician experience or arm dominance on image preference. The sonographically determined CSA of the UCLs were on average 1.4 mm(2) greater at 70° than at 30° of flexion (P < .001) when combining dominant and nondominant arms.
  
  
  CONCLUSIONS
  Static sonographic evaluation of the UCL at 70° of elbow flexion should be integrated into UCL imaging protocols. Furthermore, when performing sonographically guided procedures targeting the UCL, clinicians should consider positioning the elbow at >30° of flexion to optimize UCL conspicuity and CSA.
authors.affiliation: Department of Physical Medicine & Rehabilitation, Mayo Clinic College of Medicine, Rochester, MN.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Lueders
authors.affiliation: Swedish Spine, Sports, & Musculoskeletal Medicine, Swedish Medical Group, Seattle, WA.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Pourcho
authors.affiliation: Department of Physical Medicine & Rehabilitation, Mayo Clinic College of Medicine, Rochester, MN.
authors.forename: Jacob L
authors.initials: JL
authors.lastname: Sellon
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Rochester, MN.
authors.forename: Diane L
authors.initials: DL
authors.lastname: Dahm
authors.affiliation: Departments of Physical Medicine & Rehabilitation, Radiology and Anatomy, Mayo Clinic College of Medicine, W14 Mayo Building, 200 1st St, SW, Rochester, MN 55905.
authors.forename: Jay
authors.initials: J
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D001484:Baseball / Q000502:physiology*; D017885:Collateral Ligaments / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D004551:Elbow Joint / Q000000981:diagnostic imaging* / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D011446:Prospective Studies; D016059:Range of Motion, Articular; D014463:Ultrasonography