Articular surface area of the coronoid process and radial head in elbow extension: surface ratio in cadavers and a computed tomography study in vivo.
OBJECTIVE
To quantify the articular surface area ratio of the radial head to the coronoid process to gain a better understanding of the stress distribution across these articulations and possibly to explain the patterns of osteoarthritis that are commonly seen in the elbow.


METHODS
Thirty cadaveric elbows were harvested and dissected to allow measurement of the radial head and coronoid process articular surfaces. The articular surface areas were measured using the Image J program (National Institutes of Health, Chicago, IL). Twelve men were recruited for this study, and all received a computed tomography (CT) scan of the elbow. A 3-dimensional image of the proximal radioulnar articular surface was created using volume rendering. All specimens were measured 3 times by 2 observers.


RESULTS
In the cadaveric measurements, the mean area of the radial head articular fossa was 247.3 +/- 52.6 mm(2) (mean +/- SD). The mean area of the medial facet of the coronoid process was 232.29 +/- 36.5 mm(2), and the mean area of the lateral facet was 141.9 +/- 33.3 mm(2). The articular surface area ratio of radial head to coronoid process was 1:1.5. In the CT measurement, the mean area of the radial head articular fossa was 258.9 +/- 26.3 mm(2). The mean area of the coronoid process articular surface was 376.9 +/- 37.0 mm(2). The articular surface area ratio of radial head to coronoid process was 1:1.46.


CONCLUSIONS
The ratio of articular surface area of radial head to coronoid process is 1:1.51 in cadavers and 1:1.46 using a CT in vivo, which is the reverse of the reported force transmission ratio across the elbow joint.
Shin
Seong-Ho
SH
Department of Orthopaedic Surgery, College of Medicine, Kyungpook National University Hospital, Daegu 700-721, Korea.
Jeon
In-Ho
IH
Kim
Hyo-Jin
HJ
McCullough
Matthew
M
Yi
Jae-Hyuck
JH
Cho
Hwan-Seong
HS
Park
Il-Hyung
IH
D000328:Adult; D002102:Cadaver; D004551:Elbow Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D004838:Epiphyses; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000503:physiopathology; D011884:Radius / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D016059:Range of Motion, Articular / Q000502:physiology; D012494:Sampling Studies; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed / Q000379:methods; D014457:Ulna / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D055815:Young Adult