Relationship of individual scapular anatomy and degenerative rotator cuff tears.
BACKGROUND
The etiology of rotator cuff disease is age related, as documented by prevalence data. Despite conflicting results, growing evidence suggests that distinct scapular morphologies may accelerate the underlying degenerative process. The purpose of the present study was to evaluate the predictive power of 5 commonly used radiologic parameters of scapular morphology to discriminate between patients with intact rotator cuff tendons and those with torn rotator cuff tendons.


METHODS
A pre hoc power analysis was performed to determine the sample size. Two independent readers measured the acromion index, lateral acromion angle, and critical shoulder angle on standardized anteroposterior radiographs. In addition, the acromial morphology according to Bigliani and the acromial slope were determined on true outlet views. Measurements were performed in 51 consecutive patients with documented degenerative rotator cuff tears and in an age- and sex-matched control group of 51 patients with intact rotator cuff tendons. Receiver operating characteristic analyses were performed to determine cutoff values and to assess the sensitivity and specificity of each parameter.


RESULTS
Patients with degenerative rotator cuff tears demonstrated significantly higher acromion indices, smaller lateral acromion angles, and larger critical shoulder angles than patients with intact rotator cuffs. However, no difference was found between the acromial morphology according to Bigliani and the acromial slope. With an area under the receiver operating characteristic curve of 0.855 and an odds ratio of 10.8, the critical shoulder angle represented the strongest predictor for the presence of a rotator cuff tear.


CONCLUSIONS
The acromion index, lateral acromion angle, and critical shoulder angle accurately predict the presence of degenerative rotator cuff tears.
Department of Orthopaedics, Balgrist University Hospital, Zürich, Switzerland; Department of Orthopaedic Surgery and Traumatology, Inselspital, Bern University Hospital, Bern, Switzerland. Electronic address: bmoor@gmx.ch.
Beat K
BK
Moor
Department of Orthopaedics, Balgrist University Hospital, Zürich, Switzerland.
Karl
K
Wieser
Division of Trauma Surgery, University Hospital of Zurich, Zürich, Switzerland.
Ksenija
K
Slankamenac
Department of Orthopaedics, Balgrist University Hospital, Zürich, Switzerland.
Christian
C
Gerber
Division of Trauma Surgery, University Hospital of Zurich, Zürich, Switzerland.
Samy
S
Bouaicha
D000328:Adult; D000368:Aged; D001182:Arthroscopy; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011859:Radiography; D015203:Reproducibility of Results; D017006:Rotator Cuff / Q000000981:diagnostic imaging* / Q000601:surgery; D000070636:Rotator Cuff Injuries; D012540:Scapula / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000601:surgery; D013708:Tendon Injuries / Q000000981:diagnostic imaging / Q000601:surgery*
Rotator cuff disease; acromial morphology; acromial slope; acromion index; critical shoulder angle; lateral acromion angle; scapular anatomy