title: Three-dimensional humeral morphologic alterations and atrophy associated with obstetrical brachial plexus palsy.
abstract: BACKGROUND
  Obstetrical brachial plexus palsy (OBPP) is a common birth injury, resulting in severe functional losses. Yet, little is known about how OBPP affects the 3-dimensional (3D) humeral morphology. Thus, the purpose of this study was to measure the 3D humeral architecture in children with unilateral OBPP.
  
  
  METHODS
  Thirteen individuals (4 female and 9 male patients; mean age, 11.8 ± 3.3 years; mean Mallet score, 15.1 ± 3.0) participated in this institutional review board approved study. A 3D T1-weighted gradient-recalled echo magnetic resonance image set was acquired for both upper limbs (involved and noninvolved). Humeral size, version, and inclination were quantified from 3D humeral models derived from these images.
  
  
  RESULTS
  The involved humeral head was significantly less retroverted and in declination (medial humeral head pointed anteriorly and inferiorly) relative to the noninvolved side. Osseous atrophy was present in all 3 dimensions and affected the entire humerus. The inter-rater reliability was excellent (intraclass correlation coefficient, 0.96-1.00).
  
  
  CONCLUSIONS
  This study showed that both humeral atrophy and bone shape deformities associated with OBPP are not limited to the axial plane but are 3D phenomena. Incorporating information related to these multi-planar, 3D humeral deformities into surgical planning could potentially improve functional outcomes after surgery. The documented reduction in retroversion is an osseous adaptation, which may help maintain glenohumeral congruency by partially compensating for the internal rotation of the arm. The humeral head declination is a novel finding and may be an important factor to consider when one is developing OBPP management strategies because it has been shown to lead to significant supraspinatus inefficiencies and increased required elevation forces.
authors.affiliation: Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, USA. Electronic address: fsheehan@cc.nih.gov.
authors.forename: Frances T
authors.initials: FT
authors.lastname: Sheehan
authors.affiliation: Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, USA; Rehabilitation Medicine Department, University Hospital of Brest, Brest, France; LaTIM, INSERM U1101, Brest, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Brochard
authors.affiliation: Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, USA; Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Abrahm J
authors.initials: AJ
authors.lastname: Behnam
authors.affiliation: Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, USA; Mt Washington Pediatric Hospital, Baltimore, MD, USA.
authors.forename: Katharine E
authors.initials: KE
authors.lastname: Alter
mesh_terms: D000293:Adolescent; D001284:Atrophy; D001720:Birth Injuries / Q000150:complications*; D001847:Bone Diseases / Q000175:diagnosis* / Q000209:etiology; D020516:Brachial Plexus Neuropathies / Q000150:complications*; D002648:Child; D005260:Female; D006801:Humans; D058430:Humeral Head / Q000473:pathology; D006811:Humerus / Q000473:pathology*; D021621:Imaging, Three-Dimensional; D016916:Joint Deformities, Acquired / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D016059:Range of Motion, Articular; D015203:Reproducibility of Results
keywords: Reliability; inclination; magnetic resonance imaging; retroversion; shape; version