Pinning technique for shoulder fractures in adolescents: computer modelling of percutaneous pinning of proximal humeral fractures.
BACKGROUND
In the technique of percutaneous pinning of proximal humerus fractures, the appropriate entry site and trajectory of pins is unknown, especially in the adolescent population. We sought to determine the ideal entry site and trajectory of pins.


METHODS
We used magnetic resonance images of nonfractured shoulders in conjunction with radiographs of shoulder fractures that were treated with closed reduction and pinning to construct 3-dimensional computer-generated models. We used engineering software to determine the ideal location of pins. We also conducted a literature review.


RESULTS
The nonfractured adolescent shoulder has an articular surface diameter of 41.3 mm, articular surface thickness of 17.4 mm and neck shaft angle of 36 degrees. Although adolescents and adults have relatively similar shoulder skeletal anatomy, they suffer different types of fractures. In our study, 14 of 16 adolescents suffered Salter-Harris type II fractures. The ideal location for the lateral 2 pins in an anatomically reduced shoulder fracture is 4.4 cm and 8.0 cm from the proximal part of the humeral head directed at 21.2 degrees in the coronal plane relative to the humeral shaft.


CONCLUSIONS
Operative management of proximal humerus fractures in adolescents requires knowledge distinct from that required for adult patients. This is the first study to examine the anatomy of the nonfractured proximal humerus in adolescents. This is also the first study to attempt to model the positioning of percutaneous proximal humerus pins.
Mehin
Ramin
R
Department of Orthopaedics, Abbotsford Regional Hospital and Cancer Centre, Abbotsford, BC. rmehin@hotmail.com
Mehin
Afshin
A
Wickham
David
D
Letts
Merv
M
D000293:Adolescent; D001858:Bone Nails; D003198:Computer Simulation; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008954:Models, Biological; D019637:Orthopedic Procedures / Q000379:methods*; D011859:Radiography; D012784:Shoulder Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D012785:Shoulder Joint / Q000033:anatomy & histology*