Correlation between glenoid inclination and critical shoulder angle: a radiographic and computed tomography study.
BACKGROUND
Increased critical shoulder angles consist of both the acromial cover and glenoid inclination and have been found in patients with rotator cuff pathology. The purpose of this study was to determine the correlation of the critical shoulder angle and glenoid inclination and to determine the difference in glenoid inclination between patients with osteoarthritis and massive rotator cuff tears.


METHODS
The critical shoulder angle and glenoid inclination were measured on anteroposterior radiographs, and glenoid inclination was also measured on a validated 3-dimensional computer software program of 50 shoulders undergoing primary total shoulder arthroplasty. Twenty-five shoulders had osteoarthritis and A1 glenoids, as defined by the Walch classification, and were undergoing anatomic shoulder arthroplasty. The other 25 shoulders had massive rotator cuff tears and E0 glenoids, as defined by the Favard classification. The 2 groups were compared.


RESULTS
Critical shoulder angle and glenoid inclination were significantly correlated (R(2) = 0.7426, P < .001). Shoulders with massive rotator cuff tears (E0) demonstrated increased glenoid inclination measurements than shoulders with osteoarthritis (A1). As measured by the 3-dimensional software, the massive rotator cuff group had a glenoid inclination of 13.6° ± 4.3° and the osteoarthritis group had a glenoid inclination of 4.7° ± 5.6°. When measured by anteroposterior radiographs, the average glenoid inclination was 13.6° ± 4.6° in the massive rotator cuff group and was 7.6° ± 5.01° in the osteoarthritic group .


CONCLUSIONS
Glenoid inclination is linearly correlated with the critical shoulder angle and is significantly increased in patients with massive rotator cuff tears.
Centre Orthopédique Santy, Hôpital Privé Jean Mermoz, Lyon, France. Electronic address: matthewdaggett@gmail.com.
Matthew
M
Daggett
Centre Orthopédique Santy, Hôpital Privé Jean Mermoz, Lyon, France.
Birgit
B
Werner
Centre Orthopédique Santy, Hôpital Privé Jean Mermoz, Lyon, France.
Philipp
P
Collin
Centre Orthopédique Santy, Hôpital Privé Jean Mermoz, Lyon, France.
Marc-Olivier
MO
Gauci
Centre Orthopédique Santy, Hôpital Privé Jean Mermoz, Lyon, France.
Jean
J
Chaoui
Centre Orthopédique Santy, Hôpital Privé Jean Mermoz, Lyon, France.
Gilles
G
Walch
D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000601:surgery; D017006:Rotator Cuff / Q000000981:diagnostic imaging* / Q000601:surgery; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods*
Critical shoulder angle; glenoid inclination; rotator cuff tears