title: Supraspinatus tears: propagation and strain alteration.
abstract: It was hypothesized that there would be an alteration in strain when macroscopically normal supraspinatus tendons were subjected to three patterns of surgically created tear. The propagation of joint-side partial-thickness tears was also examined. Cadaveric shoulders were tested on a purpose-built rig with static loading from 20 to 200 N and during glenohumeral abduction from 0 degrees to 120 degrees with a 100-N tensile load. Differential variable reluctance transducers were used to calculate strain. Six-millimeter-wide midsubstance full-thickness tears (n = 2) caused an increase in bursal-side strain both with abduction 1.93% (90 degrees ) and with loading 0.33% (150 N). Intratendinous delamination (n = 2) increased joint-side strain during abduction and bursal-side strain with loading. A 2-mm-deep tear across the tendon insertion (n = 5) increased the bursal-side strain in abduction by 3.54% (120 degrees ) and with load by 2.53% (200 N). Tear propagation was observed from joint to bursal sides during abduction. Tendon failure occurred at the insertion.
authors.affiliation: Department of Mechanical Engineering, Imperial College London, England.
authors.forename: Peter
authors.initials: P
authors.lastname: Reilly
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Amis
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Wallace
authors.forename: Roger J H
authors.initials: RJ
authors.lastname: Emery
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017006:Rotator Cuff / Q000473:pathology; D000070636:Rotator Cuff Injuries; D012422:Rupture, Spontaneous / Q000473:pathology; D012785:Shoulder Joint / Q000473:pathology; D013314:Stress, Mechanical; D013708:Tendon Injuries / Q000473:pathology*