title: The biomechanical effect of clavicular shortening on shoulder muscle function, a simulation study.
abstract: Malunion of the clavicle with shortening after mid shaft fractures can give rise to long-term residual complaints. The cause of these complaints is as yet unclear.
  
  
  
  In this study we analysed data of an earlier experimental cadaveric study on changes of shoulder biomechanics with progressive shortening of the clavicle. The data was used in a musculoskeletal computer model to examine the effect of clavicle shortening on muscle function, expressed as maximal muscle moments for abduction and internal rotation.
  
  
  
  Clavicle shortening results in changes of maximal muscle moments around the shoulder girdle. The mean values at 3.6cm of shortening of maximal muscle moment changes are 16% decreased around the sterno-clavicular joint decreased for both ab- and adduction, 37% increased around the acromion-clavicular joint for adduction and 32% decrease for internal rotation around the gleno-humeral joint in resting position.
  
  
  
  Shortening of the clavicle affects muscle function in the shoulder in a computer model. This may explain for the residual complaints after short malunion with shortening.
  
  
  
  Basic Science Study. Biomechanics. Cadaveric data and computer model.
authors.affiliation: Waterland Ziekenhuis Purmerend, Waterlandlaan 250, 1441 RN Purmerend, The Netherlands. Electronic address: hillen_rj@hotmail.com.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hillen
authors.affiliation: Neuroscience Research Australia Margarete Ainsworth Building, Barker St Randwick, NSW 2031, Australia.
authors.forename: Bart
authors.initials: B
authors.lastname: Bolsterlee
authors.affiliation: Faculty Mechanical, Maritime and Materials Engineering, Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands; Department of Human Movement Sciences, Research institute MOVE, Vrije Universiteit Amsterdam, The Netherlands.
authors.forename: Dirkjan H E J
authors.initials: DHEJ
authors.lastname: Veeger
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002968:Clavicle / Q000293:injuries / Q000503:physiopathology; D003198:Computer Simulation; D005260:Female; D050723:Fractures, Bone / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008954:Models, Biological; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D009142:Musculoskeletal Physiological Phenomena; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation; D012785:Shoulder Joint / Q000503:physiopathology*
keywords: Clavicle fracture; Malunion; Musculoskeletal model; Strength