Estimation of anterior glenoid bone loss area using the ratio of bone defect length to the distance from posterior glenoid rim to the centre of the glenoid.
OBJECTIVE
Estimation of anterior glenoid bone loss is important for surgical decision-making. The purpose of this study was to describe a method for estimating anterior glenoid bone loss.


METHODS
Thirty-nine cadaveric glenoids were digitized to obtain glenoid geometry. Glenoid bare spot centre, arthroscopic centre, and centre of the inferior glenoid circle relative to the geometric centre were measured. To simulate anterior glenoid bone loss, imaginary sequential osteotomies were created 0°, 22.5°, and 45° to the superior-inferior line in a 3D digitizing programme. Per cent of anterior glenoid bone loss area was calculated as the percentage of defect area relative to the entire area of the glenoid. The relationship between area loss and ratio of bone defect length to the distance from posterior glenoid to various centres was determined.


RESULTS
As the ratio of bone defect length to the distance from posterior glenoid to all three centres increased, the per cent area of bone loss increased exponentially. The ratio using the inferior circle centre and arthroscopic centre was highly correlated to the actual glenoid bone loss in all osteotomies (R2> 0.90). The ratio using the centre of bare area had the lowest correlation. The ratio of defect length to distance from posterior glenoid to arthroscopic centre greater than 2.4 for 0° and 2.0 for 45° osteotomies results in bone loss area greater than 25 %. The bare area centre had the largest variation. Average bone loss was overestimated when the centre of bare spot was used compared to other centre locations.


CONCLUSIONS
Per cent of anterior glenoid bone loss can be estimated using the ratio of bone defect length to the distance from posterior glenoid rim to the centre of inferior glenoid circle or arthroscopic centre either preoperatively using 3D CT or arthroscopically which can be useful for determining surgical treatment.
Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System (09/151), 5901 East 7th. Street , Long Beach, CA, 90822, USA.|Ewha Womans University, Seoul, Korea.
Sang-Jin
SJ
Shin
Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System (09/151), 5901 East 7th. Street , Long Beach, CA, 90822, USA.
Bong Jae
BJ
Jun
Ewha Womans University, Seoul, Korea.
Young Won
YW
Koh
Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System (09/151), 5901 East 7th. Street , Long Beach, CA, 90822, USA.
Michelle H
MH
McGarry
Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System (09/151), 5901 East 7th. Street , Long Beach, CA, 90822, USA. tqlee@med.va.gov.|Department of Orthopaedic Surgery, University of California, Irvine, CA, USA. tqlee@med.va.gov.|Department of Biomedical Engineering, University of California, Irvine, CA, USA. tqlee@med.va.gov.
Thay Q
TQ
Lee
D000368:Aged; D001851:Bone Diseases, Metabolic / Q000000981:diagnostic imaging / Q000473:pathology; D001862:Bone Resorption / Q000000981:diagnostic imaging / Q000473:pathology*; D002102:Cadaver; D006801:Humans; D008875:Middle Aged; D010027:Osteotomy; D012540:Scapula / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology*; D012785:Shoulder Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology*; D014057:Tomography, X-Ray Computed
Bony defect; Cadaver study; Glenoid bone loss; Instability
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