title: Patterns of shoulder imbalance in adolescent idiopathic scoliosis: a retrospective observational study.
abstract: METHODS
  Retrospective cohort study.
  
  
  OBJECTIVE
  To study the relationship between the proximal spine and shoulder levels in adolescent idiopathic scoliosis (AIS).
  
  
  BACKGROUND
  It has been frequently observed that the shoulder levels do not correspond to the spinal curve direction in AIS.
  
  
  METHODS
  Eighty-five operated cases of AIS were analyzed retrospectively of which 69 were Lenke type I and II curves. Preoperative anteroposterior standing x-rays of the spine and clinical photographs were studied. T1 tilt and intercoracoid line (ICL) tilt and their mutual relationship were documented. The curve type (Lenke), magnitude, and direction of the proximal and main thoracic (PT and MT) curves were also noted.
  
  
  RESULTS
  The shoulder level as depicted by the ICL showed 3 patterns-horizontal, left side elevated, or right side elevated. The T1-ICL relationship was either concordant or discordant. In the concordant case the T1 was tilted to the same side as the ICL; and vice versa in the discordant. The shoulder level was dependent on the MT curve if the ICL tilted to the same side as the MT curve and it was dependent on the PT curve if it tilted to the same side as the PT curve. This relationship appeared unrelated to curve type.
  
  
  CONCLUSIONS
  Preoperative shoulder levels in AIS may be concordant with the T1 or discordant-each can have left or right shoulder elevation or balanced shoulders. Further, the shoulder might be MT dependent or PT dependent. Theoretically therefore, surgical balancing of the shoulder and upper instrumented vertebra placement should not depend only on the magnitude and stiffness of the PT curve.
authors.affiliation: *Department of Orthopaedics, Khoula Hospital, Mina Al Fahal, Muscat, Sultanate of Oman †Department of Orthopaedics, Sparsh Hospital, Bangalore, India ‡Department of Neurosurgery, RIPAS Hospital, Brunei Darussalam §Spine Services, Amrita Institute of Medical Sciences, Cochin, Kerala, India.
authors.forename: K Venugopal
authors.initials: KV
authors.lastname: Menon
authors.forename: Naveen
authors.initials: N
authors.lastname: Tahasildar
authors.forename: Haroon M
authors.initials: HM
authors.lastname: Pillay
authors.forename: M
authors.initials: M
authors.lastname: Anbuselvam
authors.forename: Renjit K
authors.initials: RK
authors.lastname: Jayachandran
mesh_terms: D000293:Adolescent; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D011187:Posture; D011859:Radiography; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000601:surgery*; D012782:Shoulder / Q000000981:diagnostic imaging*; D013123:Spinal Fusion / Q000379:methods*; D013131:Spine / Q000000981:diagnostic imaging / Q000601:surgery; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome