title: Infraspinatus and supraspinatus tendon strain explained using multiple regression models.
abstract: Supraspinatus tendon tears are complex yet common. We have shown that the supraspinatus and infraspinatus tendons interact, indicated by parallel changes in strain in the supraspinatus and infraspinatus with increasing size of supraspinatus tear, load applied to the supraspinatus, and changes in glenohumeral rotation but not abduction angle, suggesting disruption in the interaction between the two tendons with increase in abduction angle. While considering these factors individually is valuable, the contribution of each factor in the context of all others on strain in the supraspinatus, or on the interaction between the two tendons is unknown and has important implications in the management of rotator cuff tears. In this study, regression models using least-square estimation with backward and forward elimination were used to predict strains in the infraspinatus and supraspinatus from joint position, supraspinatus load, and supraspinatus tear size or repair. Interestingly, despite previous findings showing that supraspinatus tear size significantly affects infraspinatus strain, tear size was not a significant predictor of infraspinatus strain, emphasizing the importance of other factors evaluated such as joint position and shoulder loading in management of cuff tears and postoperative care. A better understanding of the loading environment in rotator cuff tendons necessitates multifactorial complex models.
authors.affiliation: University of Pennsylvania, Philadelphia, USA.
authors.forename: Nelly
authors.initials: N
authors.lastname: Andarawis-Puri
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Kuntz
authors.forename: Abbas F
authors.initials: AF
authors.lastname: Jawad
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Soslowsky
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D006801:Humans; D016018:Least-Squares Analysis; D008875:Middle Aged; D008954:Models, Biological; D015999:Multivariate Analysis; D012044:Regression Analysis; D000070636:Rotator Cuff Injuries; D000070599:Shoulder Injuries; D013180:Sprains and Strains / Q000150:complications / Q000503:physiopathology*; D013708:Tendon Injuries / Q000209:etiology / Q000503:physiopathology*
references.citation: J Shoulder Elbow Surg. 2002 Nov-Dec;11(6):562-9
references.pmid: 12469080
references.citation: J Shoulder Elbow Surg. 2003 Mar-Apr;12(2):134-8
references.pmid: 12700564
references.citation: J Orthop Res. 2002 Jul;20(4):869-74
references.pmid: 12168680
references.citation: Clin Orthop Relat Res. 1990 May;(254):75-80
references.pmid: 2323150
references.citation: Clin Orthop Relat Res. 1994 Jul;(304):60-7
references.pmid: 8020235
references.citation: J Shoulder Elbow Surg. 2000 Mar-Apr;9(2):163-8
references.pmid: 10810700
references.citation: J Orthop Res. 2010 Jul;28(7):846-51
references.pmid: 20058264
references.citation: Orthop Clin North Am. 1997 Apr;28(2):145-55
references.pmid: 9113711
references.citation: J Shoulder Elbow Surg. 2010 Jun;19(4):617-23
references.pmid: 20080051
references.citation: Am J Sports Med. 2009 Sep;37(9):1831-9
references.pmid: 19483078